A composition-dependent ``re-entrant'' crystallographic phase transition in the substitutional metal acetylacetonate complex (Cr1-xGax)(acac)(3)

Raghavan, Srinidhi M and Jaiswal, Piyush and Sundaram, Nalini G and Shivashankar, SA (2014) A composition-dependent ``re-entrant'' crystallographic phase transition in the substitutional metal acetylacetonate complex (Cr1-xGax)(acac)(3). In: POLYHEDRON, 70 . pp. 188-193.

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Abstract

The formation of a complete solid solution between acetylacetonate (acac) complexes of chromium and gallium, (Cr1-x,Ga-x)(acac)(3) for 0.1 <x <0.9, has been investigated through the co-synthesis method. Wellcrystallised, subliming solids are found to form for each nominal value of x, with thermal analysis confirming each composition to have a congruent melting point, making it a substitutional complex. Whereas the pure complexes (i.e. the end members of the solid solution, x = 0 and x = 1) are both centro-symmetric, a composition-dependent crystallographic phase transition to a non-centrosymmetric structure is found to occur for compositions with 0.4 < x < 0.9. Such a ``re-entrant'' crystallographic transition is interpreted to be due to the drive to overcome the disorder present in certain centrosymmetric chromium-rich compositions, by going over to a non-centrosymmetric structure with a doubling of the unit cell. The substitutional complex is shown to lead to a substitutional oxide with the beta-gallate structure. (C) 2014 Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Publication:	POLYHEDRON
Publisher:	PERGAMON-ELSEVIER SCIENCE LTD
Additional Information:	Copyright for this article belongs to the PERGAMON-ELSEVIER SCIENCE LTD, ENGLAND
Keywords:	Metal organic complexes; Single-source precursors; (Cr1-xGax)(acac)(3); ICP-OES; Re-entrant behavior; Crystal structure
Department/Centre:	Division of Chemical Sciences > Materials Research Centre Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	11 May 2014 06:39
Last Modified:	11 May 2014 06:40
URI:	http://eprints.iisc.ac.in/id/eprint/48908

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