Six New Members of A2MIIMIV3Q8 Family and Their Structural

Data reduction was done by. Bruker SAINT. Each structure was solved by direct methods and refined by the full-matrix least-squares fitting on F. 2 wit...
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Six New Members of A2MIIMIV3Q8 Family and Their Structural Relationship Xiao-Ning Hu, Lin Xiong, and Li-Ming Wu Cryst. Growth Des., Just Accepted Manuscript • Publication Date (Web): 09 Apr 2018 Downloaded from http://pubs.acs.org on April 9, 2018

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Crystal Growth & Design

Six New Members of A2MIIMIV3Q8 Family and Their Structural Relationship Xiao-Ning Hu, Lin Xiong, Li-Ming Wu* Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China

ABSTRACT: A2MIIMIV3Q8 family (A = alkali metal; MII = divalent metal; MIV = tetravalent metal; Q = chalcogenide) have attracted much attention because of their diverse structures and properties. Herein, we have successfully synthesized six new compounds as the first Mn-containing members of this family, Cs2MnGe3S8 (1), Cs2MnGe3Se8 (2), Cs2MnSn3Se8 (3), Rb2MnGe3S8 (4), Rb2MnGe3Se8 (5), and Rb2MnSn3Se8 (6). Compounds 1 and 6 crystallize in the monoclinic space group P21/n (No. 14) and P21 (No. 4), respectively. Whereas compounds 2–5 crystallize in the non-centrosymmetric orthorhombic P212121 (No. 19). According to our theoretical calculations, their energy gaps are mainly dominated by s states of MIV and p states of Q and minor Mn 3d. Plate-like crystals with sizes about 20 × 5 × 1 mm3 of 2 and 3 are obtained by Bridgeman method. In addition, we propose a structure mismatch factor that is defined as F = rெII + rMIV + 2 r 2– − 2 rA+ to provide a clear description of how three Q different structure types distribute among the A2MIIMIV3Q8 family, when 1.2 < F < 1.9, members will adopt P212121-type structure; when F is too small (< 1.2) or too large (> 1.9), P21/n or P21-type, respectively, will be taken.

INTRODUCTION Quaternary chalcogenides have attracted much attention, because of their various interesting properties. For example, the previously reported 1-4-5-12 family AMII4MIII5Q12 (A = K, Rb, Cs; MII = Mn, Zn, Cd; MIII = Ga, In; Q = S, Se, Te)1–6 and 1

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KHg4Ga5Se127 show strong infrared nonlinear optical (NLO) properties because of the aligned polarizations of the asymmetric MQ4 tetrahedral units, for instance, RbCd4In5Se122 shows very strong second harmonic generation (SHG). More interestingly, the crystallographic disorder of the tetrahedron center is considered as a structural flexibility that gives rise to multiple function. For example, the NLO active ACd4Ga5S123 also exhibits thermochromism property owing to the coexistence of Cd/Ga in the tetrahedron center. NLO active CsMn4In5Se122 and CsMn4In5Te124 also display a spin-canted antiferromagnetic property because of the coexistence of Mn/In in the tetrahedron center. Besides, the NLO active CsCd4In5Te124 with similar Cd/In disorder behaves as a solar cell absorber material on account of its direct band gap (Eg) of 1.42 eV that is mainly inherited from the CdTe binary. Another interesting family is the 2-1-3-8 family A2MIIMIV3Q8 (A = alkali metal; MII = divalent metal; MIV = tetravalent metal; Q = chalcogenide). For instance, K2ZnSn3S88 has isomeric α and β phases. Strong magnetic interactions are found in parallel to the 2

/∞[FeGe3Se8]2– layer in K2FeGe3Se8.9 K2ZnSn3Se810 exhibits the SHG intensity of 0.6 ×

AGS. Detailed crystallographic data of eleven compounds of MII = Mg, Zn, Cd, Hg; MIV = Ge, Sn; Q = S, Se, Te show insignificant changes of the bond lengths and angles, where the MII–Q bonds only vary slightly; the MIV–Q bonds are shorter in the MII–Q–MIV connection than in the MIV–Q–MIV connection, etc.11 However, these compounds belong to three different space groups of P21 (No. 4), P21/n (No. 14), and P212121 (No. 19), respectively. The reason remains unclear. In addition, the Rb- or Mn-containing 2-1-3-8 member is not known, yet. Since manganese may bring interesting magnetic properties, we start to explore the Rb/Mn/MIV/Q system. Herein, we have discovered six new Mn-containing members for the 2-1-3-8 family via high temperature solid-state reactions with chloride as a flux, Cs2MnGe3S8 (1), Cs2MnGe3Se8 (2), Cs2MnSn3Se8 (3), Rb2MnGe3S8 (4), Rb2MnGe3Se8 (5), and Rb2MnSn3Se8 (6). Syntheses, single crystal structures, electronic structures and optical 2

