Study of the Structural, Electronic and Optical Properties of 1T-ZrX₂ Materials (X=S, Se, Te)

Abstract

The Electronic and optical properties of zirconium dichalcogenides (ZrS2,ZrSe2, andZrTe2),have been explored via ab-initio methods based on the density functionaltheory (DFT) within the frame of generalized gradient approximation (GGA) and a couplingtechnique between the plane wave (PW) and the pseudo-potential (PP) approaches. Theobtained results showed that ZrS2 and ZrSe2 are semiconducting materials with energy gapsof 1.15 eV and 0.3 eV respectively from the valence band maximum located at G point andthe conduction band minimum located at L point, while ZrTe2 showed a metallic characterwith a density of states at the Fermi level of about 0.8 states/eV. Based on a Kramers–Kroniganalysis of the reflectivity, we have obtained the spectral dependence of the real andimaginary parts of the complex dielectric function (ε1 and ε2, respectively) and the refractiveindex (n). The collected data were used for the calculation of absorption coefficient,reflectivity index, conductivity, and electron energy loss function of ZrS2, ZrSe2, and ZrTe2 forradiation up to 20 eV. All three chalcogenides were found to be good absorbers of ultravioletradiation. The reflectivity of ZrS2 is low in the visible and near-ultraviolet region butincreases sharply for higher photon energies and approaches 96% at ~18.5 eV. The R(ω) spectrum of ZrTe2, on the other hand, is non-selective and remains above 50% over a widerange of energies from infrared to ultraviolet which suggeststhe potential application of thismaterial as an effective solar reflector. On the other hand, the refractive indices of ZrS2, ZrSe2,and ZrTe2 in the visible range are high. The optical spectra show moderate anisotropy concerning the electric field polarization of the incident light.