High-Temperature, High-Pressure Hydrothermal Synthesis and

Article Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX

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High-Temperature, High-Pressure Hydrothermal Synthesis and Characterization of an Acentric Borate Fluoride: Ba2B5O9F·0.5H2O Pin-Hsun Hsieh,† Cheng-En Tsai,† Bor-Chen Chang,† and Kwang-Hwa Lii*,†,‡ †

Department of Chemistry, National Central University, Zhongli, Taiwan 320, R.O.C Institute of Chemistry, Academia Sinica, Taipei, Taiwan 115, R.O.C

‡

S Supporting Information *

ABSTRACT: A new borate fluoride, Ba2B5O9F·0.5H2O, has been synthesized by high-temperature, high-pressure hydrothermal method, characterized by a combination of techniques and its structure determined by single-crystal X-ray diffraction. The compound crystallizes in the noncentrosymmetric space group P4̅n2 (No. 118) and powder SHG measurements were performed to confirm the absence of a center of symmetry. Its crystal structure is formed of a new fundamental building block which shares oxygen atoms with neighboring blocks to form a 3D borate framework with 12- and 8-ring channels where the Ba2+ cations, F− anions, and water molecules are located. The structure is compared with those of minerals and synthetic borate fluoride and chlorides with similar framework compositions. The 11B MAS NMR experimental results are in accord with those from crystal structure analysis and the resonances in the spectrum are assigned. The presence of water was confirmed by IR spectroscopy, and its content and the thermal decomposition products were determined by thermogravimetric analysis and powder X-ray diffraction.

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INTRODUCTION Ultraviolet (UV) lasers have been widely used in science and industry, and their applications include materials research, medicine, spectroscopy, microlithography, and so on.1−4 The development of nonlinear optical (NLO) crystals has therefore become an important research subject since generating UV laser by frequency doubling technique is much easier than using excimer laser or high-order harmonic generation in rare gases.5 Cleaning resonator and filling ultra-high-purity gas in the resonator are the disadvantages of excimer laser, and high-order harmonic generation in rare gases has very low efficiency. In contrast, quintupling a most common solid-state laser, such as Nd3+:YAG laser (λ = 1064 nm), with a high-performance NLO crystal is much more convenient than the previous one. However, there is no commercially available deep-UV (DUV, λ < 200 nm) NLO crystal. This is because an excellent DUV NLO crystal requires the following properties: high nonlinear coefficients under operation wavelength, wide UV transparency range (cutoff wavelength > 6.2 eV), chemical stability, high laser-induced damage threshold, appropriate birefringence in DUV to allow phase matching, and easy growth of large highquality single crystals.3,4 Borates dominate the NLO materials. The fluorinecontaining borate family which includes borate fluorides and fluoroborates has great potential as DUV NLO materials because the incorporation of an F− anion could broaden the transparent wavelength range of the materials.6−12 The crystals of beryllium borates KBe2BO3F2 (KBBF) and RbBe2BO3F2 (RBBF) are able to generate DUV laser by direct SHG.13−16 © XXXX American Chemical Society

However, the difficulty in growing large (each dimension >4 mm) single crystals for cutting crystal at phase-matching angle at DUV region has still remained very difficult.17 Therefore, there is a great deal of interest to discover new borates that satisfy the above-mentioned conditions for a functional DUV NLO material. The flux method is commonly used for the synthesis of borates. The choice of a good flux and crystal growth conditions are extremely challenging. The hydrothermal method can also be used for growing good quality crystals of borates. There are a good number of reports on the synthesis of borates under mild hydrothermal conditions, but the works using high-temperature, high-pressure hydrothermal technique are considerably in paucity. Our exploratory synthesis under high-T/high-P hydrothermal conditions at 500 °C leads to new barium borate fluoride Ba2B5O9F·0.5H2O (denoted as 1). The structure is discussed along with minerals, anhydrous borate fluoride Ba2B5O9F which was synthesized from CsF-BaF2 flux at high temperature, and the borate chlorides in the literature, Ba2B5O9Cl·0.5H2O and Ba2B5O9Cl (M = Ca, Sr, Ba, and Pb), which were hydrothermally synthesized at 200 °C and by solidstate reaction at high temperature, respectively.18−21

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EXPERIMENTAL SECTION

Synthesis and Initial Characterization. All of the chemicals were analytical-grade and used without further purification. Crystalline product of 1 was synthesized at high-temperature, high-pressure Received: April 4, 2018

