Equilibrium conditions for the alloy system (CUI _ xAgx)(Gal _ylny)(Se l _ z Tezb were determined throughout the complete range of composition. Polycrystalline samples of 125 different compositions, i.e., with x,y, and z = 0, 0.25, 0.5, 0.75, and l.0, were prepared by a melt and anneal technique. Different annealing temperatures in the range 6@..800 ·C were used depending upon the alloy composition and annealing times of up to 5 months used to attain equilibrium conditions. Debye-Scherrer x-ray powder photographs were used to investigate the equilibrium conditions. It was found that single phase chalcopyrite structure was obtained for all compositions of the copper (x = 0), indium ( y = 1), and tellurium (z = 1) sections but that miscibility gaps occurred in the silver (x = 1), gallium (y = 0), and selenium (z = 0) sections, and that these miscibility gaps extended through the general alloy system. Values oflattice parameters a and c were determined for all samples showing single phase condition and for each of the above sections the variations of a and c with composition were fitted to power series in the appropriate composition coordinates. Hence contours of constant a and constant c were determined. From the parameters for each section, general series expressions in x, y, and z were developed and the values from these compared with the experimental data for the general alloys. It is shown that a modified Weaire and Noolandi relation of the form [2 -(c/a)] = K (XI -XIII + qX VI f fits all of the experimental data. Averaged values of K and q were obtained by fitting separately to different sections of the alloy system and also to all alloys of the complete system.

Polycrystalline samples of (CuIn)1−zMn2zSe2 alloys are prepared by the melt and anneal technique and are used in differential thermal analysis, lattice parameter, optical energy gap, and magnetic susceptibility measurements. It is found that the range of single phase solid solution in CuInSe2 extends to z = 0.32 and that the transition temperature from chalcopyrite to zinc blende decreases from 810 °C at z = 0 to 510 °C at the limit of single phase behaviour. Measurements of optical energy gap and magnetic susceptibility as a function of temperature show that in all of the chalcopyrite samples ordering of the manganese on the cation sublattice occurs, while for the zincblende samples, the manganese may be ordered or disordered depending upon the heat treatment used. The magnetic data indicates that the ordering is the same as that observed previously in similar telluride alloys.

It has been shown that single phase solid solution occurs throughout the composition range of the system (Cu1−xAgx)(In1−yGay)Te2, the structure throughout being tetragonal chalcopyrite. Values of lattice parameters a and c have been determined as functions of x and y and fitted to power series expressions. Contours of constant a and constant c are plotted, and it is indicated that these parameter values can be used to determine the composition of samples in this alloy system.