The effective cation radius dependence of the unit cell parameters of In(Ga)-rich ternary compounds of [Cu2 (Se, Te)]X-[(In2, Ga2) (Se3, Te3)]1−X system

The variation of the effective cation radius (reff) with the normalized values of the unit cell parameters a, c and V with respect to their corresponding 1:1:2 phase that are formed on the In (Ga)-rich side of the pseudo-binary phase diagram, is analyzed. A linear dependence of these parameters for the tellurides and selenides of Cu-In and Cu-Ga system is found. This permits to estimate the unit cell dimensions of other ordered defects compounds of these systems, as well as sulfides, that have not been synthesized so far.