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 analyze d by reverse Monte Carlo simulations. Partial pair distribution functions ( PDF, g(Zr-O) and g(Zr-Zr)) are extracted. Coordination numbers and distance s 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 coor dination around zirconium ions. The first peak consists of four nearest oxy gen neighbors at 2.15 Angstrom. The Zr-Zr PDF of a-ZrO2 displays a broad pe ak 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 fluc tuations at larger coordination distances. (C) 2000 American Institute of P hysics. [S0021-8979(00)00723-4].