Effect of Temperature and Frequency on Dielectric Properties of Aurivillius-Type Sr_(0.9)Pb_(0.1)Bi(2-x)La_xNb_2O_9 Ferroelectric Ceramics

摘要

In the present work, keeping a small quantity of lead (10 atomic percent) at Sr site, the contents of La have been varied at Bi site to study the behavior of SBN. Samples of compositions Sr_(0.9)Pb_(0.1)Bi(2-x)La_xNb_2O_9(with x = 0.0 to 0.2) were prepared by solid state reaction method. X ray diffraction analysis reveals the formation of single phase perovskite structure. Although the perovskite structure of SBN is retained, slight changes in the lattice parameters are observed. Tetragonal strain is observed to decrease in the La doped samples. Dielectric constant and dielectric loss have been measured as a function of temperature(300-800 K) and frequency (100 Hz-100 kHz). It is observed that there is an overall decrease in dielectric constant with increasing lanthanum content. It is also observed that dielectric loss decreases with increasing amount of La content. Curie temperature is observed to decrease from 440 deg C for pure SBN to 230 deg C for La (x = 0.20) doped sample. The variation of conductivity with temperature in these samples is also reported.