Mid-Infrared Nonlinear Optical Materials Based on Metal

Review pubs.acs.org/crystal

Mid-Infrared Nonlinear Optical Materials Based on Metal Chalcogenides: Structure−Property Relationship Fei Liang,†,‡ Lei Kang,†,‡ Zheshuai Lin,*,†,‡ and Yicheng Wu† †

Crystal Growth & Design 2017.17:2254-2289. Downloaded from pubs.acs.org by UNIV OF MELBOURNE on 04/23/19. For personal use only.

Center for Crystal R&D, Key Lab Functional Crystals and Laser Technology of Chinese Academy of Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China ‡ University of Chinese Academy of Sciences, Beijing 100190, PR China ABSTRACT: Mid-infrared (IR) nonlinear optical (NLO) materials with high performance are vital to expanding the laser wavelengths into the midIR region and have important technological applications in many civil and military fields. For the last two decades metal chalcogenides have attracted great attention since many of them possess a large NLO effect, wide transparent range, moderate birefringence, and high resistance to laser damage. However, the discovery of superior mid-IR NLO metal chalcogenides is still a big challenge mainly due to the difficulty of achieving a good balance between the NLO effect and laser damage threshold (LDT). In this review, metal chalcogenides are catalogued according to the different types of microscopic building blocks. These groups include triangle planar units, tetrahedral metal-centered units, polyhedra with second-order John-Teller cations, and polyhedra with stereochemically active lone electron pairs cations, rare-earth cations, and/ or halogen anions. The determinations of these microscopic structures on mid-IR NLO properties in metal chalcogenides are summarized and analyzed combined with available experimental data and first-principle calculations. From the deduced structure−property relationship, the searching directions for new metal chalcogenides that have good mid-IR NLO performances, especially for achieving the balance between large NLO effect and high LDT, are discussed.

1. INTRODUCTION Nonlinear optical (NLO) materials are of great importance for converting laser wavelengths to spectral regions where the normal lasers operate poorly.1 In the past three decades, many useful NLO crystals in near-infrared (IR), visible, and ultraviolet regions (wavelength from 0.2 to 2 μm) have been developed, such as β-BaB2O4 (β-BBO),2 LiB3O5 (LBO),3 LiNbO3 (LN),4 KH2PO4 (KDP),5 and KTiOPO4 (KTP).6 These crystals are widely used in scientific and technological fields, including visible laser generation,7 artificial nuclear fusion,8 precision scientific instruments,9 and so on. However, NLO materials which can efficiently generate high-power midIR lasers in the spectral range of 2−25 μm are very scarce. In fact, the mid-IR lasers have significant applications in many military and civil activities, such as remote sensing,10 biological tissue visualization,11 environmental monitorin,g12 and antiterror security.13 So far, commercially available mid-IR NLO crystals are AgGaS2 (AGS), AgGaSe2 (AGSe), and ZnGeP2 (ZGP).14 They possess high second harmonic generation (SHG) coefficients of about 13 pm/V, 33 pm/V, and 75 pm/V, respectively.14 Despite the large NLO coefficient and good grow habit, these materials have drawbacks which hinder their application in midIR lasers generation. For example, the laser damage threshold (LDT) value of AGS and AGSe is too small (only about 25 MW/cm2 and 11 MW/cm2, (@1.06 μm, 35 ns),15 respectively) © 2017 American Chemical Society

to bear a high power pumping source. Meanwhile, the strong two-photon adsorption (TPA) in ZGP resulting from its narrow bandgap (2.0 eV) make it impossible to use an Nd:YAG 1064 nm laser as the pumping source.16 Thus, the currently rapid developments of mid-IR lasers urgently demand the discovery of new mid-IR NLO materials with good performance. In general, practically usable mid-IR NLO materials should satisfy the following conditions:17 (i) Broad mid-IR transparent region, which is able to run across two important atmospheric transparent windows of 3−5 μm and 8−12 μm; (ii) large SHG coefficient dij, which should be at least larger than 10 × KDP (d36 ≈ 0.39 pm/V), and at best larger than 1× AGS (d36 ≈ 13 pm/V); (iii) high LDT, which depends on the bandgap (Eg) of materials intrinsically. For a good mid-IR NLO material, the bandgap Eg should be more than 3.0 eV; (iv) moderate birefringence Δn (∼0.03−0.10), in order to achieve the phasematching condition in a frequency conversion process such as optical parametric oscillation (OPO) and optical parametric amplification (OPA). (v) Good crystal growth habit and chemical stability, which are definitely beneficial to the practical applications of mid-IR NLO crystal. It should be emphasized that the balance between SHG coefficients and bandgap is the Received: February 12, 2017 Published: March 15, 2017 2254

DOI: 10.1021/acs.cgd.7b00214 Cryst. Growth Des. 2017, 17, 2254−2289

Crystal Growth & Design

Review

ACd4Ga5S12 (A = K, Rb, Cs),65 Ba3AGa5Se10Cl2 (A = K, Rb, Cs),66 [A3X][Ga3PS8] (A = K, Rb; X = Cl, Br),67 and so on. Among these materials, KPSe6, γ-NaAsSe2, and Na2Ge2Se5 exhibit the highest SHG coefficient ever reported in inorganic materials with calculated dij = 75, 162, and 145 pm/V, respectively.68 Unfortunately, these three materials have a small bandgap below 2.5 eV, which would cause a low LDT in laser frequency conversion. In addition, ACd 4 Ga 5 S 12 65 and Ba3AGa5Se10Cl266 (A = K, Rb, Cs) showed a high SHG efficiency, 22 and 10 times larger than that of AGS, respectively. However, their birefringence is too small to achieve a phasematch under 2.05 μm fundamental laser. So they are not suitable for mid-IR laser generation by an angle-phase-match technique. Some of other chalcogenides including Ba23Ga8Sb2S3851 and A3Ta2AsS11 (A = K, Rb) are also plagued by the same disadvantages.55 Therefore, it is still a challenge to find a superior NLO material that satisfies a good balance between a high LDT and large NLO effect, as well as moderate birefringence, chemical stability, and ease in the growth of large high-quality single crystals. In spite of the situations listed above, through comprehensive surveys we find that metal chalcogenides are still the most suitable system for mid-IR NLO crystal because they have the capability to achieve a balance between LDT (intrinsically relies on bandgap) and SHG response that is as good as possible. For example, BaGa4S7 has a large bandgap 3.65 eV as well as high SHG coefficients (d33 = 12.6 pm/V).37 The bandgap of BaGa2GeS6 exceeds 3.0 eV and its NLO response is 2.1 times of AGS under 2.05 μm irradiation.44 Moreover, in metal chalcogenides the connected patterns of anionic groups display a great structural diversity. The zero-dimensional (0-D) discrete clusters, one-dimensional (1-D) chains, two-dimensional (2-D) layers, and three-dimensional (3-D) frameworks can be constructed. Thus, this family actually provides a huge reservoir for good mid-IR NLO material searching. In 2014, Chung and Kanatzidis wrote an excellent review from the viewpoint of different structure dimensions and covered many metal chalcogenide compounds which are SHG active.68 It has been highlighted that metal chalcogenides show rich structural and compositional diversity, excellent IR transparency, and good NLO performances. In addition, they discussed a new concept to fabricate fibers, thin films, and bulk glasses based on different dimensional structures. It is well-known that non-centrosymmetric (NCS) structure is the prerequisite for a SHG material. In this review, different from Chung and Kanatzidis’ viewpoint, we will focus on more microscopic NCS building units in the metal chalcogenides discovered in this decade and investigate the A-B-C-Q(-X) system (A = Ag+, Cu+, alkaline metal, alkaline earth metal and rare earth cations; B = As3+, Bi3+, Sb3+, Pb2+, Sn2+,, Te4+, Te2+, Ti4+, Zn2+,Cd2+, Hg2+ etc.; C = Al3+, Ga3+, In3+, Ge4+, Si4+, Sn4+, P5+ etc.; Q = S2−, Se2−, Te2−; and X = F−, Cl−, Br−, I−). In detail, the microscopic NCS groups include (i) triangle-planar anionic groups (such as [BS3]3−, [B3S6]3−, [HgSe3]4−); (ii) distorted polyhedra centered by stereochemically active lone pairs (SALP) cation, including As3+, Sb3+, Bi3+, Sn2+, Pb2+, Te4+/Te2+, and so on; (iii) distorted polyhedra centered by second-order Jahn−Teller (SOJT) effect d0 or d10 cation; (iv) rare-earth cations centered polyhedra, mainly including La3+, Ce3+, Pr3+, Nd3+, etc; (v) main group elements centered [MQ4] (M = XII, XIII, XIV, XV) tetrahedra in crystal structures. We will analyze the structure−property relationship in these metal chalcogenides from the available experimental and first-

key factor to achieve the good optical performance in a mid-IR NLO crystal, since an increase of Eg would result in the decrease of dij.18 In fact, it is difficult to find a material that can satisfy the above conditions simultaneously. Generally, NLO oxide materials are unsuitable for broad IR applications because of their relatively short IR absorption wavelength. For example, KTP, LN, LiIO3, and BaTeMo2O9 crystals are transparent to 4.5 μm, 5.2 μm, 6.0 μm, and 5.4 μm,15,19 respectively. They can only cover the first atmospheric transparent window (3−5 μm) and exhibit strong lattice vibration adsorption due to the photon−phonon interaction. Organic NLO crystals have a giant NLO coefficient,20 but its stability is relatively poor. Many organic NLO crystals denature or even decompose under a temperature of 300−400 K.20−22 In addition, this type of NLO crystal is usually deliquescent and soluble in water, and the examples include famous DAST and DSTMS.23,24 Halides are a type of promising source for good IR NLO materials since they often have large bandgaps (high LDT) and excellent IR transparency. For instance, the NaSb3F10 crystal has a large bandgap 5.0 eV, and its laser damage threshold is as high as about 1.3 GW/cm2.25 It also shows excellent transparency in the range of 0.25−7.8 μm with relativity high thermal stability. In addition, the LDT of CsGeCl3,26 HgBr2,27 and Rb2CdBr2I228 can reach 200 MW/cm2, 300 MW/cm2, and 190 MW/cm2, respectively, which is much larger than that of AGS (25 MW/cm2) and AGSe (11 MW/cm2). Meanwhile, these three materials are transparent up to 30 μm, 20 μm, and 14 μm,27−29 covering the two atmospheric transparent windows. However, the SHG coefficients of halides are generally much smaller compared with AGS. As reported in the literature, NaSb3F10,25 HgBr2,27 and Rb2CdBr2I228 exhibit a phase-matchable SHG efficiency of only about 3.2, 10.0, and 4.0 times that of KDP, respectively. The mechanism analysis has revealed that the large bandgaps of halides mainly result from the strong ionic characteristic of the halogen atom, which are usually unfavorable to the acquiring of a large SHG coefficient dij.30 In spite of this, it still would be a good strategy to introduce the halogen atoms into oxides or chalcogenides, thus improving the LDT of compounds while maintaining a large enough SHG coefficient, as in RbIO2F31 and NaBa4Ge3S10Cl.32 Phosphides are also a promising IR NLO material system due to their large SHG coefficient and moderate birefringence. For example, the ZnGeP233 crystal has a large SHG coefficient d33 (75 pm/V) and wide transparent region from 0.74 to 12 μm. Moreover, as the Zn and Ge atoms in ZnGeP2 are replaced by Cd and Si atoms, one may obtain another good IR NLO crystal, CdSiP2.34 This compound has a slightly larger SHG coefficient (d33 = 84.5 pm/V) than ZnGeP2 and avoids the TPA drawback at 1064 nm due to its relatively large bandgap of 2.45 eV. Unfortunately, the CdSiP2 crystal is only transparent up to 9 μm due to the vibration absorption of the Si−P bond, so it can not entirely cover the second atmospheric transparent window (8−12 μm).35 In addition, it is difficult to grow a large size CdSiP2 crystal because the quartz tube can easily explode during the crystal growth process.36 Recently, some research groups have discovered plenty of metal chalcogenides which exhibit a good IR NLO response, including BaGa4S7,37 BaGa4Se7,38 Li2Ga2GeS6,39,40 LiGaGe2Se6,41,42 BaGa2GeS6,43,44 BaGa2GeSe6,43,44 KPSe6,45−49 K 2 P 2 Se 6 , 50 Ba 23 Ga 8 Sb 2 S 38 , 51 γ-NaAsSe 2 , 52 Na 2 Ge 2 Se 5 , 53 LiAsS 2 , 54 K 3 Ta 2 AsS 11 , 55 K 4 GeP 4 Se 12 , 56,57 La 4 InSbS 9 , 58 Ba2BiInS5,59 K2Hg3Ge2S8,60 Li2CdGeS4,61−63 Na2ZnGe2S6,64 2255



Review

principles data. For some metal chalcogenides whose linear and nonlinear optical properties have not been deeply investigated, the first-principles predictions are performed by our developed computational methods69 based on the density functional theory (DFT) package CASTEP.70 Our previous work has demonstrated that these computational methods have the capability to obtain the accurate results in metal chalcogenides.17 In addition, some hypothetical materials are predicted through composition substitution or structural transformation. The stability of hypothetical materials are examined by phonon spectrum analysis.71 We believe this review, combined with Chung and Kanatzidis’, will give more comprehensive insight on this type of important optoelectronic functional material.

2. METAL CHALCOGENIDES CONTAINING VARIOUS NCS SHG ACTIVE UNITS 2.1. Metal Chalcogenides Containing Triangle-Planar Anionic Units. 2.1.1. Metal Chalcogenides Containing Triangle Planar π-Conjugated Units. As is well-known, in the UV and DUV spectral regions the mostly used NLO materials are borates in which the SHG active units are planar sp2 hybridized [BO3]3− triangles or [B3O6]3− groups.72−74 The planar boron−oxygen groups can generate the relatively strong second-order susceptibility owing to its distinctive π-conjugated electron orbitals. Meanwhile, the [BO3]3− group can have large energy bandgaps (or high LDT values) as the electronic orbitals on termined oxygen atoms are saturated.75 Analogously, [BS3]3− and [B3S6]3− planar trigonal building units are the common structural motifs having large microscopic SHG responses, since the π-conjugated electrons delocalized on the plane are very susceptible to the applied optoelectric field. So thioborates are thought to be a possible family that combines the favorable transparency and nonlinearity of sulfides with the high damage thresholds of borates. In addition, planar units are favorable to obtain large birefringence. Up to now, there are three typical types of NCS thioborates ever known, i.e., LiBaB3S6, BaB2S4, and Ba3(BS3)(SbS3). LiBaB3S6. LiBaB3S6 crystallizes in the NCS monoclinic Cc space group.76 It contains [B3S6]3− anions formed by sixmembered [B3S3] rings with three exocyclic sulfur atoms (Figure 1a). The metal cations are situated between the anion units leading to 9-fold sulfur coordination of the Ba2+ and 4fold coordination of the Li+. Our calculations demonstrate that LiBaB3S6 is a possible mid-IR NLO material owing to its large bandgap (3.92 eV), thus indicating a high LDT value. The birefringence is 0.343 at 1064 nm, which is favorable for achieving phase-match condition. However, the SHG coefficients are rather small owing to an approximately centrosymmetric arrangement of [B3S6]3− units. BaB2S4. BaB2S4 crystallizes in monoclinic space group Cc and contains [BS3]3− and [BS4]5− units in the ratio 1:1 forming infinite chains along the [001] direction.77 Ba2+ cations are located between chains leading to 10-fold sulfur coordination (Figure 1b). Our calculations show that BaB2S4 has a large bandgap more than 3.5 eV and maximum SHG coefficients d12 close to 0.6 × AGS, which satisfies a good balance between the bandgap and SHG effect. Further analysis reveals that although [BS3]3− and [BS4]5− units are both contributing to the SHG effect of BaB2S4, the former groups make the dominant contributions. Ba3(BS3)(SbS3). Ba3(BS3)(SbS3) compound features a 0D structure constructed by isolated [BS3]3− trigonal planes and discrete [SbS3]3− pyramids (Figure 1c).78 Every two isolated

Figure 1. Crystal structure of (a) LiBaB3S6, (b) BaB2S4, and (c) Ba3(BS3)(SbS3).

