# Relaxor behavior of $K_{0.5}La_{0.5}Bi_2Ta_2O_9$ ceramics

Karthik, C and Ravishankar, N and Maglione, Mario and Vondermuhll, R and Etourneau, J and Varma, KBR (2006) Relaxor behavior of $K_{0.5}La_{0.5}Bi_2Ta_2O_9$ ceramics. In: Solid State Communications, 139 (6). pp. 268-272.

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## Abstract

Potassium lanthanum bismuth tantalate $(K_{0.5}La_{0.5}Bi_2Ta_2O_9)$a new relaxor ferroelectric was synthesized via the solid-state reaction route. X-ray structural studies along with Rietveld refinement confirmed it to be an n = 2 member of the Aurivillius family of oxides and the refined lattice parameters are a = 5.512 (2) nm, b = 5.504 (2) nm and c = 25.072 (4) nm. The appearance of $1/2\{h00\}$ and $1/2\{hk0\}$ type superlattice reflections in the electron diffraction patterns reflected the presence of ordered polar regions. A broad dielectric peak associated with frequency dependent dielectric maximum temperature was observed. The value of the diffuseness parameter \gamma = 1.93, obtained from the fit of a modified Curie–Weiss law established the relaxor nature of the title compound. The dielectric relaxation obeyed the Vogel–Fulcher relation wherein $E_a=0.06$ eV and $T_v_f=396 K$. The relaxor behavior was attributed to the local polar ordering on A-sites.

Item Type: Journal Article Copyright of this article belongs to Elsevier. A. Layered perovskites;D. Ceramics;D. Dielectric response Division of Chemical Sciences > Materials Research Centre 07 Nov 2006 19 Sep 2010 04:32 http://eprints.iisc.ernet.in/id/eprint/8839