New data on the Cu2FeSnS4-Cu2ZnSnS4 pseudobinary system at 750° and 550 °C

The 750 ° and 550 °C isotherms of the Cu2FeSnS4-Cu2ZnSnS4 pseudobinary system are investigated by the evacuated silica tube technique using molten halides fluxes. The continuous variation of the a and c parameters as a function of composition points to a complete solid solution between the two end-members, in spite of the different space groups (Cu2FeSnS4: 742m; Cu2ZnSnS4: 14). Although the possible mechanism of substitution between Fe and Zn and/or between (Fe,Zn) and Cu remains unclear, the space group transition is found to occur in the compositional range 60-70 mole % Cu2ZnSnS4. Key-words: Cu2FeSnS4, Cu2ZnSnS4, pseudobinary-system, cell-parameters, solid solution.