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Double perovskite halides are a potential candidate for the applications of the solar cell, photovoltaic and thermoelectric, due to their non-toxicity and environmental stability. The density functional theory (DFT) calculation investigates the details physical properties of halides Rb 2 ScAgX 6 (X = Cl, Br, I) that can be useful for applications like thermoelectric and solar cells. The structural and thermodynamics stability is endorsed by the formation energy, tolerance factor, and Born stability criteria. The calculated indirect band gaps of 1.95 eV, 1.85, and 1.60 eV for Rb 2 ScAgCl 6 , Rb 2 ScAgBr 6 , and Rb 2 ScAgI 6 respectively, ensure the light absorption in the region of visible range. Therefore, all studied halides are widely used in optoelectronic devices like solar cells. In addition, thermoelectric properties are examined through thermal conductivity, electrical conductivity, and the Seebeck coefficient. ZT values of 0.74, 0.71, and 0.72 for Rb 2 ScAgI 6 , Rb 2 ScAgBr 6 , and Rb 2 ScAgCl 6 double perovskites are recorded, which spotlight their significance for the applications of thermoelectric. [ABSTRACT FROM AUTHOR]

We investigate zinc-blende phase Al 0.75 Mn 0.25 Y (Y=N, P, As) compounds using full-potential linear-augmented-plane wave plus local-orbital method. For computing structural and elastic properties the Generalized Gradient Approximation (GGA) has been used; whereas the electronic and magnetic properties are examined at the optimized GGA lattice parameters by employing modified Becke and Johnson local density approximation. All these compounds are found to be stable in ferromagnetic ordering in the zinc-blende structure which is supported by the computed elastic constants. The nature of electronic band structure are calculated and the nature of band gaps in the doped system is analyzed. The results are examined to identify exchange mechanism which is the main source of introducing ferromagnetism in the compounds under investigation. Spin charge density contour plots in the (1 1 0) plane and the evaluation of s–p and p–d exchange constants ( N 0 α and N 0 β ) are evaluated for understanding bonding and exchange splitting process, respectively. [ABSTRACT FROM AUTHOR]

The structural, electronic and magnetic properties of Cr-based MgSe in zinc blende phase have been investigated by employing the full-potential linear augmented plane waves plus local orbitals (FP-LAPW+lo) method within the spin-polarized density functional theory (DFT). According to our findings, Mg 1− x Cr x Se exhibits a half-metallic characteristic, where the ferromagnetic state is more favorable than the antiferromagnetic state. The band structure results of half-metallic Mg 1− x Cr x Se system for x =0.25, 0.50 and 0.75 show 100% spin-polarization at the Fermi level ( E F ). The total magnetic moment is 4 μ B which is mainly due to the Cr-3 d states at the Fermi level ( E F ). Our results indicate the presence of small magnetic moments arising from the other non-magnetic atoms as well. We also calculated the spin dependent charge densities to understand the bonding nature of the system. [ABSTRACT FROM AUTHOR]

Ab-initio calculations for V-doped BeSe and BeTe semiconductors are performed by means of all-electrons full-potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method. The structural properties are optimized using the Wu-Cohen generalized gradient approximation functional, whereas modified Becke and Jhonson local density approximation functional has been employed for evaluating the spin-polarized electronic and magnetic properties. Magnetic stability at various doping concentrations in ferromagnetic (FM) and anti-ferromagnetic (AFM) ordering is investigated by comparing the minimum total energies and enthalpies of formation (Δ H ). Studied band structures, density of states, total energy, exchange interactions and magnetic moments manifest both alloys with half-metallic ferromagnetic behavior. Moreover, their valance bands are found to be paired ferromagnetically with V atoms. Furthermore, it was observed that the magnetic moment of vanadium atom reduces from free space charge value due to p–d hybridization which yields small magnetic moments on the Be, Se and Te sites. [ABSTRACT FROM AUTHOR]

Abstract: The polycrystalline samples of the composition Ba(Ni1−x Ti x )2Fe16O27 were prepared by the conventional ceramic method with (x =0.0–1.0). Effects of titanium (Ti) doping on structural and magnetic properties of BaNi2 based W-type hexaferrites were analyzed. The samples were initially sintered in air at 1000°C for 4h and finally at 1300°C for 9h. The X-ray diffraction patterns confirm the presence of single W-hexagonal phase. The lattice parameters ‘a’ and ‘c’ were found to show irregular behavior by increasing Ti content. The variations of magnetic properties were observed by analyzing hysteresis loop of prepared samples. The results show that maximum magnetization (M) and remanence (M r ) decrease up to x ≤0.6 due to replacement of Ti ions for spin down (4f2) and spin up (12k, 2a and 2b) sublattices, but a substantial increase of M and M r for (x =0.8 and1.0) could be attributed to the replacement of Ti ions for spin down sublattices (4f2). The coercivity (H c ) was found to decrease with increasing Ti content. An increase of grain size with Ti content was also observed. Since, H c is inversely proportional to the packing fraction of magnetic materials or the grain size. [Copyright &y& Elsevier]

The mechanical, thermodynamic, electronic, and optical properties of Na 2 MoO 4 (NMO) and Na 2 WO 4 (NWO) spinels are elaborated by density functional theory (DFT) based full potential augmented plane wave method (FP-LAPW + lo). Our optimized lattice constants for the studied spinels are in good agreement with that obtained experimentally. The enthalpy of formation ensures the thermodynamic stability of NMO and NWO in the cubic phase. The Born mechanical stability criteria guarantees their mechanical stability, while Poisson ratio (ν) and Pugh's ratio (B/G) infer their brittle behavior. The Debye temperature (θ D) is significant for NMO than NWO. The wide bandgap of 3.5 eV for NMO and 4.4 eV for NWO show the maximum absorption in the ultraviolet region that increases their importance for optoelectronic applications. The optical properties are explained in term of dielectric constant, refractive index, absorption of light, reflection, and optical loss factor. [ABSTRACT FROM AUTHOR]