A

DOI: 10.1021/acs.inorgchem.8b00908 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry

between 300 and 1000 °C, which is close to the calculated value of 3.99% for an HF molecule per formula unit. Single-Crystal X-ray Diffraction. Intensity data were collected on a colorless crystal of 1 with dimensions 0.012 × 0.040 × 0.080 mm3 at 296 K over 1902 frames with φ and ω scans (width 0.5°/frame) and an exposure time of 30 s/frame using a Bruker Kappa Apex II CCD diffractometer equipped with a normal focus, 2 kW sealed tube X-ray source. Integrated intensities and unit cell constants were determined using SAINT program.27 The SADABS program was used for absorption correction (Tmin/Tmax = 0.528/0.898).28 The space group was determined to be P4̅n2 (No. 118) based on the systematic absences, statistical analysis of intensity distribution, and successful solution and refinement of the structure. The structure was solved by direct methods and successive difference Fourier synthesis. A water oxygen atom, Ow(1), was located and refined with 50% occupancy. All other atom sites were fully occupied. The H atoms were not located. The final cycles of least-squares refinement including atomic coordinates and anisotropic thermal parameters for all atoms converged at R1 = 0.0081, wR2 = 0.0206 for 1083 reflections with I > 2σ(I), GooF = 1.179, ρmax,min = 0.43 and −0.32 e·Å−3. The Flack parameter of 0.013(15) was consistent with the correct absolute structure. All calculations were performed using the SHELXTL, version 6.14 software package.29 The crystallographic data are given in Table 1, and selected bond distances are given in Table 2.

hydrothermal conditions. The reactants including 47.7 mg of H3BO3 (0.77 mmol, Merck 99.5%), 11.3 mg of BaF2 (0.06 mmol, Alfa Aesar 99%), 30.4 mg of Ba(OH)2·8H2O (0.09 mmol, Merck 98%), and 463 μL of deionized water were sealed in a 6.5 cm long gold ampule (inside diameter = 0.48 cm) and heated in a Tem-Pres autoclave at 500 °C for 2 days, cooled to 320 °C at 3 °C/hour, and then quenched at room temperature by removing the autoclave from the tube furnace. The degree of fill by water at room temperature was 55%, and the pressure at 500 °C was estimated to be 1150 bar according to the P−T diagram of pure water.22,23 The product was separated by suction filtration, washed with water, and rinsed with ethyl alcohol. The bulk product contained compound 1 and some unreacted BaF2. A pure sample of colorless columnar crystals of 1 was obtained in a yield of 12% based on barium by washing the bulk product with boiling water, as indicated by powder X-ray diffraction using a D2 PHASER diffractometer (Figure S1). Attempts to synthesize 1 under mild hydrothermal conditions (T ≈ 210 °C) were unsuccessful. A known centrosymmetric barium borate, Ba2[B5O8(OH)2](OH), was obtained instead.18 High-temperature, high-pressure hydrothermal reactions to synthesize the analogues of 1 under the same reaction conditions using BaCl2·2H2O instead of BaF2, or replacing Ba(OH)2·8H2O and BaF2 by Sr(OH)2·8H2O and SrF2 yielded Ba2B5O9Cl·0.5H2O or Sr2B5O9(OH), respectively.18,24 Although the latter two compounds resemble compound 1 in their compositions, their structures differ considerably from that of 1. The IR spectrum of 1 was recorded within the 4000−400 cm−1 region on a JASCO FTIR-4100 spectrometer using the KBr pellet method (Figure 1). The spectrum shows a weak peak at 3618 cm−1

Table 1. Crystallographic Data for Ba2B5O9F·0.5H2O (1) chemical formula formula weight crystal system space group a (Å) c (Å) V (Å3) Z T (°C) λ(Mo Kα) (Å) Dcalc (g·cm−3) μ(Mo Kα) (mm−1) R1 a wR2b

B5Ba2FHO9.5 500.74 tetragonal P4̅n2 (No. 118) 11.5259(7) 6.4812(4) 861.00(9) 4 23 0.71073 3.863 9.15 0.0081 0.0206

R1 = Σ||Fo| − |Fc||/Σ|Fo|. bwR2 = [Σw(Fo2 − Fc2)2/Σw(Fo2)2]1/2, w = 1/[σ2(Fo2) + (aP)2 + bP], P = [max(Fo2, 0) + 2(Fc)2]/3, where a = 0.081 and b = 0.51. a

Figure 1. Infrared spectrum of 1 (KBr pellet method).

