In situ study of zinc peroxide decomposition to zinc oxide by X-ray absorption spectroscopy and reverse Monte-Carlo simulations

Abstract

The Zn K-edge X-ray absorption spectroscopy has been used to investigate in situ the decomposition of zinc peroxide (ZnO2) to zinc oxide (ZnO). Principal component and linear combination analyses of the EXAFS spectra have been employed to identify the phase composition of the oxide upon heating to 900 • C. Only the ZnO2 phase has been found up to 180 • C, whereas only the nanocrystalline ZnO phase has occurred above 250 • C. Detailed structural information on the temperature dependence of the local environment of zinc atoms has been obtained using the reverse Monte Carlo simulations. A strong increase of disorder has been found upon approaching the decomposition temperature, evidenced by the broadening of Zn-O and Zn-Zn pair distribution functions and related mean-square relative displacements.