Phase transition in IV-VI compound semiconductors at high pressures

The high pressure phase transitions, the equation of state and associated volume collapses of IV - VI compound semiconductors have been analysed by means of a three-body potential (TBP) model approach. The charge-transfer effects, arising from the overlapping or deformation of the electron shells of the adjacent ions leading to the many-body (three-body) interactions, are included explicitly in the crystal potential. The TBP model explains successfully the large Cauchy-discrepancy in these IV-VI semiconductors. The agreement between the present theoretical and available experimental values on the phase transition pressures (Pt = 196, 148, 108 and 226 kbar), cohesive energy and lattice parameters are in reasonably good agreement in almost all the materials under consideration. The charge-transfer effect shows an appreciable influence on the phase transition properties of these materials. (author). 23 refs, 4 figs, 3 tabs