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.