Valence electron energy-loss spectroscopy study of ZrSiO₄ and ZrO₂

ZrSiO₄ (zircon) and m-ZrO₂ (zirconia) are fundamental and industrially important materials. This work reports the detailed valence electron energy-loss spectroscopy (VEELS) studies of these compounds. The dielectric response functions, as well as single-electron interband transition spectra, are derived from VEELS data for both ZrSiO₄ and m-ZrO₂, in the range 5-50eV using the Kramers-Kronig analysis method. Our interpretation of the interband transitions is given with the aid of ab initio calculations of density of states. The bandgap energies for both materials are also measured using VEELS. The surface and bulk plasmons are identified: the surface plasmon peaks locate at around 12eV, and two bulk plasmon peaks are ~15-16eV and ~25-27eV, respectively. Although similarities in the VEELS exist between ZrSiO₄ and m-ZrO₂, two major differences are also noticed and explained in terms of composition and structure differences.