Homogeneity of Large-scale PLZT Ceramics

Optical transmittance, grain size and ferroelectric properties are measured along the radial direction of large-scale (40-50 mmφ) PLZT-7.6/70/30 ceramics in order to evaluate the homogeneity in a plate. Ferro-antiferroelectric transition temperatures (Th) are measured by the pyroelectric method. In addition, compositional fluctuations in a PLZT plate are discussed by measuring the variation of Th. Results indicate that grain size (Gs), coercive field (Ec) and remanent polarization (Pr) are uniform within experimental errors through large-scale specimens. Optical transmittance is also uniform except at the fringe of a plate. Moreover, the optical transmittance is found to be sensitive to hot-pressing conditions and inhomogeneities in a plate, while Ec and Pr are not sensitive. Consequently, the measurement of the optical transmittance is effective in the evaluation of homogeneities in large-scale PLZT plates. Transition temperature variation indicates that the fluctuation of Zr concentration through a ceramic plate is 0.04 mol % by assuming La distribution to be uniform; the fluctuation of La concentration is 0.01 at % by assuming a uniform Zr distribution.