Study of Thermodynamics of Liquid Noble-Metals Alloys Through a Pseudopotential Theory

Abstract

On the bases of the Gibbs-Bogoliubov (GB) inequality and the Percus-Yevick (PY) hard sphere model as a reference system, a thermodynamic perturbation method has been applied with use of well recognized model potential. By applying a variation method the best hard core diameters have been found which correspond to minimum free energy. With this procedure the thermodynamic properties such as entropy and heat of mixing have been computed. The influence of local field correction function viz; Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) is also investigated. The computed excess entropy compares favourably in the case of liquid alloys while the agreement with experiment is poor in the case of heats of mixing. This may be due to the sensitivity of the heats of mixing, as pointed out already by them, with the potential parameters and the dielectric function.

Thermodynamical Investigation of Liquid Alkali Metals with Gibbs-Bogoliubov Method

“…The hard sphere reference system estimates the more promising value of excess entropy Sexs than the other system. Present results also follow the same fashion for this estimation for PYHS [3][4][5][6][7][8][9][10][11] reference system instead just as HS reference system. As compared to the Sexs by OCP reference system given in the article of Dubinin et al [1], the Sexs calculated in the HS reference system is found higher.…”

“…The Gibbs-Bogoliubov (GB) approximation has been found an appropriate tool to study the thermodynamics of liquids metals [1][2][3][4][5][6][7][8][9][10][11]. According to it, the Helmholtz free energy can be written as,…”

“…where Sgas, Sele, and SPYHS are the various entropy contributions as expressed in [1][2][3][4][5][6][7][8][9][10][11]. Further, the excess entropy Sexc can be expressed as [1][2][3][4][5][6][7][8][9][10][11],…”

“…Many of the alkali metals have their melting points at or near to room temperature which makes necessary to investigate the properties of elements of this group in the liquid phase. The pseudopotential theory has proven its importance in the study of the liquid metals and alloys [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], but the liquid state of metal is very difficult to study with a very less adjustment in the parameter(s) of model potential because of its complex electron-ion interaction behavior in this state.…”

“…Six different types of local field correction functions viz. Hartree (H) [3][4][5][6][7][8][9][10][11], Taylor (T) [3][4][5][6][7][8][9][10][11], Ichimaru-Utsumi (IU) [3][4][5][6][7][8][9][10][11], Farid et al (F) [3][4][5][6][7][8][9][10][11], Sarkar et al (S) [3][4][5][6][7][8][9][10][11] and Nagy (N) [12] are used for the first time with the said potential to the best of our knowledge. The PYHS reference system as used in [3][4][5][6][7]…”