Relaxor behavior of K0.5la0.5Bi2Nb 2O9 ceramics

Abstract

K0.5La0.5Bi2Nb2O9, a relaxor, was synthesized and the structural studies confirmed it to be an n = 2 member of the Aurivillius oxides. The 1/2{h00} and 1/2{hk0} types of superlattice reflections in the electron diffraction patterns reflected the presence of ordered polar regions. A broad dielectric peak with frequency dependent dielectric maximum temperature was observed. The dielectric relaxation obeyed the Vogel-Fulcher relation wherein Ea=0.04 eV, T f=428 K,and ω0=1010Hz. The diffuseness parameter γ= 2.003 established the relaxor nature and it was attributed to the A-site cationic disorder. The piezoelectric d31 coefficient was 0.5 pC/N at 300 K and 2 pC/N at 480 K. © 2006 American Institute of Physics.