Electrostrictive and piezoelectric effect in BaTiO3 and PbZrO3

Order-disorder mechanism is a part of phase transition nature in the ABO(3) perovskites. It is related with the existence of polar regions, which dynamics in the electric field determines the dielectric response near T-c. Temperature dependence of mechanical strain connected with polarisation change in the paraelectric phase has been investigated for the BaTiO3 and PbZrO3 single crystals. Existence of polar regions influences the electrostrictive properties and induces the piezoelectric effect in the paraelectric phase. A non-linear temperature dependence of the electrostrictive coupling between the macroscopic strain and macroscopic polarisation has been found above T-c.