PIEZOELECTRICITY AND MICROSTRUCTURES OF MODIFIED LEAD TITANATE CERAMICS

Modified lead titanate ceramics with the composition Pb0.70 Ca0.30 Ti0.94 (Co1/2W1/2)0.06 O3 with 1 mol% MnO were prepared by the mixed oxide route. By varying the sintering temperature, ceramics with average grain sizes between 2.8 and 5μm were obtained. An increase in grain size resulted in an increased electromechanical anisotropy and a decreased dielectric constant. Transmission electron microscopy was used to examine the ferroelectric domain boundaries and intergranular phases. Indications are that during poling favourably oriented domains approximately doubled in size by 90 ° type domain wall switching. Evidence was found for the existence of a vitreous intergranular phase at multiple grain junctions. EDS microanalysis indicated that the amorphous grain boundary phase had a lower lead content than the bulk material. © 1990 Chapman and Hall Ltd.