Changing dielectric properties of ferroelectric ceramics by mechanical stresses

The thermodynamical consideration of the changes in tensor components of dielectric susceptibilities of ferroelectric single-domain crystals under the influence of one-dimensional mechanical stress is done. It has been shown that the registration of such changes together with non-180/spl deg/ reorientations of domains allows us to give an adequate description of the microwave dielectric permittivity behaviour of ferroelectric ceramics. Quantitative evaluation of 90/spl deg/ reorientations share in BaTiO/sub 3/ ceramics with crystallites of different sizes have been done. Experimental data for BaTiO/sub 3/ and PZT ceramics are presented.