Temperature Raman scattering study of CaAl0.5Ta0.5O3 perovskite crystal

Temperature Raman scattering studies were performed for CaAl_0.5Ta_0.5O₃ crystal. This material features NaCl-type ordering of Al³⁺ and Ta⁵⁺ ions at the B-site superimposed onto b⁻b⁻c⁺ octahedral tilting. Because of the existing twin-related domains in crystal structure, the micro-Raman measurements were carried out at room temperature. Some differences in Raman spectra obtained using macro- and micro-Raman system were revealed. Most of the Raman modes show monotonous red-shift with the increase in temperature. Only the cubic-like fully symmetric A_1g mode slightly increases its frequency with an increase in temperature. There are no uncontinuous changes of mode frequency in the temperature range studied. It indicates the stable character of static distortions of crystal structure relying on changes of octahedra tilt angle.