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The electronic structure, elastic moduli, as well as thermodynamic features of the ferromagnetic Cd0.75TM0.25S (TM = Os or Ir) compounds in the zinc-blende phase were investigated by employing the "generalized gradient approximations" parametrized by Wu and Cohen combined with the "modified Becke-Johnson (TB-mBJ)" as well as the hybrid functional (HSE06). The predicted total magnetic moments for the transition metals Os and Ir are 4.0 μB and 3.0 μB with TB-mBJ and are 2.0 μB and 3.0 μB using the hybrid functional (HSE06) for compounds Cd0.75Os0.25S and Cd0.75Ir0.25S, respectively. The generation of magnetic moments and spin-polarization in these alloys is directly linked to the contribution coming from TM-5d states. The ferromagnetic properties of these alloys were predicted by the computed exchange constants Besides, the increase in the porosity paramete N 0 α and N 0 β . The Total and partial densities of states (TDOS/PDOS) and the behavior of electronic band structures (EBS) were also calculated to describe the ferromagnetic semiconducting and half-metallic (HM) characteristics with TB-mBJ and the hybrid functional (HSE06). According to the findings, Cd0.75Os0.25S is a half-metallic ferromagnetic (HM) material with a full polarization spin distribution of electrons at the Fermi energy level, exhibiting metallicity for the majority spin and a semiconducting nature for the minority spin. In contrast, Cd0.75Ir0.25S is a ferromagnetic half-semiconductor (HSC) with two distinct gaps depending on the up and down spin configurations. Calculations of the elastic constants, Young and shear moduli reveal that the compound Cd0.75TM0.25S (TM = Os or Ir) is mechanically stable, has a high degree of anisotropy, and is naturally ductile. Furthermore, the "quasi-harmonic Debye model" was performed to examine the thermodynamic properties of the studied compounds, including the thermal capacity, entropy and Debye temperature. [ABSTRACT FROM AUTHOR]

This study employed density functional theory (DFT) embedded in Wien2K code to evaluate the physical features of the XGeCl3 (X = Rb/Cs) cubic halide perovskites. The structural optimization has been performed considering generalized gradient approximation (GGA) and electronic properties have been computed considering modified Becke‐Johnson potential (mBJ). The formation energy and phonon dispersion analysis establish the stability of the investigated compounds. Mechanical stability is further confirmed by the computed diverse elastic coefficients. It has been discovered that the examined substances are naturally ductile. The refractive index, reflectivity, and absorption coefficient, are among the optical parameters that have been estimated and analyzed. Interesting results have been obtained for the transport properties of XGeCl3 (X = Rb/Cs). The XGeCl3 (X = Rb/Cs) exhibits a high Seebeck coefficient (X = Rb/Cs) and the largest figure of merit (about 0.99), indicating significant potential for thermoelectric applications. [ABSTRACT FROM AUTHOR]

In this work, the band structure feature, charge carrier mobility, optical properties, and photocatalytic performance of platinum-based vacancy-ordered double perovskites Rb2PtX6 (X = Cl, Br, and I) are investigated. The results show the semiconducting character of all three materials with band gap values equal to 3.39 eV, 2.76 eV, and 1.45 eV, for Rb2PtCl6, Rb2PtBr6, and Rb2PtI6, respectively. Furthermore, the calculated electron and hole effective masses yield a higher relative mass of hole-electron pairs (D), resulting in a slow recombination rate in these materials. The optical properties are also calculated, where the entitled materials show high absorption intensities in the visible and ultraviolet regions. Moreover, it is discovered that the Rb2PtCl6 and Rb2PtBr6 compounds can produce both oxygen and hydrogen at the same time. In contrast, the Rb2PtI6 material has a poor water-splitting ability and may be a promising photocatalyst for CO2 photoreduction. [ABSTRACT FROM AUTHOR]

The optimized structural parameters, electronic structure, and thermoelectric coefficients of the chalcopyrite alloys Cu1–xNaxTlSe2, with x = 0.00, 0.25, and 0.50 were studied through density functional theory calculations. The Wu–Cohen generalized gradient and the Tran–Blaha modified Becke–Johnson approximations have been employed to describe the exchange–correlation potential. Energy band structure analysis reveals that CuTlSe2 is a semi-metal, while Cu0.25Na0.75TlSe2 and Cu0.50Na0.50TlSe2 alloys are semiconductors with gaps of approximately 0.17 eV and 0.35 eV, respectively. The total and partial densities of states were calculated and discussed. Examining the charge density, we point out the formation of the Na–Se ionic bond when Cu is replaced by the Na atom, which is responsible for the metal–semiconductor transition in the Cu1–xNaxTlSe2 alloys. Moreover, variations of the Seebeck coefficient, electrical conductivity, electronic and lattice thermal conductivity, power factor, and figure of merit of the Cu1–xNaxTlSe2 alloys with temperature and chemical potential were explored. The obtained results show that the value of the figure of merit increases when doping CuTlSe2 with sodium to reach 0.46 and 0.87 for p-type Cu0.75Na0.25TlSe2 and n-type Cu0.50Na0.50TlSe2, respectively. [ABSTRACT FROM AUTHOR]

