Raman scattering study of phase transition in Lu₂O₃-Ta₂O₅

The lutetium tantalate compounds obtained from Lu₂O₃-Ta₂O₅ with a molar ratio of 0.515:0.485 were studied by Raman scattering and x-ray diffraction. The results of the room temperature Raman scattering indicate that the sample has a phase transition between 1830 ℃ and 1872 ℃, the polycrystalline is a mixture of M'-LuTaO₄ and Lu₃TaO₇ (Fm3m) when it is prepared at 1830 ℃, and a mixture of M-LuTaO₄ (B112/b) and Lu₃TaO₇ (Fm3m) when it is prepared at above 1872 ℃. The sample melts at a temperature of 2050 ℃. The phase transition of the sample prepared at 2050 ℃ was also investigated by the high-temperature Raman spectra, and the result indicates that no phase transition occurs between room temperature and 1400 ℃, which is consistent with the results from the x-ray diffraction.