DETERMINATION OF SPATIAL DISTRIBUTION OF POLARIZATION AND SPACE CHARGE IN FERROELECTRIC CERAMICS USING LASER INTENSITY MODULATION METHOD.

A method for measuring the spatial distribution of combined polarization and space charge in poled polymer electrets was recently developed. The technique, called the laser intensity modulation method, was modified in order that it could be used with ferroelectric ceramic samples having thicknesses of the order of 1 mm rather than the tens of micrometers found in conventional polymer films. PZT ceramics with a high Sn content and with compositions close to the PbZrTiO//3 phase boundary were studied. The effects of poling conditions on polarization and space charge distributions in the two ferroelectric phases were examined. The distributions were unexpectedly nonuniform, possibly due to large amounts of trapped space charge.