Table 2. Selected Bond Lengths (Å) for Ba2B5O9F·0.5H2O (1)

and a weak broad band centered at about 3556 cm−1, which are in the region expected for stretching vibrations of water molecule, and a weak peak at 1596 cm−1 due to the H−O−H bending vibration.25 Strong bands in the regions 1350−1550 cm −1 and 900−1300 cm −1 corresponding to BO3 and BO4 groups, respectively, were also observed.26 EDS analysis was performed on a field emission scanning electron microscope (JEOL JSM-7000F) equipped with an energy dispersive spectrometer (Oxford INCA Energy) to confirm the presence of Ba, F, and B (Figure S2). thermogravimetric analysis (TGA) was performed on a 6.5 mg powder sample of 1 in an alumina crucible using a NETZSCHSTA 449 F3 thermal analyzer. The sample was heated from 50 to 1100 °C at 10 °C/min under flowing argon. Meanwhile, the thermal decomposition product of 1 was investigated by heating a powder sample in a Pt crucible in air at 850 °C for 5 h, then cooling to room temperature, and measuring the powder X-ray diffraction pattern. The pattern indicated that the decomposition product was β-BaB2O4 (Figure S3); therefore, compound 1 decomposes according to the following equation: Ba2B5O9F· 0.5H2O(s) → 2 β-BaB2O4(s) + 1/2 B2O3(s) + HF(g). B2O3 was not observed in the diffraction pattern because it was in the vitreous form. As shown in Figure S4, the TGA curve shows a weight loss of 3.7%

B(1)−O(1) B(1)−O(3) B(2)−O(1) B(3)−O(3) B(3)−O(5) F(2)−Ba(1)

1.433(2) 1.476(3) 1.467(2) (2×) 1.384(3) 1.357(3) 2.7886(2) (4×)

B(1)−O(2) B(1)−O(4) B(2)−O(5) B(3)−O(4) F(1)−Ba(1)

1.471(2) 1.517(3) 1.493(2) 1.362(3) 2.6489(2) (4×)

The SHG responses of a powder sample of 1 were measured because SHG is a sensitive and definite test of the absence of an inversion center of crystalline materials. A definite green light was detected when the powder sample was exposed to fundamental output (λ = 1064 nm) of a pulsed Nd:YAG laser, which confirms the absence of a center of symmetry in the structure of 1 (Figure S5). However, the intensity of green light degraded under prolonged laser radiation. Solid-State NMR Measurements. The 11B MAS NMR spectrum was measured at r.t. on a Varian Infinity-plus 500 spectrometer with an 11.74 T magnet. For magic angle spinning (MAS) NMR experiments, a 4 mm CP-MAS probe was used with a zirconia rotor at 159.95 MHz. The sample spinning speed of 12 kHz was employed. The spectrum B

DOI: 10.1021/acs.inorgchem.8b00908 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry was referenced to external NaBH4(s) powder (−42.06 ppm).30 The 17° pulse length of 1.04 μs and repetition delay of 5 s were used.

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RESULTS AND DISCUSSION Structures. The crystal structure of 1 consists of the following unique units: B(1)O4 and B(2)O4 tetrahedra, B(3)O3 triangle, one Ba and two F atoms, and one H2O group. B(1), B(3), and Ba(1) atoms are at general positions; B(2) atom is at 4 g special position with a local symmetry of C2; F(1) and F(2) atoms are at 2a and 2b special positions with a local symmetry of 4̅. Ow(1) atom is at 4f special position with a local symmetry of C2. The occupancy factor for Ow(1) atom is 0.5, and all other atom sites are fully occupied. Bond-valence sums were calculated and the values for Ba, B, and F atoms are in agreement with their valences.31 Ow(1) atom had a valence sum of 0.35, and all other O atoms had values close to 2. The value for Ow(1) atom indicates a water oxygen. As shown in Figure 2, the fundamental building block (FBB) of the structure contains two three-membered rings of one BO3

Figure 3. Perspective view of the structure of 1 viewed along the c axis. Key: bright green tetrahedra, BO4; green triangles, BO3; yellow circles, F atoms; blue circles, Ba atoms; red circles, water oxygen atoms.

