The effect of electrode materials on measured piezoelectric properties of ceramics and ceramic-polymer composites

The effect of electrodes on the measurement of dielectric, piezoelectric, and mechanical properties of lead zirconate-titanate (PZT) ceramics and of 1-3 connectivity ceramic-polymer composites was studied. While fired silver and evaporated silver electrodes were found to have little effect on the measurements, silver epoxy electrodes resulted in a significant reduction in the measured values of the dielectric and piezoelectric constants. In the 1-3 composites the effect was independent of the ceramic content. The observations can be understood on the basis of a model which takes account of the capacitance at the ceramic-electrode interface due to the presence of pores and binder material. It was found that the effect of the electrodes can be nullified by the deposition of a thin metal film on the specimen before the electrode was applied.