Caractérisation structurale et vibrationnelle du ZnO par approches expérimentales et calculs ab-initio

Abstract

We have studied the structural, elastic, and electronic properties of zinc oxide (ZnO) in the wurtzite phase using first-principles calculations based on Density Functional Theory (DFT), implemented through the CASTEP code with the GGA-PBESOL approximation, combined with experimental characterization by FTIR and UV-Visible spectroscopy. We study the lattice parameters (a and c), elastic constants (C₁₁, C₁₂, C₁₃, C₃₃, C₄₄, C₆₆), mechanical moduli (B, G, E), Poisson's ratio (ν), Debye temperature (θD), band structure and density of states (DOS). The theoretical results show that the lattice parameters (a = 3.2372 Å, c = 5.2237 Å) are in excellent agreement with available experimental data from the literature. We find that ZnO is a direct-bandgap semiconductor at the Γ point, with ductile character (B/G = 3.94 > 1.75) and good thermal stability (θD = 387.84 K). Experimentally, FTIR spectroscopy reveals an absorption band at 422 cm⁻¹ attributed to Zn-O bond stretching, confirming the high purity of the sample, while UV-Visible spectroscopy yields an optical bandgap of 3.16 eV determined by the Tauc method, is in good agreement with experimental values reported in the literature