Microstructural and electrical transport properties of uniaxially pressed Bi_(1.65)Pb_(0.35)Sr_2Ca_(2.5)Cu_(3.5)O_(10+δ) ceramic superconductors

摘要

Abstract We have studied the effect of the pelletization pressure on microstructural and electrical transport properties of superconducting ceramics with starting composition given by the formula $$text {Bi}_{1.65}text {Pb}_{0.35}text {Sr}_2text {Ca}_{2.5}text {Cu}_{3.5}text {O}_{10+delta }$$ Bi 1.65 Pb 0.35 Sr 2 Ca 2.5 Cu 3.5 O 10 + δ . The experimental data of electrical measurements was processed in order to obtain the weak-link resistivity, the orientation probability of the grains’ a -axes along a certain preferential direction, the slope of the linear part in the temperature dependence of the ab-planes resistivity, and the intrinsic effective anisotropy of the grains, of each sample. In contrast with the behaviour of $$text {Bi}_{1.65}text {Pb}_{0.35}text {Sr}_2text {Ca}_{2}text {Cu}_{3}text {O}_{10+delta }$$ Bi 1.65 Pb 0.35 Sr 2 Ca 2 Cu 3 O 10 + δ ceramics, the Ca, Cu enriched samples exhibit a reduction of their effective anisotropy at sample level and weak links resistivity with increasing compacting pressures. In addition, a compacting pressure of around 488 MPa may affect considerably the electrical and structural parameters of the material. The results suggest that a combined effect of the pelletization pressure and the doping with Ca and Cu can be used to improve the electrical transport properties of these materials for technological applications.