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2005
Niobium
I 5100
35- 018
Mixed-Metal Tellurites: Synthesis, Structure, and Characterization of
Na1.4Nb 3Te4.9O18 and NaNb3Te4O16. — Single crystals of Na1.4 Nb3Te4.9O18 are prepared by solid state reaction of Nb2O5, Na2CO3, and TeO2 (Pt crucible, 760 °C, 15 h,
72% yield). The compound crystallizes in the monoclinic space group C2/m with Z = 4.
Crystals of NaNb3Te4O16 are obtained from the reaction of Nb 2O5, Na2TeO3, and TeO2
(Pt crucible, 8000 °C, 15 h, 32% yield). This compound crystallizes in the monoclinic
space group P21/m with Z = 2. Both compounds exhibit three-dimensional structures
composed of NbO6 octahedra, TeO4, and TeO3 polyhedra. The Nb5+ and Te4+ cations are
in asymmetric coordination environments attributable to second-order Jahn-Teller effects. The compounds are further characterized by IR and Raman spectroscopy,
UV/Vis diffuse reflectance spectroscopy, TGA, and dielectric measurements. —
(OK, K. M.; HALASYAMANI*, P. S.; Inorg. Chem. 44 (2005) 11, 3919-3925; Dep.
Chem., Univ. Houston, Houston, TX 77204, USA; Eng.) — Schramke
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