RBS and ion channeling studies of Ag-doped YBa2Cu3O7−δ targets and films

Abstract

The location of Ag in Ag-doped YBa 2 Cu 3 O 7−δ (YBCO) films and other high - T c materials (such as Ag-doped BiSrCaCuO films and Ag-sheathed textured BiSrCaCuO wires) is a very important issue for improving high - T c materials. In this work, laser ablated and DC magnetron sputtered YBCO films on (1 0 0) LaAlO 3 and (1 0 0) SrTiO 3 were prepared from sintered Ag-YBCO composite targets (nominally containing 5 wt% Ag) and studied by Rutherford Backscattering Spectrometry (RBS) and ion channeling techniques using 2.0 MeV 4 He + and 7 Li + beams. We have found that the Ag-YBCO targets contain about 3 wt% Ag and most of the retained Ag atoms form some small size Ag precipitates with a typical size smaller than a few microns. We have demonstrated that in very good single crystalline YBCO films, the percentage of retained Ag in substitutional sites can be estimated by ion channeling technique. For example, we have found that about 1.2 wt% Ag atoms remain in the laser ablated Ag-doped films prepared from the Ag-YBCO target and about two-thirds of the retained Ag atoms occupy substitutional sites. The sputtered films contain less retained Ag atoms since the deposition temperature is higher and deposition time is longer than those for laser ablated films.