equal occupancy, is coordinated to two Ba atoms and Hbonded to two framework oxygen atoms, as inferred from the Ow(1)···O distances. During this work, we have also synthesized the anhydrous borate fluoride Ba2B5O9F using CsF-BaF2 flux at high temperature. It crystallizes in the monoclinic space group Pc (No. 7) with a = 6.6685(4) Å, b = 11.3476(7) Å, c = 13.2160(7) Å, β = 119.829(3)°, and R1 = 0.035. However, the crystals suffer from twinning. More than 10 crystals were selected from different reaction products and their intensity data collected, but all of them gave nonpositive definite thermal parameters for a number of oxygen and boron atoms. Acceptable structural refinement results have not been obtained. The structure of Ba2B5O9F consists of the following distinct units: six BO4 tetrahedra, four BO3 triangles, four Ba atoms, and two F atoms. The asymmetric unit of the structure contains two FBBs, and each one is a double-ring pentaborate polyanion [B5O12]9− containing two three-membered rings of one BO3 triangle and two BO4 tetrahedra that link through a common BO4 tetrahedron. The descriptor for this FBB is 2Δ3□:⟨Δ2□⟩−⟨Δ2□⟩, which has also been observed in the minerals probertite, NaCa[B5O7(OH)4]·3H2O,34 and hilgardite, Ca2[B5O9]Cl·H2O,35 and the synthetic compounds Ba2[B5O9]Cl·0.5H2O and M2[B5O9]Cl (M = Ca, Sr, Ba, and Pb).18−21 Probertite adopts a 1D chain structure, whereas Ba2[B5O9]Cl·0.5H2O, M2[B5O9]Cl (M = Ca, Sr, Ba, and Pb) and Ba2B5O9F have the hilgardite-type 3D framework structure. It is also noted that Ba2[B5O9]Cl·0.5H2O and M2[B5O9]Cl (M = Ca, Sr, Ba, and Pb) crystallize in the orthorhombic space group Pnn2, but their unit cell dimensions and structural projections along the c-axis look similar to those of 1 (Figure 4a). However, the FBB of the borate chloride differs considerably from that of 1 as shown by Figure 4b. The FBB of Ba2[B5O9]Cl·0.5H2O is chiral, and there are l-B5O12 and dB5O12 configurations according to Ghose.36 These FBBs link by sharing tetrahedral vertices to form infinite chains along the c axis. Two enantiomorphous chains which are glide planerelated are formed from FBBs in l and d configurations. These infinite chains are interlinked to adjacent chains via BO3 triangles, forming a 3D borate framework with 8- and 9-ring channels along the c axis.

Figure 2. A fundamental building block of the structure of 1 containing two BO3 triangles and three BO4 tetrahedron.

triangle and two BO4 tetrahedra which share an edge formed by two tetrahedra, and an additional tetrahedron is attached to a tetrahedral vertex. According to Burns et al.,32 the descriptor for this decorated FBB is 2Δ3□:⟨Δ2□⟩⟨Δ2□⟩□, where Δ and □ represent BO3 and BO4 groups, respectively, and the number of connecting lines between the delimiters indicates the number of borate polyhedra common to two rings. To our knowledge, this FBB is observed for the first time. It is noted that the FBB of the aluminoborate NaBa4(AlB4O9)2Br3 is similar to that of 1 if the decorated AlO4 group is replaced by BO4.26 The FBB of 1 is chiral, and there are two possible stereoisomeric configurations which are related by n-glide plane. These FBBs link by sharing tetrahedral vertices to form infinite chains along the c axis, giving a repeat distance of 6.4812(4) Å. These infinite chains are connected to adjacent chains through triangular corners along the a and b axes, generating a 3D borate framework with 12- and 8-ring channels (Figure 3). The Ba and F atoms are located at sites in the 12ring channels, whereas the water molecules in the 8-ring channels. Ba is coordinated by two F atoms, six O atoms, and one H2O molecule. Each F atom is bonded to four Ba atoms with d(F−Ba) = 2.7886(2) Å for F(1) and 2.6489(2) Å for F(2). The FBa4 tetrahedra share opposite edges to form an infinite chain along the c axis. Chains of this kind have also been observed in SiS2 and BeCl2 as well as in the anion of K[FeS2].33 The water molecule, which is disordered over two sites with C