[SbS3]3− pyramids along the c axis are antialigned, so they have less contribution to the SHG effect. The Ba2+ cations exhibit typical 8- or 9-fold coordination. Ba3(BS3)(SbS3) has a moderate direct bandgap of 2.62 eV and is almost transparent in the range of 2.5−11 μm.78 A strong absorption band in the IR spectra and weak absorption bands in the Raman spectra from 800 to 900 cm−1 (around 11.8−12.5 μm) are assigned to the stretching vibrational modes of the [BS3] group. The calculated static birefringence of Ba3(BS3)(SbS3) is 0.05, which is close to that of AGS (0.039), indicating that it can achieve phase-matchable.78 Ba3(BS3)(SbS3) exhibits a strong SHG efficiency about three times as large as that of AGS under the same condition. It seems that the π-conjugated [BS3]3− group is suitable to be a good fundamental building block for mid-IR NLO materials. However, in contrast to stable [BO3]3− groups, the [BS3]3− groups are very sensitive to air and humidity and not stable even under an ambient environment.79 This actually suggests that thioborates might be practically applied as good mid-IR NLO materials if the problem of chemical stability could be overcome. 2.1.2. Metal Chalcogenides Containing d 10 Cation Centered [MQ3] Units. In addition to the sp2 hybridized [BS3]3−, d10 cations centered trigonal planar units are sometimes seen in metal complexes, such as [AgS3]7− in La 3 AgSnS 7 , 80 [CuS 3 ] 7− in La 3 CuGeS 7 , 81 [ZnSe 3 ] 4− in Hg3ZnSe3Br2,82 and [HgSe3]4− in BaHgSe2.83 Here, we take BaHgSe2 as a representative example to show the structure and NLO properties in this type of metal chalcogenide. BaHgSe2. BaHgSe2 belongs to the orthorhombic NCS space group Pmc2 1.83 It contains corner-sharing [Hg(1)Se 3]4− trigonal planar structural units (Figure 2a) and isolated [Hg(2)Se2]2− linear structural units (Figure 2b). The [Hg(1)Se3]4− triangles are aligned parallel to each other within an individual chain along the a-axis, but neighboring chains are tilted with respect to each other (Figure 2c), which may not be 2256



Review

coordination environments (so forming SALP cations) and summarize their experimental linear and nonlinear properties. LiAsS2 type. LiAsS2 crystallizes in the polar space group Cc.54 It features a 1D infinite [AsS2]− chains along the c axis, which are made of condensed trigonal pyramidal units [AsS3]3−. Every corner-sharing [AsS3]3− trigonal pyramid has two different sulfur atoms: a bridging atom S(2) and a terminal atom S(1) (Figure 3); thus the SALP 4s2 electrons on As atoms will be

Figure 2. Coordination environment of (a) triangle planar [Hg(1)Se3]4−, (b) linear [Hg(2)Se2]2−, and (c) crystal structure of BaHgSe2. Reprinted with permission from ref 83, Copyright 2016 American Chemical Society.

ideal for NLO performance. However, the compound still exhibits a large SHG response, which is about 1.5 times that of AGS with a similar particle size under 2.09 μm fundamental light.83 Our first-principles calculations reveal that the largest SHG coefficient d33 is 39.87 pm/V, and the contribution is mainly from [Hg(1)Se3]4− triangles (79%). More importantly, BaHgSe2 melts congruently at a rather low temperature of 638 °C, which is valuable for the growth of bulk single crystals by the Bridgman-Stockbarger technique.83 So, the study of BaHgSe2 demonstrates that [HgSe3]4− triangles can serve as a new kind of basic functional unit in mid-IR NLO materials. The incorporation of triangle planar units may lead to the discovery of a new class of practically applicable mid-IR NLO materials. Table 1 lists the experimental and calculated linear and nonlinear optical properties in the metal chalcogenides compounds containing the planar [MQ3] units. Clearly, these compounds possess a large birefringence (>0.05) owing to strong anisotropy of planar units. A large net polarization would be obtained when the microscopic susceptibility does not cancel out. In particular, d10 cations centered planar units may be a potential direction for exploration of new mid-IR NLO materials. 2.2. Metal Chalcogenides Containing SALP Cations Centered Units. Generally, in As3+, Sb3+, Bi3+, Sn2+, Pb2+, and Te4+/Te2+ the s2 electrons on the outermost electronic shell are not shared with another ions and form lone-pair electrons. Under external optoelectric field interactions, they could exhibit a very large second-order optical response. Therefore, the compounds containing the cations with lone-pair electrons provide good platforms for searching new IR materials with a giant SHG effect. Up to now, many compounds in this type of mid-IR NLO metal chalcogenide have been discovered. In this section, we choose some representative metal chalcogenides in which the cations with lone pairs electrons locate in low-

Figure 3. Crystal structure of (a) NCS LiAsS2 (b) CS NaAsS2, (c) a signal 1D infinite [AsS2]− chains. White balls: Li/Na; red balls: As; yellow balls: S. Adapted and reprinted with permission from ref 54, Copyright 2008 John Wiley & Sons Inc.

superposed along the c axis. The NCS structure of Li1−xNaxAsS2 is stable up to 40% Na+ doping. A further increase in the Na fraction leads to a structural transition from NCS Cc to CS Pbca space group. The SHG intensity of LiAsS2 and Li0.6Na0.4AsS2 is 10 and 30 times that of AGSe at 790 nm, respectively.54 Unluckily, the bandgap of LiAsS2 is only 1.60 eV, comparable to AGSe (1.80 eV), which is too small to bear a high-power pumping laser source. Furthermore, powder SHG measurement sindicated that it is not type-I phase-matchable in the examined spectral region,54 resulting in the difficulty of achieving a noticeable SHG output. β-LiAsSe2 and γ-NaAsSe2 type. AAsSe2 (A = Li, Na) have been identified as a new class of polar direct-band gap semiconductors.52 They consist of infinite single chains of [AsSe2]− derived from corner-sharing pyramidal [AsSe3]3− units with SALP electrons on As atoms. β-LiAsSe2 crystallizes in the NCS space group Cc and is isostructural with LiAsS2 (Figure 4a). The [AsSe3]3− pyramid

Table 1. Experimental and Calculated Eg, dij, and Δn in the Metal Chalcogenides Compounds Containing [MQ3] Planar Units compounds LiBaB3S6 BaB2S4

76

77

Ba3(BS3)(SbS3)78 Zn0.2Ba2B2S5.284 BaHgSe283 a

space group

Eg (eV)

SHG efficiency

3.92

a

no data

Cc

3.61

a

no data

P−62m I−42m Pmc21

2.62 3.54 1.56

Cc

3.0 × AGS (@2050 nm, 30−46 μm) 50 × SiO2 (@1064 nm, 45−63 μm) 1.5 × AGS (@2090 nm, 105−150 μm)

calculated dij (pm/V)

Δn (cal)

d11 = −3.18; d12 = 3.46; d23 = −2.98; d33 = 0.96 (static) d12 = 7.16; d13 = −6.18; d23 = −3.47; d33 = 0.79 (static) d21 = −d22 = 2.73(@2050 nm)

0.343 (@1064 nm)

0.050 (static)

d33 = 39.87; dpowder = 26.54 (static)

0.147 (@1064 nm)

0.068 (@1064 nm)

Calculated bandgap by DFT methods. 2257



Review

Ag3MS3 (M = As/Sb). The proustite Ag3AsS3 and Ag3SbS3 are natural mineral species and crystallize in the trigonal R3c space group.86,87 We select Ag3AsS3 as an example to describe the crystal structure. Each As atom is coordinated by three S atoms, forming a trigonal pyramid [AsS3]3− unit (Figure 5a),

Figure 4. Crystal structure of (a) β-LiAsSe2, (b) γ-NaAsSe2 viewed down the a-axis, (c) γ-NaAsSe2 viewed down the b-axis, and (d) δNaAsSe2, (e) the zweier chain in β-LiAsSe2, (f) the vierer single chain in γ-NaAsSe2. White balls: Li/Na; cyan balls: As; red balls: Se. Adapted and reprinted with permission from ref 52, Copyright 2010 American Chemical Society.

Figure 5. Crystal structure of Ag3SbS3 viewed along (a) the [110] direction and (b) the [001] direction.

provides the molecular building units in the zweier single chain via corner bridging (Figure 4e). In comparison, γ-NaAsSe2 crystallizes in the NCS space group Pc. The structure consists of densely packed parallel [AsSe2]− polymeric anionic chains and Na+ ions (Figure 4b,c). Interestingly, the [AsSe2]− polymeric anionic chains in γ-NaAsSe2 are different with that in β-LiAsSe2. This new vierer single chain (Figure 4f) conformation preserves the NCS structure with higher Na+ substitution in the Li1−xNaxAsSe2 system in comparison to the Li1−xNaxAsS2 system, where there is only 40% Na substitution with preservation of the NCS structure. The fully Na substituted phase in the Li1−xNaxAsSe2 system was found to adopt two structural forms γ-NaAsSe2 and δ-NaAsSe2 (Figure 4d). First-principles calculations and experiments showed there is a very small energy difference between the γ and δ polymorph, and the former is the thermodynamically stable phase.52 The energy band gaps of these compounds are located in 1.11−1.75 eV, depending on the structure type and composition. In the wavelength range of 700−900 nm, SHG effects of β-Li0.2Na0.8AsSe2, γ-Li0.2Na0.8AsSe2, and γ-NaAsSe2 are ∼55, 65, and 75 times stronger than that of AGSe, respectively.52 The values are huge, especially for the Na-rich compounds. As pointed by M. G. Kanatzidis, besides the strong SALP electrons on the [AsSe3]3− units, the decrease in dimensionality with more substitution of the larger size Na+ ion is responsible for the higher SHG efficiency of the Na-rich compounds.52 As the Na+ ions substitute for Li+, the [AsSe2]− chains are increasingly separated from one another, and interchain interactions are weakened, thereby lowering the dimensionality of the system. The density functional theory (DFT) calculated d33 value for γ-NaAsSe2 is 162.3 pm/V,85 which is the highest static SHG coefficient to date among the materials with bandgaps more than 1.0 eV. Particle size dependent SHG measurements indicated that all three materials are nonphase-matchable at 790 nm.52

and each Ag+ ion adopts an unsymmetrical T-shaped geometry [AgS3]5− (Figure 5c). The T-shaped [AgS3]5− units are connected via corners to give two sets of helical chain [AgS 2 ] 3− along the c axis. These chains are further interconnected via the bridging S atoms leading to a 3D network. The polar character of Ag3AsS3 and Ag3SbS3 is the result of the combination of unsymmetric helical chains [AgS2]3− and trigonal [AsS3]3−/[SbS3]3− pyramids with SALP electrons. Kurtz-Perry measurement demonstrates that Ag 3 AsS 3 powders display an SHG response about 1.1 times that of AGS, which is consistent with SHG coefficients (d31 = 10.4 pm/V).87 It shows a very steep and strong absorption edge at 2.03 eV, which is smaller than AGS (2.78 eV). The IR spectrum shows a good transmittance between 2.5−12.5 μm, except a strong absorption band at 1600 cm−1 because of As−S bond vibration.87 Therefore, Ag3AsS3 is a promising mid-IR NLO material. It has been used in SHG of CO2 laser as well as sumfrequency generation (SFG) of between CO2 and He−Ne lasers in 1970s.88 However, its LDT value is too small, only 12 MW/cm2 (@1064 nm, 18 ns).15 Ag3SbS3 has a relatively wider bandgap of 2.2 eV than that of Ag3AsS3. The experimental measurement demonstrated that an effective nonlinear coefficient deff of Ag3SbS3 is equal to 7.8 pm/V under 10.6 μm.1 Unluckily, its LDT value is only 9 MW/ cm2 (@1064 nm, 17 ns),88 which is too small to bear high power laser. Ba2SbInSe5. Ba2SbInSe5 crystallizes in the NCS space group Cmc21.89 For a single [InSbSe5]4− anionic chain, the 5s2 lone pair electrons in the heavily distorted [SbSe6]9− octahedron, which are essential for the strong SHG response, are approximately pointing to the same direction roughly along the b axis (Figure 6). However, every two adjacent chains can 2258



Review

Meanwhile, this compound has a moderate bandgap of 2.38 eV.59 Ba23Ga8Sb2S38. Ba23Ga8Sb2S38 crystallizes in the NCS polar space group Cmc21 and exhibits an unusual 0D structure.51 The chemical formula can be rewritten to [(Ba2+)23(GaS45−)8(SbS33−)2], which contains totally isolated [GaS4]5− tetrahedra and discrete [SbS3]3− pyramids with SALP electrons on Sb atoms (Figure 8). Structural analyses revealed that the second

Figure 6. Structure of the [InSbSe5]4− chain in compound Ba2InSbSe5, Ba2+ is omitted for clarity. Reprinted with permission from ref 89, Copyright 2013 Elsevier.

be grouped into a pair within which the polarization of 5s2 lone pair electrons is almost canceled with each other. Such an arrangement is destructive for the generation of a large overall NLO response. Indeed, Ba2InSbSe5 displays an SHG signal intensity of only 1/10 of AGSe with a similar particle size.89 In addition, Ba2SbInSe5 has a small bandgap equal to 1.92 eV.89 Ba2BiInS5. Ba2BiInS5 adopts the Ba2SbInS5 structure type and crystallizes in the NCS orthorhombic Cmc21 space group.59 The crystal structure consists of 1D [BiInS5]4− anionic polymeric chains with charge-compensating Ba2+ ions. An edge-sharing [BiS5]7− tetragonal-pyramid chain and a cornersharing [InS4]5− tetrahedra chain are interconnected with each other via corner-sharing S atoms to form the cis [BiInS5]4− anionic chain (Figure 7a). This arrangement leads to the Bi3+

Figure 8. Crystal structure of Ba23Ga8Sb2S38. Only half of the Sb atoms are shown because of the 50% occupancy. Adapted and reprinted with permission from ref 51, Copyright 2012 American Chemical Society.

building unit, [SbS3]3− contributes negligibly to the SHG intensity because of overall centrosymmetric packing. Nevertheless, it helps to realize the disconnection of the asymmetric [GaS4]5− building units, which remarkably leads to a strong powder SHG intensity. Ba23Ga8Sb2S38 exhibits the strongest SHG response in the IR region reported for sulfides to date (∼22 times that of AGS) though it is type-I nonphasematchable.51 It is clear that the constructive alignment of the dipole moments of the isolated [GaS4]5− distorted tetrahedra gives rise to such a strong SHG response. Moreover, isolated [GaS4]5− units have four dangling terminal S atoms, and thus, Ba23Ga8Sb2S38 has a higher sulfur ionic bonding component than any known 1D/2D/3D Ga/S species that contains bridging S. These features make Ba23Ga8Sb2S38 easily polarizable, and a very strong SHG intensity can be realized. In addition, the bandgap of Ba23Ga8Sb2S38 is comparable with AGS (2.84 eV vs 2.70 eV).51 Cs5BiP4Se12. Cs5BiP4Se12 compound grows naturally as nanowires that crystallize in the polar Pmc21 space group.90 It features discrete molecular [Bi(P2Se6)2]5− anions, which are isolated by Cs+ cations (Figure 9a). There are two crystallographically unique Bi atoms, and each octahedrally coordinated Bi3+ center is capped by two chelating tridentate [P2Se6]4− units from opposite directions (Figure 9b). So there should be SALP 6s2 electrons on Bi(1) and Bi(2), as in Ba2BiInS5. Cs5BiP4Se12 has a small bandgap 1.85 eV and is optically transparent from the visible to the mid-IR region (0.67−18.7 μm). The SHG intensity of Cs5BiP4Se12 is two times larger than that of AGSe under 2.0 μm.90 SnGa4Q7 (Q = S, Se). SnGa4Q7 (Q = S, Se) compounds crystallize in same monoclinic Pc space group,91 so we take SnGa4S7 as an example to describe the crystal structure. The remarkable structures of the 3D frameworks were formed by the tetranuclear secondary basic structure unit [Ga4S11]10‑, which was constructed with four [GaS4]5− tetrahedra, and [SnS4]6− tetragonal pyramids locate in the cavities (Figure 10a). The Sn2+ atom is bonded to four S atoms at two short and two long distances, forming the [SnS4]6− tetragonal pyramid, which are antiparallel in interlayer and parallel in intralayer along the b axis, respectively. The electron localization function (ELF) calculations display a nonspherical symmetric density distribu-

Figure 7. (a) Crystal structure of Ba2BiInS5, (b) PED maps for compound Ba2BiInS5 from 2.5 eV to the Fermi level, and the electron density is represented from blue (0.0 e/Å3) to red (0.11 e/Å3). Adapted and reprinted with permission from ref 59, Copyright 2011 American Chemical Society.

lone-pair electrons in a parallel alignment fashion. In addition, partial electron density (PED) calculations showed that Bi3+ lone pair electrons are stereochemically active (Figure 7b).59 As a result, Ba2BiInS5 exhibits a comparable type-I phasematchable SHG response with that of KTP.59 It is reasonable that the pseudo six-coordination environment of Bi3+ may decrease the stereochemically activity of 6s2 electrons. Accordingly, the SHG response of Ba2BiInS5 is much weaker than that of LiAsS2. 2259



Review

structure. In addition, their bandgaps are large up to 3.10 and 2.55 eV,91 respectively, which can effectively attenuate the TPA effect pumped by the 1064 nm laser. They are both promising IR NLO materials if large size crystals could be grown. SnGa2GeS6. SnGa2GeS6 compound crystallizes in the NCS space group Fdd2.92 Ga and Ge atoms are randomly occupied in the ratio of Ga:Ge (2:1). In the structure, Sn2+ is coordinated to a distorted square-pyramid of five S atoms, demonstrating the stereochemical activity of the lone pair electrons, while the Ga and Ge atom are both tetrahedrally coordinated to four S atoms (Figure 11a). This compound exhibits a weak powder

Figure 11. (a) Crystal packing structure of SnGa2GeS6 viewed down the b-axis with the unit cell marked. (b) Macroscopic packing of [SnS5]8− square-pyramid in the structure. Reprinted with permission from ref 92, Copyright 2015 Royal Society of Chemistry.

