Flexoelectric polarization of barium strontium titanate in the paraelectric state

The strain-gradient-induced polarization (flexoelectric effect) was investigated in Ba0.67Sr0.33TiO3 (BST) ceramic at temperatures above the 21degreesC Curie point. At 23degreesC the flexoelectric coefficient mu(12) was more than one order of magnitude greater than the highest value measured in lead magnesium niobate ceramic. Over the temperature range of linear Curie-Weiss behavior, the coefficient mu(12) was roughly proportional to the dielectric permittivity; however, the constant of proportionality was higher than predicted for simple ionic solids. The unexpected behavior in the BST ceramic suggests the need for a broader database of flexoelectric coefficients. (C) 2002 American Institute of Physics.