Effect of Temperature and Frequency on Dielectric Properties of Aurivillius Type Sr_0.9Pb_0.1Bi_2-xLa_xNb₂O₉ Ferroelectric Ceramics

Abstract

In the present work, keeping a small quantity of lead (10 atomic %) at Sr site, the contents of La have been varied at Bi site to study the behavior of SBN. Samples of compositions Sr_0.9Pb_0.1Bi_{2 − x} La _x Nb₂O₉ (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°C for pure SBN to 230°C for La (x = 0.20) doped sample. The variation of conductivity with temperature in these samples is also reported.

Keywords:

• Dielectric constant
• dielectric loss
• Curie temperature
• ferroelectric ceramics

Acknowledgment

The authors would like to thank Prof. P. B. Sharma, Principal, Delhi College of Engg., for his support and encouragement for the present work.