Oxygen exchange in YBa2Cu3O6+x high superconductor

A segnential kinetic analysis of oxygen absorption in YBa2Cu3O6+x is given. Investigations are conducted in a high pressure reactor with constant volume within 150-700 deg C temperature interval and at 1.4-10.7 atm oxygen pressure. Two oxygen absorption stages in tetra-phase are detected. The first one is linked with the production of oxygen solid solution in Cu(1) layers with 0.07±0.01 eV activation energy. The second stage is oxygen diffusion in the system of short disordered chains (Cu-O)n with 0.30±0.01 eV activation energy. As a result of chain growth and their interaction during the second stage an ortho-phase is produced. In this case a further reduction of the reaction rate takes place. Structural and chemical reactions for multistage character of oxygen absorption are discussed