resumo
Polar fluctuations were found in KTaO3 when K+ was substituted with Mn2+ on the A-site. The temperature dependence of the real part of the dielectric permittivity of (K1-2xMnx square(x))TaO3 ceramics (x=0-0.05) shows a diffuse maximum between 50-100 K in the frequency range 10(2)-10(6) Hz, shifting to higher temperature with increasing frequency and Mn content. The results are analyzed using a modified Curie-Weiss law, the Cole-Cole equation and the Arrhenius law. Here it is suggested that the observed relaxor-type dielectric behavior is attributed to the formation of electric dipoles originating from two distinct sources; one from an atomic off-center position when Mn2+ substitutes for K+ and one from the anion deficiencies formed by these aliovalent substitutions. (C) 2010 American Institute of Physics. [doi:10.1063/1.3481857]
palavras-chave
DIELECTRIC RESPONSE; FERROELECTRICS
categoria
Physics
autores
Axelsson, AK; Pan, YY; Valant, M; Vilarinho, PM; Alford, NM
nossos autores
Paula Maria Lousada Silveirinha Vilarinho
Vice-Diretoragradecimentos
The authors would like to acknowledge Victor Bovtun and Jan Petzelt, Institute of Physics of the ASCR, Prague, Czech Republic for their helpful discussions. Also acknowledgment to Alexander Tkach at Department of Physics of Science Faculty, University of Porto, Portugal for his kind assistance of low frequency measurements. We acknowledge support from the Engineering and Physical Sciences Research Council and the Leverhulme Trust.