Theoretical Prediction of Lanthanum Composition Effects on Structural, Electronic and Thermal Properties of LaxSc1-XN Alloys.

Abstract In this paper we have study the structural, electronic and thermal properties of LaxSc1−xN ternary alloys in rock-salt structure by the use of full potential linearized augmented plane wave (FP-LAPW) method based to the density functional theory (DFT). For calculate the exchange-correlation energy and potential we are used both the Wu-Cohen generalized gradient (WC-GGA) approximation and the modified Becke-Johnson(mBJ).We investigated the fact of composition on lattice parameters, bulk modulus and band gap. The variation of calculated lattice constant with lanthanum composition is almost linear and shows a small deviation of the obtained results from Vegard’s law. The semiconductor nature of binary compounds ScN and LaN was confirmed. Our finding indicates that the LaxSc1−xN alloys are semiconductor with x = 0.5 and 0.75, on the contrary for x = 0.25 has a metallic nature. Lastly, the effect of thermal macroscopic properties is also investigated employing the quasi-harmonic Debye model in which the lattice vibrations are taken into account. We have found a good accord between our results and the experimental data and previous theoretical results available in the literature for the binary compounds which can be a support for the ternary alloys in the future.