Synthesis, structure refinement and vibrational spectroscopy studies of the Bi1-xTa1-xTe2xO4 (0 ≥ x ≥ 0.2) solid solution with stibiotantalite type structure

In the present study we report the synthesis, crystal structure and vibrational spectroscopy studies of Bi-1_Ta-x(1)_xTe2xO4 orthorhombic solid solutions (0 <= x <= 0.2). Rietveld refinements showed that this solid solution is continuous adopting Pnna (no.52) space group. The structure is formed by (Bi/Te-(1))0(6) and (Ta/Te-(2))0(6) octahedra.The (Ta/Te-(2))0(6) octahedra linked over four corners and thus the structure can be viewed as consisting of sheets of (Ta/Te-(2))0(6)vertical bar(3)- units separated by Bi3+ cations. The infrared spectra of Bi-1_Ta-x(1)_(x)Te(2x)O(4)oxides at room temperature showed some characteristic vibration bands assigned to Bi -O and Ta-O vibrations. Raman spectra of this crystalline solid solution series are interpreted by means of "internal mode" approach. Assignments of the Ta-O and Bi-O vibrational stretching modes, as well as some of other modes, have been made.(C) 2012 Elsevier B.V All rights reserved.