Influence of the spark-plasma texturing conditions on the intragranular features of Bi-2223 ceramic samples

Abstract

The influence of the spark-plasma texturing (SPT) conditions on the intragranular superconducting properties of $$\hbox {Bi}_{1.65}\hbox {Pb}_{0.35}\hbox {Sr}_2\hbox {Ca}_2\hbox {Cu}_3\hbox {O}_{10+\delta }$$ (Bi-2223) samples has been investigated. Also, the SPT samples were subjected to a post-annealing heat treatments (PAHT) in different times. Intragranular superconducting features, extracted from magnetoresistance measurements, $$\rho (T,H)$$ , in applied magnetic fields up to 9 T, were studied by analyzing the temperature dependence of the in-plane upper critical field, $$H^{ab}_\text{c2}(T)$$ , and the magnetic field dependence of the pinning energy at zero temperature, U(0, H). The results indicated that, before and after the PAHT, values of the $$H^{ab}_\text{c2}(0)$$ , obtained by using the Werthamer–Helfand–Hohenberg formula, increased $$\sim 21 \%$$ , i.e., from 115.8 to 140.2 T. We have also found that the effective intragranular pinning energy at zero applied magnetic field, $$U_0 = U(0,0)$$ , also increased over approximately three times, from 0.28 to 0.98 eV. These results strong strongly indicate that the SPT process is responsible for inducing deoxygenation at the intragranular level of ceramic samples, a feature presumably occurring near of the end of planar defects.