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 ( ZnO 2 ) 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 degrees C. Only the ZnO 2 phase is found up to 180 degrees C, whereas only the nanocrystalline ZnO phase is occurring above 250 degrees 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.