Negative thermal expansion in Th{sub 2}O(PO{sub 4}){sub 2}

Journal Article · Tue Nov 15 00:00:00 EST 2011 · Materials Research Bulletin

DOI:https://doi.org/10.1016/J.MATERRESBULL.2011.08.003· OSTI ID:22210090

Wallez, Gilles ^[1]; Clavier, Nicolas; Dacheux, Nicolas ^[2]; Bregiroux, Damien ^[1]

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1. Chimie ParisTech, UPMC Univ. Paris 06, CNRS-UMR 7574, Laboratoire de Chimie de la Matiere Condensee de Paris (LCMCP), 75005 Paris (France)
2. Institut de Chimie Separative de Marcoule, UMR 5257 - CNRS/CEA/UM2/ENSCM, Site de Marcoule, BP 17171, 30207 Bagnols/Ceze cedex (France)

Highlights: {yields} Dithorium oxide phosphate shows a continuous negative thermal expansion over a 600 {sup o}C range. {yields} Negative expansion arises from oxygen rocking and cations repulsions. {yields} Big and high-charge thorium IV appears ideal for generating negative expansion. -- Abstract: High temperature X ray diffraction performed on recently discovered orthorhombic Th{sub 2}O(PO{sub 4}){sub 2} shows a continuous linear thermal contraction (-1.6 x 10{sup -6} {sup o}C{sup -1}) in 20-600 {sup o}C range and a near-zero expansion at higher temperatures resulting from a dual structural deformation involving oxygen oscillations and inter-cations repulsions. Although similar mechanisms were observed in isotypic Zr{sub 2}O(PO{sub 4}){sub 2} (+1.5 x 10{sup -6} {sup o}C{sup -1}) and U{sub 2}O(PO{sub 4}){sub 2} (-1.4 x 10{sup -6} {sup o}C{sup -1}), those observed in Th{sub 2}O(PO{sub 4}){sub 2} are particularly intense because of the high ionic radius of tetravalent thorium.

• OSTI ID: 22210090
• Journal Information: Materials Research Bulletin, Vol. 46, Issue 11; Other Information: Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CATIONS
ORTHORHOMBIC LATTICES
PHOSPHATES
THERMAL EXPANSION
X-RAY DIFFRACTION