Mazumder, S and Ghosh, Jiten (2010) Phenomena and mechanism on phase transformation twinning in nanocrystalline BaTiO3. In: Conference of 2010 MRS Spring Meeting, 5 - 9 April, 2010, San Francisco, CA.

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The detailed structure of nanocrystalline BaTiO 3 powder during ball milling has been studied using XRD & TEM. The study illustrates important advances in understanding atomic scale properties of this material. Ferroelectric BaTiO3 powder undergoes phase transformation along the sequence Cubic(Pm3m)-tetragonal(P4mm)-orthohombic (Amm2)-rhombohedral(R3m) structure when pressureless sintered samples are cooled from high temperature to low temperature. The high to low symmetry phases are not related to group subgroup symmetry as transformation is discontinuous and first order in nature and the twin relationship in me low symmetry is forbidden by Landau theory. In case of ball milled BaTiO 3 powder a continuous and diffusionless phase transition occur via second order to and from a metastable intermediate phase. In this pathway crystallites in the aggregation are twinned and the twin structure is related to crystal point group m3m which in the present case is illustrated as having 6mm symmetry formed under low driving force. The unit cell evolution due to phase transition and the crystallographic relationship are established.The phase transformation, coalescence and twin structure of thermally annealed BaTiO 3 nanocrystals under high vacuum has been investigated using in situ high temperature XRD. The structure analysis is performed with the use of the method of computer modelling of disorder structure and simulation of corresponding diffraction pattern. © 2010 Materials Research Society.

Item Type: Conference or Workshop Item (Paper)
Additional Information: Conference of 2010 MRS Spring Meeting; Conference Date: 5 April 2010 through 9 April 2010; Conference Code: 82894
Uncontrolled Keywords: Atomic scale; Ball-milled; Computer modelling; Driving forces; First order; High temperature; High vacuum; High-to-low; In-situ; Landau theory; Low temperatures; Metastable intermediate; Nanocrystallines; Phase transformation; Pressureless-sintered; Second orders; Structure analysis; TEM; Twin relationship; Twin structure; Unit cells; XRD, Ball milling; Barium titanate; Coalescence; Computer simulation; Diffraction; Nanocrystalline powders; Phase transitions; Sintering, Crystal symmetry
Subjects: Electronics
Engineering Materials
Depositing User: Bidhan Chaudhuri
Date Deposited: 12 Feb 2013 08:20
Last Modified: 28 Mar 2016 17:51

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