X-ray and neutron diffraction of yttrium-barium-copperotide: Modeling diffraction intensity variations produced by surface leaching

摘要

High normal current fluences have long been reported to produce major changes in the x-ray diffraction pattern of YBa_2Cu_3O_7-x(YBCO). These x-ray diffraction effects have now been shown to result from the removal of barium from the YBCO near-surface lattice together with the formation of a thin barium oxide overlayer. Neutron diffraction reveals that the bulk crystallographic structure remains unaltered by charge fluences of more than 40 million C/cm_2, and Auger electron spectroscopy confirms the presence of surface barium enrichment.