Investigation of Structural Phase Transition of PbS

The high-pressure structural phase transition of semiconductor PbS has been investigated, using the three body potential (TBP) model. Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and related volume collapses obtained from this model show a generally good agreement with available results. Moreover, the elastic properties of PbS are also investigated. 1. Introduction In current years, IV–VI semiconductors are one of the most important narrow gap materials in electronics. These semiconductors are widely applied in fundamental information of solid-state electronic device fabrication. In this group of semiconductors, lead chalcogenides PbX ( = S, Se, and Te) are primarily semiconducting materials [1]. Lead chalcogenides are well known to be good materials for thermoelectric due to their low thermoconductivity. Lead chalcogenides remain one of the basic materials of modern infrared optoelectronics [2]. The structural high pressure behaviour of lead chalcogenides has paid considerable interest from both theoretical and experimental works [3–10]. Among these lead chalcogenides the lead sulphide PbS is useful as detector in infrared radiation. PbS crystallizes in the rocksalt (NaCl) type ( ) structure at normal condition. First-order phase transition of PbS has been studied using high-pressure X-ray diffraction [4–7]. The ab initio electronic study of pressure induced structural phase transition of lead sulphide has been carried out by Bencherif et al. [8]. Phase transformation and conductivity in nanocrystal PbS under pressure have been investigated by Jiang et al. [9]. Zhang et al. investigated the elastic properties of PbS [10]. First-principles study of to phase transition in PbS has been performed by Bhambhani et al. [11]. It seems from the above literature that the present compound is less studied; we applied the three-body potential (TBP) model to the present compound for studying the high-pressure phase transition and volume collapse. The need of inclusion of three-body interaction forces was emphasized by many workers for the betterment of results [12, 13]. The model and calculation is given in Section 2 and the result and discussion is given in Section 3. 2. Model and Calculation Application of pressure directly results in compression leading to the increased charge transfer (or three body interaction effect [14]) due to the deformation of the overlapping electron shell of the adjacent ions (or nonrigidity of ions) in solids. These effects have been included in the Gibbs free energy as a