The alloys of with the cross‐substitutionally derived ternary compounds and are considered. It is found, in the case of the ternaries themselves, that neither is completely stable and that both tend to decompose under certain conditions of annealing. The alloys have been prepared by melt and anneal method, with due regard to the stability of the ternary concerned. By x‐ray powder photograph techniques, the composition ranges for single phase zinc blende or chalcopyrite structure or for twophase behavior have been determined and the lattice parameter data are given. For the single phase alloys, values of optical energy gap have been determined by the usual I. R. absorption method.