In Situ Study of Zinc Peroxide Decomposition to Zinc Oxide by X-Ray Absorption Spectroscopy and Reverse Monte Carlo Simulations

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