Electronic structure, structural phase stability, optical and thermoelectric properties of Sr2AlM'O6 (M' = Nb and Ta) from first principle calculations

Abstract

Please cite this article as: B. Rameshe, M. Rajagopalan, B. Palanivel, Electronic structure, structural phase stability, optical and thermoelectric properties of Sr 2 AlM'O 6 (M'=Nb and Ta) from first principle calculations, Computational Condensed Matter (2015), Abstract First principle calculations are performed to investigate the electronic structure, structural phase stability, optical properties and thermoelectric properties of double perovskite oxide semiconductors namely Sr 2 AlM'O 6 (M'= Nb and Ta) in the cubic symmetry using WIEN2k. In order to study the ground state properties of these compounds, the total energies are calculated as a function of reduced volumes and fitted with Brich Murnaghan equation. The estimated ground state parameters are comparable with the available experimental data. Calculations of electronic band structure on these compounds have been carried out using generalized gradient approximations and modified Becke-Johanson potential (TB-mBJ). The calculated band gap for Sr 2 AlNbO 6 and Sr 2 AlTaO 6 with GGA and TB-mBJ reveal that these compounds exhibit semiconducting behavior with a direct band gap. To explore the optical transitions in these compounds, the real and imaginary parts of the dielectric function, refractive index, extinction coefficient, reflectivity, optical absorption coefficient, real part of optical conductivity and the energy-loss function are calculated at ambient conditions and analyzed both with GGA and TB-mBJ potentials. Investigations of the thermoelectric properties of these compounds have been carried out by the calculations of transport coefficients based on Boltzmann transport theory in order to analyze the variation of Seebeck's coefficient at different temperatures for various carrier concentrations based on the electronic structure near the valence band maxima.

Investigation on the electronic structure, optical, elastic, mechanical, thermodynamic and thermoelectric properties of wide band gap semiconductor double perovskite Ba2InTaO6

“…[25][26][27] Wide band gap materials have also been given attention for their high-temperature thermoelectric properties, 28 and further, double perovskites have also been investigated for their electronic, thermoelectric, optical and magnetic properties using DFT. [29][30][31] Ba 2 InTaO 6 , an important member of the vast perovskite family, has not yet been investigated for its structural, elastic, mechanical, thermodynamic and thermoelectric properties. Lufaso et al 32 have investigated Ba 2 InTaO 6 and found it to crystallize in an ordered cubic double perovskite structure with a lattice parameter of 8.2814Å.…”

Promising electronic structure of double perovskite Sr2TiMoO6: Spin-polarized DFT+U approach

“…In theoretically, structure of double perovskite A 2 BBÓ 6 can be verified by the tolerance factor (T f ), which is defined using the following formula: in the range from 0.78 to 1.05, the compound crystal structure of double perovskite comes from orthorhombic, tetragonal, and cubic to hexagonal. The double perovskite is cubic structure with Fm3 ̅ m space group (225) as ≈ 1 [10,16,17]. The T f and the crystal structure of double perovskite Sr 2 TiMoO 6 have been predicted using the Structure Prediction Diagnostic Software (SPuDS) [18,19].…”

“…Double perovskites materials are exploited in a variety of physical properties such as half metallic [1], optoelectronic [2,3] magnetocaloric [4,5], antiferromagnetic [6], ferromagnetic [7], making their widely used in spintronic and optoelectronic devices [8,9]. In addition, double perovskites have been attracted attentions for thermoelectric performance due to good durability and low synthesis cost [10][11][12][13]. Because of high electronic conductivity and low thermal conductivity, double perovskite Sr 2 TiMoO 6 exhibits as promising thermoelectric material [14,15].…”

Band structure and transport studies of half Heusler compound DyPdBi: An efficient thermoelectric material

“…Further, one can see that the conduction band minimum lies almost along the Fermi energy level except in the vicinity of the Γ point, but the valence band maximum lies just below the Fermi level at about 0.2eV at the Γ point, showing semiconducting-like nature. The presence of such flat bands at the valence band maximum corresponds to a large effective mass and is another key factor to improve the thermoelectric efficiency [40]. Thereby it is inferred that DyPdBi could be semimetallic since it exhibits metallic nature for spin-up band structure calculations, and semi-conducting like behaviour for spin-down calculations.…”

“…The transport properties of DyPdBi were calculated by using the Boltz-TraP code [27] interfaced to the Wien2k program. For background, we refer to the description of Rameshe, et al [40]: The calculations are based on a semi-classical treatment for the solution of the Boltzmann equation utilizing the relaxation time approximation and the rigid body approximation. The Seebeck Coefficient (S), as a function of temperature (T ) and doping (ρ), is given by…”