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 Bi1−xTa1−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))O6 and (Ta/Te(2))O6 octahedra, The (Ta/Te(2))O6 octahedra linked over four comers and thus the structure can be viewed as consisting of sheets of [(Ta/Te(2))O6]3− units separated by Bi3+ cations. The infrared spectra of Bi1−xTa1−xTe2xO4 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.