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properties as well as the growth of centimeter size single crystals using Bridgman method are studied. We also proposed a structure mismatch factor (F = rெII + rMIV + 2 r 2– − Q 2 rA+ ) to describe the phase map of this family. The P212121 structure will be adopted when 1.2 < F < 1.9, otherwise, the structure will be the P21/n-type with F < 1.2, or P21-type with F > 1.9, which means if the A+ is too small or too large to fit well in the cavity, the symmetry of the 2-1-3-8 family compound will decrease. EXPERIMENTAL SECTION Syntheses. CsCl, RbCl, Mn, Ge, Sn, S, and Se higher than 99.9% were used as purchased from Aladdin Chemistry Co. Taking compound 2 as an example, a mixture of CsCl (0.2713 g), Mn (0.0443 g), Ge (0.0878 g), and Se (0.2545 g) in a molar ratio of 4 : 2 : 3 : 8 was load into a silica tube inside a glovebox. Subsequently, the assembly was flame sealed under 10−6 Pa, and then heated to 673 K in 20 h, dwell for 10 h, then heated to 1073 K in 20 h, maintained for 100 h, and finally cooled to 623 K at a rate of 3 K/h. The product was washed by distilled water to remove the chloride. The dark-red plate-like crystals were obtained (Figure 1b). Single Crystal and Powder X-ray Diffraction (XRD). Single crystal X-ray diffraction data were collected with ω and f scans at room temperature on a Mercury Bruker APEX-II CCD diffractometer with Mo Kα radiation. Data reduction was done by Bruker SAINT. Each structure was solved by direct methods and refined by the full-matrix least-squares fitting on F2 with the SHELXTL software package12 and checked with the ADDSYM algorithm by PLATON13. Crystal structure refinement results were listed in Table 1, coordinates and equivalent isotropic displacement parameters were shown in Table S1, and selected bond lengths and angles were presented in Table 2. The absolute structure parameters of 2–6 was 0.05(4), 0.20(3), 0.022(8), −0.01(3) and 0.042(10), respectively. The flack factor of 3 was 0.20(3) indicating a 20% twining in this crystal. Powder XRD data were collected on Bruker D8 Advance X-ray Diffractometer, using 3

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Cu Kα1 radiation with a scan step of 0.02º and a φ scan with a rotation speed of 15 r/min. Energy Dispersive X-ray Spectroscopy (EDS). Semi-quantitative EDS on single crystal was performed by a field emission scanning electron microscopy (FESEM, S-8010, Hitachi) equipped with an energy dispersive X-ray spectroscope (XFlash6160, BRUKER). The results indicated the existence of Cs/Rb, Mn, Ge/Sn, and S/Se, while no other element was detected. Differential Scanning Calorimetry. With the aid of a METTLER TOLEDO DSC2 thermal analyzer, data were collected on crystalline samples (about 25 mg) in a crucible heated from 298 to 998 K at a rate of 5 K/min, under nitrogen flow. UV-vis Diffuse-Reflectance Spectroscopy. UV-vis reflectance experiments were performed on SHIMADZU UV-2600, at room temperature, from 220 to 1400 nm and BaSO4 as a reference. The reflectance data were converted by Kubelka-Munk function: F(R) = (1 − R)2 ⁄ 2R and the Eg was calculated through the formula: Eg = hc ⁄ λ. Raman Spectra. The Raman spectra were recorded on a Lab RAM Aramis spectrometer equipped with a 532 nm laser at room temperature on polycrystalline powder with the spectral resolution of 1 cm−1. Second Harmonic Generation (SHG) Measurements. Non-centrosymmetric 2–6 were sieved into a series of specific particle sizes of 25–45, 45–75, 75–109, 109–150, and 150–212 µm, respectively. AgGaS2 (supplied from Anhui Institute of Optics and Fine Mechanics Chinese Academy of Sciences) was ground and sieved into the same size range as a reference. The powder SHG signals were measured on a modified Kurtz-NLO system using a 2.05, 1.5 and 1.0 µm laser radiations. Bridgman Crystal Growth. A Bridgman crystal growth furnace (Fuzhou Lester laboratory equipment co., LTD), was used to grow large-size single crystals. About 5 g pure polycrystalline samples of 2 or 3 were loaded into a silica tube with Φ = 11 mm with a tapered end, and subsequently flame-sealed under 5 × 10−4 Pa. The assembly was put into the upper zone, heated to 1073 K and the lower zone to 673 K in 12 h, respectively, 4