DOI: 10.1021/acs.inorgchem.8b00908 Inorg. Chem. XXXX, XXX, XXX−XXX

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determined by single-crystal X-ray diffraction. The thermal decomposition products were also characterized. This compound consists of a new fundamental building block and its crystal structure differs considerably from the related minerals and synthetic compounds with similar framework compositions. This work demonstrates once again that high-temperature, high-pressure hydrothermal reaction is a powerful method to synthesize and grow crystals of new phases. Further exploratory synthesis and characterization of metal borates and related materials for nonlinear optical applications is in progress.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.8b00908. SHG measurement results, X-ray powder diffraction patterns, and the connectivity between BO4 groups and Ba2+ cations (PDF)

Figure 4. (a) Projection of the structure of 1 (left) and Ba2[B5O9]Cl· 0.5H2O (right). Key: green polyhedra, BO4 and BO3; yellow circles, F or Cl atoms; blue circles, Ba atoms; red circles, water oxygen atoms. (b) Section of an infinite chain parallel to the c axis. The fundamental building block is highlighted in red. 11

B MAS NMR Spectroscopy. 11B is a spin-3/2 nuclide with high natural abundance and high sensitivity. Tetrahedral BO4 has a narrow and symmetric absorption peak because of the small quadrupole interaction, whereas the trigonal BO3 shows a significant second-order quadrupolar coupling resulting in a broad and asymmetric line shape.37,38 As shown in Figure 5

Accession Codes

CCDC 1832980 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_ [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Pin-Hsun Hsieh: 0000-0003-3854-9034 Kwang-Hwa Lii: 0000-0003-3150-1361 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We thank the Ministry of Science and Technology of Taiwan for financial support.

Figure 5. 11B MAS NMR of 1 collected at 11.74 T.

a broad resonance from 8 to 20 ppm corresponds to B(3)O3, and the two sharp peaks represent the BO4 groups. Their chemical shifts are in agreement with those in the literature.39 The peaks at 1.383 ppm and −0.144 ppm can be assigned to B(1)O4 and B(2)O4, respectively, on the basis of relative integrated intensity. The peak assignment can also be understood by the connectivity between BO4 groups and Ba2+ cations as shown in Figure S6. The B(1)O4 group coordinates to Ba2+ cations with an average Ba−O bond length of 2.724 Å, whereas the value for B(2)O4 is 2.877 Å. The Ba2+ cations can reduce the electron density around the B atom and the nucleus is deshielded. The interaction between B(1)O4 and Ba2+ cations is stronger and the signal for B(1) is therefore more downfield.

REFERENCES

(1) Savage, N. Ultraviolet Lasers. Nat. Photonics 2007, 1, 83−85. (2) (a) Chen, C.; Liu, L.; Wang, X.; Tressaud, A.; Poeppelmeier, K. Fluorine-Containing Beryllium Borates as Nonlinear Optical Crystals for Deep-Ultraviolet Laser Generation. Photonic Electron. Prop. Fluoride Mater. 2016, 113. (b) Pan, S.; Wang, Y.; Poeppelmeier, K. R. Frequency-Doubling Oxide Flurides, Borate Fluorides, and Fluoroxoborates. Photonic Electron. Prop. Fluoride Mater. 2016, 311. (3) Tran, T. T.; Yu, H.; Rondinelli, J. M.; Poeppelmeier, K. R.; Halasyamani, P. S. Deep Ultraviolet Nonlinear Optical Materials. Chem. Mater. 2016, 28, 5238−5258. (4) Halasyamani, P. S.; Zhang, W. Viewpoint: Inorganic Materials for UV and Deep-UV Nonlinear-Optical Applications. Inorg. Chem. 2017, 56, 12077−12085. (5) Yao, W.; He, R.; Wang, X.; Lin, Z.; Chen, C. Analysis of DeepUV Nonlinear Optical Borates: Approaching the End. Adv. Opt. Mater. 2014, 2, 411−417. (6) Wu, H.; Yu, H.; Yang, Z.; Hou, X.; Su, X.; Pan, S.; Poeppelmeier, K. R.; Rondinelli, J. M. Designing a Deep-ultraviolet Nonlinear Optical Material with a Large Second Harmonic Generation Response. J. Am. Chem. Soc. 2013, 135, 4215−4218.

