Contribution à l’étude des propriétés physiques des composés de type Zintl à structure LaLi3Sb2

Abstract

We have studied the structural, optical, electronic and thermoelectric properties of the CaA2X2 (A=Cd, Zn; X = P, As) compound using the full potential augmented plane wave plus local orbital’s method (FP-APW + lo). The exchange correlation potential was treated with both the generalized gradient approximation (WC-GGA), and the local density approximation (LDA) then the modified Becke-Johnson potential (TB-mBJ). Besides, the estimated ground state properties such as the lattice constants and the external parameter agree well with the available experimental data. Using the GGA-TB-mBJ approach, the calculated band structure shows that CaCd2P2, CaCd2As2 compounds are semiconductors, with a direct gap (Γ-Γ) of about 1.78 eV, 1.2 eV, respectively. Compounds CaZn2P2, CaZn2As2 are also semiconductors, with an indirect gap (M-Γ) of about 1.38 eV, 1.17 eV, respectively. Optical properties reveal a strong response of these materials in the energy range between the visible light and extreme UV regions make them a good candidate for the optoelectronic devices. Thermoelectric properties such as thermal conductivity, electrical conductivity, Seebeck coefficient, power factor and merit factor are calculated. We note that the all compounds CaCd2P2, CaCd2As2, CaZn2P2 and CaZn2As2 show promising thermoelectric properties.