Paradox associated with cohesive energy of IV-VI semiconductors

Abstract

Cohesive energy of elemental systems is simply the heat of sublimation. However, the cohesive energy for compounds depends on the final products when vaporized. Different descriptions exist based on the final products and a wide range of value has been reported. Here, we compare the cohesive energy reported in the literature for IV-VI (compound) semiconductors and discuss the paradox associated with it. By analysing different descriptions and the value obtained, we argue that the heat of sublimation of IV-VI compounds is the cohesive energy per molecule (as they evaporate in a molecular form) and is much lower that the cohesive energy per atom and the cohesive energy per atom depends on the final products when the solid is vaporized into atoms.