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and dwelled for 24 h, then lowered at a rate of 1.2 mm/h before the furnace was switched off. The obtained ingots were seen in Figure 8. Computational Procedures. The plane-wave density functional theory (DFT) implemented in the Vienna ab initio simulation package (VASP)14 was employed to study the electronic structure. We adopted an additional on-site orbital-dependent correlation Hubbard U (LDA + U) as density functional to calculate the common bonding electrons and the highly correlated Mn-d electrons separately, setting U values of 6.1 eV and 6.0 eV only for Mn2+ in A2MnMIV3Se8 and A2MnMIV3S8, respectively.15 The projector augmented wave (PAW) potentials were employed and the magnetic moment of the crystal was determined by the spin-polarized calculations16 (more details in SI). RESULTS AND DISCUSSION Syntheses. Compounds A2MnMIV3Q8 (A = Cs, Rb; MIV = Ge, Sn; Q = S, Se), 1–6, were synthesized by the high temperature solid-state reactions. Compound 2 was firstly found when we tried to synthesize Cs-Mn-Ge-Se quaternary compounds. In order to increase the yield, different reaction temperatures and loading molar ratios of CsCl or Mn were systematically studied. The optimal condition was thus established to be using the molar ratio of 4 : 2 : 3 : 8 of CsCl : Mn : Ge : Se and reacting at 1073 K for 100 h. The by-product was washed by distilled water. The purity of each compound was verified by the powder XRD pattern (Figure 2). The size of the as-synthesized single crystals of compounds 2, 3, 5, and 6 were obviously bigger than those of 1 and 4, and other members obtained by flame-melting rapid-cooling reaction11 or molten polychalcogenide flux method8 (Figure 1). This may suggest that the large size crystal growth of these compounds is feasible. Crystal structure. Single X-ray crystal diffraction data indicate that compound 1 crystallizes in centrosymmetric space group P21/n (No. 14) and is isostructural to Cs2ZnGe3S811; isostructural 2–5 belong to non-centrosymmetric space group P212121 (No. 19) taking the Cs2HgGe3Se8 type11, whereas 6 adopts the non-centrosymmetric P21 (No. 4) 5

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K2ZnSn3Se8 structure type10. As shown in Table 1, 1–6 possess the similar unit cell parameters, but they belong to 3 different space groups. Despite of their different symmetries, 1–6 share similar layered structure motif with the major difference being the slight distortion within the layer (Figure 3c). Taking 2 as an example, there are 2 crystallographic independent Cs, one Mn, 3 Ge and 8 Se atoms in a unit, and all occupy the 4a Wyckoff site. As shown in Figure 3a, each 2/∞[MnGe3Se8]2− layer is composed by 1

/∞[MnGeSe6]6– chains that are linked by MnSe4 and GeSe4 tetrahedra alternatively via

corner-sharing along the a direction. Further, the neighboring chains are linked into a layer by [Ge2Se6]4− dimers via corner-sharing along the c direction (Figure 3b). The bond distances of 3.42–4.18, 2.15–2.27, 3.58–4.12, 2.29–2.42, and 2.45–2.58 Å are corresponding to the Cs–S, Ge–S, Cs–Se, Ge–Se and Sn–Se bonds, respectively, which are consistent with those in the Cs2MIIMIV3Q8 family11. The bond distances 3.36–3.86, 2.40–2.44, 3.44–4.09, and 2.52–2.60 Å of Rb–S, Mn–S, Rb–Se, and Mn–Se bonds, respectively, are comparable with those of Rb2Hg3Sn2S8 (3.28–3.88 Å)17, Li4MnGe2S7 (2.40–2.46 Å)18, (RbCl)2Cs5(Ga15Ge9Se48) (3.49–3.99 Å)19, and CsGdMnSe3 (2.50–2.59 Å)20. Rafael Besse et al. previously suggested that 2D layered structure of A2MIIMIV3Q8 is only stable when the average of r

Q2–

+ rA+ is smaller than 1.5 Å or larger than 1.8 Å.21

However, a few exceptions are found as Cs2CdGe3S811, Cs2HgSn3S811, Cs2ZnGe3S811, K2ZnSn3Se810, and compounds 1 and 4–6 (Table S2). But why these above mentioned 8 compounds in this family exhibit lower symmetry is yet unclear. Morris et al. suggested that, in case of Cs2ZnGe3S8, the small size of Ge4+, S2–, and Zn2+ may be the reason.10–11, 22, 23

This also explains the case of Cs2MnGe3S8 (1), because Mn2+ and Zn2+ have the

similar ionic radii (Mn2+ vs Zn2+, 0.66 vs 0.60 Å)22. However, this fails in Rb2MnGe3S8 (4) case that adopts higher symmetry P212121 (No. 19) where Rb+ is smaller (Rb+ vs Cs+, 1.63 vs 1.78 Å).22,24 In addition, why K2ZnSn3Se810 and 6 crystallize in lower symmetry P21 (No. 4) is unknown. 6

