Phase transformations in CuO caused by bombardment by He+ ions and by the action of spherical shock waves

The valence state of copper ions and the phase composition of copper monoxide CuO subjected to bombardment by He+ ions and explosive shock waves are studied by the methods of x-ray photoelectron spectroscopy (XPS) and x-ray emission spectroscopy (XES). Measurements of photoelectron Cu 2p and emission O K-alpha spectra revealed a decrease in the concentration of Cu2+ ions and partial reduction of CuO to Cu2O as a result of both ion bombardment and shock-wave loading. The concentration of the Cu2O phase attained values of 10-15%. The Cu2O phase is revealed by the XPS and XES methods even at concentrations lower than its threshold concentration for detection by x-ray diffraction measurements. This points to the effectiveness of XPS and XES techniques in studying nanocrystalline materials and defect structures containing finely dispersed inclusions. A model for the emergence of Cu2O due to the formation of charged clusters under the action of stress waves is proposed. (C) 2002 MAIK "Nauka/Interperiodica".