The resistance transitions of Gd-diffused polycrystalline Y123 samples were measured as a function of temperature and magnetic field. It was deduced from experimental results that the activation energy increased when the diffusion annealing temperature increased and also the activation energy of Gd-diffused samples were larger than that undoped Y123 sample. The magnetic field dependence of U follows a power law, i.e. U ∝ H−α, with the values of α were 0.42, 0.56 and 0.61, respectively, for pure Y123, and Gd-diffused Y123 at 800 and 900C. The changing of α-values from 0.42 to 0.61 imply that the thermally activated dissipative resistivity was directly associated with pinning mechanism changes from intrinsic planar defects pinning to extrinsic point defects pinning because of large Gd content into Y123 sample by the means of diffusion annealing temperature increasing. The possible reasons for the effect of Gd-diffusion upon the pinning behavior were considered here.

Gadolinium Diffusion-Doping for Enhancing Activation Energy in Superconducting YBa2Cu3O7−x. K.Öztürk, Ş.Çelik, E.Yanmaz: Journal of Alloys and Compounds, 2008, 462[1-2], 19-23