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Hence, we propose a structure mismatch factor F to describe the map of the structure type for A2MIIMIV3Q8 family. We define F = rெII + rMIV + 2 r 2– − 2 rA+ , the ionic Q radius is the revised effective ionic radii of Shannon & Prewitt22, rA+ is taken when the –



coordination number of the A cation is 9. Note that, K2ZnSn3S88 belonging to P1 or Pa3, and K2FeGe3Se89 showing supercell are not considered herein, because of their completely different structure. Otherwise all the known members are taken into consideration (Table S3). Figure 4 shows that along with the increase of F, 18 members of this family are grouped into three categories. When F falls in the range of 1.2–1.9, high symmetry P212121 type is favored; when F < 1.2, P21/n type will be adopted; when F > 1.9, the structure will have the lowest symmetry P21. According to this rule, we propose many new members are to be discovered, such as Cs2MgGe3S8 (F = 1.08), Rb2MgGe3Se8 (F = 1.66), and Rb2MgGe3Te8 (F = 2.12) adopting P21/n, P212121 and P21 symmetries, respectively. Note that there is an exception, Cs2HgSn3Se8 (P212121) and Rb2MnSn3Se8 (P21) having the same F = 1.91 belong to different space groups. To simplify, the F only reflects the difference parallel to the 1/∞[MIIMIVQ6]6– chains, while the distance between two adjacent 1/∞[MIIMIVQ6]6– is not taken into account, which is mainly determined by the MIV and Q atoms. Hence, the distance between two adjacent 1

/∞[MIIMIVQ6]6– chains is similar in these two exceptional compounds, which is more

suitable for Cs+, according to other similar compounds listed in Table S3. Optical properties. The solid-state diffuse reflectance spectra shown in Figure 5 reveal the Eg of 1–6 are 2.93, 1.74, 1.86, 3.01, 1.72 and 1.83 eV, respectively. As Table S2 listed, the value of Eg decreases with the increase of cell volume. Ongoing from S to Se, Sn to Ge, or Rb to Cs, the corresponding Eg has changed about 1.20, 0.10 or 0.10 eV, respectively. According to the density of states in Figure 7, the Eg is mainly dominated by MIV and Q atoms, whereas A atoms have little contribution, which is consistent with the experimental observations. Similar phenomena have been found in related systems, such 7

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as, β-K2Hg3Sn2S8 (2.50 eV) vs β-Rb2Hg3Sn2S8 (2.48 eV),24 Li2CdGeS4 (3.10 eV) vs Li2CdSnS4 (3.26 eV)25. The Raman spectra (Figure 6) show the similarities between the Cs-analogue and Rb-analogues. Along with the increase of formula weight (Se vs S; Sn vs Ge), the absorption peaks shift from 379 cm−1 to the lower wavenumbers of 214 and 204 cm−1, as found by the Rb-analogues. The peaks at 153, 350, 379, and 380 cm−1 in 1 and 4 are assigned to be the Mn–S and Ge–S bonding interactions. The 105, 199, and 214 cm−1 peaks in 2 and 106, 199, and 215 cm−1 in 5 are probably attributed to the Mn−Se and Ge−Se vibrations modes. And those at 128, 190, and 204 cm−1 in 3 and 127, 191, and 203 cm−1 in 6 maybe due to the Mn–Se and Sn–Se bonds. These results are accordant with those found in other related compounds.17, 27 The second harmonic generation signals of the 5 non-centrosymmetric 2–6 were measured on a modified Kurtz-NLO system using 2.05, 1.5 and 1.0 µm laser radiations, respectively. No SHG signals at 1.5 and 2.05 µm laser radiations were found, and only very weak signals were found at 1.0 µm radiation. Judging from the crystal structure as seen in Figure 3a, the orientations of the tetrahedron belonging to the neighboring 1

/∞[MnGeSe6]6– chains are directing oppositely, and the linker [Ge2Se6]4− dimer acts as a

mirror plane, which may lead to the considerable polarity cancellation and thus give rise to very weak even null SHG signals. Electronic structure calculations. The LDA + U method was utilized to calculate the electronic structure. The electronic band structure and the density of states of Rb2MnGe3Se8 (5) are discussed in detail as an example. The band structure (Figure S2e) reveals that the band gap, determined by the spin-up to spin-up channel, is about 0.9 eV, being smaller than the experimental value, which is mostly because the DFT underestimates Eg owning to the insufficient description of the eigenvalues of the electronic states. The Figure 7b indicates that the s and p states of Ge, Se atoms in the spin-up and spin-down polarized directions make different contribution to the valence 8

