Studies on the structural and ionic transport properties at elevated temperatures of La1-xMnO3 +/-delta synthesized by a wet chemical method

Jena, Hrudananda and Kutty, Govindan KV and Kutty, TRN (2003) Studies on the structural and ionic transport properties at elevated temperatures of La1-xMnO3 +/-delta synthesized by a wet chemical method. In: Journal of Alloys and Compounds, 350 (1-2). 102-112 .

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Abstract

Structural transformation and ionic transport properties are investigated on wet-chemically synthesized La1-xMnO3 (X=0.0-0.18) compositions. Powders annealed in oxygen/air at 1000-1080 K exhibit cubic symmetry and transform to rhombohedral on annealing at 1173-1573 K in air/oxygen. Annealing above 1773 K in air or in argon/helium at 1473 K stabilized distorted rhombohedral or orthorhombic symmetry. Structural transformations are confirmed from XRD and TEM studies. The total conductivity of sintered disks, measured by four-probe technique, ranges from 5 S cm(-1) at 298 K to 105 S cm(-1) at 1273 K. The ionic conductivity measured by blocking electrode technique ranges from 1.0X10(-6) S cm(-1) at 700 K to 2.0X10(-3) S cm(-1) at 1273 K. The ionic transference number of these compositions ranges from 3.0X10(-5) to 5.0X10(-5) at 1273 K. The activation energy deduced from experimental data for ionic conduction and ionic migration is 1.03-1.10 and 0.80-1.00 eV, respectively. The activation energy of formation, association and migration of vacancies ranges from 1.07 to 1.44 eV. (C) 2002 Elsevier Science B.V. All rights reserved.

Item Type:	Journal Article
Publication:	Journal of Alloys and Compounds
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Electrode materials;Rare earth compounds;Chemical synthesis; X-ray diffraction;Ion conduction
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	24 Aug 2011 06:29
Last Modified:	24 Aug 2011 06:29
URI:	http://eprints.iisc.ac.in/id/eprint/40229

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