Kumar, Sunil and Varma, KBR (2014) Relaxor behaviour in BaBi4Ti4O15 ceramics fabricated using the powders obtained by mechanochemically assisted synthesis route. In: BULLETIN OF MATERIALS SCIENCE, 37 (6). pp. 1233-1241.
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Abstract
Mechanochemically activated reactants were found to facilitate the synthesis of fine powders comprising 200-400 nm range crystallites of BaBi4Ti4O15 at a significantly lower temperature (700 A degrees C) than that of solid-state reaction route. Reactants (CaCO3, Bi2O3 and TiO2) in stoichiometric ratio were ball milled for 48 h to obtain homogeneous mixture. The evolution of the BaBi4Ti4O15 phase was systematically followed using X-ray powder diffraction (XRD) technique. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to probe its structural and microstructural details. The electron diffraction studies established the presence of correlated octahedral rotations and associated long-range polar ordering. High-resolution TEM imaging nevertheless revealed structural inhomogeneities leading to intergrowth defects. Dense BaBi4Ti4O15 ceramics with an average grain size of 0.9 mu m were fabricated using mechanochemically assisted synthesized powders at relatively low temperature (1000 A degrees C). The effect of grain size on the dielectric and relaxor behaviour of BaBi4Ti4O15 ceramics was investigated. Fine-grained ceramics (average grain size similar to 0.9 mu m) showed higher diffusion in phase transition, lower temperature of phase transition, lower Vogel-Fulcher freezing temperature and higher activation energy for the polarization reversal than those for coarse-grained ceramics (average grain size similar to 7 mu m) fabricated via the conventional solid-state reaction route.
| Item Type: | Journal Article |
|---|---|
| Publication: | BULLETIN OF MATERIALS SCIENCE |
| Publisher: | INDIAN ACAD SCIENCES |
| Additional Information: | Copyright for this article belongs to the INDIAN ACAD SCIENCES, C V RAMAN AVENUE, SADASHIVANAGAR, P B #8005, BANGALORE 560 080, INDIA |
| Keywords: | BaBi4Ti4O15; mechanochemical synthesis; relaxor ferroelectrics; TEM; dielectric properties |
| Department/Centre: | Division of Chemical Sciences > Materials Research Centre |
| Date Deposited: | 12 Jan 2015 05:49 |
| Last Modified: | 12 Jan 2015 05:49 |
| URI: | http://eprints.iisc.ac.in/id/eprint/50587 |
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