Study of the FCC-Au properties in a wide range of temperatures and pressures

Abstract

The properties of the FCC-of the gold crystal were calculated using an analytical method (without computer modeling) in the temperature range: T=10-1337 K and pressures: P=0-110 GPa. The following properties were calculated: state equation, Debye temperature, first and second Gruneisen parameters, elastic modulus (BT), thermal expansion coefficient (αp), isochoric (Cv) and isobaric (Cp) heat capacity, specific surface energy. Derivatives of these properties also have been calculated both by temperature along three isobars and by pressure along three isotherms. The obtained results showed good agreement with the other authors results. It was shown that there is a certain temperature TB in which the product α_pBT does not change during the crystal compression. At T>TB, the α_pBT function increases, and at T<TB, it decreases with an increase in pressure. For FCC-Au has been received T_B=132 K. It was shown that the isotherms of the baric derivative of elastic modulus B'(P) intersect at the point: P>21.58 GPa, and B'(P)=7.43. At P<21.58 GPa, the C'v(P) function increases, and at P>21.58 GPa, it decreases with increasing temperature. It was shown that the isotherm of the baric derivative of the isochoric heat capacity C'v(P) has a minimum, and the isotherm of the baric derivative of the isobaric heat capacity C'_p(P) has both a minimum and a maximum. Based on the obtained dependencies, some approximations, which are used to calculate the properties of the crystal under high P-T-conditions, have been analyzed. Keywords: gold, pressure, elastic modulus, thermal expansion, heat capacity, Debye temperature, Gruneisen parameter, surface energy.