The Pressure Dependence Of The Dielectric Response And Its Relation To The Electrostriction

Based on Landau-Devonshire theory, the effect of elastic stress upon the dielectric response is analyzed for ferroelectric, antiferroelectric, and relaxor ferroelectric materials. It is shown that besides the direct coupling between stress and polarization which leads to the thermodynamic equivalence to direct electrostriction, an extra coupling occurs in systems with non-zero polarization. In ferroelectric and antiferroelectric materials the effect is quite straightforward and relations are derived between stress coefficients and direct electrostriction. For relaxor ferroelectrics the relation cannot be defined thermodynamically because of the dispersive contribution to the response from switching of polar micro regions, however, the qualitative trends can be predicted and are in concert with measured properties.