Experimental researches of phase transitions in ceramics on the basis of barium-strontiumtitanate

Abstract

Application of piezoelectric crystals in acoustics demands special attention as for their nonlinear properties. It is necessary to consider piezoelectric nonlinearity and electrostriction of these crystals besides elastic nonlinearity. Nonlinear acoustic effects in piezoelectric crystals are very interesting, in particular at temperature close to temperature of phase transition. In a vicinity of phase transition the crystal lattice is labile, strong anharmonicity of phonon – phonon and photon – phonon interactions have been observed. In some solid state and liquid substances at certain external influences the phase transformations take place without change of a physical state. Thus, on the basis of described method and with various samples piezoelectric ceramics it is possible to investigate the acoustic anisotropy formed by rotating electric field at the temperatures below the 50°С.