Role of interfacial charge in the piezoelectric properties of ferroelectric 0-3 composites

We investigated the effects of compensating charges (at the inclusion-matrix interface) on the piezoelectric properties of ferroelectric 0-3 composites. Our previously developed model [C. K. Wong, Y. M. Poon, and F. G. Shin, J. Appl. Phys. 90, 4690 (2001)] has been extended to include the additional contribution from the deformation of the inclusion particles due to the applied stress in the piezoelectric measurement. The relative significance of this contribution is mainly determined by the amount of compensating interfacial charge, which is significantly governed by the degrees of poling of the constituent materials in the composite sample. This model provides an explanation to an anomaly in the piezoelectric coefficients of 0-3 composite samples with the matrix and inclusion phases polarized in opposite directions. Explicit expressions in closed form have been derived for the effective d(33), d(31), and d(h) coefficients. After taking into consideration the degree of poling of the constituents and the effects of the compensating interfacial charges, theoretical predictions show good agreement with published experimental data. Goodness of fit is not limited to low volume concentration of inclusions. (C) 2005 American Institute of Physics.