Particle-Size Effect on the Ferroelectric Phase Transition in PbSc1/2Ta1/2O3 Ceramics

Abstract

The particle-size dependence on the ferroelectric phase transition in nanocrystalline PbSc1/2Ta1/2O3 ceramics has been investigated for particles in the 0.01-0.16 mu m size range. The phase transition was monitored through measurement of the dielectric constant as a function of temperature, variable temperature x-ray diffraction, and differential scanning calorimetry. The c/a tetragonality ratio decreased monotonically with particle size, reducing to unity at 0 degrees C for particles less than or equal to 0.053 mu m in size. The ferroelectric transition temperature T-c decreased gradually and the phase transition became more diffuse in nature as the particle size decreased. Below a mean particle size of 0.02 mu m there was no peak in either the dielectric constant or the differential scanning calorimetry curve as a function of temperature, even though variable temperature x-ray diffraction could detect tetragonality indicative of ferroelectric distortions at sufficiently low temperatures down to the smallest crystallite size of 0.01 mu m. (C) 1998 American Institute of Physics. [S0021-8979(98)07610-5].