Pore structure dependence with the sintering time for dense ceramic bulk YBa2Cu3Oy

Technological applications of bulk high-TC superconductors, in particular of YBa2Cu3Oy, require polycrystalline materials with improved physical properties which strongly depend on the presence of pores and their characteristics. In this work we have studied the pore structure and their principal features in dense YBa2Cu3Oy samples prepared with different sintered times. The samples were prepared through a classic solid state reaction method. The critical temperatures of the samples were measured by using zero field cooling magnetization. The pore structure and their features were studied through N2 sorption measurements. Our experimental results show that the principal characteristics of the pore structure depend on the sintering time. In particular, samples sintered during 24 h show a higher porosity and external surface area, as also a more heterogeneous pore distribution slightly shifted to the low pore widths region, when compared to other samples sintered by using different times. Our work shows the importance of the sintering conditions regarding the controlling of the porous character of bulk YBCO superconductors.