Browsing by Author "MILI Ilyas"

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    Contribution à l’étude des propriétés structurales et de transport électronique des matériaux thermoélectriques.
    (université de msila, 2023) MILI Ilyas
    Based on the electronic structure, the physical properties of Zintl alloys 〖Ca〗_(1-x) 〖Yb〗_x 〖Zn〗_2 〖Sb〗_2 and 〖Ca〗_(1-x) 〖Eu〗_x 〖Zn〗_2 〖Sb〗_2 (x=0,0.25,0.5,0.75,1) are studied. We perform ab-initio calculations within the WIEN2K code, which is based on the density functional theory (DFT). The calculations of the transport coefficients such as electrical conductivity, electronic thermal conductivity and Seebeck coefficient were carried out using the BoltzTrap code based on the semi-classical Boltzmann transport theory. The lattice thermal conductivity treated as independent thermoelectric parameter following the Slacks equation, with the help of Gibbs program to determine the Debye temperature, Grüneisen parameter... The transport properties can be significantly changed by varying the composition x. The increasing of x composition leads the compound to be more metallic behavior and the reducing of x decrease the carrier concentration, and make the material more semiconducting. The thermal and electrical conductivity is found to be significantly increased with increasing the Yb or Eu doping as a result of a shortening of electron’s lifetime. For the two alloys 〖Ca〗_(1-x) 〖Yb〗_x 〖Zn〗_2 〖Sb〗_2 and 〖Ca〗_(1-x) 〖Eu〗_x 〖Zn〗_2 〖Sb〗_2, when 0