Abstract
The magnet-resistivity measurements of the Y-based Y3Ba5Cu8O18-x superconductor under different magnetic fields ranging from 0 to 200 mT have been carried out to understand the dissipation mechanisms in the resistive transition. Samples were synthesized in air by solid-state reaction method. Three models are employed to investigate the broadening of the resistive transition. The Ambegaokar-Halperin phase slip (AH), thermally activated flux creep (TAFC) models for granular superconductors, and Kosterlitz-Thouless (KT) model describing the vortex-antivortex unbinding for 2D. Phase analysis by X-ray diffraction (XRD) and morphology examination by scanning electron microscopy (SEM) were carried out. The AH and TAFC models cannot explain the whole of the broadening of resistive transition; a small temperature range is not described by these two models. Furthermore, our experimental data shows a good agreement with the KT model over the entire transition range justifying the picture of vortex-antivortex unbinding.