Figure 9. (a) Crystal structure of Cs5BiP4Se12 viewed down the a-axis and (b) coordination environments of Bi and P atoms in Cs5BiP4Se12. Adapted and reprinted with permission from ref 90, Copyright 2009 American Chemical Society.

SHG signal only about 1/4 that of AGS.92 Figure 11b shows the overall arrangement of the [SnS5]8− square pyramids: although they are almost aligned in parallel in a pseudo chain along the c direction, the orientation of such adjacent pseudo chains is tilted toward each other at a large degree, which is unfavorable for generating a large NLO response. The UV−visNIR diffuse reflectance spectrum shows that the bandgap of SnGa2GeS6 is 2.04 eV,92 which is consistent with the dark red color of the crystal. PbGa4S7. PbGa4S7 crystallizes in space group Pc of the monoclinic system (Figure 12a).93 The Ga atoms are coordinated by four S atoms in the distorted [GaS4]5− tetrahedra, while Pb atoms are bonded to five S atoms, forming [PbS5]8− distorted quadrangular pyramids with one S atom at the apex, proving the existence of the SALP 6s2 electrons on Pb cations (Figure 12b). PbGa4S7 exhibits a relatively large bandgap of 3.08 eV and pretty strong SHG response larger than AGS.93 It is noted that there are two kinds of microscopic NLO active building blocks, namely, the [PbS5]8− and [GaS4]5− units, which contributes to the SHG response of PbGa4S7. The overall polar arrangement of the [GaS4]5− units is beneficial for generating large NLO responses. But the spatial arrangement of the [PbS5]8− quadrangular pyramid is a bit complicated. Figure 12c illustrates that the [PbS5]8− units have the same orientation in the layers parallel to the ac plane, which would be conducive for enhancing the NLO response. However, these [PbS5]8− quadrangular pyramids are almost antiparallel in adjacent layers along the b axis, which is unfavorable for generating a large NLO response. That is, the SALP 6s2 electrons on Pb2+ do not contribute significantly to the overall NLO response. PbGa2MSe6 (M = Si,Ge). Owing to the slightly different radii of Si and Ge, PbGa2SiSe6 and PbGa2GeSe6 belong to different space groups, Cc and Fdd2, respectively.94 Due to the poor

Figure 10. (a) Crystal structure of SnGa4S7 viewed along the a axis and c axis (b) The ELF map of SnGa4Se7 at (001) plane cutting through the Sn and Ga atoms and the ELF value ranging from 0 (blue) to 1 (red). Adapted and reprinted with permission from ref 91, Copyright 2014 American Chemical Society.

tion around each Sn atom, indicating the presence of 5s2 SALP electrons (Figure 10b).91 SnGa4S7 and SnGa4Se7 show a strong phase-matching SHG response, which is 1.3 and 3.8 times that of AGS, respectively.91 The SHG responses of these two compounds are evidently boosted by the [SnQ4]6− unit with a quadrangular pyramid 2260



Review

calculated SHG tensor component d33 is 224.7 pm/V at 2.0 μm.94 Pb4Ga4GeQ12 (Q = S, Se). Pb4Ga4GeQ12 (Q = S, Se) compounds crystallize in same monoclinic P−421c space group.95 Pb4Ga4GeS12 and Pb4Ga4GeSe12 are semiconductors with optical bandgaps of 2.35 and 1.91 eV, respectively. Figure 14a shows the structure of Pb4Ga4GeSe12, in which the major

Figure 14. (a) Crystal packing structure of Pb4Ga4GeSe12. (b) The electron localization function (ELF) isofurfaces for the (020) plane of Pb4Ga4GeSe12, contours are from 0 to 0.7. Adapted and reprinted with permission from ref 95, Copyright 2015 American Chemical Society. Figure 12. (a) Crystal packing structure of PbGa4S7 viewed down the b-axis with the unit cell marked. (b) Macroscopic packing of [PbS5]8− quadrangular pyramid in the structure. Reprinted with permission from ref 93, Copyright 2015 Royal Society of Chemistry.

structural motif is a 3D network constructed by chains of [GaSe4]5− tetrahedra that are interconnected by separated [GeSe4]4− tetrahedra at regular intervals. Pb2+ cations locate between the chains. The measurement of particle size versus SHG intensity indicates a nonphase-matchable behavior in Pb4Ga4GeSe12. Pb4Ga4GeSe12 is only 2 times larger than AGS at a particle size of 30−46 μm,95 which is lower than PbGa2GeSe6 discussed in the last subsection. The ELF map indicates a spherelike isosurface at the Pb2+ site (Figure 14b), which means the 6s2 electrons on Pb2+ are stereochemically inert. Consequently, the polarization associated with the Pb2+ cation should be negligible in the Pb4Ga4GeSe12 compounds. As a result, the SHG effect of Pb4Ga4GeSe12 is weaker than PbGa2GeSe6, since the Pb2+ 6s2 lone pair electrons are active in the latter compound. AAg2TeS6 (A = Rb, Cs). The layered compounds RbAg2TeS6 and CsAg2TeS6 crystallize in the NCS space group P63cm,96 in which Te is in a formal oxidation state of +4, making trigonal pyramidal [TeS3]2− isoelectronic to [AsS3]3−. As a result, strong SALP 5s2 electrons exist on the Te atoms. Both compounds are composed of intercalated layers of neutral [Ag2TeS3] and [(A+)2(S6)2−] salt (A = Rb, Cs), which are flat and lie perpendicular to the c axis (Figure 15a). In the [Ag2TeS3] layer, the [AgS4]7− polyhedra themselves are combined via common S atom corners to a network and [TeS3]2− trigonal pyramid locate in the channels (Figure 15b). UV−vis absorption spectroscopy reveals a band gap of 2.04 eV for RbAg2TeS6 and CsAg2TeS6.96 CsAg2TeS6 exhibits a relatively weaker SHG response compared with AGSe. Phasematching experiments using different sized particles of

quality of PbGa2SiSe6 samples, no SHG signal was measured, so we focus on PbGa2GeSe6. In this structure, all of the Ga atoms and mixed (Ga/Ge) positions are bonded to four Se atoms forming the [GaSe4]5− and [(Ga/Ge)Se4] tetrahedra. And the [PbSe4]6− tetra-pyramids are located in the cavities (Figure 13a).94 The partial electron density (PED) contour demonstrates the lone pair 6s2 electrons of stereochemical activity in the [PbSe4]6− unit clearly (Figure 13b). PbGa2GeSe6 exhibits a strong SHG response of 5 times that of AGS, and the largest

Figure 13. (a) Crystal packing structure of PbGa2GeSe6 viewed along the a-axis, (b) PED maps for PbGa2GeSe6 from −5 eV to the Fermi level, and the electron density is represented from blue (0.0 e/Å3) to red (0.138 e/Å3). Adapted and reprinted with permission from ref 94, Copyright 2015 American Chemical Society. 2261



Review

balance between a high LDT and strong SHG effect, the compounds containing SALP electrons might not be the superior candidates for mid-IR NLO applications. 2.3. Metal Chalcogenides Containing SOJT Effect Metal Cations Centered Units. Another common strategy aimed at obtaining large NLO responses in a material is to incorporate asymmetric building units with second-order Jahn− Teller (SOJT) distortions into the crystal structure. The SOJT effect is often encountered in octahedral groups of the d0 or d10 transition metals. The d0 transition metal cations include Ta5+, Zr4+, Nb5+, Ti4+, Mo6+, etc. and d10 metal cations include Zn2+, Cd2+, etc. Note that the number of metal chalcogenides containing SOJT polyhedra is much smaller compared with the SOJT oxides.68 In addition to commonly known octahedra, it is remarkable that the SOJT effect may also occur in other types of polyhedra.102 2.3.1. Metal Chalcogenides Containing d0 Transition Metal Cations Centered Units. It is known that in octahedrally coordinated d0 transition metal oxides, the average distortion scale is as follows: Mo6+ ≈ V5+ ≫ W6+ ≈ Ti4+ ≈ Nb5+ > Ta5+ ≫ Zr4+ ≈ Hf4+.102,103 This tendency should be the same in the chalcogenides, but detailed regulation is still unclear since only a very limited number of metal chalcogenides with d0 transition metal cations centered units have been found until now. CsTaS3. CsTaS3 crystal crystallizes in P63mmc space group,104 just similar to the BaVS3 structure type. Ta5+ centers are slightly displaced along the [111] direction in the [TaS6] octahedra, creating two discrete sets of Ta−S bond distances as a result of the C3 SOJT effect (Figure 17). So the [TaS6] group is the most typical SOJT octahedron in metal chalcogenides. Unfortunately, there is no SHG response in CsTaS3 because of its inversion center. AZrPSe6 (A = K, Rb, Cs). The compounds AZrPSe6 (A = K, Rb, Cs) crystallize in the same polar space group Pmc21,105 so we take KZrPSe6 as an example. It features parallel chains of the infinite 1D [ZrPSe6]− anion separated by the alkali metal K+ ions (Figure 18a). Zr4+ ions are coordinated to seven Se atoms in a distorted SOJT [ZrSe7] bicapped trigonal prismatic geometry (Figure 18b). All Zr4+ ions are connected to the [PSe3]− polymeric backbone formed by the condensation of corner-sharing tetrahedral [PSe4]3− units (Figure 18c). Each P atom has a terminal P−Se bond projecting out from the 1D [PSe3]− chain structure. The Zr atoms are also bridged with Se22− groups. So, the chemical formula could be rewritten as [K+Zr4+ P5+(Se2−)4(Se2)2−]. All three compounds show very strong and sharp absorption edges at ∼2 eV.105 In general, changes of the alkali metal do not show a major effect on the band gap of the covalent network. Under similar experimental conditions, the SHG response of crystalline RbZrPSe6 and CsZrPSe6 are ∼15 and 10 times stronger than that of AGSe.105 The K analogue shows a weaker SHG signal intensity than AGSe. Phase matching experiments of CsZrPSe6 indicate that this material is type-I phase matchable.105 TiP2S6. TiP2S6 belongs to Fdd2 space group and contains [TiS6]8− distorted SOJT octahedra.106 In the structure, each P atom is surrounded by three S atoms, and every two P atoms are interconnected, forming a [P2S6]4− group. The P−P atom pairs are located within the planes perpendicular to the c-axis and have a parallel orientation with each other (Figure 19). The further interconnections between [P2S6]4− and [TiS6]8− groups construct a 3D network. In this way the Ti atoms attain a distorted octahedral coordination with distances Ti−S ranging

Figure 15. Crystal structure of CsAg2TeS6 viewed down the c-axis (a) and b-axis (b). Adapted and reprinted with permission from ref 96, Copyright 2010 American Chemical Society.

CsAg2TeS6 indicate that the material is phase-matchable under 1800 nm.96 Cs2TeS2. In addition to [TeS3]2− units, [TeS2]2− units can also be an NLO active group, as in Cs2TeS2.97 It crystallizes in the NCS space group Cmc21 with four formula units per unit cell. The Te2+ cation is surrounded by two sulfide anions in a Vshape, forming a boomerang-like complex [TeS2]2− anion (Figure 16a). This ligand carries two lone-pair electrons at the

Figure 16. (a) Crystal structure of Cs2TeS2, (b) electron localization function (ELF) map of Te atom (Cs+ is omitted for clarity), the rainbow hemispheres are SALP electrons.

central Te2+ cation, which are stereochemically active (Figure 16b). All NLO-active units are stacked parallel to the (010) plane, forming a large dipole moment in the crystal. Accordingly, we predict that Cs2TeS2 will exhibit a strong SHG response. Our calculations demonstrate that Cs2TeS2 has a very large SHG coefficient d33 (−128.07 pm/V), which is comparable with γ-NaAsSe2 (d33 = 162.3 pm/V).85 This result further confirms that SALP electrons can effectively enhance the SHG effect. To date, there are no measurements about SHG effect of Cs2TeS2. The DFT calculated bandgap is 2.04 eV, which is consistent with its dark-red color in experiments.97 Our predictions are waiting for experimental verifications. The experimental and calculated results of the key NLO parameters in the NLO metal chalcogenides are summarized in Table 2. It is noted that many compounds exhibit a stronger SHG effect compared with AGS. In particular, β-LiAsSe2, γNaAsSe2, PbGa2GeSe6, and CsTeS2 possess giant SHG dij coefficients of more than 100 pm/V. However, most of compounds listed in Table 2 have a relatively small bandgap, which can lead to the negative effect of SALP electrons for enlarging the bandgap. From the viewpoint of maintaining 2262


a

2263

R3m Cc Pc

R3c Cmc21 Cmc21

Cmc21 Cmc21 Cmc21 Pmc21

Pc Pc Fdd2

Pc Fdd2 P−421c Ama2

P63cm Cmc21

Tl3AsSe315 β-LiAsSe252,98 γ-NaAsSe252,85,99

Ag3SbS31 Ba2SbInSe589 Ba23Ga8Sb2S3851

Ba2BiInS559,100 Ba2BiInSe5100 Ba2BiInTe5100 Cs5BiP4Se1290

SnGa4S791 SnGa4Se791 SnGa2GeS692

PbGa4S793 PbGa2GeSe694 Pb4Ga4GeSe1295 Pb5Ga6ZnS15101

CsAg2TeS696 Cs2TeS297

2.04 2.04a

3.08 1.96 1.91 2.32

3.10 2.55 2.04

1.55 1.40 1.28a 1.85

2.2 1.92 2.84

0.96 1.11 1.75

1.60 2.01

Eg (eV)

