Structural, magnetic, electronic, optical and mechanical properties of actinide perovskite oxides XAnO3 [X = Cs+, Ba2+; An = Np5+, Np4+]: GGA, GGA+U and GGA+U+mBJ investigations.

First-principles density functional theory (DFT)-based calculations were performed to investigate the structural, magnetic, electronic, optical and mechanical properties of two actinide perovskite oxides XAnO3, where [X = Cs+, Ba2+; An = Np5+, Np4+]. Wien2k software is utilized with GGA, GGA + U and GGA + U + mBJ potentials. The unit cell volumes for cubic (Pm-3m) structure of XAnO3 are optimized to achieve the ground state energy and equilibrium parameters. Substitution of X- and An-sites increases the lattice constant, a0 = 4.3998 Å (X = Cs+) and a0 = 4.4378 Å (X = Ba2+). The calculated band structure plus total and partial density of states using these methods confirm the 100 % spin-polarization and half-metallic (HM) nature of XAnO3 with Eg↓ = 2.731, 3.896 and 3.787 eV (X = Cs+); 3.891, 3.929 and 4.329 eV (X = Cs+). Total magnetic moment per unit cell of XAnO3 is respectively MTot = 2.0 and 3.0 µB revealing their ferromagnetic (FM) behavior with high Curie temperature (TC) within GGA, GGA + U and GGA + U + mBJ. Mechanical and thermodynamic stability of XAnO3 have been proved via the elastic parameters, sound velocity, Debye and melting temperatures, and enthalpy of formation. In addition, XAnO3 show amazing optical responses include high absorption, conductivity, refractivity, and reflectivity. These investigated properties confirm that XAnO3 materials have FM-HM and high optical characteristics and they perfectly suitable for many spintronics and optoelectronics applications such as sensors, storage devices and photodiodes.

Consequences of Tuning Rare-Earth RE3+-Site and Exchange-Correlation Energy U on the Optoelectronic, Mechanical, and Thermoelectronic Properties of Cubic Manganite Perovskites REMnO3 for Spintronics and Optoelectronics Applications.

Both rare-earth SmMnO3 and EuMnO3 compounds that belong to transition-metal-based manganite perovskites REMnO3 have been studied deeply in this paper. The structural, elastic, optoelectronic, magnetic, mechanical, and thermoelectronic properties of cubic SmMnO3 and EuMnO3 compounds have been computed using the full-potential linearized augmented plane-wave (FP-APLW) method in the frame of density functional theory (DFT). To compute the ground-state energy, the effect of exchange-correlation potential was treated via the application of generalized gradient approximation within Perdew, Burke, and Ernzerhof (PBE-GGA) plus its corrected method (GGA + U). The spin-polarized results of band structures, density of states (DOS), and magnetic moments show that SmMnO3 and EuMnO3 have ferromagnetic half-metallic (FM-HM) behavior. Optical responses of dielectric function (ε(ω)) are explained by computing the real ε1(ω) and imaginary ε2(ω) parts of ε(ω), refractive index n(ω), extinction coefficient k(ω), absorption coefficient α(ω), optical conductivity σ(ω), reflectivity R(ω), and energy loss function L(ω) using GGA and GGA + U. Also, we computed and discussed the thermoelectronic properties of SmMnO3 and EuMnO3, including Seebeck coefficient (S), holes and electrons charge carrier concentration (n), electrical conductivity (σ/τ), power factor (S 2σ/τ), figure of merit (ZT), thermal conductivity (κ), and specific heat capacity (C V), as a function of temperature (T), using GGA and GGA + U methods based on BoltzTrap scheme. The present results confirm the perfect mechanical and thermal stability of two perovskites which make SmMnO3 and EuMnO3 promising materials for spintronics, optoelectronics, high-temperature, and other related applications.

Thermal, electro-magnetic and thermoelectric investigation of CoNb1-x Ti x Sn (x = 0, 0.75, 0.5, 1) half-Heusler alloy.

In this work, structural, thermal, electro-magnetic and thermoelectric attributes of CoNb1-x Ti x Sn (x = 0, 0.75, 0.5, 0.25, 0) alloys have been investigated using density functional theory (DFT). The structural reforms, brought to CoNbSn, portray the increase in its rigidity when increasing the Ti content substituted at the Nb site. They also remodel the character of the alloy from semiconducting paramagnetic to half-metallic ferromagnetic nature. By investigating elastic properties that are interlinked with structural optimizations and enthalpy of formation, studied alloys displayed stable structure. Thermoelectric properties such as Seebeck coefficient (S), electrical conductivity (σ/τ) and power factor (S 2 σ/τ), are calculated based on the Boltzmann transport theory. Results revealed that for x = 0.75 in CoNb1-x Ti x Sn, a temperature dependent switch from n-type to p-type is observed. According to the results obtained, CoNb1-x Ti x Sn alloys could have potential thermoelectric applications.