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band (VB) and conduction band (CB), since the s and p states coupling with the different Mn-d states of the ferromagnetic configuration. Moreover, Mn has unpaired electrons and the 3d states behave totally differently (located near −5 eV in the spin-up direction and 4 eV in the spin-down direction, respectively) and the VBM mostly consists of Se 4p and Ge 4s mixing with minor Mn 3d states, and the CBM is composed of Ge 4s, Se 4p and Mn 3d states. Bridgman crystal growth. According to the DSC results shown in Figure S1a, compound 2 melt at about 981 K. Although 3 exhibits two exothermic peaks in Figure S1b, which are caused by the decomposition under the DSC measurement condition (under nitrogen flow), annealing 3 at 993 K in a silica tubing under vacuum does not show any decomposition. (Figure S1c) About 5 g polycrystalline sample was loaded into a silica tube (Φ = 11 mm) with a tapered end and flame-sealed under 5 × 10−4 Pa. The upper and lower zone were heated to 1073 and 673 K, respectively. And the silica tube was lowered at a rate of 1.2 mm/h and a temperature gradient of 1~2 K/mm. Cone-like polycrystalline ingots were obtained, as seen in Figure 8. About 20 × 5 × 1 mm3 plate-like crystals could be separated from the polycrystalline ingots, which are much bigger than that of Cs2HgSn3Se8 (2 mm × 3 mm) reported11. CONCLUSION Six new chalcogenides, Cs2MnGe3S8 (1), Cs2MnGe3Se8 (2), Cs2MnSn3Se8 (3), Rb2MnGe3S8 (4), Rb2MnGe3Se8 (5), and Rb2MnSn3Se8 (6) have been synthesized via modified solid-state reactions. Compound 1 crystallizes in centrosymmetric space group P21/n (No. 14) taking the Cs2ZnGe3S8 structure type11, whereas isostructural 2–4 crystallize in non-centrosymmetric P212121 (No. 19) adopting Cs2HgGe3Se8 type11, and 6 crystallizes in non-centrosymmetric space group P21 (No. 4) showing K2ZnSn3Se8 structure type10. They are all layered structures constructed by chains of vertex-sharing MnQ4 and MIVQ4 tetrahedra that are linked into sheet by [MIV2Q6]4− dimers. The identity change of A and MIV only distort slightly within the layers. LDA + U calculation reveals 9

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the direct bandgap semiconductor nature of the title compounds, and MIV and Q states mainly determine the Eg. About 20 × 5 × 1 mm3 plate-like crystals of 2 and 3 are obtained by Bridgeman method. More interestingly, we introduce a mismatch factor, F, defined as F = rெII + rMIV + 2 r

Q2–

− 2 rA+ that gives a clear description of the structure distribution

of the A2MIIMIV3Q8 family. When 1.2 < F < 1.9, P212121-type structure will be adopted; when F < 1.2 or F > 1.9, P21/n-type or P21-type will be adopted, respectively. The insight in this work may help the structure understanding of related systems, and provides some useful information on large crystal growth.

ASSOCIATED CONTENT

Supporting Information. Crystal data, Cell volume and energy band gap, and DSC diagram, graphs of calculated band structure and density of states.

AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected]. (L.-M.W.) Tel: 86-010-62209980 ORCID Li-Ming Wu: 0000-0001-8390-2138 Notes The authors declare no competing financial interest. CCDC: 1587770 Cs2MnGe3S8 (1) CCDC: 1587776 Cs2MnGe3Se8 (2) CCDC: 1587875 Cs2MnSn3Se8 (3) CCDC: 1587876 Rb2MnGe3S8 (4) CCDC: 1587877 Rb2MnGe3Se8 (5) CCDC: 1587878 Rb2MnSn3Se8 (6) 10

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ACKNOWLEDGMENTS This research was supported by the National Natural Science Foundation of China under Projects 21571020 and 21671023.

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Infrared Nonlinear Optical Material KHg4Ga5Se12 Exhibits Good

Phase-Matchability and Exceptional Second Harmonic Generation Response. Chem. Mater. 2017, 29, 7993–8002. (8) Fard, Z. H.; Kanatzidis, M. G. Phase-Change Materials Exhibiting Tristability: Interconverting Forms of Crystalline α-, β- and Glassy K2ZnSn3S8. Inorg. Chem. 2012, 51, 7963–7965. (9) Feng, K.; Wang, W. -D.; He, R.; Kang, L.; Yin, W. -L.; Lin, Z. -S.; Yao, J. -Y.; Shi, Y. 11

