title: Synthesis, Crystal Structure, and Properties of Bi3TeBO9or Bi3(TeO6)(BO3): A Non-Centrosymmetric Borate-Tellurate(VI) of Bismuth.
abstract: Pale-yellow single crystals of the new borate tellurate(VI) Bi3TeBO9were obtained by reaction of stoichiometric amounts of Bi2O3, B2O3, and Te(OH)6at 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 BO3units and nearly undistorted TeO6octahedra. The Bi3+cations are located in between in octahedral voids. The BiO6octahedra are significantly distorted to a [3+3] pattern (2.25/2.50 Å) due to the ns2configuration. 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 TeVIand BiIIIin octahedral voids and BIIIin trigonal- planar voids. The vibrational spectra show the typical features of BO3and TeO6units with a significant10B/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 of11B show an anisotropic signal with a quadrupole coupling constant of CQ=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). Bi3TeBO9decomposes in air at 825 °C to Bi2TeO5.
authors.affiliation: Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität, Albertstraße 21, 79104, Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Daub
authors.affiliation: Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität, Albertstraße 21, 79104, Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Krummer
authors.affiliation: Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität, Albertstraße 21, 79104, Freiburg, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Hoffmann
authors.affiliation: Institut für Geowissenschaften, Abt. Kristallographie, Goethe-Universität, Altenhöferallee 1, 60438, Frankfurt am Main, Germany.
authors.forename: Lkhamsuren
authors.initials: L
authors.lastname: Bayarjargal
authors.affiliation: Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität, Albertstraße 21, 79104, Freiburg, Germany.|Freiburger Materialforschungszentrum FMF, Albert-Ludwigs-Universität, Stefan-Meier-Straße 25, 79104, Freiburg, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Hillebrecht
keywords: SHG; borate tellurate(VI); crystal structure; non-centrosymmetric; synthesis