Correlation between ionic charge and the mechanical properties of complex structured solids

An empirical relationship previously introduced by the authors, relating the ground state properties such as bulk modulus and cohesive energy of rock-salt and zinc blende structured solids to the product of their ionic charges, is shown to be applicable with minor modifications to the more complex class of ternary chalcopyrite semiconductors. The bulk moduli of AIBIIIC2VI and AIIBIVC2V chalcopyrite semiconductors exhibit a linear relationship when plotted on a log-log scale against the nearest neighbour distance d (A), but fall on two straight lines according to the product of the ionic charge of the compounds. On the basis of this result a simple bulk modulus-microhardness relationship is proposed and used to estimate the microhardness of these semiconductors. We have applied the proposed relation to AIBIIIC2VI and AIIBIVC2V chalcopyrite semiconductors and found a better agreement with experimental data than the values found by earlier researchers. The results for bulk modulus differ from the experimental ones by 0% (CuAlS2), 0% (CuGaSe2), 2% (CuGaS2), 4.8% (CuInSe2), 6% (AgGaS2), 6.2% (CdSiP2) and 0% (CdGeAs2)