The bulk modulus of ThO2: an experimental and theoretical study

• Published in: Journal of alloys and compounds Vol. 381; no. 1-2; pp. 37 - 40
• Main Authors: OLSEN, J. Staun, GERWARD, L, KANCHANA, V, VAITHEESWARAN, G
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier 03-11-2004
• Subjects: Condensed matter: structure, mechanical and thermal properties; Equations of state of specific substances; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Physics; Actinides; Equations of state; Generalized gradient approximation; XRD; electron band calculation; Synchrotron radiation; Bulk modulus; Synchrotron radiation; Local density approximation; High pressure; LMTO method; Thorium; X-ray diffraction; Crystal binding and equation of state
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2004.04.099

The chemistry of actinide oxides is a complex field, with complications stemming from non-stoichiometry and often from self-damage resulting from decay of radioactive isotopes. Interest in thorium dioxide is not confined to its use as a nuclear material, but also as a solid-state electrolyte and it is traditionally used in fluorescent tubes. In view of the large scatter in the literature, we have re-evaluated the high-pressure behaviour and the bulk modulus of thorium dioxide, experimentally using high-pressure X-ray diffraction (XRD) in conjunction with synchrotron radiation. To compare with the experimental measurements, theoretical calculations were performed using the full-potential linear muffin-tin orbital method (FP-LMTO) together with the local density approximation (LDA) as well as the generalised gradient approximation (GGA). The experimental value for the bulk modulus is found to be 195.3 - 2.0 GPa, which compares well with the calculated value of 198 GPa obtained by using the generalised gradient approximation to the exchange correlation potential.