resumo
Dielectric properties of perovsldte structured (Ba0.85Ca0.15)(Zr0.1Ti0.9)O-3; [BCZT], ferroelectric ceramics prepared by the conventional solidstate reaction method were investigated by AC impedance spectroscopy. To obtain high density samples, the pressed pellets were sintered at 1450 degrees C and 1500 degrees C for 4 h. Polarization-Electric field (P-E) measurements of the ceramic samples sintered at 1500 degrees C showed higher remnant polarization (P-r=12.20 mu C/cm(2)) and coercive field (E-c=4.50 kV/cm) values when compared to P-r=8.02 mu C/cm(2) and E-c=3.80 kV/cm respectively for the samples sintered at 1450 degrees C. In addition, BCZT sintered at 1500 degrees C showed higher dielectric constant as compared to the one sintered at 1450 degrees C. However, the dielectric constant measured as a function of frequency for both the sintered samples showed single maximum value at similar to 105 degrees C, which is attributed to the structural phase transition (Curie temperature, T-c) from ferroelectric, tetragonal phase to paraelectric, cubic phase. AC impedance analysis over the frequency range of 100 Hz to 1 MHz for the ceramic sintered at 1500 degrees C, showed mainly bulk contribution up to 250 degrees C while bulk and grain-boundary contributions were present above 250 degrees C. Activation energies for conductivity were found to be strongly frequency dependent. The activation energy values are attributed to the conduction of oxygen vacancies via hopping mechanism. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
palavras-chave
PIEZOELECTRIC PROPERTIES; TITANATE CERAMICS; TEMPERATURE; COEFFICIENT; CRYSTALS; STRAIN
categoria
Materials Science
autores
Rafiq, MA; Rafiq, MN; Saravanan, KV
nossos autores
Venket
Bolseiro de pós-DoutoramentoGrupos
agradecimentos
Muhammad Asif Rafiq acknowledges the finanical and infrastructure support of Department of MME, UET Lahore. KVS acknowledges UGC, Govt. of India for providing the Start-up Grant and other infrastructure facilities and the Foundation for Science and Technology (FCT), Portugal for the Grant SFRH/BPD/80742/2011SFRH/BPD/80742/2011. The authors acknowledge Prof. Paula Vilharinho and Prof. Elisabaete Costa, Universidade de Aveiro, for extending the infrastructural and laboratory facilities.