Internal friction study of YSr2Cu3−xFexO7−δ

The internal friction of YSr2Cu3−xFexO7−δ (x=0.35, 0.5 and 1) ceramics was measured by the vibrating-reed method from liquid nitrogen temperature to room temperature at kilohertz frequencies. Two mechanical energy dissipation peaks appeared around 200 and 250 K (labeled as P4 and P3, respectively) for x=0.35 sample. With increasing Fe content, P4 shifts toward higher temperature and P3 is depressed. These results provide more information on their origin of them in YBa2Cu3O7−δ (Y123) and show a crucial relationship between P4 peak and the CuOx chain layers.