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Thermoelectric properties of the LiZnX (X =P, As and Sb) filled-tetrahedral compounds: an ab initio FP-LAPW study
Allali D.1,2, Zerarga F.3, Bouhemadou A.4, Boudiaf K.4, Sahnoune F.1
1 University of M’sila, Physics and Chemistry of Materials Lab, Faculty of Science, Department of Physics, 28000 M’sila-Algeria.
2 University of M’sila, Faculty of Technology, B.P. 166 Ichbilia, 28000, M’sila, Algeria.
E-mail: allalidjamel79@yahoo.fr
3 University Abderrahmane Mira, Department of Physics, 06000 Bejaia, Algeria.
4 Laboratory for Developing New Materials and their Characterization, University of Setif 1, 19000 Setif, Algeria.

Electronic and thermoelectric properties of three principal representatives of the LiZnP, LiZnAs and LiZnSb filled-tetrahedral compounds have been studied ab initio.  We use the full-potential Linearized augmented plane-wave plus local orbitals method (FP-LAPW+lo) as implemented in the Wien2K code [1] with the original TB-mBJ [2-4] functional to model the exchange-correlation potential. Qualitatively, the investigated compounds show similar energy band dispersion; indirect band gap Г-X was found for the three considered compounds. A combination between The FP-LAPW+lo band stucture and the semi-classical Boltzmann transport theory were used to investigate the thermoelectric properties [5], the potential of the studied compounds as thermoelectric materials at three applied temperature (i.e., T=300, 600 and 900 K) was assessed. The calculated values of the Seebeck coefficient (i.e., 265, 259 and 248 µV/K) decreases going from LiZnP to LiZnAs to LiZnSb, this can be attributed to the trend of semiconducting materials where Seebeck coefficient decreases with decreasing band gap. The thermoelectric efficiency was evaluated through calculating figure of merit ZT. Intrinsically, figure of merit is about 0.8, this value might be greater by tuning the electronic structure via hole-doping.

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