Electron-beam-irradiation effects in bulk YBa2Cu3O7−x

Abstract

Irradiation effects on thin foils of bulk YBa2Cu3O7−x have been studied in a transmission electron microscope using 100-, 150-, 200-, 250-, and 300-keV electrons at 83 and 300 K. The disordering of the oxygen atoms and vacancies in the O(4) and O(5) sites in the Cu-O planes during irradiation was monitored by measuring the splitting of the (11̄0) diffraction spots in the [001] diffraction pattern. The results show that YBa2Cu3O7−x is insensitive to 100-keV electron irradiation. Irradiation by higher-energy electrons leads to irradiation-induced oxygen disordering of the oxygen atoms and vacancies, mainly by single displacement events. The excellent fit of the data to a disordering model suggests that the displacement threshold energy for oxygen in YBa2Cu3O7−x is around 18 eV and that irradiation-assisted oxygen reordering occurs in YBa2Cu3O7−x at 300 K, but not at 83 K.