Structural, Thermodynamic and Magneto-Electronic Properties of Cd_0.75Cr_0.25Se and Zn_0.75Cr_0.25S: An <i>Ab-Initio</i> Study

Abstract

Using the full-potential linearized augmented plane wave plus local orbital method based on spinpolarized density functional theory, we investigate the parameters of the structure, the electronic, magnetic, and thermodynamic properties of cubic zinc-blende Cd0.75Cr0.25Se and Zn0.75Cr0.25S ordered ferromagnetic materials. We adopt the Perdew-Burke-Ernzerhof generalized gradient approximation and the modified Becke-Johnson exchange potential for the exchange-correlation energy and potential. Furthermore, the effect of high pressure on the normalized unit cell volume, bulk modulus, and Grüneisen parameter for both CdSe and ZnS binary compounds as well as for Cd0.75Cr0.25Se and Zn0.75Cr0.25S partially substituted materials was also predicted. The results indicate that both these materials are stabilized in the ferromagnetic phase. Using the modified Becke-Johnson approach and Perdew-Burke-Ernzerhof generalized gradient approximation, our calculations also demonstrate that both Cd0.75Cr0.25Se and Zn0.75Cr0.25S alloys are semiconductors with the magnetic moment of 4 µB per formula unit. Furthermore, the calculations of the s-d exchange constant and p-d exchange constant clearly indicate the magnetic nature of these compounds. Finally, in order to gain further information, basic thermodynamic properties such as heat capacity, thermal expansion coefficient, and entropy have been explored using the quasi-harmonic Debye model.

Debye temperature of CaO under high pressure up to 65.2 GPa

“…We observe that the bulk modulus B of CaO compound increases with increasing pressure up to 65.2 GPa. The results are consistent with the values reported for CdSe, Cd0.75Cr0.25Se, ZnS, and Zn0.75Cr0.25S materials [29]. Compared with the bulk modulus B at equilibrium, our obtained data of B using the experimental elastic constants measured by Speziale et al [6] are somewhat larger than both the ab initio plane-wave pseudopotential DFT method [2] and semi-empirical approach [5] at high pressure.…”

Structural and Thermodynamic Properties oF Cu2ZnSnS4 Material: Theoretical Prediction

“…8 that the CV of Cu2ZnSnS4 material increases exponentially with the temperature for T < 400 K, while for high temperature, it approaches the DuLong-Petit limit, indicating that at high temperature, all phonon modes are sufficiently excited by the thermal energy [34]. Due to general laws of thermodynamics and the same nature of materials as semiconductors, it can be observed that similar qualitative behaviors from the quantitative point of view have been reported for CV versus temperature for ScP material [32], copper chloride (CuCl) and copper bromide (CuBr) compounds [34], group Ⅲ-phosphide semiconducting materials [35], for boron antimonide (BSb) compound in cubic zinc-blende structure [36], and for both Cd0.75Cr0.25Se and Zn0.75Cr0.25S ternary materials [37]. At 298 K, the constant volume heat capacity CV was found to be at around 376.44 Jmol -1 K -1 .…”