MICROSTRUCTURAL EFFECTS ON DIELECTRIC AND PIEZOELECTRIC BEHAVIOR OF CALCIUM-MODIFIED LEAD TITANATE CERAMICS

This work presents an analysis on the main microstructural parameters that affect the dielectric and piezoelectric behavior of ceramics of calcium-modified lead titanate with Ca/Pb = 26/74. To this aim, ceramics were prepared under different sintering conditions to get a series of materials with different microstructures. Compositional and microstructural characterization was achieved by x-ray diffraction, energy dispersion spectroscopy, and optical microscopy. Computerized image analysis was carried out on the micrographs to determine grain and pore size distributions. These distributions were thoroughly analyzed using probability plots. Electromechanical coupling factors and piezoelectric coefficients were measured by the resonance method on thickness poled thin disks and rectangular bars. A similar combined effect of the grain size and the percentage of porosity on the inverse of the permittivity, the coupling factors at room temperature, and the temperature behavior of the electromechanical coupling factor k(31) is found.