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Phase Equilibria and Dielectric Properties in Perovskite-Like (1-x)LaCa0.5Zr0.5O3-xATiO3 (A=Ca,Sr) Ceramics

Published

Author(s)

Igor Levin, Terrell A. Vanderah, T J. Coutts, S M. Bell

Abstract

Phase equilibria and dielectric properties were analyzed for selected compositions in both LaCao 5ZrO.503-CaTiO3 (LCZ-CT) andLaC@.5Zro,O,-SrTiO3 (LCZ-ST) systems using X-ray powder diffraction and transmission electron microscopy. The end-memberLaCao.,Zro.503 does not occur as a single phase, but rather as a mixture of a perovskite-type phase with approximate compositionLao.94CaO.53ZrO.5303 Plus a minor amount of La,03. This perovskite phase exhibited a combination of 1: I ordering of Ca and Zr on thB-sites and octahedral tilting. In the (1-x)LCZ-xCT system, the compositions x= 1/3 and x= 1/2 yielded single phases with perovsklike structures featuring similar 1: I B-site ordering superimposed onto octahedral tilting. The x = 1/2 composition in the LCZ-STsystem resides in a two-phase field and contains a major perovskite phase and La2O3; the B-cations in the perovskite phase remaindisordered at all temperatures. The approximate boundaries of perovskite-like phase fields in the La2O,-AT'03-CaZrO, (A=Ca,Sr)systems were outlined, as well as schematic diagram for perovskite B-cation ordering transitions in the LCZ-CT system. The dieletproperties of the compositions investigated were measured at microwave frequencies and were correlated with the observed structurebehavior.
Citation
Journal of Materials Research
Volume
17
Issue
No. 7

Keywords

cation ordering dielectric properties, perovskite, phase equilibria, transmission electron microscopy, zirconates

Citation

Levin, I. , Vanderah, T. , Coutts, T. and Bell, S. (2002), Phase Equilibria and Dielectric Properties in Perovskite-Like (1-x)LaCa<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>3</sub>-xATiO<sub>3</sub> (A=Ca,Sr) Ceramics, Journal of Materials Research (Accessed April 18, 2024)
Created July 1, 2002, Updated February 19, 2017