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CONCLUSION A new borate fluoride, Ba2B5O9F·0.5H2O, has been synthesized by a high-temperature, high-pressure hydrothermal method, characterized by IR, 11B MAS NMR spectroscopy, powder SHG measurement, and TGA, and its crystal structure D

DOI: 10.1021/acs.inorgchem.8b00908 Inorg. Chem. XXXX, XXX, XXX−XXX

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Noncentrosymmetric NaBa4(AlB4O9)2Br3. Cryst. Growth Des. 2013, 13, 3514−3521. (27) Sheldrick, G. M. SAINT, version 7.68A. University of Göttingen: Germany, 2009. (28) Sheldrick, G. M. SADABS, version 2008/1. University of Göttingen: Germany, 2008. (29) Sheldrick, G. M. SHELXTL Programs, version 6.14. Bruker AXS GmbH: Karlsruhe, Germany, 2000. (30) Hayashi, S.; Hayamizu, K. Shift References in High-Resolution Solid-State NMR. Bull. Chem. Soc. Jpn. 1989, 62, 2429−2430. (31) Brown, I. D.; Altermatt, D. Bond-valence Parameters Obtained from a Systematic Analysis of the Inorganic Crystal Structure Database. Acta Crystallogr., Sect. B: Struct. Sci. 1985, 41, 244−247. (32) Burns, P. C.; Grice, J. D.; Hawthorne, F. C. Borate Minerals. I. Polyhedral Clusters and Fundamental Building Blocks. Can. Mineral. 1995, 33, 1131−1151. (33) Müller, U. Inorganic Structural Chemistry; John Wiley & Sons: Chichester, 1992; Chpt. 15. (34) Menchetti, S.; Sabelli, C.; Trosti-Ferroni, R. Probertite, CaNa[B5O7(OH)4]·3H2O a Refinement. Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1982, 38, 3072−3075. (35) Burns, P. C.; Hawthorne, F. C. Refinement of the Structure of Hilgardite-1A. Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1994, 50, 653−655. (36) Ghose, S. Stereoisomerism of the Pentaborate Polyanion [B5O12]9‑, Polymorphism and Piezoelectricity in th Hilgardite Group of Minerals: A Novel Class of Polar Borate Zeolite. Am. Mineral. 1982, 67, 1265−1272. (37) MacKenzie, K. J. D.; Smith, M. E. Multinuclear Solid-State NMR of Inorganic Materials. Amsterdam, 2002; Chapter 7. (38) Kroeker, S.; Stebbins, J. F. Three-Coordinated Boron-11 Chemical Shifts in Borates. Inorg. Chem. 2001, 40, 6239−6246. (39) Turner, G. L.; Smith, K. A.; Kirkpatrick, R. J.; Oldfield, E. Boron-11 Nuclear Magnetic Resonance Spectroscopic Study of Borate and Borosilicate Minerals and a Borosilicate Glass. J. Magn. Reson. 1986, 67, 544−550.

