Order-disorder behaviour and tetragonal distortion of chalcopyrite compounds

The order-disorder behaviour and the tetragonal distortion of chalcopyrite compounds ABC2 can be described in terms of the difference in electronegativity Δsub(chiAB) between the A-C and B-C bonds. This difference in electronegativity, defined on the basis of the Pauli-force model potential, is parametrizing the difference between the A-C and B-C interactions. It appears to be possible to give one single relation for the tetragonal distortion as a function of the parameter Δsub(chiAB) for the I-III-VI2 and II-IV-V2 chalcopyrites. In addition it appears that chalcopyrites with Δsub(chiAB) < 0.09 possess an order-disorder solid state transition, whereas the chalcopyrites with Δsub(chiAB) > 0.09 remain in the ordered chalcopyrite structure up to their melting point. (author)