Investigation of the Structural, Elastic, Electronic, and Optical Properties of Half-Heusler CaMgZ (Z = C, Si, Ge, Sn, Pb) Compounds

This study has explored numerous physical properties of CaPd$_3$Ti$_4$O$_{1}$2 (CPTO) and CaPd$_3$V$_4$O$_{12}$ (CPVO) quadruple perovskites employing the density functional theory (DFT) method. The mechanical permanence of these two compounds was observed by the Born stability criteria as well. The band structure of CPTO reveals a 0.88 and 0.46 eV direct narrow band gap while using GGA-mBJ and GGA-PBE potentials, respectively, which is an indication of its fascinating semiconducting nature. The calculated partial density of states indicates the strong hybridization between Pd-4d and O-2p orbital electrons for CPTO, whereas Pd-4d and V-3d-O-2p for CPVO. The study of the chemical bonding nature and electronic charge distribution graph reveals the coexistence of covalent O-V/Pd bonds, ionic O-Ti/Ca bonds, as well as metallic Ti/V-Ti/V bonding for both compounds. The Fermi surface of CPVO ensures a kind of hole as well as electron faces simultaneously, indicating the multifarious band characteristic. The prediction of the static real dielectric function (optical property) of CPTO at zero energy implies its promising dielectric nature. The photoconductivity and absorption coefficient of CPBO display good qualitative compliance with the consequences of band structure computations. The calculated thermodynamic properties manifest the thermodynamical stability for CPBO, whereas phonon dispersions of CPVO exhibit stable phonon dispersion in contrast to slightly unstable phonon dispersion of CPTO. The predicted Debye temperature ($\theta_D$) has been utilized to correlate its topical features including thermoelectric behaviors. The studied thermoelectric transport properties of CPTO yielded the Seebeck coefficient (186 V/K), power factor (11.9 Wcm$^{-1}$K$^{-2}$), and figure of merit (ZT) value of about 0.8 at 800 K, indicating that this material could be a promising candidate for thermoelectric applications. 

https://doi.org/10.1016/j.rinp.2022.105977

First-principles calculations to investigate structural, elastic, electronic, thermodynamic, and thermoelectric properties of CaPd3B4O12 (B = Ti, V) perovskite

Insight on the lattice dynamics, thermodynamic and thermoelectric properties of CdYF3 perovskite: A DFT study

Optical and electronic properties of defect chalcopyrite ZnGa2Se4: Experimental and theoretical investigations

In order to control the magnetic properties and electronic structures of black phosphorene (BP) monolayer, the structures, electronic and magnetic properties of non-metallic elements doped BP monolayer without or with defects including P vacancy (VP) have been studied by density functional theory (DFT). Defective BP appears ferromagnetic metallicity, and the magnetic moment is 0.086 μB. The magnetism mainly comes from the spin polarization of P atoms near the defect point. For non-metallic elements doped intrinsic BP, system doped with B and N shows P-type semiconductor. C doped shows non-magnetic metal properties. Odoped exhibits magnetic P-type semiconductor. Si and S doped shows ferromagnetic metal properties. The magnetism mainly comes from the spin polarization of P atoms near the defect point, and a small part comes from doped atoms. In the case of non-metallic elements doped defective BP, the results show that flaw-b-C and flaw-s-Si exhibit non-magnetic metallic properties. The flaw-b-S shows P-type semiconductor with indirect band gap of 0.712 eV. Other systems exhibit ferromagnetic metallicity, and the magnetism mainly comes from the spin polarization of P atoms near defect point. Non-metallic elements doped BP monolayer without or with point defects can effectively adjust magnetic properties and electronic structures. 

First-principles calculations to investigate electronic structures and magnetic regulation of non-metallic elements doped BP with point defects.

Ab initio density functional theory is employed to investigate the structural, elastic, electronic and optical properties of the half-Heusler NaScSi alloy. The lattice constants are very near to the available theoretical data. In addition, besides the GGA approximation, the modified Becke–Johnson exchange potential is also used to improve the direct X→X band gap value. Furthermore, the elastic constants and related elastic moduli confirm its stability and brittle behaviour in the type I structure. The influence of pressure on Cij constants, bulk modulus B, Cauchy pressure, Poisson ratio ν, shear modulus, B/G ratio and anisotropy factor A are analysed. Additionally, the strong absorption is extended between the visible domain and that of the ultraviolet is predicted.

Theoretical investigations of structural, mechanical, electronic and optical properties of NaScSi alloy

A series of full-Heusler based on rare earth Ag2YB (Y = Nd, Sm, Gd) are studied by linearized augmented plane waves with total potential (FP-LAPW) method. We have investigated the structural and elastic properties with generalized gradient approximation (GGA) using Perdew–Burke–Ernzehrof parameterization for electron exchange and correlation. We have found that our three compounds are stable in AlCu2Mn-type structure (FM) states that are ductile and anisotropic at equilibrium state. The lattice parameters, elastic constants, and their associated parameters are compared with other available experimental and theoretical results. The electronic and magnetic properties are studied with GGA and GGA + U approximations. Based on the quasi-harmonic Debye model, we have studied the variation of heat capacity and coefficient of thermal expansion as a function of temperature.

Structural, mechanical, magnetic, electronic, and thermal investigations of Ag2YB (Y = Nd, Sm, Gd) full-Heusler alloys

In this study, we are interested in the calculations of physicochemical properties of a new full-Heusler Mn2IrGe alloy. The calculations are performed by the full-potential linearized augmented plane wave (FP-LAPW) method within the spin density-functional theory. As exchange–correlation potential, the generalized gradient approximation formulated by Perdew, Burke, and Ernzerhof (GGA-PBE) and the modified Becke-Johnson potential (mBJ)-GGA-PBE were used. Our results have shown the structural stability and ductile character for Mn2IrGe in the CuHg2Ti-type structure. The magnetic and electronic properties reveal a half-metallic ferrimagnetic (HM-FIM) behavior of Mn2IrGe at the equilibrium lattice parameter which can be influenced by the variation of hydrostatic pressure. An integer value equal to 3 μB has been recorded for the total magnetic moment, and it is in good agreement with the Slater–Pauling rule. The thermodynamic properties including Debye temperature, heat capacity, and entropy have been estimated with different temperatures and pressures using the Debye quasi-harmonic model. This new full-Heusler can be viewed as a good candidate for spintronics.

Saliha Azzi

Papers

Theoretical investigations of structural, mechanical, electronic and optical properties of NaScSi alloy

Structural, mechanical, magnetic, electronic, and thermal investigations of Ag2YB (Y = Nd, Sm, Gd) full-Heusler alloys

Electronic and magnetic investigation of half-metallic ferrimagnetic full-Heusler Mn2IrGe