This paper investigates in detail the structural, magnetic, and optoelectronic properties of Cd0.75TM0.25S (TM = Os and Ir) alloys having a zinc-blende structure of the ferromagnetic phase using the full potential linearized augmented plane-wave (FP-LAPW) method as implemented in the Wien2k package. The exchange–correlation potential was treated with the generalized gradient approximation (GGA). Moreover, the GGA + U + SO approximation (where U denotes the Hubbard Coulomb energy and SO is the spin orbit coopling) are employed to treat the d electrons properly. The analysis of the values of formation energy, formation enthalpy, phonon spectra and the exchange interaction parameters show that the investigated alloys are stable and can be synthesized. The densities of states (DOS) indicate that Cd0.75TM0.25S (TM = Os and Ir) exhibits metallic nature using both GGA and GGA + SO. The half-metallic nature for Cd0.75Os0.25S and the ferromagnetic half-semiconductor nature for Cd0.75Ir0.25S have been predicted by GGA + U. Both considered alloys become ferromagnetic-semiconductors by using GGA + SO + U, where the computed band gaps are 0.52 for Cd0.75Os0.25S and 0.72 for Cd0.75Ir0.25S. The dielectric function's real and imaginary portions ε ′ ω , ε ″ ω , absorption coefficient α (ω) , and refractive index n (ω) were evaluated using a radiation range up to 30 eV. For CdS, the observed results are on par with previously published experimental and theoretical results. Our findings imply that these materials might be of potential use in future spintronic devices. [ABSTRACT FROM AUTHOR]

In this study, an analysis of the effect of Na substitution on the electronic, structural and thermoelectric (TE) properties of the Li2CuAs material is presented. The study is performed by employing the full-potential linearized augmented plane wave plus local orbital method designed within the density functional theory. To carry out the calculations related to the band structure, generalized gradient approximation by Wu-Cohen (WC-GGA) in combination with Trans Blaha-modified Becke-Johanson mBJ (TB-mBJ) potential is employed. Our results at the level of the WC-GGA approach show that there is no bandgap, whereas, at the level of the TB-mBJ approximation, the material displays bandgap with Na substitution, which is found to be further increased with the increasing Na concentration. To understand the role of different electronic states on the bandgap structure, the total and partial densities of states are also analysed. Furthermore, the temperature effect on the Seebeck coefficient, electronic thermal conductivity, electrical conductivity, power factor and figure of merit are computed. Our obtained results of the TE properties of Li2CuAs at different Na compositions suggest that this compound is a potential candidate for thermoelectricity. [ABSTRACT FROM AUTHOR]

In this work, first-principles calculations were utilised to study the structural, magnetic and electronic properties of Mn 2 PtZ (Z = V, Co) based on density functional theory (DFT). These compounds are predicted to be more stable in the Cu 2 MnAl structure and the FM ground state is energetically favourable, with magnetic moments of 4.93 and 9.04 μ B / f.u. for Mn 2 PtV and Mn 2 PtCo compounds, respectively. Additionally, the computed total magnetic moments of both compounds agree well with the Slater–Pauling rule, M T = N V - 24, and the main contribution in these magnetic moments emanates from Mn atoms for both materials. Through the results on the spin-polarised electronic properties (band structures and densities of states), it is found that both alloys reveal a complete half-metallic (HM) character with a half-metallic gap using GGA + U + TB-mBJ approximation. [ABSTRACT FROM AUTHOR]

The thermoelectric (TE) materials convert heat directly into electricity or transport thermal energy by the application of an electric current. This class of materials has been known for over a century, but the limited efficiency has slowed down their development. However, due to the discovery of new materials and the control of dimensionality, thermoelectric has regained its interest in recent years. Inspired by the fascinating properties of 2D graphite many new 2D materials are designed. The prediction of low dimensional materials and the exploration of their electronic and thermoelectric properties have demonstrated that the low dimensional approach is effective for the enhancement of the figure of merit ZT. In this review, we discuss the thermoelectricity phenomena and the latest theoretical investigations performed in developing and designing new 2D thermoelectric materials. Besides, the different strategies to improve the thermoelectric performance that could be used in the new 2D thermoelectric materials will be highlighted. [ABSTRACT FROM AUTHOR]

Using the augmented plane wave + local orbitals method with different approximation functionals, we investigate systematically the electronic, optical and elastic properties of stannite-type Cu2CdGeSe4. Among different approximation functionals, the modified Becke-Johnson (mBJ) potential with Hubbard-corrected parameter U (mBJ + U) gives the most reliable results on the electronic properties of Cu2CdGeSe4 in comparison with the experimental data. Elastic modulus, elastic constants and the Poisson's ratio of Cu2CdGeSe4 were calculated using the Elastic software package. Optical properties such as wide spectrum of absorbed photon energy, namely 1.3-27.2 eV, high absorption coefficient (above 104 cm−1) and optical anisotropy suggest the application of Cu2CdGeSe4 in solar cells. [ABSTRACT FROM AUTHOR]