The pressure-effects on phase transitions, band structures, electronic and elastic properties of ternary compounds ZnXP2 (X = Si, Ge, Sn) by first principle calculations. (21st September 2018)

• Record Type: Journal Article
• Authors: Liu, Hui; Zhao, Beijun; Yu, You; He, Zhiyu; Xiao, Jianping; Huang, Wei; Zhu, Shifu; Chen, Baojun; Xie, Linhua
• Is Part Of: Materials research express. Volume 5:Number 12(2018)
• Publication Date: 2018-09-21
• Subjects: chalcopyrite -- phase transition -- elastic properties -- pressure effect -- DFT calculation; Materials science -- Research -- Periodicals; Materials science -- Periodicals; 620.11
• DOI: 10.1088/2053-1591/aae11e
• Languages: English
• ISSNs: 2053-1591

Abstract

Abstract: We performed the first principle calculations on phase transitions, band structures, electronic and elastic properties for ternary compounds ZnXP2 (X = Si, Ge, Sn) under pressure conditions. In the frame of density function theory, we used Ultrasoft pseudo-potentials and generalized gradient approximation method in our calculations. The optimized structural parameters are well consistent with available experimental and theoretical data. The enthalpy calculations show the first-order structural phase transitions (from chalcopyrite to rock-salt) happen at 46.8 GPa, 44.2 GPa, and 32.5 GPa for ZnSiP2, ZnGeP2 and ZnSnP2, respectively, along with the volume collapsing and bond length decreasing. The calculations of pressure-effects on band structures, electronic properties and bonding natures show the energy gaps decrease with increased pressure and disappear at the transition pressures. This effect is related to the evolution of bonding from the mixture of covalent-ionic to mainly ionic character in the chalcopyrite and rock-salt phases, respectively. The elastic parameters are discussed in detail under pressure conditions, such as elastic constants C ij, bulk modulus B, shear modulus G, Young's modulus E, Poisson ratio ν and Zener anisotropy factor A . Our results indicate the tetragonal chalcopyrite is easier to be compressed than to be sheared and structural anisotropy becomes obvious under hydrostatic pressure condition. It directly leads to micro-cracks and produces mechanical variations in crystal structure, resulting in the occurrence of structure transition. Finally, we obtained the Debye temperature for chalcopyrite ZnXP2 at ambient condition.