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Author: Bhandari, Shalika R. × End date: 2024 × Start date: 2020 × DDC: 540 × Publisher: London : RSC Publishing × WGL Institute: IFWD ×

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    Structural stability, electronic, optical, and thermoelectric properties of layered perovskite Bi2LaO4I
    (London : RSC Publishing, 2022) Joshi, Radha K.; Bhandari, Shalika R.; Ghimire, Madhav Prasad
    Layered perovskites are an interesting class of materials due to their possible applications in microelectronics and optoelectronics. Here, by means of density functional theory calculations, we investigated the structural, elastic, electronic, optical, and thermoelectric properties of the layered perovskite Bi2LaO4I within the parametrization of the standard generalized gradient approximation (GGA). The transport coefficients were evaluated by adopting Boltzmann semi-classical theory and a collision time approach. The calculated elastic constants were found to satisfy the Born criteria, indicating that Bi2LaO4I is mechanically stable. Taking into account spin-orbit coupling (SOC), the material was found to be a non-magnetic insulator, with an energy bandgap of 0.82 eV (within GGA+SOC), and 1.85 eV (within GGA+mBJ+SOC). The optical-property calculations showed this material to be optically active in the visible and ultraviolet regions, and that it may be a candidate for use in optoelectronic devices. Furthermore, this material is predicted to be a potential candidate for use in thermoelectric devices due to its large value of power factor, ranging from 2811 to 7326 μW m−1 K−2, corresponding to a temperature range of 300 K to 800 K.
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    Electronic, magnetic, optical and thermoelectric properties of Ca2Cr1−xNixOsO6 double perovskites
    (London : RSC Publishing, 2020) Bhandari, Shalika R.; Yadav, D.K.; Belbase, B.P.; Zeeshan, M.; Sadhukhan, B.; Rai, D.P.; Thapa, R.K.; Kaphle, G.C.; Ghimire, Madhav Prasad
    With the help of density functional theory calculations, we explored the recently synthesized double perovskite material Ca2CrOsO6 and found it to be a ferrimagnetic insulator with a band gap of ∼0.6 eV. Its effective magnetic moment is found to be ∼0.23 μB per unit cell. The proposed behavior arises from the cooperative effect of spin–orbit coupling and Coulomb correlation of Cr-3d and Os-5d electrons along with the crystal field. Within the ferrimagnetic configuration, doping with 50% Ni in the Cr-sites resulted in a half-metallic state with a total moment of nearly zero, a characteristic of spintronic materials. Meanwhile, the optical study reveals that both ε1xx and ε1zz decrease first and then increase rapidly with increasing photon energy up to 1.055 eV. We also found optical anisotropy up to ∼14 eV, where the material becomes almost optically isotropic. This material has a plateau like region in the σxx and σzz parts of the optical conductivity due to a strong 3d–5d interband transition between Cr and Os. In addition, we performed thermoelectric calculations whose results predict that the material might not be good as a thermoelectric device due to its small power factor.