  A thermodynamic model of formation of multi-component solid solutions as a
thermodynamic mixture of their binary components, is proposed. There are
obtained expressions for the effective temperature of the equilibrium state of
the solid solution of binary components, and for the excess Gibbs energy of
formation of such a solution. The thermodynamic parameters of formation of
solid solutions are calculated for CdZnTeSe compounds with an arbitrary
concentration of the doping elements. There is revealed a new thermodynamic
effect of a decrease in the excess Gibbs energy in the solid solutions which
contain mixed binary components formed during simultaneous doping of the
cationic and anionic subsystems. Such an effect is connected with emergence of
strong covalent bonds in the mixed binary component ZnSe which is a part of the
quaternary solid solution. This may explain a considerable decrease in the
number of extended defects observed at the growth of CdZnTeSe crystals. The
proposed theory allows different generalizations, and makes it possible to
quantitively predict changes of the expected defect quality of the crystals at
variations in the composition of the solid solutions.
