X-ray and dielectric studies of Pb4.9Ca0.1Ge3O11 ferroelectric ceramics

Polycrystalline samples of modified lead germanate, Pb4.9Ca0.1Ge3O11, have been prepared by a solid-state reaction technique. Preliminary structural studies reveal that the basic structure of Pb5Ge3O11 remains unaltered by incorporation of a small amount of Ca2+ ions in place of divalent Pb2+ ions. Dielectric permittivity and loss were measured both as a function of frequency (100 Hz to 10 kHz) and temperature (room temperature to 200 degrees C). Dielectric anomaly or phase transition in the compound was observed at a temperature of 118 +/- 2 degrees C. Diffusivity in the phase transition has been found to be 1.4. ac conductivity and activation energ,oy in the compound have been calculated from dielectric data.