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-G.; Wu, Y. -C. K2FeGe3Se8: A New Antiferromagnetic Iron Selenide. Inorg. Chem. 2013, 52, 2022–2028. (10) Zhou, M. -L.; Jiang, X. -X.; Yang, Y.; Guo, Y. -W.; Lin, Z. -S.; Yao, J. -Y.; Shi, Y. -G.; Wu, Y. -C. K2ZnSn3Se8: A Non-Centrosymmetric Zinc Selenidostannate(IV) Featuring Interesting Covalently Bonded [ZnSn3Se8]2− Layer and Exhibiting Intriguing Second Harmonic Generation Activity. Chem. Asian J. 2017, 12, 1282–1285. (11) Morris, C. D.; Li, H.; Jin, H.; Malliakas, C. D.; Peters, J. A.; Trikalitis, P. N.; Freeman, A. J.; Wessels, B. W. Kanatzidis, M. G. Cs2MIIMIV3Q8 (Q = S, Se, Te): An Extensive Family of Layered Semiconductors with Diverse Band Gaps. Chem. Mater. 2013, 25, 3344–3356. (12) Sheldrick, G. M. SHELXL-2014/7, Program for the Solution of Crystal Structures. University of Gӧttingen, Germany, 2014. (13) Spek, A. L. SQUEEZE, Incorporated into PLATON: A Multipurpose Crystallographic Tool. University of Utrecht, Utrecht, The Netherlands, 2005. (14) Kresse, G.; Furthmüller, J. Efficient Iterative Schemes for ab initio Total-Energy Calculations Using A Plane-Wave Basis Set. Phys. Rev. B. 1996, 54, 11169–11186. (15) Youn, S. J.; Min, B. I.; Freeman, A. Crossroads Electronic Structure of MnS, MnSe, and MnTe. J. Phys. Stat. Sol.(b) 2004, 241, 1411–1414. (16) Kresse,

G.; Joubert, D. From Ultrasoft

Pseudopotentials to the Projector

Augmented-Wave Method. Phys. Rev. B 1999, 59, 1758−1775. (17) Marking, G. A.; Hanko, J. A.; Kanatzidis, M. G. New Quaternary Thiostannates and Thiogermanates A2Hg3M2S8 ( A = Cs, Rb; M = Sn, Ge) through Molten A2Sx· Reversible Glass Formation in Cs2Hg3M2S8. Chem. Mater. 1998, 10, 1191–1199. (18) Kaib, T.; Haddapour, S.; Andersen, H. F.; Mayrhofer, L.; Jӓrvi, T.; Moseler, M.; Mӧller, K. -C.; Dehnen, S. Quaternary Diamond-Like Chalcogenidometalate Networks as Efficient Anode Material in Lithium-Ion Batteries. Adv. Funct. Mater. 2013, 23, 5693–5699. (19) Huang-Fu, S. -X.; Shen, J. -N.; Lin, H.; Chen, L.; Wu, L. -M. Supercubooctahedron (Cs6Cl)2Cs5[Ga15Ge9Se48] Exhibiting Both Cation and Anion Exchange. Chem. Eur. J. 2015, 21, 9809–9815. (20) Mitchell, K.; Huang, F. -Q.; Caspi, E.; McFarland, A. D.; Haynes, C. L.; Somers, R. C.; 12

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Jorgensen, J. D.; Duyne, R. P. V.; Ibers, J. A. Syntheses, Structure, and Selected Physical Properties of CsLnMnSe3 (Ln = Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y) and AYbZnQ3 (A = Rb, Cs; Q = S, Se, Te). Inorg. Chem. 2004, 43, 1082–1089. (21) Besse, R.; Silva, J. L. F. D. The Role of the Alkali and Chalcogen atoms on the Stability of the Layered Chalcogenide A2MIIMIV3Q8 (A = Alkali-Metal; M = Metal-Cations; Q = Chalcogen) Compounds: A Density Functional Theory Investigation within Van der Waals Corrections. J. Phys.: Condens. Matter 2017, 29, 035402. (22) Shannon, R. D. Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chalogenides. Acta Crystallogr., Sect. A. 1976, 32,751–767. (23) Hwang, S. -J.; Iyer, R. G.; Kanatzidis, M. G. Quaternary Selenostannates Na2–xGa2–xSn1+xSe6 and AGaSnSe4 (A = K, Rb, and Cs) through Rapid Cooling of Melts. Kinetics versus Thermodynamics in the Polymorphism of AGaSnSe4. J. Solid State Chem. 2004, 177, 3640–3649. (24) Wu, K.; Yang, Z. -H.; Pan, S. -L. Na2Hg3M2S8 (M = Si, Ge, and Sn): New Infrared Nonlinear Optical Materials with Strong Second Harmonic Generation Effects and High Laser-Damage Thresholds. Chem. Mater. 2016, 28, 2795–2801. (25) Liao, J. -H.; Marking, G. M.; Hsu, K. F.; Matsushita, Y.; Ewbank, M. D.; Borwick, R.; Cunningham, P.; Rosker, M. J.; Kanatzidis, M. G. α- and β-A2Hg3M2S8 ( A = Cs, Rb; M = Ge, Sn): Polar Quaternary Chalcogenides with Strong Nonlinear Optical Response. J. Am. Chem. Soc. 2003, 125, 9484–9493. (26) Lekse, J. W.; Moreau, M. A.; McNerny, K. L.; Yeon, J.; Halasyamani, P. S.; Aitken, J. A. Second-Harmonic

Generation

and

Crystal

Structure

of

the

Diamond-Like

Semiconductors Li2CdGeS4 and Li2CdSnS4. Inorg. Chem. 2009, 48, 7516–7518. (27) Wu, K.; Yang, Z. -H.; Pan, S. -L. Na2BaMQ4 (M = Ge, Sn; Q = S, Se): Infrared Nonlinear Optical Materials with Excellent Performances and that Undergo Structural Transformations. Angew. Chem. Int. Ed. 2016, 55, 6713–6715.

