CHANNELING ANALYSIS OF THE OXYGEN SUBLATTICES IN OXIDE SINGLE-CRYSTALS

Recent studies of the processes leading to oxygen atom displacement in Y(Eu)BaCuO and UO2 single crystals are reviewed. Radiation damage for mation and its transformations were measured for UO2 single crystals. In order to improve the O-signal to U-background ratio use was made of the broad resonance of the O-16(alpha, alpha)O-16 scattering occurrin g at 7.6 MeV. Thus, it was possible to detect oxygen at almost the sam e counting rate as uranium. The uranium atom displacements produced by ion bombardment influence strongly ion channeling on both sublattices . In contrast O-atom displacements can only be detected by ion channel ing on the O sublattice. He-4 ion channeling and resonant scattering a t 3.05 MeV were used to analyze Y(Eu)BaCuO single crystals and a- and c-axis oriented epitaxial layers. In contrast to UO2, oxygen atom disp lacements influence ion channeling along c-axis where mixed Cu-O rows appear. The anomalous increase in width and decreasing depth of angula r scans for Cu and O were observed at temperatures below T(c). This wa s mainly attributed to a decrease of the total displacement amplitude of the apical oxygen by 3.5 pm. A much smaller decrease of the displac ement amplitude in the order of 0.3 and 1.5 pm can also occur for the Cu and for other O atoms, respectively. The detailed analysis of the c hanneling results for both types of crystals was only possible using t he Monte Carlo simulation method.