resumo
Polycrystalline samples of BaFe0.5Nb0.5O3 and (1 - x)Ba(Fe0.5Nb0.5)O-3-xSrTiO(3) [referred as BFN and BFN-ST respectively] (x = 0.00, 0.15 and 0.20) have been synthesized by a high-temperature solid-state reaction technique. The XRD patterns of the BFN and BFN-ST at room temperature show a monoclinic phase. The microstructure of the ceramics was examined by the scanning electron microscopy (SEM) and shows the polycrystalline nature of the samples with different grain sizes, which are inhomogeneously distributed through the sample surface. Detailed studies of dielectric and impedance properties of the materials in a wide range of frequency (100 Hz-5 MHz) and temperatures (30-270 degrees C) showed that properties are strongly temperature and frequency dependent. Complex Argand plane plot of epsilon '' against epsilon' usually called Cole-Cole plots is used to check the polydispersive nature of relaxation phenomena in above mentioned compounds. Relaxation phenomena of non-Debye type have been observed in the BFN and BFN-ST ceramics, as confirmed by the Cole-Cole plots. (C) 2010 Elsevier B.V. All rights reserved.
palavras-chave
TITANATE CERAMICS; BAFE0.5NB0.5O3; POLARIZATION; RELAXOR; FERROELECTRICS; PERMITTIVITY; TEMPERATURE; FREQUENCIES; RELAXATION; CRYSTALS
categoria
Chemistry; Materials Science; Metallurgy & Metallurgical Engineering
autores
Singh, NK; Kumar, P; Rai, R
nossos autores
Radheshyam Rai
Bolseiro de pós-DoutoramentoGrupos
agradecimentos
The authors are grateful to DRDO, for providing financial assistance for this research grant. The authors also acknowledge Prof. R.N.P. Choudary, IIT Kharagpur, India for some help in experimental work and suggestion.