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

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, g(Zr-O) and g(Zr-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 Angstrom) corresponding to an eightfold oxygen coordination around zirconium ions. The first peak consists of four nearest oxygen neighbors at 2.15 Angstrom. The Zr-Zr PDF of a-ZrO2 displays a broad peak between 3.2 and 5.2 Angstrom consisting of twelve zirconium next nearest neighbors at an average distance of about 4 Angstrom and weak density fluctuations at larger coordination distances. (C) 2000 American Institute of Physics. [S0021-8979(00)00723-4].