3.0 eV and dij > 10 × KDP), so they might be promising candidates for midIR NLO applications. The detailed linear and nonlinear optical properties of above compounds are listed in Table 7. In addition, there are quite a few other types of metal chalcogenides which contain alkalineearth metal cations, such as Ba 4 CuGa 5 S 12− x Se x , 1 9 3 Ba5In4Te4S7,197 BaCdSnS4,198 Ba3CdSn2S8,198 BaCdSnSe4,199 and Ba4Ga4GeSe12.200 These compounds are SHG active, and the above discussions on structure−property relationship are also available. But they are not discussed here due to the length limit of this review. From the data in Table 7, one may conclude that the bandgap of metal chalcogenides can be enlarged by introducing the alkaline-earth metal cations with low electronegativity, similar to the cases in Section 2.6.1. BaGa4S7, BaGa2SiS6, and Na2BaGeS4 possess a wide bandgap of 3.54 eV, 3.75 eV, and 3.70 eV, respectively.37,43,148 This indicates that these compounds would have a much higher LDT value than AGS. Indeed, the measurements on large single crystals revealed that the LDT value of BaGa4S7 is three times that of AGS.201 Up to now, the Ba-containing compounds are the most studied, but the research on Ca- and Sr-containing compounds is relatively scarce, so the further studies are desirable. In addition, great efforts should be made to grow high quality single crystals for these materials. In summary, we believe that more promising materials must exist with superior mid-IR NLO performance in the metal chalcogenides containing main group cations centered tetrahedra. The comprehensive investigations on this materials family combined experiments and analysis procedures should be focused on. 2.7. Diamond-Like (DL) Structure Metal Chalcogenides. In Section 2.6.1., we have discussed the metal chalcogenides that contain main group cations centered tetrahedra and alkali/coin metal cations, In fact, another type of compound exists with similar structure features called diamond like (DL) structures. Many of them exhibit superior mid-IR NLO properties,165 so we specially discuss them in this section. DL compounds, like chalcopyrite (AGS and ZnGeP2), represent structures that are derived from that of diamond, in either cubic or hexagonal closest packing forms.208 These compounds are built from tetrahedral building blocks that are oriented along one special crystallographic axis, rendering the structures inherently NCS, the first criterion for SHG. In addition, the aligned arrangement of tetrahedra would result in the additive superposition of the microscopic second-order susceptibility tensors of the units, and exhibit a large SHG response. Furthermore, the very abundant stoichiometry and composition in the DL metal chalcogenides actually provides a large treasury for synthesis and design of new materials with

superior mid-IR NLO performances. This makes DL compounds attractive materials in NLO applications. 2.7.1. Normal Diamond-Like (DL) Structure Metal Chalcogenides. Normal DL structures derive from the sphalerite or wurtzite structure. The cation and anion sublattices are both the closest packing form. Indeed, all atoms are located in tetrahedral coordination environments. There are no defect cation sites in the crystal structure.208 Binary Normal DL Chalcogenides. The typical binary DL structures include sphalerite (α-ZnS) and wurtzite (β-ZnS) structure. α-ZnS belongs to the cubic F−43m space group, while β-ZnS belong to the hexagonal P63mc space group. Their crystal structures are displayed in Figure 49a,b. Clearly, all

Figure 49. Crystal structure of α-ZnS, (b) β-ZnS, (c) AGS, (d) LiGaS2.

[ZnS4]6− tetrahedra in sphalerite and wurtzite structures are arranged aligned along the [111] and [001] directions, respectively. This structure feature is very favorable for the superposition of microscopic second-order susceptibility of [ZnS4]6− anion units. Both experimental and calculated SHG coefficients reveal that the two crystals have a large NLO effect (>8 pm/V),165,209 as listed in Table 8. Meanwhile, both α-ZnS and β-ZnS possess a large bandgap (>3.0 eV).210,211 Hence, one may conclude that the DL structure can reach a good balance between the NLO effect and bandgap. Nevertheless, the optical refractive indices in α-ZnS are isotropy, and the birefringence is zero owing to its cubic structure, while β-ZnS only has a very small birefringence 0.003 because the [ZnS4]6− tetrahedra are little distorted from the regular tetrahedral shape in the wurtzite structures. Therefore, binary normal DL metal sulfides are not suitable for mid-IR SHG application owing to their small birefringence. Ternary Normal DL Chalcogenides. The commonly existing ternary normal DL metal chalcogenides can be catalogued into three types: I−III−VI2, I2−IV-VI3, and I3−V−VI4. The I−III− VI2 type (I = Li, Ag, Cu; IV = Al, Ga, In; VI = S, Se, Te) compounds usually have the chalcopyrite structure, while I3− V−VI4 type (I = Li, Ag, Cu; V = P, As, Sb; VI = S, Se, Te) compounds usually have the enargite or famatinite structure. The I2−IV−VI3 type (I = Ag, Cu; IV = Si, Ge, Sn; VI = S, Se, Te) compounds are usually featured with the renierite structure which is much less common than the former two structures. Up to now, only the NLO properties of I−III−VI2 types have been studied systematically. Many of them are also commercial IR NLO crystals, including AGS, AGS, LiGaS2, LiGaSe2, LiInS2, LiInSe2, etc.143 Quarternary Normal DL Chalcogenides. The known quarternary normal DL metal sulfides have three formulas, including I2−II−IV−VI4, I−II2−III−VI4, and I4−II−IV2−VI7. 2278



Review

Table 8. Experimental and Calculated Eg, dij, and Δn of Normal DL Compounds compounds

space group

Eg (exp)

Δn (cal)


SHG efficiency

Binary Normal DL Compounds d36 = 15.29 (static) d33 = −12.35 (static) Tenary Normal DL Compounds

α-ZnS165,209 β-ZnS165,209

F43̅ m P63mc

3.60 3.49

d36 = 10.25 d33 = 9.51

I−III−VI2 AgGaS214,15,164 AgGaSe214,15,164 AgGaTe214,15,164 LiGaS215,215,216

I−42d I−42d I−42d Pna21

2.78 1.83 1.36 4.15

d36 d36 d36 d31

LiGaSe215,215,216

Pna21

3.57

d31 = −10; d32 = −7.7; d33 = 18.20

LiGaTe2216,217 I2−IV−VI3 Ag2GeS3165,218 I3−V−VI4 Li3PS417,165

I−42d

2.31

Cc

0 (0.000) 0.003 (@2090 nm) 0.004 (@2000 nm)a

0.031(@1064 0.044(@1064 0.011(@1064 0.014(@2090

d36 = 34.5

d36 = 14.1 (static) d36 = 45.2 (static) d36 = 99 (static) d31 = −6.1; d32 = −5.51; d33 = 12.86 (static) d31 = −10.2; d32 = −9.67; d33 = 23.97 (static) d36 = −50.4 (static)

1.98

no data

d33 = 36 (static)

0.09 (static)

Pmn21

3.68

no data

wurtz-stannite Li2CdGeS462,165,219

Pmn21

3.10

70 × SiO2 (@1064 nm)

Li2CdSnS462,165,219

Pmn21

3.26

100 × SiO2 (@1064 nm)

α-Cu2ZnSiS4165,213 lithium cobalt(II) silicate Li2MnGeS4165,214 α-Li2MnSnS4165,212 wurtz−kesterite β-Cu2ZnSiS4165,213 β-Li2MnSnS4212 Li2ZnGeSe4220 Li2ZnSnSe4220 Stannite Cu2CdSnS4165,213 I4−II-IV2-VI7 Li4HgGe2S7221

Pmn21

3.00

Pna21 Pna21

a

= = = =

13 33 51 −5.8; d32 = −5.1; d33 = 10.7

d15 = −3.08; d24 = −4.03; d33 = 4.32 (static) Quaternary Normal DL Compounds

nm) nm) nm) nm)

0.053(@1000 0.020(@1000 0.016(@1000 0.040(@2000

nm)a nm)a nm)a nm)a

0.016 (@2090 nm) 0.050(@2000 nm)a 0.032 (@2090 nm) 0.094 (@5.3 μm)a

0.044 (@2090 nm)

dij = 7.5 ± 1 (@1064 nm, 125−150 μm)

d15 = 2.27; d24 = 3.57; d31 = 2.13; d32 = 1.96; d33 = 7.64 (static) d15 = 2.22; d24 = 2.85; d31 = 0.96; d32 = 0.96; d33 = 4.78 (static) d33 = −10.06 (static)

0.052 (@2090 nm)

3.06 2.6−3.0

dij = 7.5 ± 2.5 (@1064 nm, 125−150 μm) 2% × AGSe (@1064 μm)

d33 = 9.92 (static) d33 = 6.25 (static)

0.010 (@2090 nm) 0.011 (@2090 nm)

Pn Pn Pn Pn

3.20 2.6−3.0 1.86 1.87

dij = 7.5 ± 1 (@1064 nm, 125−150 μm) 2% × AGSe (@1064 μm) dij = 21.6 (@2100 nm, 125−150 μm) dij = 26.1 (@2100 nm, 125−150 μm)

d11 = 12.02 (static)

0.035 (@2090 nm)

I−42m

0.92

dij = 31 ± 3.5 (@2600 nm, 90−106 μm)

d36 = −25.42 (static)

0.134 (@2090 nm)

Cc

2.75

1.5 × AGS (@2090 μm, 200−250 μm)

d11 = 5.77; d15 = 13.62; d12 = −8.08; d13 = 10.42; d24 = −7.86; d33 = −14.36; (static)

0.009 (static) 0.023 (@2090 nm)

0.009 (static) 0.018 (@2090 nm)

Experimental results.

Till now, only I2−II−IV−VI4 type compounds have been studied owing to their good NLO properties, so we focus on this type here. In this type of quarternary normal DL material six structures have been reported, three of which are derived from hexagonal lonsdaleite, wurtz-stannite (space group Pmn21), lithium cobalt(II) silicate Li2CoSiO4 (space group Pna21), and wurtz-kesterite (space group Pn), respectively, while the other three are derived from the cubic diamond structures for stannite (space group 14̅2m), kesterite (space group 14̅), and disordered kesterite (space group 14̅2m), respectively.212 To date, only the former three space groups has been reported to be SHG active.61,62,213,214 (i) Wurtz-stannite Li2CdGeS4 and Li2CdSnS4 are the first compounds to report the SHG effects in quarternary DL chalcogenides.62 Both materials crystallize in the orthorhombic space group Pmn21. All of the tetrahedral building blocks are oriented along the c axis, resulting a polar structure (Figure 50). The [CdS4]6−, [(Ge/Sn)S4]4− tetrahedra are fairly regular,

while the greatest distortion from ideal occurs in the [LiS4]7− tetrahedra. Samples of Li2CdGeS4 and Li2CdSnS4 exhibit SHG response of approximately 70 and 100 times that of α-quartz, i.e., 0.5 and 0.7 times that of AGS, respectively.62 The SHG signals are relatively weak. But in the latest experiment, Li2CdGeS4

Figure 50. Crystal structure of Li2CdGeS4 viewed down the c-axis (a) and b-axis (b). Adapted and reprinted with permission from ref 62, Copyright 2009 American Chemical Society. 2279



Review

space for the explorations of good mid-IR NLO materials in the DL metal chalcogenides, as demonstrated by the pyramidal graph of normal DL structures plotted in Figure 53. Very

showed a high SHG response comparable to benchmark materials AGS, and the absolute dij value of crystal is estimated to be 25.8 pm/V at 3.3 μm.61 The particle-size-dependent SHG experiment indicates that Li2CdGeS4 is phase-matchable at λ > 1.5 μm. More importantly, Li 2 CdGeS 4 and Li 2 CdSnS 4 compounds are found to have the bandgaps of 3.10 and 3.26 eV,62 respectively, larger than commercial AGS (2.70 eV), implying that they would have a higher LDT value. (ii) Lithium cobalt(II) silicate. In the Li2MnGeS4 structure, each cation coordinates to four tetrahedral sulfide anions, and all of the tetrahedra align along the c axis, rendering the NCS structure (Figure 51).214 Li2MnGeS4 is assigned as a direct-gap

Figure 53. Pyramidal graph of normal DL compounds constructed from single-element DL structure to multielement DL structures.

recently, the quaternary sulfide DL compound Li4HgGe2S7 has been reported to exhibit excellent performances with concurrently large NLO coefficients and impressive LDT, which satisfy the essential requirements of mid-IR NLO candidates.221 The perspective of normal diamond-like structures has been analyzed in detail in our previous work.165 2.7.2. Defect Diamond-Like (DL) Structure Metal Chalcogenides. The defect DL structure is a variation of the normal DL structure in which some chalcogen anions have less than four neighbor atoms. Because of the existence of cations deficiency, the defect DL metal chalcogenides have a relatively looser 3D structure compared with the normal structures. Taking the ternary metal sulfide HgGa2S4 as an example, it can be considered that half of the Ag+ sites in the AgGaS2 structure are replaced by Hg2+ cations, while the other half of the Ag+ sites remain void (Figure 54). HgGa2S4 possesses a rather wide

Figure 51. Crystal structure of Li2MnGeS4 viewed down the c-axis (a) and a-axis (b). Green tetrahedra: [LiS4]; blue tetrahedra: [MnS4]; red tetrahedra: [GeS4]. Adapted and reprinted with permission from ref 214, Copyright 2015 American Chemical Society.

semiconductor, yielding a bandgap of 3.06 eV. Taking AGSe as a reference, Li2MnGeS4 exhibits a moderate SHG effect with dij = 7.5 ± 2.5 pm/V.214 (iii) Wurtz-kesterite. Li2ZnGeSe4 and Li2ZnSnSe4 crystallize in the NCS space group Pn, and all of the tetrahedra align along the a axis (Figure 52).220 The SHG response of compounds is

Figure 52. Crystal structure of Li2ZnGeSe4 viewed down the (a) a-axis and (b) b-axis. Adapted and reprinted with permission from ref 220, Copyright 2015 Royal Society of Chemistry.

also comparable to AGSe under the same condition.220 The dij values for Li2ZnGeSe4 and Li2ZnSnSe4 are approximately 9.5 pm/V and 11.5 pm/V, respectively. The measured bandgap is only 1.86 eV, implying a low LDT, which is inconvenient for many practical applications. In addition to the normal DL compounds mentioned above, α/β-Cu2ZnSiS4,213 Cu2CdSnS4,213 and α/β-Li2MnSnS4212 are also reported to be SHG active. The properties of the normal DL metal chalcogenides in this subsection are listed in Table 8. As Pamplin pointed out in 1981,222 “there are a thousand adamantine phases (i.e., DL structures) from which to choose device material”. The diversity of the DL compounds is presented not only in the variety of many stoichiometric ratios, but also in many possibilities of choices for the [MQ4] microscopic building blocks. Hence, there must exist plenty of

Figure 54. Crystal structure of (a) HgGa2S4 and (b) AgGaS23.

bandgap of 2.84 eV and a very large SHG effect, which is about three times larger than that of AgGaS2.223,224 In addition, this material has moderate optical anisotropy with a uniaxial birefringence of 0.054.224 Analogous to the normal DL metal sulfides, we divide the defect DL structures into three categories: binary, ternary, and quarternary defect DL structures, including Ga2S3, Zn3(PS4)2, InPS4, LiZnPS4, AgZnPS4, etc. Binary Defect DL Chalcogenides. The most known binary defect DL chalcogenide is Ga2S3. There are two phases of Ga2S3 2280