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Table 1. Crystallographic data and refinement details of compounds 1−6. formula

Cs2MnGe3S8 (1)

Cs2MnGe3Se8 (2)

Cs2MnSn3Se8 (3)

Rb2MnGe3S8 (4)

Rb2MnGe3Se8 (5)

Rb2MnSn3Se8 (6)

formula weight

795.01

1170.21

1308.51

700.13

1075.33

1213.63

crystal system

Monoclinic

Orthorhombic

Orthorhombic

Orthorhombic

Orthorhombic

Monoclinic

crystal color

Yellow

Red

Red

Yellow

Red

Red

space group

P21/n (No. 14)

P212121 (No. 19)

P212121 (No. 19)

P212121 (No. 19)

P212121 (No. 19)

P21 (No. 4)

a (Å)

7.3721(2)

7.6376(7)

7.8798(3)

7.2756(4)

7.5809(4)

7.7864(4)

b (Å)

17.1142(5)

12.6484(11)

12.7040(5)

12.1668(8)

12.4969(8)

12.6343(6)

c (Å)

12.6481(4)

17.7625(13)

18.4556(8)

16.8351(8)

17.5804(10)

18.4878(9)

β (°)

97.4362(11)

/

/

/

/

95.8099(18)

V (Å3)

1582.36(8)

1715.9(3)

1847.50(13)

1490.26(15)

1665.53(17)

1809.41(15)

Z

4

4

4

4

4

4

Dc (g/cm3)

3.337

4.530

4.704

3.121

4.288

4.455

µ (mm−1)

11.976

27.041

24.290

14.391

29.358

26.181

1.105

1.042

1.158

1.058

1.119

1.079

R1, wR2 (I > 2σ(I))

0.0304, 0.0423

0.0619, 0.1206

0.0885, 0.1422

0.0343, 0.0609

0.0610,0.1421

0.0647, 0.1622

R1, wR2 (all data)

0.0438, 0.0445

0.1197, 0.1444

0.1188, 0.1505

0.0486, 0.0652

0.1290,0.1852

0.1018, 0.1865

largest diff. peak and hole (e/Å3)

1.124, −0.683

2.418, −1.809

2.422, −2.229

0.733, −0.586

2.155, −2.197

1.986, −2.476

absolute structure parameter

/

0.05(4)

0.20(3)

0.022(8)

−0.01(3)

0.042(10)

GOOF on F2 a

a

R1 = Σ||Fo| − |Fc||/Σ|Fo|, wR2 = [Σw(Fo2 − Fc2)2/Σw(Fo2)2]1/2

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Crystal Growth & Design

Table 2. Selected bond lengths (Å) and angles (deg) for compounds 1–6. Cs2MnGe3S8 (1)

Cs2MnGe3Se8 (2)

Cs2MnSn3Se8 (3)

Mn1–S1

2.4230(11)

Mn1–Se1

2.534(4)

Mn1–Se1

2.545(7)

Mn1–S2

2.4348(11)

Mn1–Se2

2.548(4)

Mn1–Se2

2.547(6)

Mn1–S3

2.4204(12)

Mn1–Se3

2.538(6)

Mn1–Se3

2.552(8)

Mn1–S4

2.3982(12)

Mn1–Se4

2.554(6)

Mn1–Se4

2.567(8)

S3–Mn1–S1

110.11(4)

Se1–Mn1–Se2

99.20(17)

Se1–Mn1–Se3

97.7(3)

S4–Mn1–S1

104.21(4)

Se1–Mn1–Se3

109.65(18)

Se1–Mn1–Se4

112.8(3)

S1–Mn1–S2

115.75(4)

Se1–Mn1–Se4

113.90(18)

Se3–Mn1–Se4

119.8(2)

S4–Mn1–S2

109.08(4)

Se2–Mn1–Se3

114.33(19)

Se1–Mn1–Se2

112.6(2)

S2–Mn1–S2

110.24(4)

Se2–Mn1–Se4

112.39(19)

Se3–Mn1–Se2

108.8(2)

S4–Mn1–S3

106.94(4)

Se3–Mn1–Se4

107.38(18)

