Chemical-State Studies of Oxygen-Released Y-Ba-Cu Oxide

Abstract

Thermal release of oxygen from a high- T c compound, YBa 2 Cu 3 O 7 , and the subsequent changes of the chemical states were examined by a thermal desorption method and X-ray photoelectron spectroscopy. The former gives a spectrum with two peaks around 480°C and 700°C. The latter suggests that the 480°C peak corresponds to oxygens in the one dimensional CuO chains in the unit cell of the lattice, and the 700°C peak to one of the oxygens above and below the central copper atom. With the release of these oxygens, the copper atoms in the compound change from a pure Cu 2+ state into a Cu 1+ dominant state.