Dielectric behavior of nanocomposites of lead sulphide and ferroelectric glass ceramics

Abstract

Glass ceramics containing micrometer-sized lead zirconate titanate have been synthesized and nanometer-sized lead sulphide (PbS) phase has been grown within these by treatment in hydrogen sulphide gas. The PbS particle sizes vary from 4.4 to 15.3 nm. Dielectric measurements on the nanocomposites have been carried out in the temperature range 120-300 K. The dielectric constant values for composites containing PbS exhibit drastic increase as compared to those of the glass ceramic samples. For specimens with PbS size varying from 4.4 to 15.3 nm the corresponding volume fraction of PbS being 0.07 and 0.14 the values range from 900 to 3500 at a frequency of 1 kHz. Bergman's [D. J. Bergman, Phys. Rev. C 43, 377 (1978)] analytical formulation with some density functions has been used to calculate the value of effective dielectric permittivity for the various nanocomposites. The theoretical values do not show any agreement with the experimentally observed data. However, more spectral weight functions need to be tried before any conclusion can be drawn regarding the mechanism responsible for the present experimental data. © 1998 American Institute of Physics.