Review

closest-packing, and the Zn2+ cations are located in threequarters of the tetrahedral voids, forming the corner-sharing [ZnS4]6− tetrahedra. The calculated bandgap of Zn3(PS4)2 is 3.19 eV, which is consistent with experimental results (3.07 eV). In addition, the SHG response of Zn3(PS4)2 is 1.6 times of that AGS.17 Therefore, Zn3(PS4)2 is a good candidate for midIR NLO application. (ii) InPS4. InPS4 is isostructural to a UV NLO material BPO4 and belongs to I4̅ space group.228 As plotted in Figure 56b, this compound has a 3D framework that consists of corner-sharing [InS4]5− and [PS4]3− tetrahedra. InPS4 has been studied in detail as a promising mid-IR NLO material since the 1980s. The measured SHG coefficient d ij ≈ 25 pm/V and birefringence Δn = 0.048, which are comparable to those of AGS.228 More importantly, the bandgap of InPS4 is 3.12 eV, larger than that of AGS, suggesting a higher LDT value. Quarternary defect DL chalcogenides. In fact, the number of quaternary defect DL structures is scarce, and only four compounds, i.e., LiZnPS4,230 AgZnPS4,231 CuHgPS4,232 and CuInGeS4,233 have been synthesized. Since the latter two compounds have disordered structures, LiZnPS4 and AgZnPS4 are selected to discuss the optical properties in quaternary defect DL compounds. LiZnPS4 and AgZnPS4. LiZnPS4 and AgZnPS4 have a similar 3D framework and defect concentration just like HgGa2S4.230,231 The only difference between two compounds is that S atoms are cubic closest-packing and hexagonal closestpacking in LiZnPS4 and AgZnPS4, respectively (Figure 56c,d). Theoretical calculations showed that these two compounds have a large bandgap (>3.0 eV), high SHG coefficient (∼1 × AGS), and moderate birefringence (0.05−0.08), suggesting that they might be the promising materials for practical mid-IR NLO applications. This conclusion has also been confirmed by the recent experiments.17,229 Table 9 lists the details of linear and nonlinear optical properties for the mentioned defect DL metal chalcogenides. Clearly, quite a few compounds satisfy the key balance of a good IR NLO materials (Eg > 3.0 eV and dij > 13 pm/V), in which HgGa2S4 and InPS4 have been demonstrated to exhibit superior NLO performance in the IR region.170 In addition, the moderate birefringence is also favorable to achieve phase matchable in practical applications. Accordingly, defect DL metal chalcogenides might be good candidates for mid-IR NLO crystals. Considering the situation that the defect DL metal sulfides have not been widely concerned, it may be reasonably

with different space groups F−43m (α-phase) and Cc (βphase).225,226 α-Ga2S3 adopts sphalerite structure and every Ga3+ cation is partially occupied (66.7%) (Figure 55a). In

Figure 55. Crystal structure of (a) α-Ga2S3 and (b) β-Ga2S3.

comparison, the β-Ga2S3 crystal contains corner-shared [GaS4]3− tetrahedra and S atoms are hexagonal closest-packing (Figure 55b). They exhibit comparatively large SHG effects of about 0.5 and 0.7 times that of KTP, for α-Ga2S3 and β-Ga2S3 respectively, in which the former is nonphase matchable, and the latter is phase matchable under 1910 nm. In addition, both phases of Ga2S3 possess close optical band gaps of about 2.80 eV,225 which are consistent with their yellow color. All these properties make them very promising practical mid-IR NLO materials. Ternary defect DL chalcogenides. Here we choose Zn3(PS4)2 and InPS4 as representatives to describe the structures and NLO performance in this type of chalcogenides. (i) Zn3(PS4)2 Zn3(PS4)2 crystallizes in P−4n2 space group230 and has a unique valence electron concentration number equal to 4.92 in all known metal thisophosphates. As displayed in Figure 56a, the [PS4]5− tetrahedra are arranged within cubic

Figure 56. Crystal structure of (a) LiZnPS4 and (b) AgZnPS4.

Table 9. Experimental and Calculated Eg, dij, and Δn of Defect DL Structures space group

Eg (exp)

α-Ga2S3225 β-Ga2S3225

F4̅3m Cc

2.80 2.80

0.5 × KTP (@1910 nm, 50−75 μm) 0.7 × KTP (@1910 nm, 50−75 μm)

HgGa2S4224,227 Zn3(PS4)217 InPS417,228 LiZnPS417

I4̅ P4n̅ 2 I4̅ I4̅

2.84 3.07 3.12 3.44

d36 = 31.5; d31 = 10.4 (@1064 nm) 1.6 × AGS (@2090 nm, 105−150 μm) d31 = 36; d36 = 28 0.8 × AGS (@2090 nm, 105−150 μm)

AgZnPS4229

Pna21

2.76

1.8 × AGS (@2090 nm, 105−150 μm)

compounds

a

Δn (cal)


SHG efficiency

d14 = 20.32 (@1910 nm) d11 = 28.18; d12 = 14.34; d13 = 24.87; d15 = 7.06; d24 = 15.26; d33 = 7.61 (@ 1910 nm) d36 = 25.15 (static) d15 = −d24 = 16.28 (static) d15 = 13.98; d14 = 15.12 (static) d15 = −d24 = 0.89; d14 = 10.42 (static) d15 = 10.10; d24 = 9.19; d33 = −17.04 (static)

0.000 0.025 (static)

0.078 0.036 0.023 0.072

(@2090 (@2090 (@2090 (@2090

nm) 0.045 (@1076 nm)a nm) nm) 0.048 (@1064 nm)a nm)

0.051 (@2090 nm)

Experimental results. 2281



Review

predicted that there would exist many superior mid-IR NLO materials in this system.165 2.8. Metal Chalcogenides Containing Halogen Elements. Halide IR NLO materials usually possess large band gaps (3.3 eV, 4.3 eV, and 5.0 eV for HgBr2, SbF3, and NaSb3F10, respectively)25,27,234 and high LDTs (1.3 and 0.3 GW/cm2 for NaSb3F10 and HgBr2, respectively),25,27 but their NLO responses are usually much smaller than those of chalcogenides.30 Therefore, if one could incorporate the advantages of chalcogenides (large NLO response) and those of halides (large bandgap and laser damage threshold) into one compound, the resulting material would possibly have superior mid-IR NLO performance. Up to now, a few works about mixed chalcogenhalogen compounds have been reported, and here the recent developments are summarized in this aspect. Ba3AGa5Se10Cl2 (A = K, Rb, Cs). Ba3AGa5Se10Cl2 (A = K, Rb, and Cs) represent a new type of NCS structure that is constructed by supertetrahedral clusters in the tetragonal space group I4.̅ 66 It features the supertetrahedral [Ga4Se10]8− cluster (T2) and tetrahedron [GaSe4]5− (T1). The 3D anionic covalent framework of [Ga5Se10]5− is interpenetrated by Ba2+/Cs+ cations and Cl− anions (Figure 57).

Figure 58. (a) Crystal structure of Ba4MGa4Se10Cl2. (b) The static polarizations of [Ga4Se10]8− (T2) and [MSe4] (T1) clusters are zero because that of each individual tetrahedron is canceled by symmetry operation. Adapted and reprinted with permission from ref 235, Copyright 2015 John Wiley.

Nevertheless, the calculated birefringence values (Δn) for all compounds are smaller than 0.01, indicating their nonphasematchable behaviors, which is consistent with experimental observations.235 NaBa4Ge3S10Cl. NaBa4Ge3S10Cl crystallizes in the hexagonal space group P63.32 In its structure (Figure 59a), each Ge atom is connected to four S atoms with distorted tetrahedral geometry, and three such [GeS4]4− tetrahedra are further linked by sharing corner S atoms to generate the isolated [Ge3S9]6− ring (Figure 59b). The Na atoms are connected to S and Cl atoms to generate trigonal bipyramids [NaS3Cl2]7− with the two Cl atoms as the apexes. The Ba1 atom is coordinated to seven S atoms and one Cl atom, while the Ba2 atom is linked by seven S atoms (Figure 59c). The absorption edge of NaBa4Ge3S10Cl is 355 nm, corresponding to the band gap of 3.49 eV.32 It shows a moderate NLO response about one-third of that of AGS, which agree well with calculated dpowder = 3.44 pm/V.32 It is noted that the [Ge3S9]6− rings are aligned in almost the same direction in a single pseudolayer, which should generate a strong NLO response. However, two adjacent pseudolayers are related by the 63 screw axis; thus the orientations of the [Ge3S9]6− rings are rotated by 60°, and only the polar arrangement of the Ge− S2 bonds is maintained, which reduces the overall macroscopic NLO effect. Very recently, three novel quaternary compounds, Ba4Ge3S9Cl2, Ba4Si3Se9Cl2, and Ba4Ge3Se9Cl2, have been synthesized by a rational tailored approach on the basis of NaBa4Ge3S10Cl, in which Ba4Ge3S9Cl2 exhibits a stronger SHG response than that of AGS.236 [A3X][Ga3PS8](A = K, Rb; X = Cl, Br). In this series of compounds, all of them feature a 2D structure constructed from polar stacking of DL [Ga3PS10]6− clusters, and A+/X− ions are located in interlayer spaces.67 Every [Ga3PS10]6− cluster consists of three corner-sharing [GaS4]5− tetrahedra in the ab plane and a capping [PS4]3− tetrahedron along the c direction (Figure 60a,d). The cationic [A3X]2+ layers can be considered

Figure 57. Crystal structure of Ba3CsGa5Se10Cl2. Light blue: Cl−; dark blue: Cs+/Ba2+; red: T1 tetrahedron [GaSe4]5−; green: T2 supertetrahedral cluster [Ga4Se10]8−. Adapted and reprinted with permission from ref 66, Copyright 2012 American Chemical Society.

The optical band gaps for K, Rb, and Cs compounds are approximately 2.04, 2.05, and 2.08 eV, respectively, as reported in 2012.66 Meanwhile, these compounds were measured to exhibit a very strong SHG effect large up to 100× AGS.66 However, in 2015, the bandgaps of these three compounds were redetermined to be 3.22 eV, 3.23 eV, and 3.25 eV, respectively. 23 5 The corrected SHG coefficients of Ba3CsGa5Se10Cl2 were d14 = 12.86 and d15 = 10.84 pm/V (@ 2050 nm), which is comparable to AGS. However, the birefringence values (Δn) are found to be very small, 0.007, 0.006, and 0.011 for K, Rb, and Cs compounds,66 which are not suitable for achieving the phase-matching condition. Ba4MGa4Se10Cl2 (M = Zn, Cd, Mn, Cu/Ga, Co, Fe). Compounds Ba 4 MGa 4 Se 1 0 Cl 2 are an analogue of Ba3CsGa 5Se 10Cl2.235 It features a 3D network that is constructed by super-tetrahedral [Ga4Se10]8− T2 clusters with simple [MSe4] T1 tetrahedra. Such an open network is characterized by channels that accommodate the counter Ba2+ cations and Cl− anions (Figure 58). The optical bandgaps of Ba4MGa4Se10Cl2 were measured to be approximately 3.08−1.88 eV (Table 10).235 In addition, the SHG responses of Zn-, Cd-, and Mn compounds are about 59, 52, and 30 times that of AGS in the particle size of 30−46 μm. 2282


I4̅

I4̅

I4̅

Ba3CsGa5Se10Cl266,235

Ba4ZnGa4Se10Cl2235

Ba4CdGa4Se10Cl2235

I4̅ I4̅ I4̅ I4̅ P63 P63

P63 P63 Pmn21 Pmn21 Pm

Pm

P212121 P63mc P63mc

Ba4MnGa4Se10Cl2 Ba4Cu0.5Ga4.5Se10Cl2235 Ba3CsInGa4Se10Cl2237 Ba6Cs2InGa9Se20Cl4237 NaBa4Ge3S10Cl32 Ba4Ge3S9Cl2236

Ba4Si3Se9Cl2236 Ba4Ge3Se9Cl2236 [K3Cl][Ga3PS8]67 [Rb3Cl][Ga3PS8]67 [K3Br][Ga3PS8]67

[Rb3Br][Ga3PS8]67

(Sb7S8Br2)(AlCl4)3238 LaCa2GeS4Cl3239 Hg3AsE4X240 (E = S, Se; X = Cl, Br, I)

235

I4̅

I4̅

space group

Ba3RbGa5Se10Cl266,235

Ba3KGa5Se10Cl2

66,235

compounds

2283

2.03

3.50

1.76 1.89 3.60 3.65 3.85

2.78 2.54 2.90 3.01 3.49 2.91

2.93

2.04, 3.22 2.05, 3.23 2.08, 3.25 3.08

Eg (exp)

d14 = 69.8; d15 = 47.6; d14 = 12.8; d15 = 10.8; (@2050 nm) d14 = 16.2; d15 = 12.9; (@2050 nm) d14 = 21.3; d15 = 9.01; (@2050 nm)

d33 = 6.81; d15 = −2.72 (static) d33 = 20.02; d15 = 33.63 (@2050 nm)

100 × AGS (@2050 nm, 30−46 μm) 59 × AGS (@2050 nm, 30−46 μm) 52 × AGS (@2050 nm, 30−46 μm) 30 × AGS (@2050 nm, 30−46 μm) 39 × AGS (@2050 nm, 30−46 μm) 70 × AGS (@2050 nm, 30−46 μm) 64 × AGS (@2050 nm, 30−46 μm) 1/3 × AGS (@2090 nm, 100 μm) 2.4 × AGS (@2050 nm, 46−74 μm)

1.0 × KDP (@1800 nm, 45−63 μm) SHG active (@1064 nm) SHG active (@1064 nm)

9.0 × AGS (@1064 nm, 200−250 μm) 2.0 × AGS (@1950 nm, 200−250 μm)

d15 = 26.7; d24 = 26.1; d33 = 26.5 (@1064 nm) d15 = 30.7; d24 = 30.3; d33 = 29.8 (@1064 nm) d11 = 45.2; d12 = 45.3; d13 = 44.1; d15 = 44.6; d24 = 45.0; d33 = 43.6 (@1064 nm) d11 = 50.9; d12 = 50.2; d13 = 49.2; d15 = 50.1; d24 = 49.7; d33 = 48.5 (@1064 nm)

d14 = 72.5; d15 = 46.5; (@2050 nm)

20 × AGS (@2050 nm, 30−46 μm)

weak signal weak signal 4.0 × AGS (@1064 nm, 200−250 μm) 1.0 × AGS (@1950 nm, 200−250 μm) 5.0 × AGS (@1064 nm, 200−250 μm) 1.1 × AGS (@1950 nm, 200−250 μm) 7.0 × AGS (@1064 nm, 200−250 μm) 1.2 × AGS (@1950 nm, 200−250 μm)

d14 = 73.2; d15 = 39.3; (@2050 nm)


10 × AGS (@2050 nm, 30−46 μm)

SHG efficiency

Table 10. Experimental and Calculated Eg, dij, and Δn in the Metal Chalcogenides Contain Halogen Elements

0.019 (static)

0.011 (static) 0.006 (static) 0.007 (static) 0.002 (static) 0.004 (static)

Δn (cal)

Crystal Growth & Design Review



Review

compounds mentioned above, the LaCa2GeS4Cl3,239 and Hg3AsE4X (E = S, Se; X = Cl, Br, I)240 compounds are also SHG active. Mixed chalcogen-halogen compounds can integrate the advantages of chalcogenides (large SHG coefficient) and (Cl/Br)-halides (large bandgap and high LDT) into one compound, which may provide a new opportunity to design new superior mid-IR NLO materials.

3. CONCLUSIONS AND OUTLOOK In summary, we have reviewed the recent development of metal chalcogenides, focusing on abundant chemical composition, flexible structure, and rich building units, especially their promising applications as mid-IR NLO materials. The triangle planar units, tetrahedral units, SALP units, SOJT units, rareearth units, and halogen atoms afford many opportunities for exploring new NLO materials. On the basis of our analysis and discussions, some general rules could be concluded: (i) Metal chalcogenides have wide IR transparent regions (usually beyond 11 μm) than oxides because of the lower bond stretching frequency, so they are inherently favorable for IR applications. (ii) From S, Se to Te, the chalcogen atom is more and more polarizable. As a result, the bandgap of compounds usually decreases, while the SHG effect and birefringence increase significantly. (iii) The introduction of SALP or SOJT effect cations would improve the structural anisotropy, resulting in a strong SHG response and large birefringence. However, it has a negative influence on the bandgap enlargement of metal chalcogenides. (iv) The introduction of the rare-earth elements would narrow the bandgap considerably. But it can provide an opportunity to find new functional materials, such as luminescent material and magnetic material. (v) The introduction of the halogen elements (especially chlorine anions) would enlarge the bandgap of metal chalcogenides. Meanwhile, it maintains the advantages of chalcogenide compounds (large NLO response), so this is a very promising direction for developing new IR NLO materials. (vi) Polar aligned DL structure (including normal and defect DL structures) is the most favorable system for mid-IR NLO crystal owing to its large bandgap, sufficient SHG effect, and moderate birefringence. Besides, large size crystals may be grown easily due to its stable closest packing anion sublattice. For the future development of IR NLO materials, researchers should focus on the following aspects: (i) Searching new SHG active building units. For example, triangle planar units [MQ3], aligned supertetrahedra (such as [Ga 4 Se 10 ] 8− in Ba 3 CsGa 5 Se 10 Cl 2 and [Ga3PS10]6− in [K3Cl][Ga3PS8]) and possible mixed [MQ m X n ] anion units (such as [Ge 4 S 6 Br 4 ] in Ge4S6Br4).241 These may also lead to new NLO crystals with rich structural and compositional diversity. (ii) Growing large size crystals. Though many metal chalcogenides possess excellent SHG properties, large size crystals for practical applications have not been obtained. Therefore, priority should be given to the compounds which are melting congruently, since they can be grown by the Bridgman-Stockbarger technique. In addition, many important physical measurements require large size crystals, including IR absorption edge, LDT value and SHG tensor component and so on. In fact, almost all optical properties in this review were measured by powder samples, and the redetermination based on

Figure 59. (a) Crystal structure of NaBa4Ge3S10Cl. the coordination environments of (b) Ge atoms and (c) Na+ and Ba2+ cations in NaBa4Ge3S10Cl. Adapted and reprinted with permission from ref 32, Copyright 2014 Royal Society of Chemistry.

