resumo
Structural, dielectric and magnetic properties of dense Gd-doped strontium titanate ceramics prepared by the conventional mixed oxide method are studied. Lattice parameter is found to decrease linearly in the Sr1-1.5xGd xTiO3 system, confirming the incorporation of Gd onto the Sr site of the perovskite lattice of strontium titanate up to x=0.05. Real and imaginary parts of the dielectric permittivity of Sr1-1.5xGd xTiO(3) ceramics exhibit a relaxation between 100 Hz and 1 MHz in the temperature range of 17-261k, slightly shifting to higher temperatures with increasing Gd content. Such dielectric behaviour is attributed to the relaxation of individual dipoles formed by off-centre displacement of Gd3+ ions on Sr sites in a highly polarizable lattice of strontium titanate. Other dielectric relaxations observed in Sr(1-1.5)xGd xTiO(3) from 125 to 300K are attributed to the oxygen vacancy related mechanisms. No magnetic anomaly but paramagnetic behaviour is observed for Sr1-1.5xGd xTiO(3) ceramics, indicating an absence of the magnetic order and hence magnetoelectric coupling.(C) 2017 Elsevier Ltd. All rights reserved.
palavras-chave
THERMOELECTRIC PERFORMANCE; SRTIO3; RELAXATION; SR1-XCAXTIO3; BI-SRTIO3; RELAXOR; IONS
categoria
Materials Science
autores
Tkach, A; Amaral, JS; Vitor, SAB; Vilarinho, PM
nossos autores
João Cunha de Sequeira Amaral
Investigador Auxiliar
Oleksandr Tkach
Investigador Auxiliar
Paula Maria Lousada Silveirinha Vilarinho
Vice-Diretor
Vitor Brás Sequeira Amaral
Professor CatedráticoProjectos
CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)
Projeto de Investigação Exploratória: João Amaral (IF/01089/2015)
RMNE-UA-National Network of Electron Microscopy (REDE/1509/RME/2005 )
agradecimentos
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement as well as within FCT independent researcher grants IF/00602/2013 (AT) and IF/01089/2015 (JSA). SEM/EDS characterization was supported by the project REDE/1509/RME/2005.