Orientational Relaxation in Ferroelectrics of Tetragonal Symmetry

The energy absorption caused by rotation of the spontaneous and induced polarization vectors in external longitudinal alternating-sign stress field is calculated for the barium titanate ferroelectric of tetragonal symmetry. The acoustic absorption coefficient, the internal friction, and the E effect together with their frequency and orientational dependences are derived in terms of elastic and piezoelastic constants, components of the electrostriction tensor, and rotational dissipation coefficients. The given dissipation type can dominate in ferroelectric magnets with strong coupling of their elastic, electrical, and magnetic subsystems.