Dynamic Spectral Response of Solid Solutions of the Bismuth-Strontium Ferrite Bi 1- x Sr x FeO 3- δ in the Frequency Range 0.3-200 THz

Ceramic samples of Bi1 − x Sr x FeO3 − δ have been investigated using X-ray diffraction analysis, Raman spectroscopy, and infrared spectroscopy. It has been shown that the spectra of these solid solutions should be considered as a superposition of resonant phonon responses of the cubic perovskite and a relaxation response. No relaxators are observed in the pure compounds BiFeO3 and SrFeO3 − δ. It has been found that two concentration phase transitions occurs with the symmetry changes \(R3c \leftrightarrow Pm\bar 3m\) in the range 0.1 < x < 0.2 and \(Pm\bar 3m \leftrightarrow P4mm\) in the range 0.8 < x < 1.0.