DIELECTRIC, PYROELECTRIC AND PIEZOELECTRIC PROPERTIES OF CALCIUM-MODIFIED LEAD MAGNESIUM TANTALATE-LEAD TITANATE CERAMICS

Dielectric, pyroelectric and piezoelectric properties of relaxer ferro electrics in solid solution, formulated 0.65(Pb1-xCax)(Mg1/3Ta2/3)O-3- 0.35PbTiO(3), have been investigated. Complete single-phase perovskite with high density was obtained with all samples fired at 1250 degrees C. The Curie temperature and pyroelectric peak temperature decrease a lmost linearly as the amount of Ca in the compositions increases. The transition temperature of the solid solutions can easily be controlled by Ca additions in the PMT-PT. Dielectric, pyroelectric and piezoelec tric constants achieved maximum values for x=0.02. Compositions near 0 .65PMT-0.35PT-0.12Ca have been identified to have high dielectric cons tants (similar to 15000) and low dissipation factors (similar to 0.015 ) near room temperature.