Electron energy loss spectroscopy of copper-oxygen systems at the Cu L-edge

Electron Energy Loss Spectroscopy (EELS) experiments were performed on the copper-oxygen system in conjunction with a cuprous oxide intergranular phase which has been identified in the YBa₂Cu₃O_7-x superconductor system. The objective was to confirm the +1 oxidation state necessary in the copper to achieve the stoichiometry predicted by energy-dispersive X-ray analysis and crystallography from electron microdiffraction. The near edge structure of the copper L_2,3 edge was studied for samples of pure Cu, CuO, Cu₂O, and YBa₂Cu_37-x intergranular phase. The near edge region is region is dominated by white lines in the oxidized stage and their ratios are quite adequate for valence determination. Analysis of the resulting spectra bore out the predicted results.