Reverse Monte Carlo analysis of extended x-ray absorption fine structure spectra of monoclinic and amorphous zirconia

Abstract

Extended x-ray absorption fine structure spectra of monoclinic zirconia (m-ZrO2) and of amorphous zirconia (a-ZrO2) in form of a thin film are analyzed by reverse Monte Carlo simulations. Partial pair distribution functions (PDF, gZr–O and gZr–Zr) are extracted. Coordination numbers and distances determined for m-ZrO2 are identical to results of structural analysis by diffraction. The local structure of a-ZrO2 consists of a widely spread Zr–O shell (from 1.9 to 3.3 Å) corresponding to an eightfold oxygen coordination around zirconium ions. The first peak consists of four nearest oxygen neighbors at 2.15 Å. The Zr–Zr PDF of a-ZrO2 displays a broad peak between 3.2 and 5.2 Å consisting of twelve zirconium next nearest neighbors at an average distance of about 4 Å and weak density fluctuations at larger coordination distances.