Raman-spectroscopic investigation of Ba2InTaO6Ba2InTaO6 and Sr2InTaO6Sr2InTaO6 perovskites

Raman spectroscopy was employed to investigate the structures and phonon modes of Ba2InTaO6Ba2InTaO6 and Sr2InTaO6Sr2InTaO6 ceramics. It was found that Ba-based samples belong to the tetragonal P4/mncP4/mnc (#128 or D4h6) space group, while Sr-based materials belong to the monoclinic P21/nP21/n (#14 or C2h5) space group. Low-temperature measurements did not show any phase transition down to 77 K. Lorentzian lines were used to fit the experimental data, which presented 14 phonon modes for Ba2InTaO6Ba2InTaO6 and 24 modes for Sr2InTaO6Sr2InTaO6, in perfect agreement with the theoretical factor-group analyses for the proposed structures. This paper reports, for the first time, a tetragonal P4/mncP4/mnc structure for an indium-containing perovskite material.

Raman analysis of Ba2InTaO6Ba2InTaO6 and Sr2InTaO6Sr2InTaO6 perovskites. Two different spectral profiles are clearly observed, which indicates that the ceramics likely to occur in different structures. Barium perovskites exhibit 14 Raman-active bands in a tetragonal structure, while strontium-based materials show 24 phonon modes associated with a lower-symmetry structure (monoclinic).Figure optionsDownload as PowerPoint slide