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Equation of State and Thermal Expansivity under the Effect of High Pressure and High Temperature
Author(s) -
Kumar M.,
Upadhyay S. P.
Publication year - 1994
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221840107
Subject(s) - thermal expansion , van der waals force , thermodynamics , chemistry , work (physics) , equation of state , dipole , thermal , pressure coefficient , theorem of corresponding states , van der waals equation , ionic bonding , van der waals radius , physics , ion , molecule , organic chemistry
A simple method is developed to investigate interatomic separations and thermal expansion coefficients at pressures ranging from the atomspheric one up to the structural transition pressure, and temperatures ranging from RT to the melting temperature. The calculations are performed using an ionic model based on Harrison's quantum mechanical form for the overlap repulsive energy which takes into account the interactions up to second neighbours. The van der Waals dipole‐dipole and dipole‐quadrupole interactions evaluated from more accurate methods are also included in the model. The results depend sensitively on temperature and pressure. The thermal expansion coefficient increases with temperature, while this increase becomes rather slow as pressure is increased. A strong decline of the thermal expansion coefficient with pressure at a constant temperature is also obtained. The results are compared with available experimental data, and good agreement supports the validity of the method developed in the present work.