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Negative thermal expansion in rare earth molybdates

Sumithra, S and Umarji, AM (2006) Negative thermal expansion in rare earth molybdates. In: Solid State Sciences, 8 (12). pp. 1453-1458.

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Abstract

Negative thermal expansion in rare earth molybdates of $A_2Mo_3O_{12}$ family (A = Y, Er, Yb and Lu) is measured by high temperature X-ray diffraction and dilatometry. Rare earth molybdates which are isostructural with the corresponding rare earth tungstates, also exhibit this phenomena attributed to transverse acoustic vibrations. The rare earth molybdates of A2M3O12 family with an orthorhombic structure (A = Y, Er, Yb and Lu) are highly hygroscopic and exhibit negative thermal expansion after the complete removal of water molecules. Axial thermal expansion co-efficient calculated from high temperature X-ray diffraction (RT-1073K) shows rare earth size effect. As the ‘A’ cation decreases in size, the thermal expansion co-efficient along ‘b’ axis and the linear thermal expansion co-efficient become less negative. The thermal expansion behaviour of the tetragonal $La_2Mo_3O_{12}$ is also reported to demonstrate the effect of crystal structure.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Elsevier
Keywords: Negative thermal expansion;Molybdates;High temperature X-ray diffraction;Dilatometry
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Date Deposited: 31 Jan 2007
Last Modified: 19 Sep 2010 04:34
URI: http://eprints.iisc.ernet.in/id/eprint/9628

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