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The electronic behavior, ferromagnetism and optical characteristics of MgTM2O4 (TM = V, Fe) cubic spinels are investigated using the full-potential linearized augmented plane wave (FP-LAPW) approach, which involves concepts of density functional theory. The calculated band structures reveal half-metallic behavior in MgV2O4 and a ferromagnetic semiconducting nature in MgFe2O4. Moreover, the density of states (DOS) reveals that the magnetism results from the strong hybridization between Fe/V-3d and O-2p states, due to which Fe/V magnetic moments are reduced because magnetic moments appear at Mg and O sites. Hence, the spinels have importance for spintronic applications. The ferromagnetic phase stability is confirmed by the values of released energy, which are consistent with the computed values of the crystal field and exchange energies. The dielectric constant and refractive index values are large for MgV2O4 but small for MgFe2O4 due to their half-metallic and semiconducting nature, respectively. The blueshift of the absorption spectrum makes the spinels attractive for optical applications. The electrical and thermal conductivity are also computed using BoltzTraP code, and potential energy conversion applications are suggested. [ABSTRACT FROM AUTHOR]

The variant double perovskites are considered novel materials for solar cells and optoelectronic applications. Here, we explored electronic, mechanical, and optical characteristics of Cs2SeX6 (X = Cl, Br, I) by density functional theory (DFT) analysis. The tolerance factor between 0.97–1.0 signifies the structural stability of the investigated compounds while thermodynamic and mechanical stabilities were ensured by positive frequencies of phonon dispersion as well as elastic constants. Moreover, the Poisson and Pugh's ratios are explored for brittle and ductile behavior. The Debye and melting temperatures have also been reported through mechanical analysis. The tuning of the bandgap takes place from 3.10 to 2.64 eV and then 1.15 eV by substitution of Cl with Br and I, respectively. The optical spectra show a shift in absorption region from ultraviolet-to-visible. In addition, the low light reflection and optical energy loss range (0.0–3.0 eV) promises potential of the studied potential for solar cells and optoelectronics uses. [ABSTRACT FROM AUTHOR]

Magnesium containing chalcogenides received considerable attention for solar cells. Herein, using modified Backe and Johnson potential the electronic, characteristics of MgLa2(S/Se)4 are computed, and band gaps of 2.4 and 2.1 eV were found for MgLa2S4 and MgLa2Se4, respectively. The absorption in visible increases their significance for optoelectronic applications. The optical characteristics were determined by dielectric constant and refractive index and as absorption coefficient. Moreover, the thermoelectric characteristics, including thermal and electrical conductivities, Seebeck coefficient, power factor, and figure of merit, were analyzed by BoltzTraP code. The calculated Pugh (> 1.75) and Poisson (> 0.26) values revealed their ductile behavior. MgLa2S4 showed a high value of melting and Debye temperature as compared to MgLa2Se4. Finally, partial covalent bonding was found by electron density plots. [ABSTRACT FROM AUTHOR]

This work presents the influence of external pressure (in the range of 0 to 20 GPa) on the optoelectronic and thermoelectric response of magnesium-based perovskites oxide (MgHfO3) in the cubic phase. The calculations have been performed by using Perdew–Burke–Ernzerhof (PBEsol) generalized gradient approximations functional within density functional theory calculation. Our results show a striking transition of intrinsic indirect bandgap at high symmetry point Г–M to direct bandgap at Г–Г point at a pressure of 20 GPa. The subsequent optical and thermoelectric parameters have been modified with pressure. To examine the influence of pressure on the optical properties, we performed a comprehensive analysis of the optical characteristics of MgHfO3. Calculations for thermoelectric properties have been performed using semi-classical Boltzmann transport theory in the BoltzTrap code. The investigations of thermoelectric properties cover the pressure dependence of electrical and thermal conductivities, Seebeck coefficient, and power factor. Our results show that MgHfO3 demonstrates large absorption of light in the ultraviolet region and high thermal efficiency, providing a new pathway for experimentalists for energy renewable device fabrication. [ABSTRACT FROM AUTHOR]

The influence of indium on the properties of Cu0.5Zn0.5Fe2O4 nano ferrites synthesized by sol–gel auto-combustion technique was studied. X-ray diffraction (XRD) analysis demonstrated that pure and substituted ferrites possessed cubic spinel structure. The lattice parameter increases with the inclusion of In3+ for x ≤ 0.16 and decreases subsequently. A linear decrease in crystallite size was found as concentration of indium increased. X-ray density, strain, and dislocation density were increased as indium content increases. Hopping lengths as well as radii of A and B sites revealed increasing behavior up to x = 0.16 and decreased thereafter. The spectral bands indicated the formation of spinel structure. The band positions were altered with the increase of In3+ contents. The inclusion of indium ions increases the value of dielectric parameters while magnetic parameters decreased. This increase in dielectric parameters and decrease in magnetization proposed that synthesized magnetic oxides may have potential in the fabrication of switching and high-frequency devices. [ABSTRACT FROM AUTHOR]

The spinel chalcogenides Zn/CdSc2Se4 are evaluated by first-principle approach to compute optoelectronic and transport characteristics. The formation energy computations favour their thermodynamic stability. The direct bandgaps 1.0 and 0.80 eV are evaluated of the most versatile modified Becke and Johnson potential. The optical spectra have been analysed in terms dielectric constants. The absorption region expands from visible to ultraviolet, which is suitable for optoelectronics. The bandgap-dependent transport characteristics are addressed by classical theory of Boltzmann using BoltzTraP code, and a high figure of merit was noted. Finally, electron density measures the polar covalent bond in Sc-Se and Zn/Cd-Se. [ABSTRACT FROM AUTHOR]

The structural, magnetic, dielectric, and surface morphology of BiSnxFe1-xO3 (x = 0.0 to 1.0) was analyzed experimentally. The samples were synthesized by a simple chemical micro-emulsion method. The X-ray diffraction (XRD) analysis reveals structural distortion at A site and B site of BFO due to Sn doping in rhombohedral phase. The EDX data certify Sn is well incorporated in BiFeO3. The effect of Sn doping on crystal size and grain size has also been addressed. The FTIR analysis elaborates absorption at 555 cm−1 which is due to stretching and bending vibrations of O–Fe–O bonds. The magnetic properties are illustrated by vibrating sample magnetometer (VSM). The magnetic moments and exchange mechanism described theoretically by DFT analysis which support the experimental results. The dielectric behavior of studied materials has been evaluated by dielectric constant (ɛʹ), tangent loss (tanδ), real and imaginary part of impedance, and Cole–Cole plots in 1–3 GHz. The spin-orientated magnetism and dielectric response increase their potential for microwave absorber and sensor. [ABSTRACT FROM AUTHOR]