Role of initial potassium excess on the properties of potassium tantalate ceramics
authors Tkach, A; Vilarinho, PM; Almeida, A
nationality International
journal JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
author keywords Tantalates; Ceramics; Powders-solid state reaction; Defects; Dielectric properties
keywords MICROWAVE DIELECTRIC-PROPERTIES; KTAO3; TEMPERATURE
abstract Potassium tantalate (KTaO(3) - KT) ceramics with controlled initial K/Ta ratio=1, 1.02 and 1.05 were synthesised by solid-state reaction. Crystal structure and microstructure of the sintered ceramics were examined by XRD and SEM/EDS, respectively. Their dielectric properties were then studied as a function of the temperature over the radio frequency range. Ceramics with K/Ta ratio=1 exhibits potassium-poor secondary phases, in contrast to ceramics with initial K/Ta ratio = 1.05, where no secondary phases are detected. Moreover, the grain size increases dramatically with K/Ta ratio >1. The quantum paraelectric behaviour of KT ceramics is weakly affected by the variation of K/Ta ratio and their dielectric response is well described by Barrett's equation. Though, no anomaly is induced in the dielectric permittivity by potassium excess, it yields an increase of its lowest temperature magnitude up to similar to 4000, which is to the best of our knowledge, the highest value ever reported for KT ceramics. (C) 2011 Elsevier Ltd. All rights reserved.
publisher ELSEVIER SCI LTD
issn 0955-2219
year published 2011
volume 31
issue 13
beginning page 2303
ending page 2308
digital object identifier (doi) 10.1016/j.jeurceramsoc.2011.06.012
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000293931000016
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