Study of the physical properties of new materials for application in the field of energy
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Date
2024
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Publisher
université de msila
Abstract
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Our thesis explores double half-Heusler alloys class of multifunctional materials. The main objective of our research is to investigate the structural, electronic, optical, elastic and thermoelectric properties of double half Heusler alloys ScX´Y2Sn2 (X´=Nb, Ta; Y=Ni, Pd, Pt). The current computations are conducted utilizing the full potential linearized augmented plane wave approach (FP-LAPW) that is based in density functional theory (DFT) that was carried out using WIEN2K code. the total energy is calculated by considering the exchange-correlation potential using the Local Density Approximation (LDA) and Generalized Gradient Approximation (GGA). Moreover, the Engel-Vosko (EV-GGA) and mBJ approaches are utilized to calculate the electronic and optical properties. The band structure of our double Heusler alloys exhibits semiconductors behavior, as evidenced by indirect band gaps ranging from 0.47 to 0.851 eV. Density of state diagrams reveal that d states predominate in the valence and conduction bands for atoms of Ni, Pd, Pt, Ta, and Sc. Furthermore, the optical properties, including the dielectric function, refractive index, reflectivity spectra, optical conductivity, and the energy loss function, are also considered. In addition, the elastic constants, the bulk modulus B and the shear modulus G were determined, identified the mechanical stability of our alloys. The BoltzTrap code, which is based on the semi-classical Boltzmann transport theory, was utilized to compute the transport coefficients, including electrical conductivity, electronic thermal conductivity, and Seebeck coefficient. The lattice thermal conductivity regarded as independent thermoelectric parameter following the Slacks equation, with the help of Gibbs program to obtain the Debye temperature, Grüneisen parameter...
The thermoelectric analysis suggests that these double half Heusler alloys are p-type materials. Furthermore, these alloys are considered as a potential candidate for thermoelectric devices
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Keywords
Double half Heusler alloys, DFT, EV-GGA approximation, electronic structure, optical, elastic, anisotropy, thermoelectric