Synthesis, Crystal Structure, and Properties of Bi₃TeBO₉ or Bi₃(TeO₆)(BO₃): A Non-Centrosymmetric Borate-Tellurate(VI) of Bismuth

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• 作者：Dr. Michael Daub ; Michael Krummer ; Dr. Anke Hoffmann ; Dr. Lkhamsuren Bayarjargal and Prof. Harald Hillebrecht
• 刊名：Chemistry - A European Journal
• 出版年：2017
• 出版时间：January 26, 2017
• 年：2017
• 卷：23
• 期：6
• 页码：1331-1337
• 全文大小：2030K
• ISSN：1521-3765

文摘

Pale-yellow single crystals of the new borate tellurate(VI) Bi₃TeBO₉ were obtained by reaction of stoichiometric amounts of Bi₂O₃, B₂O₃, and Te(OH)₆ at 780 °C. The non-centrosymmetric crystal structure (P6₃, Z=2, a=8.7454(16), c=5.8911(11) Å, 738 refl., 43 param, R1=0.037, wR2=0.093) contains isolated trigonal-planar BO₃ units and nearly undistorted TeO₆ octahedra. The Bi³⁺ cations are located in between in octahedral voids. The BiO₆ octahedra are significantly distorted to a [3+3] pattern (2.25/2.50 Å) due to the ns² configuration. According to the structural features, the formula can be written as Bi₃(TeO₆)(BO₃). Alternatively, the structure can also be described as hcp of oxygen with Te^VI and Bi^III in octahedral voids and B^III in trigonal- planar voids. The vibrational spectra show the typical features of BO₃ and TeO₆ units with a significant ¹⁰B/¹¹B isotopic splitting of the IR-active B−O valence mode (1248 and 1282 cm⁻¹). The UV/Vis spectrum shows an optical band edge with an onset around 480 nm (2.6 eV). MAS-NMR spectra of ¹¹B show an anisotropic signal with a quadrupole coupling constant of C_Q=2.55 MHz. and a very small deviation from rotational symmetry (η=0.2). The isotropic chemical shift is 20.1 ppm. The second harmonic generation (SHG) test was positive with an activity comparable to potassium dihydrogen phosphate (KDP). Bi₃TeBO₉ decomposes in air at 825 °C to Bi₂TeO₅.