tailieunhanh - Thermodynamic properties of some rare-earth metals

Thermodynamic properties of rare-earth metals have been studied using staistical moment method. The analytic expressions of the Helmholtz free energy and thermodynamic quantities were obtained. Present SMM results of nearest neighbor distance, linear thermal expansion coefficient and specific heats at constant pressure for Th and Ce metals are compared with the experimental results. | JOURNAL OF SCIENCE OF HNUE Natural Sci. 2011 Vol. 56 No. 7 pp. 58-64 THERMODYNAMIC PROPERTIES OF SOME RARE-EARTH METALS Vu Van Hung Hanoi National University of Education Dang Thanh Hai Vietnam Education Publishing House E-mail bangvu57@ Abstract. Thermodynamic properties of rare-earth metals have been studied using staistical moment method. The analytic expressions of the Helmholtz free energy and thermodynamic quantities were obtained. Present SMM results of nearest neighbor distance linear thermal expansion coefficient and specific heats at constant pressure for Th and Ce metals are compared with the experimental results. Keywords Thermodynamic rare-earth metals staistical moment method. 1. Introduction Recently there has been a great interest in the study of rare-earth metals since they provide us a wide variety of academic problems as well as the technological ap- plications. Various theoretical studies of simple noble and transition metals 1-3 have been made so far based on pseudopotential theory but relatively few attempts have been made on rare-earth and actinide elements such as La Yb Ce and Th 4-6 by the same method. Rosengren et al 7 have investigated the lattice dynam- ics of thorium using pseudopotential due to Krasko and Gurskii 8 . and 9 have calculated the phonon dispersion of La Yb Ce and Th. Recently Pandya et al 10 have investigated the phonon dispersion curves phonon density of states Debye-Waller factor mean square displacements and equation of state for thorium. and 11 also have calculated the phonon dispersion curves phonon density of states Debye temperature Gr uneisen parameters and dynamic elastic constants for La Yb Ce and Th. Most of the previous theoretical studies however are concerned with the ma- terials properties of rare-earth metals at absolute zero temperature and temperature dependence of the thermodynamic quantities has not been studied in detail. The purpose of the present article