DIFFUSION OF COMPONENTS AND IMPURITIES IN CLUSTERIZING SOLID-SOLUTIONS

The self-diffusion and impurity diffusion coefficients are determined for clusterizing solid solutions of the A(IV)B(IV) type and also for A 1-x(II)B(x)(II)C(III) and A1-x(III)B(x)(II)C(V) solutions on the assum ption that the binding energy of the diffusing component of the solid solution depends linearly on the number of strongly bound atoms in the immediate surrounding medium. The condition for the existence of a mi nimum of the free energy is used to find the equilibrium values of the clusterization coefficient for certain values of the binding energy a nd temperature. The calculated values are in satisfactory agreement wi th the measurements of this coefficient in the case of the semiconduct or Cd0.2Hg0.8Te. This value of the clusterization coefficient is used to calculate the distribution functions of atoms in terms of the numbe r of the nearest neighbors, i.e., in accordance with the binding energ ies. It is assumed that the diffusion lasts a sufficient time, so that the state of the solid solution no longer varies with time, and the t otal diffusion flux is written in the form of a sum of fluxes with wei ghting factors governed by the distribution functions of the binding e nergies of the atoms. Calculations have shown that the diffusion coeff icient of a slow component of a clusterizing solid solution may be sev eral orders of magnitude lower than in a homogeneous solid solution of the same composition. On the other hand, the diffusion coefficient of a fast component and of a substitutional impurity in a clusterizing s olid solution may be considerably higher than in a homogeneous solutio n.