Impurity determination by thermal analysis : I. The melting curve of a gradually frozen sample

Abstract

A temperature-heat content relation is presented for binary systems which show solid solutions. Contrary to previous equations, the present equation accounts for the very restricted rate of diffusion in the solid. The equation is based on local equilibrium during freezing and melting. The equation obtaining to the comparative method of impurity determination and applicable to a gradually frozen sample is identical to the equation previously derived on the basis of total equilibrium. The corresponding equations of the absolute method differ considerably. Experiments confirm the local equilibrium theory and show the inadequacy of the total equilibrium theory.