In this work, we have performed Raman scattering measurements in Ba 2 BiSbO 6 ceramics in the temperature range from 10 to 573 K. The Raman spectra were examined using group theory to analyze the decomposition of the reducible representation of the vibrational modes and with a virtual octahedral model. At room temperature, five modes were observed. At low temperatures, the spectra subtly showed the rhombohedral-monoclinic phase transition, which was identified by changes in the Raman intensity of the bending and symmetrical stretching SbO 6 octahedral modes. The cubic-rhombohedral phase transition was not clearly evident in the high-temperature Raman data.
The electric properties of the complex double perovskite Ba 2 BiSbO 6 have been investigated using impedance spectroscopy in the frequency range from 1 Hz up to 1 MHz and in the temperature range from room temperature up to 560 K. There are two contributions to the electrical properties due to the grain and grain boundary. The oxygen vacancies play an important role in the conductivity and strongly increase the dielectric constant at high temperatures. The analysis of the frequency dependence of the conductivity clearly shows the structural phase transition of this compound near 515 K.
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