RBS AND ION CHANNELING STUDIES OF AG-DOPED YBA2CU3O7-DELTA TARGETS AND FILMS

The location of Ag in Ag-doped YBa2Cu3O7-delta(YBCO) films and other h igh-T-c materials (such as Ag-doped BiSrCaCuO films and Ag-sheathed te xtured BiSrCaCuO wires) is a very important issue for improving high-T , materials. In this work, laser ablated and DC magnetron sputtered YB CO films on(1 0 0) LaAlO3 and (1 0 0) SrTiO3 were prepared from sinter ed Ag-YBCO composite targets (nominally containing 5 wt% Ag) and studi ed by Rutherford Backscattering Spectrometry (RES) and ion channeling techniques using 2.0 MeV He-4(+) and Li-7(+) beams. We have found that the Ag-YBCO targets contain about 3 wt% Ag and most of the retained A g atoms form some small size Ag precipitates with a typical size small er than a few microns. We have demonstrated that in very good single c rystalline YBCO films, the percentage of retained Ag in substitutional sites can be estimated by ion channeling technique. For example, we h ave found that about 1.2 wt% Ag atoms remain in the laser ablated Ag-d oped films prepared from the Ag-YBCO target and about two-thirds of th e retained Ag atoms occupy substitutional sites. The sputtered films c ontain less retained Ag atoms since the deposition temperature is high er and deposition time is longer than those for laser ablated films. ( C) 1998 Elsevier Science B.V.