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Thermodynamic properties of free standing thin metal films: Temperature and pressure dependences

The explicit expressions of the lattice constant, thermal expansion coefficient, and specific heats at the constant volume and those at the constant pressure, CV and CP of the metal thin films are derived in closed analytic forms in terms of the power moments of the atomic displacements. The thermodynamic quantities of Au, Ag, Cu and Al metal thin films are calculated as a function of the temperature and pressure, and they are in good agreement with the corresponding results obtained from other theoretical calculations and experimental values. The effective pair potentials work well for the calculations of fcc metal thin films. | Communications in Physics, Vol. 24, No. 2 (2014), pp. 177-191 THERMODYNAMIC PROPERTIES OF FREE STANDING THIN METAL FILMS: TEMPERATURE AND PRESSURE DEPENDENCES VU VAN HUNG Vietnam Education Publishing House DUONG DAI PHUONG Hanoi National University of Education NGUYEN THI HOA Fundamental Science Faculty, University of Transport and Communications E-mail: vanha318@yahoo.com Received 06 March 2014 Accepted for publication 06 May 2014 Abstract. The moment method in the statistical dynamics (SMM) is used to study thermodynamic properties of free standing thin metal films with face-centered cubic structure (fcc) taking into account the anharmonicity effects of the lattice vibrations and hydrostatic pressures. The explicit expressions of the lattice constant, thermal expansion coefficient, and specific heats at the constant volume and those at the constant pressure, CV and CP of the metal thin films are derived in closed analytic forms in terms of the power moments of the atomic displacements. The thermodynamic quantities of Au, Ag, Cu and Al metal thin films are calculated as a function of the temperature and pressure, and they are in good agreement with the corresponding results obtained from other theoretical calculations and experimental values. The effective pair potentials work well for the calculations of fcc metal thin films. Keywords: moment method; thermodynamic properties; high pressure; equation of state; thin film I. INTRODUCTION Films materials have become interesting for recent years. They have been found to show different physical, chemical, and mechanical properties comparing to bulk materials [1, 2]. Therefore, knowledge of the thermodynamic properties of thin films are important for their technological applications. The dependence on pressure of the thermodynamic properties of thin film is of great interest not only from a fundamental point of view but also for technological applications [3-10]. In general, investigating for dependence on pressure