Change in the Thermodynamic Properties of a Si-Ge Solid Solution at a Decrease of the Nanocrystal Size

The equation of state and the thermodynamic properties of the substitutional solid solution Si0.5Ge0.5 are calculated in the framework of the " medium atom" model. The changes in the equation of state and the thermodynamic properties upon the transition from a macrocrystal to a nanocrystal of 222 atoms with the geometric Gibbs surface are calculated using the RP-model of nanocrystal. The calculations have been performed along isotherms T = 100, 300, and 1000 K in the pressure range -1< P < 7 GPa. The changes in the properties is studied at the isochoric and also isobaric (P = 0) decrease of the number of atoms in the nanocrystal. It is shown that, at the isobaric (P = 0) decrease in the size, the specific volume of the Si-0.5-Ge-0.5 nanocrystal increases the more significantly, the higher the nanocrystal temperature.