Figure 60. Crystal structure of [A3X][Ga3PS8] (A = K, Rb; X = Cl, Br). The [Ga3PS10]6− cluster layers in Cl-compounds (a) and Brcompounds (d), cationic [A3X]2+ layers in Cl-compounds (c) and Brcompounds (f), and an overview of the 3D frameworks in Clcompounds (b) and Br-compounds (e). Adapted and reprinted with permission from ref 67, Copyright 2016 Royal Society of Chemistry.

as formed by the distorted X-centered quadrangular pyramids, [XA5]4+, which are corner-shared with each other along the aand b-directions (Figure 60c,f). Interestingly, despite the same stoichiometric ratio, the Cl-analogues and the Br-analogues crystallize in different space groups Pmn21 and Pm, respectively (Figure 60b,e). In the Br-analogues, the neighboring [Ga3PS10]6− cluster layers stack along the c-direction without a transversal shift in the ab-plane. In comparison, in the Clanalogues the neighboring [Ga3PS10]6− cluster layers are stacked with a slight shift along the a-axis and the b-axis, which results in the doubling of the c parameter of unit cell. Differential scanning calorimetry (DSC) measurements show that these four compounds are congruently melting at a relatively low temperature (Tm < 700 °C), so the large crystal could be grown using the Bridgman method. Their bandgaps are large up to 3.60, 3.65, 3.85, and 3.50 eV, respectively,67 which is much larger than AGS. Moreover, these compounds also show a strong SHG response, about 1.0, 1.1, 1.2, and 2.0 times that of AGS at 1950 nm.67 Therefore, this series of compounds are potentially superior candidates for mid-IR NLO materials, and more efforts should be performed to grow large bulk single crystals. Table 10 lists the key NLO parameters for the metal chalcogenides containing halogen elements discussed in this section. Up to now, research on mixed halogen and chalcogen elements is relatively scarce. In addition to the four series 2284



Review

(10) Willer, U.; Saraji, M.; Khorsandi, A.; Geiser, P.; Schade, W. Opt. Lasers Eng. 2006, 44, 699−710. (11) Pestov, D.; Wang, X.; Ariunbold, G. O.; Murawski, R. K.; Sautenkov, V. A.; Dogariu, A.; Sokolov, A. V.; Scully, M. O. Proc. Natl. Acad. Sci. U. S. A. 2008, 105, 422−427. (12) Pushkarsky, M.; Tsekoun, A.; Dunayevskiy, I. G.; Go, R.; Patel, C. K. N. Proc. Natl. Acad. Sci. U. S. A. 2006, 103, 10846−10849. (13) Pushkarsky, M. B.; Dunayevskiy, I. G.; Prasanna, M.; Tsekoun, A. G.; Go, R.; Patel, C. K. N. Proc. Natl. Acad. Sci. U. S. A. 2006, 103, 19630−19634. (14) Ohmer, M. C.; Pandey, R.; Bairamov, B. H. MRS Bull. 1998, 23, 16−20. (15) David, N. Nikogosyan; Nonlinear Optical Crystals: A Complete Survey; Springer Press, 2005. (16) Schunemann, P. G. Crystal growth and properties of nonlinear optical materials. In Perspectives on Inorganic, Organic, and Biological Crystal Growth: From Fundamentals to Applications 2007, 916, 541− 559. (17) Kang, L.; Zhou, M. L.; Yao, J. Y.; Lin, Z. S.; Wu, Y. C.; Chen, C. T. J. Am. Chem. Soc. 2015, 137, 13049−13059. (18) Jackson, A. G.; Ohmer, M. C.; LeClair, S. R. Infrared Phys. Technol. 1997, 38, 233−244. (19) Zhang, W. G.; Tao, X. T.; Zhang, C. Q.; Gao, Z. L.; Zhang, Y. Z.; Yu, W. T.; Cheng, X. F.; Liu, X. S.; Jiang, M. H. Cryst. Growth Des. 2008, 8, 304−307. (20) Takahashi, Y.; Onduka, S.; Brahadeeswaran, S.; Yoshimura, M.; Mori, Y.; Sasaki, T. Opt. Mater. 2007, 30, 116−118. (21) Dalton, L. R.; Sullivan, P. A.; Bale, D. H. Chem. Rev. 2010, 110, 25−55. (22) Sullivan, P. A.; Dalton, L. R. Acc. Chem. Res. 2010, 43, 10−18. (23) Pan, F.; Wong, M. S.; Bosshard, C.; Gunter, P. Adv. Mater. 1996, 8, 592−595. (24) Yang, Z.; Mutter, L.; Stillhart, M.; Ruiz, B.; Aravazhi, S.; Jazbinsek, M.; Schneider, A.; Gramlich, V.; Guenter, P. Adv. Funct. Mater. 2007, 17, 2018−2023. (25) Zhang, G.; Qin, J. G.; Liu, T.; Li, Y. J.; Wu, Y. C.; Chen, C. T. Appl. Phys. Lett. 2009, 95, 261104. (26) Zhang, J.; Su, N. B.; Yang, C. L.; Qin, J. G.; Ye, N.; Wu, B. C.; Chen, C. T. Proc. SPIE 1998, 3556, 1−3. (27) Liu, T.; Qin, J.; Zhang, G.; Zhu, T.; Niu, F.; Wu, Y.; Chen, C. Appl. Phys. Lett. 2008, 93, 091102. (28) Wu, Q.; Meng, X. G.; Zhong, C.; Chen, X. G.; Qin, J. G. J. Am. Chem. Soc. 2014, 136, 5683−5686. (29) Lin, Z. G.; Tang, L. C.; Chou, C. P. Opt. Mater. 2008, 31, 28− 34. (30) Kang, L.; Ramo, D. M.; Lin, Z. S.; Bristowe, P. D.; Qin, J. G.; Chen, C. T. J. Mater. Chem. C 2013, 1, 7363−7370. (31) Wu, Q.; Liu, H. M.; Jiang, F. C.; Kang, L.; Yang, L.; Lin, Z. S.; Hu, Z. G.; Chen, X. G.; Meng, X. G.; Qin, J. G. Chem. Mater. 2016, 28, 1413−1418. (32) Feng, K.; Kang, L.; Lin, Z. S.; Yao, J. Y.; Wu, Y. C. J. Mater. Chem. C 2014, 2, 4590−4596. (33) Boyd, G. D.; Buehler, E.; Storz, F. G. Appl. Phys. Lett. 1971, 18, 301−304. (34) Zawilski, K. T.; Schunemann, P. G.; Pollak, T. C.; Zelmon, D. E.; Fernelius, N. C.; Hopkins, F. K. J. Cryst. Growth 2010, 312, 1127− 1132. (35) Zhang, G. D.; Ruan, H. P.; Zhang, X.; Wang, S. P.; Tao, X. T. CrystEngComm 2013, 15, 4255−4260. (36) Zhang, G. D.; Tao, X. T.; Ruan, H. P.; Wang, S. P.; Shi, Q. J. Cryst. Growth 2012, 340, 197−201. (37) Lin, X. S.; Zhang, G.; Ye, N. Cryst. Growth Des. 2009, 9, 1186− 1189. (38) Yao, J. Y.; Mei, D. J.; Bai, L.; Lin, Z. S.; Yin, W. L.; Fu, P. Z.; Wu, Y. C. Inorg. Chem. 2010, 49, 9212−9216. (39) Kim, Y.; Seo, I.-S.; Martin, S. W.; Baek, J.; Halasyamani, P. S.; Arumugam, N.; Steinfink, H. Chem. Mater. 2008, 20, 6048−6052. (40) Isaenko, L. I.; Yelisseyev, A. P.; Lobanov, S. I.; Krinitsin, P. G.; Molokeev, M. S. Opt. Mater. 2015, 47, 413−419.

large size crystals is necessary for eventually evaluating the practical application prospect of NLO materials. (iii) Developing metal chalcogenides with multifunctions. Besides SHG properties, polar chalcogenides may also display piezoelectricity, pyroelectricity, and ferroelectricity. The introduction of magnetic centers may also provide ferromagnetic properties and magnetoelectric modulation. Furthermore, thermoelectric properties can also be measured for those narrow bandgap, heavy element enrichment metal chalcogenides. Doping of luminescent rare-earth ions into SHG active structures may also lead to luminescence and self-frequency doubling (SFD) laser materials. (iv) Exploring the relationship between structure and properties in mid-IR NLO materials. Without a doubt, the elucidation of the relationship can significantly prompt the discovery of superior mid-IR NLO metal chalcogenides. Up to now, studies on this aspect have made great progress. The SHG effects, bandgaps, and refractive indices can be determined from the atomic structures in metal chalcogenides. However, it is still unclear how the microscopic structures accurately affect the IR absorption edges, birefringence dispersion, and LDT values. Especially, the latter two properties may play a crucial role in achieving high-power harmonic output. We believe the first-principles calculations, combined with experimental measurements, will play an important role in this aspect.

■

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Fei Liang: 0000-0002-4932-1329 Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This work was supported by China “863” Project (No. 2015AA034203) and the National Natural Science Foundation of China under Grant Nos. 91622118, 91622124, 11474292, and 51602318.

■

REFERENCES

(1) Petrov, V. Prog. Quantum Electron. 2015, 42, 1−106. (2) Chen, C. T.; Wu, B. C.; Jiang, A. D.; You, G. M. Sci. Sin. Ser. B 1985, 28, 235−243. (3) Chen, C. T.; Wu, Y. C.; Jiang, A. D.; Wu, B. C.; You, G. M.; Li, R. K.; Lin, S. J. J. Opt. Soc. Am. B 1989, 6, 616−621. (4) Boyd, G. D.; Nassau, K.; Miller, R. C.; Bond, W. L.; Savage, A. Appl. Phys. Lett. 1964, 5, 234−236. (5) Haussuhl, S. Z. Kristallogr. - Cryst. Mater. 1964, 120, 401−414. (6) Bierlein, J. D.; Vanherzeele, H. J. Opt. Soc. Am. B 1989, 6, 622− 633. (7) Wang, L. S.; Cao, Z. S.; Wang, H.; Zhao, H.; Gao, W.; Yuan, Y. D.; Chen, W. D.; Zhang, W. J.; Wang, Y. J.; Gao, X. M. Opt. Commun. 2011, 284, 358−362. (8) Chernov, A. A.; Zaitseva, N. P.; Rashkovich, L. N. J. Cryst. Growth 1990, 102, 793−800. (9) Zhou, Y.; Wang, G. L.; Li, C. M.; Peng, Q. J.; Cui, D. F.; Xu, Z. Y.; Wang, X. Y.; Zhu, Y.; Chen, C. T.; Liu, G. D.; Dong, X. L.; Zhou, X. J. Chin. Phys. Lett. 2008, 25, 963−965. 2285



Review

(73) Chen, C. T.; Lin, Z. S.; Wang, Z. Z. Appl. Phys. B: Lasers Opt. 2005, 80, 1−25. (74) Lin, Z. S.; Jiang, X. X.; Kang, L.; Gong, P. F.; Luo, S. Y.; Lee, M. H. J. Phys. D-Appl. Phys. 2014, 47, 19. (75) Chen, C. T.et al. Borate Nonlinear Optical; Wiley-VCH: Berlin, Germany, 2012. (76) Hiltmann, F.; Krebs, B. Z. Anorg. Allg. Chem. 1995, 621, 424− 430. (77) Hammerschmidt, A.; Doch, M.; Wulff, M.; Krebs, B. Z. Anorg. Allg. Chem. 2002, 628, 2637−2640. (78) Li, Y. Y.; Li, B. X.; Zhang, G.; Zhou, L. J.; Lin, H.; Shen, J. N.; Zhang, C. Y.; Chen, L.; Wu, L. M. Inorg. Chem. 2015, 54, 4761−4767. (79) Lian, Y. K.; Wu, L. M.; Chen, L. Dalton Trans. 2017, doi: . (80) Zeng, H. Y.; Zheng, F. K.; Guo, G. C.; Huang, J. S. J. Alloys Compd. 2008, 458, 123−129. (81) Poduska, K. M.; DiSalvo, F. J.; Min, K.; Halasyamani, P. S. J. Alloys Compd. 2002, 335, L5−L9. (82) Chen, H. L.; Kuang, H. M.; Chen, W. T. Russ. J. Inorg. Chem. 2012, 57, 1064−1066. (83) Li, C.; Yin, W. L.; Gong, P. F.; Li, X. S.; Zhou, M. L.; Mar, A.; Lin, Z. S.; Yao, J. Y.; Wu, Y. C.; Chen, C. T. J. Am. Chem. Soc. 2016, 138, 6135−6138. (84) Kim, Y.; Martin, S. W.; Ok, K. M.; Halasyamani, P. S. Chem. Mater. 2005, 17, 2046−2051. (85) Song, J.-H.; Freeman, A. J.; Bera, T. K.; Chung, I.; Kanatzidis, M. G. Phys. Rev. B: Condens. Matter Mater. Phys. 2009, 79, 245203. (86) Hulme, K. F.; Jones, O.; Davies, P. H.; Hobden, M. V. Appl. Phys. Lett. 1967, 10, 133−135. (87) Zhao, R. Q.; Zhou, J.; Liu, X.; Li, R.; Tang, Q. L. Inorg. Chem. Commun. 2014, 46, 17−20. (88) Hanna, D. C.; Rutt, H. N.; Stanley, C. R.; Smith, R. C.; LutherDavies, B. IEEE J. Quantum Electron. 1972, 8, 317−324. (89) Hao, W. Y.; Mei, D. J.; Yin, W. L.; Feng, K.; Yao, J. Y.; Wu, Y. C. J. Solid State Chem. 2013, 198, 81−86. (90) Chung, I.; Song, J.-H.; Jang, J. I.; Freeman, A. J.; Ketterson, J. B.; Kanatzidis, M. G. J. Am. Chem. Soc. 2009, 131, 2647−2656. (91) Luo, Z. Z.; Lin, C. S.; Cui, H. H.; Zhang, W. L.; Zhang, H.; He, Z. Z.; Cheng, W. D. Chem. Mater. 2014, 26, 2743−2749. (92) Lin, Z. H.; Li, C.; Kang, L.; Lin, Z. S.; Yao, J. Y.; Wu, Y. C. Dalton Trans. 2015, 44, 7404−7410. (93) Li, X. S.; Kang, L.; Li, C.; Lin, Z. S.; Yao, J. Y.; Wu, Y. C. J. Mater. Chem. C 2015, 3, 3060−3067. (94) Luo, Z. Z.; Lin, C. S.; Cui, H. H.; Zhang, W. L.; Zhang, H.; Chen, H.; He, Z. Z.; Cheng, W. D. Chem. Mater. 2015, 27, 914−922. (95) Chen, Y. K.; Chen, M. C.; Zhou, L. J.; Chen, L.; Wu, L. M. Inorg. Chem. 2013, 52, 8334−8341. (96) Nguyen, S. L.; Jang, J. I.; Ketterson, J. B.; Kanatzidis, M. G. Inorg. Chem. 2010, 49, 9098−9100. (97) Babo, J.-M.; Wolff, K. K.; Schleid, T. Z. Anorg. Allg. Chem. 2013, 639, 2875−2881. (98) Ni, B. L.; Zhou, H. G.; Jiang, J. Q.; Li, Y.; Zhang, Y. F. Acta Phys. Chim. Sin. 2010, 26, 3052−3060. (99) Ma, Z. J.; Wu, K. C.; Sa, R. J.; Li, Q. H.; Zhang, Y. F. J. Alloys Compd. 2013, 568, 16−20. (100) Lin, C. S.; Luo, Z. Z.; Cheng, W. D.; Zhang, H.; Zhang, W. L. J. Mater. Chem. 2012, 22, 21713−21719. (101) Duan, R. H.; Yu, J. S.; Lin, H.; Zheng, Y. J.; Zhao, H. J.; HuangFu, S. X.; Khan, M. A.; Chen, L.; Wu, L. M. Dalton Trans. 2016, 45, 12288−12291. (102) Ok, K. M.; Halasyamani, P. S.; Casanova, D.; Llunell, M.; Alemany, P.; Alvarez, S. Chem. Mater. 2006, 18, 3176−3183. (103) Halasyamani, P. S.; Poeppelmeier, K. R. Chem. Mater. 1998, 10, 2753−2769. (104) Pell, M. A.; Vajenine, G. V. M; Ibers, J. A. J. Am. Chem. Soc. 1997, 119, 5186−5192. (105) Banerjee, S.; Malliakas, C. D.; Jang, J. I.; Ketterson, J. B.; Kanatzidis, M. G. J. Am. Chem. Soc. 2008, 130, 12270−12272. (106) Jandali, M. Z.; Eulenberger, G.; Hahn, H. Z. Anorg. Allg. Chem. 1980, 470, 39−44.

