Acoustic anomalies in SrTiO$_{3}$–BiFeO$_{3}$ solid solutions

The results of acoustic investigations of solid solutions SrTiO$_{3}$–BiFeO$_{3}$in the temperature range from 100 to 650 K have been presented. The measurements of the velocity and attenuation of the longitudinal ultrasonic mode at a frequency of 10 MHz were carried out by the pulse-echo method. The observed anomalies in velocity and attenuation correlate with the maxima of the dielectric constant in the temperature range of the relaxor state. In addition, the attenuation peaks in the temperature range 400–600 K, which define Burns and T$^*$ temperatures, which are characteristic of relaxors, have been identified. The obtained results have allowed the clarifying of the phase diagram of the solid solution system SrTiO$_{3}$–BiFeO$_{3}$.