Magnetotransport and structural properties of superconducting BPSCCO thick film on MgO substrate

Superconducting thick films of Bi _1.8Pb _0.4Sr ₂Ca _2.2Cu ₃O _x (BPSCCO) have been prepared on MgO single crystal sub-strates by employing a screen-printing method. Using this technique, we have prepared several samples utilizing different experimental conditions. Optimization of properties such as film thickness, microstructure, phase formation and annealing time was carefully monitored to obtain samples with transport properties that are quite sensitive to relatively low magnetic fields. The thick film was characterized using XRD, SEM, I-V characteristics and magnetoresistance methods. The microstructural analysis revealed that the samples were superconducting with the existence of a considerable number of weak links between the grains and at the grain boundaries. When the R-B curves were plotted at T = 77 K and at relatively low applied magnetic fields up to 100 G, the value of the normalized resistance was well fitted to the relation R(B)/R(B = 0) = 1 + αB ², where a is a constant. Samples were also measured after several thermal cycles to check the reproducibility at various experimental conditions. It was demonstrated that the I- V curves were independent of the number of thermal cycles and exhibited no significant change at relatively low currents and magnetic fields.