The thermal behavior of mixed-layer Aurivillius phase Bi13Fe5Ti6O39

The mixed-layer perovskite-like compound Bi13Fe5Ti6O39 with Aurivillius phase structure Bim+1Fem−3Ti3O3m+3 (m = 5.5) was synthesized by the solid-state reactions method. The thermal behavior of Bi13Fe5Ti6O39 in the range from 2 to 1450 K was studied by the differential scanning calorimetry, the impedance spectroscopy and the analysis of temperature dependences of the permittivity and magnetization. The temperature of decomposition and the temperatures of phase transitions were determined. It was shown that Bi13Fe5Ti6O39 combines the ferroelectricity with the magnetic ordering below the temperature 173 ± 4 K. The data obtained in thermal measurements showed that the thermal behavior of mixed-layer compound Bi13Fe5Ti6O39 and Aurivillius phases Bim+1Fem−3Ti3O3m+3 with an integer m was analogous. The mechanism of thermal degradation Bi13Fe5Ti6O39 was described as sequential peritectic decomposition into compounds of the same homologous series having a smaller m (m ≤ 5.5). Bi13Fe5Ti6O39 has a semiconductor-like type of conductivity and undergoes high- and low-temperature phase transitions.