(41) Mei, D. J.; Yin, W. L.; Feng, K.; Lin, Z. S.; Bai, L.; Yao, J. Y.; Wu, Y. C. Inorg. Chem. 2012, 51, 1035−1040. (42) Yelisseyev, A. P.; Isaenko, L. I.; Krinitsin, P.; Liang, F.; Goloshumova, A. A.; Naumov, D. Y.; Lin, Z. S. Inorg. Chem. 2016, 55, 8672−8680. (43) Yin, W. L.; Feng, K.; He, R.; Mei, D. J.; Lin, Z. S.; Yao, J. Y.; Wu, Y. C. Dalton Trans. 2012, 41, 5653−5661. (44) Lin, X. S.; Guo, Y. F.; Ye, N. J. Solid State Chem. 2012, 195, 172−177. (45) Chung, I.; Do, J.; Canlas, C. G.; Weliky, D. P.; Kanatzidis, M. G. Inorg. Chem. 2004, 43, 2762−2764. (46) Chung, I.; Jang, J. I.; Malliakas, C. D.; Ketterson, J. B.; Kanatzidis, M. G. J. Am. Chem. Soc. 2010, 132, 384−389. (47) Chung, I.; Kim, M.-G.; Jang, J. I.; He, J.; Ketterson, J. B.; Kanatzidis, M. G. Angew. Chem., Int. Ed. 2011, 50, 10867−10870. (48) Haynes, A. S.; Saouma, F. O.; Otieno, C. O.; Clark, D. J.; Shoemaker, D. P.; Jang, J. I.; Kanatzidis, M. G. Chem. Mater. 2015, 27, 1837−1846. (49) Jang, J. I.; Haynes, A. S.; Saouma, F. O.; Otieno, C. O.; Kanatzidis, M. G. Opt. Mater. Express 2013, 3, 1302−1312. (50) Chung, I.; Malliakas, C. D.; Jang, J. I.; Canlas, C. G.; Weliky, D. P.; Kanatzidis, M. G. J. Am. Chem. Soc. 2007, 129, 14996−15006. (51) Chen, M. C.; Wu, L. M.; Lin, H.; Zhou, L. J.; Chen, L. J. Am. Chem. Soc. 2012, 134, 6058−6060. (52) Bera, T. K.; Jang, J. I.; Song, J.-H.; Malliakas, C. D.; Freeman, A. J.; Ketterson, J. B.; Kanatzidis, M. G. J. Am. Chem. Soc. 2010, 132, 3484−3495. (53) Chung, I.; Song, J.-H.; Jang, J. I.; Freeman, A. J.; Kanatzidis, M. G. J. Solid State Chem. 2012, 195, 161−165. (54) Bera, T. K.; Song, J.-H.; Freeman, A. J.; Jang, J. I.; Ketterson, J. B.; Kanatzidis, M. G. Angew. Chem., Int. Ed. 2008, 47, 7828−7832. (55) Bera, T. K.; Jang, J. I.; Ketterson, J. B.; Kanatzidis, M. G. J. Am. Chem. Soc. 2009, 131, 75−77. (56) Morris, C. D.; Chung, I.; Park, S.; Harrison, C. M.; Clark, D. J.; Jang, J. I.; Kanatzidis, M. G. J. Am. Chem. Soc. 2012, 134, 20733− 20744. (57) Jang, J. I.; Park, S.; Harrison, C. M.; Clark, D. J.; Morris, C. D.; Chung, I.; Kanatzidis, M. G. Opt. Lett. 2013, 38, 1316−1318. (58) Zhao, H.-J.; Zhang, Y. F.; Chen, L. J. Am. Chem. Soc. 2012, 134, 1993−1995. (59) Geng, L.; Cheng, W. D.; Lin, C. S.; Zhang, W. L.; Zhang, H.; He, Z. Z. Inorg. Chem. 2011, 50, 5679−5686. (60) Liao, J. H.; Marking, G. M.; Hsu, K. F.; Matsushita, Y.; Ewbank, M. D.; Borwick, R.; Cunningham, P.; Rosker, M. J.; Kanatzidis, M. G. J. Am. Chem. Soc. 2003, 125, 9484−9493. (61) Brant, J. A.; Clark, D. J.; Kim, Y. S.; Jang, J. I.; Zhang, J.-H.; Aitken, J. A. Chem. Mater. 2014, 26, 3045−3048. (62) Lekse, J. W.; Moreau, M. A.; McNerny, K. L.; Yeon, J.; Halasyamani, P. S.; Aitken, J. A. Inorg. Chem. 2009, 48, 7516−7518. (63) Jang, J. I.; Clark, D. J.; Brant, J. A.; Aitken, J. A.; Kim, Y. S. Opt. Lett. 2014, 39, 4579−4582. (64) Li, G. M.; Wu, K.; Liu, Q.; Yang, Z. H.; Pan, S. L. J. Am. Chem. Soc. 2016, 138, 7422−7428. (65) Lin, H.; Zhou, L. J.; Chen, L. Chem. Mater. 2012, 24, 3406− 3414. (66) Yu, P.; Zhou, L. J.; Chen, L. J. Am. Chem. Soc. 2012, 134, 2227− 2235. (67) Liu, B. W.; Zeng, H. Y.; Jiang, X. M.; Wang, G. E.; Li, S. F.; Xu, L.; Guo, G. C. Chem. Sci. 2016, 7, 6273−6277. (68) Chung, I.; Kanatzidis, M. G. Chem. Mater. 2014, 26, 849−869. (69) Lin, J.; Lee, M. H.; Liu, Z. P.; Chen, C. T.; Pickard, C. J. Phys. Rev. B: Condens. Matter Mater. Phys. 1999, 60, 13380−13389. (70) Clark, S. J.; Segall, M. D.; Pickard, C. J.; Hasnip, P. J.; Probert, M. J.; Refson, K.; Payne, M. C. Z. Kristallogr. - Cryst. Mater. 2005, 220, 567−570. (71) Baroni, S.; de Gironcoli, S.; Dal Corso, A.; Giannozzi, P. Rev. Mod. Phys. 2001, 73, 515−562. (72) Becker, P. Adv. Mater. 1998, 10, 979−992. 2286



Review

(144) Yin, W. L.; Feng, K.; Hao, W. Y.; Yao, J. Y.; Wu, Y. C. Inorg. Chem. 2012, 51, 5839−5843. (145) Susa, K.; Steinfink, H. Inorg. Chem. 1971, 10, 1754−1756. (146) Yohannan, J. P.; Vidyasagar, K. J. Solid State Chem. 2016, 238, 147−155. (147) Wu, K.; Yang, Z. H.; Pan, S. L. Inorg. Chem. 2015, 54, 10108− 10110. (148) Wu, K.; Yang, Z. H.; Pan, S. L. Chem. Mater. 2016, 28, 2795− 2801. (149) Schwer, H.; Keller, E.; Kramer, V. Z. Kristallogr. - Cryst. Mater. 1993, 204, 203−213. (150) Lin, H.; Chen, L.; Zhou, L. J.; Wu, L. M. J. Am. Chem. Soc. 2013, 135, 12914−12921. (151) Lin, H.; Liu, Y.; Zhou, L. J.; Zhao, H. J.; Chen, L. Inorg. Chem. 2016, 55, 4470−4475. (152) Wu, Y. D.; Bensch, W. J. Solid State Chem. 2009, 182, 471− 478. (153) Huang, J. B.; Mamat, M.; Pan, S. L.; Yang, Z. H. J. Solid State Chem. 2016, 239, 30−35. (154) Aitken, J. A.; Larson, P.; Mahanti, S. D.; Kanatzidis, M. G. Chem. Mater. 2001, 13, 4714−4721. (155) Schimek, G. L.; Pennington, W. T.; Wood, P. T.; Kolis, J. W. J. Solid State Chem. 1996, 123, 277−284. (156) Schimek, G. L.; Kolis, J. W. Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1997, 53, 991−992. (157) Auernhammer, M.; Effenberger, H.; Irran, E.; Pertlik, F.; Rosenstingl, J. J. Solid State Chem. 1993, 106, 421−426. (158) Teske, C. L. Z. Naturfor. Sect. B-a J. Chem. Sci. 1979, 34, 544− 547. (159) Eisenmann, B.; Hansa, J.; Schafer, H. Rev. Chim., Miner 1984, 21, 817−823. (160) Badikov, V.; Mitin, K.; Noack, F.; Panyutin, V.; Petrov, V.; Seryogin, A.; Shevyrdyaeva, G. Opt. Mater. 2009, 31, 590−597. (161) Chung, I.; Jang, J. I.; Gave, M. A.; Weliky, D. P.; Kanatzidis, M. G. Chem. Commun. 2007, 4998−5000. (162) Fan, Y. H.; Jiang, X. M.; Liu, B. W.; Li, S. F.; Guo, W. H.; Zeng, H. Y.; Guo, G. C.; Huang, J. S.; Zhang, M.-J. Inorg. Chem. 2017, 56, 962−973. (163) Lin, H.; Chen, L.; Yu, J. S.; Chen, H.; Wu, L. M. Chem. Mater. 2017, 29, 499−503. (164) Bai, L.; Lin, Z. S.; Wang, Z. Z.; Chen, C. T.; Lee, M. H. J. Chem. Phys. 2004, 120, 8772−8778. (165) Liang, F.; Kang, L.; Lin, Z. S.; Wu, Y. C.; Chen, C. T. Coord. Chem. Rev. 2017, 333, 57−70. (166) Li, S. F.; Liu, B. W.; Zhang, M. J.; Fan, Y. H.; Zeng, H. Y.; Guo, G. C. Inorg. Chem. 2016, 55, 1480−1485. (167) Zhou, M. L.; Li, C.; Li, X. S.; Yao, J. Y.; Wu, Y. C. Dalton Trans. 2016, 45, 7627−7633. (168) Li, G. M.; Liu, Q.; Wu, K.; Yang, Z. H.; Pan, S. L. Dalton Trans. 2017, 46, 2778−2784. (169) Li, S. F.; Jiang, X. M.; Liu, B. W.; Yan, D.; Lin, C. S.; Zeng, H. Y.; Guo, G. C. Chem. Mater. 2017, 29, 1796. (170) Petrov, V. Opt. Mater. 2012, 34, 536−554. (171) Krymus, A. S.; Myronchuk, G. L.; Parasyuk, O. V.; Lakshminarayana, G.; Fedorchuk, A. O.; El-Naggar, A.; Albassam, A.; Kityk, I. V. Mater. Res. Bull. 2017, 85, 74−79. (172) Ni, Y. B.; Wu, H. X.; Xiao, R. C.; Huang, C. B.; Wang, Z. Y.; Mao, M. S.; Qi, M.; Cheng, G. C. Opt. Mater. 2015, 42, 458−461. (173) Mei, D. J.; Gong, P. F.; Lin, Z. S.; Feng, K.; Yao, J. Y.; Huang, F. Q.; Wu, Y. C. CrystEngComm 2014, 16, 6836−6840. (174) Reshak, A. H.; Azam, S. Opt. Mater. 2014, 37, 97−103. (175) Lin, H.; Zheng, Y. J.; Hu, X. N.; Chen, H.; Yu, J. S.; Wu, L. M. Chem. - Asian J. 2017, 12, 453−458. (176) Cheng, X. D.; Wu, H. X.; Tang, X. L.; Wang, Z. Y.; Xiao, R. C.; Huang, C. B.; Ni, Y. B. Acta Phys. Sin. 2014, 63, 184208. (177) Eisenmann, B.; Jakowski, M.; Schafer, H. Rev. Chim., Miner 1983, 20, 329−337. (178) Benghia, A.; Dahame, T.; Bentria, B. Opt. Mater. 2016, 54, 269−275.

