A Comparative Study of the Effect of Strain on the Electronic and Optical Properties of Filled and Unfilled Ba8Si46 Type I-clathrate

N.A. Mahammedia,b, R. Belkada c and M. Ferhatb,d aLaboratoire de Physique des Matériaux LPM, Amar Télidji University of Laghouat, BP 37G, Laghouat 03000, Algeria bSemiconductors and Functional Materials Laboratory SFML, Amar Télidji University, Laghouat cCRTSE, Research Center in Semiconductor Technology for the Energetic, Algiers, Algeria dDepartment of Physics, University of the West Indies, Kingston 07, Jamaica

Full Text PDF

A first principles calculations study is carried out to theoretically investigate the effect of compressive and tensile strains on the structural, electronic and optical properties of type-I guest-free Si46 and barium-filled Ba8Si46 clathrates. The electronic band structure of the unfilled Si46 clathrate revealed a semiconducting behaviour with a quasi-direct band gap of 1.36 eV. Under hydrostatic pressure, the bandgap magnitude of the guest-free Si46 behaves monotonously. For the Ba doped Si46 clathrate (Ba8Si46) structure, the strain has no significant effect on the electronic band structure, while its impact on the optical properties is appreciable. The optical properties, such as the dielectric function and the absorption were computed for different strain variations, which are clearly enhanced for both the unfilled Si46 and Ba-filled Ba8Si46 clathrates when the pressure is 1 GPa in the direction of a compressive state.

DOI: 10.12693/APhysPolA.132.836 topics: First-principles calculations, Ba8Si46 clathrates, cage structure mechanical properties, electronic structure properties