Se4–Mn1–Se2

105.2(3)

Rb2MnGe3S8 (4)

Rb2MnGe3Se8 (5)

Rb2MnSn3Se8 (6)

Mn1–S1

2.418(2)

Mn1–Se1

2.532(4)

Mn1–Se1

2.520(7)

Mn1–S2

2.419(2)

Mn1–Se2

2.541(4)

Mn1–Se3

2.529(7)

Mn1–S3

2.425(3)

Mn1–Se3

2.542(5)

Mn1–Se4

2.535(8)

Mn1–S4

2.442(3)

Mn1–Se4

2.554(5)

Mn1–Se2

2.598(7)

S1–Mn1–S2

100.22(8)

Se1–Mn1–Se2

97.63(15)

Se1–Mn1–Se4

112.9(3)

S1–Mn1–S3

108.04(9)

Se1–Mn1–Se3

110.56(16)

Se1–Mn1–Se3

97.5(3)

S2–Mn1–S3

115.04(9)

Se1–Mn1–Se4

114.44(16)

Se4–Mn1–Se3

119.7(3)

S1–Mn1–S4

111.42(9)

Se2–Mn1–Se3

114.84(16)

Se1–Mn1–Se2

112.6(3)

S2–Mn1–S4

112.53(9)

Se2–Mn1–Se4

112.44(16)

Se4–Mn1–Se2

105.4(3)

S3–Mn1–S4

109.24(9)

Se3–Mn1–Se4

106.98(17)

Se3–Mn1–Se2

108.9(3)

Rb2MnSn3Se8 (6) Mn2–Se8

2.528(7)

Se8–Mn2–Se7

109.8(2)

Se7–Mn2–Se5

112.2(3)

Mn2–Se6

2.552(7)

Se8–Mn2–Se6

95.8(3)

Se6–Mn2–Se5

108.3(2)

Mn2–Se7

2.561(8)

Se7–Mn2–Se6

114.2(3)

Mn2–Se5

2.586(8)

Se8–Mn2–Se5

115.7(2)

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Figure 1. Single crystal photos of the as-synthesized (a) Cs2MnGe3S8 (1), (b) Cs2MnGe3Se8 (2), (c) Cs2MnSn3Se8 (3), (d) Rb2MnGe3S8 (4), (e) Rb2MnGe3Se8 (5), and (f) Rb2MnSn3Se8 (6).

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Crystal Growth & Design

Figure 2. Experimental and simulated powder XRD patterns of (a) Cs2MnGe3S8 (1), (b) Cs2MnGe3Se8 (2), (c) Cs2MnSn3Se8 (3), (d) Rb2MnGe3S8 (4), (e) Rb2MnGe3Se8 (5), and (f) Rb2MnSn3Se8 (6).

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Figure 3. (a) Single crystal structure of Cs2MnGe3Se8 (2) viewed down the a axis. (b) A single

2

/∞[MnGe3Se8]2− layer viewed down the b axis with crystallographically

independent atoms marked. (c) The comparison of the layer motif among Cs2MnGe3S8 (1), Cs2MnGe3Se8 (2) and Rb2MnSn3Se8 (6).

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Crystal Growth & Design

Figure 4. The relationship of space group and structure mismatch factor F in A2MIIMIV3Q8 family. (Red: compounds reported herein, formula details listed in Table S3.)

Figure 5. UV-vis diffuse-reflectance spectra of Cs2MnGe3S8 (1), Cs2MnGe3Se8 (2), Cs2MnSn3Se8 (3), Rb2MnGe3S8 (4), Rb2MnGe3Se8 (5), and Rb2MnSn3Se8 (6).

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Figure 6. Raman spectra of (a) Cs2MnGe3S8 (1), (b) Cs2MnGe3Se8 (2), (c) Cs2MnSn3Se8 (3), (d) Rb2MnGe3S8 (4), (e) Rb2MnGe3Se8 (5), and (f) Rb2MnSn3Se8 (6).

Figure 7. The density of states of (a) Rb2MnGe3S8 (4), (b) Rb2MnGe3Se8 (5), (c) Rb2MnSn3Se8 (6). 20

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Crystal Growth & Design

Figure 8. Polycrystalline ingots and cleaved crystals of (a) Cs2MnGe3Se8 (2) and (b) Cs2MnSn3Se8 (3).

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For Table of Contents Use Only Six New Members of A2MIIMIV3Q8 Family and Their Structural Relationship Xiao-Ning Hu, Lin Xiong, Li-Ming Wu* Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China

Six new Mn-containing compounds of A2MIIMIV3Q8 family are synthesized and characterized. Their single crystal structures, electronic structures and optical properties as well as the single crystal growth utilizing Bridgman method are reported. A mismatch factor, F, is introduced to give a clear description of the structure distribution of this family.

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