(107) Boucher, F.; Evain, M.; Brec, R. Acta Crystallogr., Sect. B: Struct. Sci. 1995, 51, 952−961. (108) Durichen, P.; Bensch, W. Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1998, 54, 706−708. (109) Pearson, R. G. Proc. Natl. Acad. Sci. U. S. A. 1975, 72, 2104− 2106. (110) Pearson, R. G. J. Am. Chem. Soc. 1969, 91, 4947−4955. (111) Chen, M. C.; Li, L. H.; Chen, Y. B.; Chen, L. J. Am. Chem. Soc. 2011, 133, 4617−4624. (112) Yu, H. H.; Pan, Z. B.; Zhang, H. J.; Wang, J. Y. J. Materiomics 2016, 2, 55−65. (113) Fang, Q. N.; Lu, D. Z.; Yu, H. H.; Zhang, H. J.; Wang, J. Y. Opt. Lett. 2016, 41, 1002−1005. (114) Chen, M. C.; Li, P.; Zhou, L. J.; Li, L. H.; Chen, L. Inorg. Chem. 2011, 50, 12402−12404. (115) Kleinman, D. A. Phys. Rev. 1962, 126, 1977−1979. (116) Levine, B. F. IEEE J. Quantum Electron. 1973, 9, 946−954. (117) Wynne, J. J. Phys. Rev. Lett. 1971, 27, 17−20. (118) Levine, B. F.; Miller, R. C.; Nordland, W. A. Phys. Rev. B 1975, 12, 4512−4521. (119) Shi, Y.-F.; Chen, Y.-k.; Chen, M.-C.; Wu, L.-M.; Lin, H.; Zhou, L.-J.; Chen, L. Chem. Mater. 2015, 27, 1876−1884. (120) Daszkiewicz, M.; Gulay, L. D.; Lychmanyuk, O. S. Acta Crystallogr., Sect. B: Struct. Sci. 2009, 65, 126−133. (121) Hwu, S. J.; Bucher, C. K.; Carpenter, J. D.; Taylor, S. P. Inorg. Chem. 1995, 34, 1979−1980. (122) Iyer, A. K.; Yin, W. L.; Rudyk, B. W.; Lin, X. S.; Nilges, T.; Mar, A. J. Solid State Chem. 2016, 243, 221−231. (123) Hartenbach, I.; Schleid, T. J. Solid State Chem. 2003, 171, 382− 386. (124) Guo, S. P.; Guo, G. C.; Wang, M. S.; Zou, J. P.; Xu, G.; Wang, G. J.; Long, X. F.; Huang, J. S. Inorg. Chem. 2009, 48, 7059−7065. (125) Zhao, H. J. J. Solid State Chem. 2015, 227, 5−9. (126) Zhen, N.; Nian, L. Y.; Li, G. M.; Wu, K.; Pan, S. L. Crystals 2016, 6, 121. (127) Li, S. F.; Zeng, H. Y.; Jiang, X. M.; Liu, B. W.; Guo, G. C. J. Chin. Soc. Rare. Earths 2016, 34, 685−692. (128) Li, P.; Li, L. H.; Chen, L.; Wu, L. M. J. Solid State Chem. 2010, 183, 444−450. (129) Zhao, H. J.; Zhou, L. J. Eur. J. Inorg. Chem. 2015, 2015, 964− 968. (130) Zhang, M. J.; Li, B. X.; Liu, B. W.; Fan, Y. H.; Li, X. G.; Zeng, H. Y.; Guo, G. C. Dalton Trans. 2013, 42, 14223−14229. (131) Zhou, L. J.; Chen, L.; Li, J. Q.; Wu, L. M. J. Solid State Chem. 2012, 195, 166−171. (132) Wang, Y.; Zou, X. C.; Feng, X.; Shi, Y. F.; Wu, L. M. J. Solid State Chem. 2017, 245, 110−114. (133) Zhao, H. J. Z. Anorg. Allg. Chem. 2016, 642, 56−59. (134) Lemley, J. T.; Jenks, J. M.; Hoggins, J. T.; Eliezer, Z.; Steinfink, H. J. Solid State Chem. 1976, 16, 117−128. (135) Rudorff, W.; Schwarz, H. G.; Walter, M. Z. Anorg. Allg. Chem. 1952, 269, 141−152. (136) Sturza, M.; Bugaris, D. E.; Malliakas, C. D.; Han, F.; Chung, D. Y.; Kanatzidis, M. G. Inorg. Chem. 2016, 55, 4884−4890. (137) Luo, Z. Z.; Lin, C. S.; Cheng, W. D.; Zhang, H.; Zhang, W. L.; He, Z. Z. Inorg. Chem. 2013, 52, 273−279. (138) Luo, Z. Z.; Lin, C. S.; Zhang, W. L.; Zhang, H.; He, Z. Z.; Cheng, W. D. Chem. Mater. 2014, 26, 1093−1099. (139) Feng, K.; Jiang, X. X.; Kang, L.; Yin, W. L.; Hao, W. Y.; Lin, Z. S.; Yao, J. Y.; Wu, Y. C.; Chen, C. T. Dalton Trans. 2013, 42, 13635− 13641. (140) Richards, W. D.; Wang, Y.; Miara, L. J.; Kim, J. C.; Ceder, G. Energy Environ. Sci. 2016, 9, 3272−3278. (141) Zhu, Z.; Chu, I.-H.; Ong, S. P. Chem. Mater. 2017, DOI: 10.1021/acs.chemmater.6b04049. (142) Wu, X. W.; Hu, Y.; Pan, H.; Su, Z. RSC Adv. 2016, 6, 99475− 99481. (143) Isaenko, L. I.; Yelisseyev, A. P. Semicond. Sci. Technol. 2016, 31, 123001. 2287



Review

(179) Badikov, V.; Badikov, D.; Shevyrdyaeva, G.; Tyazhev, A.; Marchev, G.; Panyutin, V.; Petrov, V.; Kwasniewski, A. Phys. Status Solidi RRL 2011, 5, 31−33. (180) Tyazhev, A.; Kolker, D.; Marchev, G.; Badikov, V.; Badikov, D.; Shevyrdyaeva, G.; Panyutin, V.; Petrov, V. Opt. Lett. 2012, 37, 4146− 4148. (181) Kato, K.; Okamoto, T.; Mikami, T.; Petrov, V.; Badikov, V.; Badikov, D.; Panyutin, V. Proc. SPIE, 2013, 8604, 860416.10.1117/ 12.2002929 (182) Mei, D. J.; Yin, W. L.; Bai, L.; Lin, Z. S.; Yao, J. Y.; Fu, P. Z.; Wu, Y. C. Dalton Trans. 2011, 40, 3610−3615. (183) Yao, J. Y.; Yin, W. L.; Feng, K.; Li, X. M.; Mei, D. J.; Lu, Q. M.; Ni, Y. B.; Zhang, Z. W.; Hu, Z. G.; Wu, Y. C. J. Cryst. Growth 2012, 346, 1−4. (184) Zhang, X.; Yao, J. Y.; Yin, W. L.; Zhu, Y.; Wu, Y. C.; Chen, C. T. Opt. Express 2015, 23, 552−558. (185) Yang, F.; Yao, J. Y.; Xu, H. Y.; Feng, K.; Yin, W. L.; Li, F. Q.; Yang, J.; Du, S. F.; Peng, Q. J.; Zhang, J. Y.; Cui, D. F.; Wu, Y. C.; Chen, C. T.; Xu, Z. Y. Opt. Lett. 2013, 38, 3903−3905. (186) Yang, F.; Yao, J. Y.; Xu, H. Y.; Zhang, F. F.; Zhai, N. X.; Lin, Z. H.; Zong, N.; Peng, Q. J.; Zhang, J. Y.; Cui, D. F.; Wu, Y. C.; Chen, C. T.; Xu, Z. Y. IEEE Photonics Technol. Lett. 2015, 27, 1100−1103. (187) Yuan, J. H.; Li, C.; Yao, B. Q.; Yao, J. Y.; Duan, X. M.; Li, Y. Y.; Shen, Y. J.; Wu, Y. C.; Cui, Z.; Dai, T. Y. Opt. Express 2016, 24, 6083− 6087. (188) Kostyukova, N. Y.; Boyko, A. A.; Badikov, V.; Badikov, D.; Shevyrdyaeva, G.; Panyutin, V.; Marchev, G. M.; Kolker, D. B.; Petrov, V. Opt. Lett. 2016, 41, 3667−3670. (189) Xu, W. T.; Wang, Y. Y.; Yan, C.; Xu, D. G.; Yao, J. Y.; Fan, F.; Duan, P.; Yang, Z.; Liu, P. X.; Shi, J.; Liu, H. X.; Yao, J. Q.; 2015 40th International Conference on Infrared, Millimeter and Terahertz Waves, 2015. (190) Li, X. S.; Li, C.; Gong, P. F.; Lin, Z. S.; Yao, J. Y.; Wu, Y. C. J. Mater. Chem. C 2015, 3, 10998−11004. (191) Badikov, V. V.; Badikov, D. V.; Laptev, V. B.; Mitin, K. V.; Shevyrdyaeva, G. S.; Shchebetova, N. I.; Petrov, V. Opt. Mater. Express 2016, 6, 2933. (192) Liu, B. W.; Zeng, H. Y.; Zhang, M. J.; Fan, Y. H.; Guo, G. C.; Huang, J. S.; Dong, Z. C. Inorg. Chem. 2015, 54, 976−981. (193) Kuo, S. M.; Chang, Y. M.; Chung, I.; Jang, J. I.; Her, B. H.; Yang, S. H.; Ketterson, J. B.; Kanatzidis, M. G.; Hsu, K. F. Chem. Mater. 2013, 25, 2427−2433. (194) Rad, H. D.; Hoppe, R. Z. Anorg. Allg. Chem. 1981, 483, 18−25. (195) Wu, K.; Su, X.; Pan, S. L.; Yang, Z. H. Inorg. Chem. 2015, 54, 2772−2779. (196) Wu, K.; Yang, Z. H.; Pan, S. L. Angew. Chem. Inter. Ed. 2016, 55, 6712−6714. (197) Tan, D. M.; Lin, C. S.; Luo, Z. Z.; Zhang, H.; Zhang, W. L.; He, Z. Z.; Cheng, W. D. Dalton Trans. 2015, 44, 7673−7678. (198) Zhen, N.; Wu, K.; Wang, Y.; Li, Q.; Gao, W. H.; Hou, D. W.; Yang, Z. H.; Jiang, H. D.; Dong, Y. J.; Pan, S. L. Dalton Trans. 2016, 45, 10681−10688. (199) Wu, K.; Su, X.; Yang, Z.; Pan, S. Dalton Trans. 2015, 44, 19856−19864. (200) Yin, W. L.; Iyer, A. K.; Li, C.; Lin, X. S.; Yao, J. Y.; Mar, A. J. Solid State Chem. 2016, 241, 131−136. (201) Guo, Y. F.; Zhou, Y. Q.; Lin, X. S.; Chen, W. D.; Ye, N. Opt. Mater. 2014, 36, 2007−2011. (202) Boursier, E.; Segonds, P.; Menaert, B.; Badikov, V.; Panyutin, V.; Badikov, D.; Petrov, V.; Boulanger, B. Opt. Lett. 2016, 41, 2731− 2734. (203) Boursier, E.; Segonds, P.; Debray, J.; Inacio, P. L.; Panyutin, V.; Badikov, V.; Badikov, D.; Petrov, V.; Boulanger, B. Opt. Lett. 2015, 40, 4591−4594. (204) Lai, W. H.; Haynes, A. S.; Frazer, L.; Chang, Y. M.; Liu, T. K.; Lin, J. F.; Liang, I. C.; Sheu, H. S.; Ketterson, J. B.; Kanatzidis, M. G.; Hsu, K. F. Chem. Mater. 2015, 27, 1316−1326.

(205) Haynes, A. S.; Liu, T.-K.; Frazer, L.; Lin, J.-F.; Wang, S.-Y.; Ketterson, J. B.; Kanatzidis, M. G.; Hsu, K.-F. J. Solid State Chem. 2017, 248, 119−125. (206) Yin, W. L.; Lin, Z. H.; Kang, L.; Kang, B.; Deng, J. G.; Lin, Z. S.; Yao, J. Y.; Wu, Y. C. Dalton Trans. 2015, 44, 2259−2266. (207) Yin, W. L.; Iyer, A. K.; Li, C.; Yao, J. Y.; Mar, A. J. Mater. Chem. C 2017, 5, 1057−1063. (208) Parthé, E. Crystal Chemistry of Tetrahedral Structures; Gordon and Breach Science Publishers Inc: New York, 1964. (209) Zhang, K. C., Wang, X. M. Nonlinear Optics: Crystal Materials Science; Science Press, 2006. (210) Mendil, R.; Ben Ayadi, Z.; Djessas, K. J. Alloys Compd. 2016, 678, 87−92. (211) Tsuji, I.; Shimodaira, Y.; Kato, H.; Kobayashi, H.; Kudo, A. Chem. Mater. 2010, 22, 1402−1409. (212) Devlin, K. P.; Glaid, A. J.; Brant, J. A.; Zhang, J.-H.; Srnec, M. N.; Clark, D. J.; Soo Kim, Y. S.; Jang, J. I.; Daley, K. R.; Moreau, M. A.; Madura, J. D.; Aitken, J. A. J. Solid State Chem. 2015, 231, 256−266. (213) Rosmus, K. A.; Brant, J. A.; Wisneski, S. D.; Clark, D. J.; Kim, Y. S.; Jang, J. I.; Brunetta, C. D.; Zhang, J.-H.; Srnec, M. N.; Aitken, J. A. Inorg. Chem. 2014, 53, 7809−7811. (214) Brant, J. A.; Clark, D. J.; Kim, Y. S.; Jang, J. I.; Weiland, A.; Aitken, J. A. Inorg. Chem. 2015, 54, 2809−2819. (215) Petrov, V.; Yelisseyev, A.; Isaenko, L.; Lobanov, S.; Titov, A.; Zondy, J. J. Appl. Phys. B: Lasers Opt. 2004, 78, 543−546. (216) Bai, L.; Lin, Z. S.; Wang, Z. Z.; Chen, C. T. J. Appl. Phys. 2008, 103, 083111. (217) Isaenko, L.; Krinitsin, P.; Vedenyapin, V.; Yelisseyev, A.; Merkulov, A.; Zondy, J. J.; Petrov, V. Cryst. Growth Des. 2005, 5, 1325−1329. (218) Reshak, A. H.; Kamarudin, H.; Auluck, S. J. Mater. Sci. 2013, 48, 1955−1965. (219) Reshak, A. H. J. Appl. Phys. 2016, 119, 095709. (220) Zhang, J.-H.; Clark, D. J.; Brant, J. A.; Sinagra, C. W., III; Kim, Y. S.; Jang, J. I.; Aitken, J. A. Dalton Trans. 2015, 44, 11212−11222. (221) Wu, K.; Yang, Z. H.; Pan, S. L. Chem. Commun. 2017, 53, 3010. (222) Pamplin, B. Prog. Cryst. Growth Charact. 1980, 3, 179−192. (223) Badikov, V. V.; Don, A. K.; Mitin, K. V.; Seregin, A. M.; Sinaiskii, V. V.; Schebetova, N. I. Quantum Electron. 2003, 33, 831− 832. (224) Umemura, N.; Mikami, T.; Kato, K. Opt. Commun. 2012, 285, 1394−1396. (225) Zhang, M. J.; Jiang, X. M.; Zhou, L. J.; Guo, G. C. J. Mater. Chem. C 2013, 1, 4754−4760. (226) Collin, G.; Flahaut, J.; Guittard, M.; Loireaulozach, A. M. Mater. Res. Bull. 1976, 11, 285−292. (227) Andreev, Y. M.; Geiko, P. P.; Badikov, V. V.; Panyutin, V. L.; Shevyrdyaeva, G. S.; Ivaschenko, M. V.; Karapuzikov, A. I.; Sherstov, I. V. 9th Joint International Symposium on Atmospheric and Ocean Optics/ Atmospheric Physics, Tomsk, Russia 2002, 120−127. (228) Jantz, W.; Koidl, P.; Wettling, W. Appl. Phys. A: Solids Surf. 1983, 30, 109−115. (229) Zhou, M. L.; Kang, L.; Yao, J. Y.; Lin, Z. S.; Wu, Y. C.; Chen, C. T. Inorg. Chem. 2016, 55, 3724−3726. (230) Jorgens, S.; Johrendt, D.; Mewis, A. Z. Anorg. Allg. Chem. 2002, 628, 1765−1769. (231) Toffoli, P.; Rouland, J. C.; Khodadad, P.; Rodier, N. Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1985, 41, 645−647. (232) Menzel, F.; Brockner, W.; Carrillocabrera, W. Heteroat. Chem. 1993, 4, 393−398. (233) Gorgut, G. P.; Fedorchuk, A. O.; Kityk, I. V.; Sachanyuk, V. P.; Olekseyuk, I. D.; Parasyuk, O. V. J. Cryst. Growth 2011, 324, 212−216. (234) Zhang, G.; Liu, T.; Zhu, T. X.; Qin, J. G.; Wu, Y. C.; Chen, C. T. Opt. Mater. 2008, 31, 110−113. (235) Li, Y. Y.; Liu, P. F.; Hu, L.; Chen, L.; Lin, H.; Zhou, L. J.; Wu, L. M. Adv. Opt. Mater. 2015, 3, 957−966. (236) Liu, P. F.; Li, Y. Y.; Zheng, Y. J.; Yu, J. S.; Duan, R. H.; Chen, H.; Lin, H.; Chen, L.; Wu, L. M. Dalton Trans. 2017, 46, 2715−2721. 2288



Review

(237) Li, Y. Y.; Liu, P. F.; Lin, H.; Wang, M. T.; Chen, L. Inorg. Chem. Front. 2016, 3, 952−958. (238) Zhang, Q.; Chung, I.; Jang, J. I.; Ketterson, J. B.; Kanatzidis, M. G. J. Am. Chem. Soc. 2009, 131, 9896−9897. (239) Gitzendanner, R. L.; DiSalvo, F. J. Inorg. Chem. 1996, 35, 2623−2626. (240) Beck, J.; Hedderich, S.; Kollisch, K. Inorg. Chem. 2000, 39, 5847−5850. (241) Krebs, B. Angew. Chem., Int. Ed. Engl. 1983, 22, 113−134.

2289


Mid-Infrared Nonlinear Optical Materials Based on Metal

Recommend Documents