Estimation of point defect parameters of solids on the basis of a defect formation model of melting (II). Vacancy formation enthalpy in relation to the heat of fusion and the increase of volume due to melting

Abstract

Abstract The mole fraction of vacancies within melts at their melting points is found to be x L = = 0.125 in the case of elements (with exception of inert gases), alkali halides, binary oxides and organic compounds. As to inert gases it is x L = 0.194. The formation enthalpy of vacancies (Schottky defects) is given by h S = L / x L ( L heat of fusion) in every case. The increase of volume due to melting can be explained well by the vacancy model of melting: Δ V = V S x L ( V S formation volume of Schottky defects).