(7) Wu, H.; Yu, H.; Zhang, W.; Cantwell, J.; Poeppelmeier, K. R.; Pan, S.; Halasyamani, P. S. Top-Seeded Solution Crystal Growth and Linear and Nonlinear Optical Properties of Ba4B11O20F. Cryst. Growth Des. 2017, 17, 1404−1410. (8) Zhang, G.; Liu, Z.; Zhang, J.; Fan, F.; Liu, Y.; Fu, P. Crystal Growth, Structure, and Properties of a Non-Centrosymmetric Fluoride Borate, Ba3Sr4(BO3)3F5. Cryst. Growth Des. 2009, 9, 3137−3141. (9) Yu, H.; Wu, H.; Pan, S.; Yang, Z.; Su, X.; Zhang, F. A Novel Deep UV Nonlinear Optical Crystal Ba3B6O11F2, with a New Fundamental Building Block, B6O14 Group. J. Mater. Chem. 2012, 22, 9665−9670. (10) Zhang, B.; Shi, G.; Yang, Z.; Zhang, F.; Pan, S. Fluorooxoborates: Beryllium-Free Deep-Ultraviolet Nonlinear Optical Materials without Layered Growth. Angew. Chem., Int. Ed. 2017, 56, 3916−3919. (11) Han, S.; Wang, Y.; Zhang, B.; Yang, Z.; Pan, S. A Member of Fluorooxoborates: Li2Na0.9K0.1B5O8F2 with the Fundamental Building Block B5O10F2 and a Short Cutoff Edge. Inorg. Chem. 2018, 57, 873− 878. (12) Chen, C.; Wang, Y.; Xia, Y.; Wu, B.; Tang, D.; Wu, K.; Wenrong, Z.; Yu, L.; Mei, L. New Development of Nonlinear Optical Crystals for the Ultraviolet Region with Molecular Engineering Approach. J. Appl. Phys. 1995, 77, 2268−2272. (13) Wu, B.; Tang, D.; Ye, N.; Chen, C. Linear and Nonlinear Optical Properties of the KBe2BO3F2 (KBBF) Crystal. Opt. Mater. 1996, 5, 105−109. (14) Chen, C.; Xu, Z.; Deng, D.; Zhang, J.; Wong, G. K. L.; Wu, B.; Ye, N.; Tang, D. The Vacuum Ultraviolet Phase-matching Characteristics of Nonlinear Optical KBe2BO3F2 Crystal. Appl. Phys. Lett. 1996, 68, 2930−2932. (15) Chen, C.; Wang, Y.; Wu, B.; Wu, K.; Zeng, W.; Yu, L. Design and Synthesis of an Ultraviolet-transparent Nonlinear Optical Crystal Sr2Be2B2O7. Nature 1995, 373, 322−324. (16) Chen, C.; Luo, S.; Wang, X.; Wang, G.; Wen, X.; Wu, H.; Zhang, X.; Xu, Z. Deep UV Nonlinear Optical Crystal: RbBe2(BO3)F2. J. Opt. Soc. Am. B 2009, 26, 1519−1525. (17) Chen, C. T.; Wang, G. L.; Wang, X. Y.; Xu, Z. Y. Deep-UV Nonlinear Optical Crystal KBe2BO3F2Discovery, Growth, Optical Properties and Applications. Appl. Phys. B: Lasers Opt. 2009, 97, 9−25. (18) Ferro, O.; Merlino, S.; Vinogradova, S. A.; Pushcharovsky, D. Y.; Dimitrova, O. V. Crystal Structures of Two New Ba Borates Pentaborate, Ba2[B5O9]Cl·0.5H2O and Ba2[B5O8(OH)2](OH). J. Alloys Compd. 2000, 305, 63−71. (19) Zhang, F.; Zhang, F.; Jia, D.; Pan, S. Synthesis, Characterization and Nonlinear Optical Property of the Barium Borate Halide Ba2B5O9Cl·H2O0.5. Mater. Focus 2015, 4, 44−49. (20) Held, P.; Liebertz, J.; Bohaty, L. Crystal Structure of Dibarium Pentaborate Chloride, Ba2B5O9Cl. Z. Kristallogr. - New Cryst. Struct. 2002, 217, 463−464. (21) Egorova, B. V.; Olenev, A. V.; Berdonosov, P. S.; Kuznetsov, A. N.; Stefanovich, S. Yu.; Dolgikh, V. A.; Mahenthirarajah, T.; Lightfoot, P. Lead-Strontium Borate Halides with Hilgardite-Type Structure and Their SHG. J. Solid State Chem. 2008, 181, 1891−1898. (22) Kennedy, G. C. Pressure-Volume-Temperature Relations in Water at Elevated Temperatures and Pressures. Am. J. Sci. 1950, 248, 540−564. (23) Rabenau, A.; Rau, H. Crystal Growth and Chemical Synthesis under Hydrothermal Conditions. Philips Technol. Rev. 1969, 30, 89− 96. (24) McMillen, C. C.; Heyward, C.; Giesber, H.; Kolis, J. Crystal Structures of the Novel Hydrated Borates Ba 2 B 5 O 9 (OH), Sr2B5O9(OH) and Li2Sr8B22O41(OH)2. J. Solid State Chem. 2011, 184, 2966−2971. (25) Wei, Q.; Cheng, J. W.; He, C.; Yang, G. Y. An Acentric Calcium Borate Ca2[B5O9]·(OH)·H2O: Synthesis, Structure, and Nonlinear Optical Property. Inorg. Chem. 2014, 53, 11757−11763. (26) Yu, H.; Pan, S.; Wu, H.; Yang, Z.; Dong, L.; Su, X.; Zhang, B.; Li, H. Effect of Rigid Units on the Symmetry of the Framework: Design and Synthesis of Centrosymmetric NaBa4(B5O9)2F2Cl and E

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