The influence of sintering temperature on the microstructure and superconducting properties ofBi1.7Pb0.4Sr1.8Nd0.2Ca1.1Cu2.1O8+δ superconductor

Abstract

The effect of sintering temperature on the microstructure and superconducting properties ofBi1.7Pb0.4Sr1.8Nd0.2Ca1.1Cu2.1O8+δ has been investigated. The samples are prepared by the solid-stateroute. Remarkable variations in microstructure, critical current density(JC) and flux pinning properties have been observed for Nd-substitutedsamples, sintered at different temperatures in the range846–852 °C. The flux pinningforce (FP) calculated fromthe field-dependent JC values show that the irreversibility lines (IL) of Nd-substituted samples shift towards higherfields to different extents depending on the sintering temperature. The samples sintered at846 °C show maximumflux pinning force (FP) of 631 kN m−3 and thepeak position of FP shifts to higher fields (0.8 T) as against262 kN m−3 and 0.44 T for thesamples sintered at 852 °C and 18 kN m−3 and0.08 T for the undoped sample sintered at its optimum sintering temperature, respectively. But the self-fieldJC value of thesamples sintered at 846 °C is lower than that of the samples sintered at852 °C. The samplessintered at 852 °C showmaximum self-field JC due to improved microstructure. The changes in microstructure followed by very high enhancement ofself-field JC, JC–B characteristic andpinning force density (FP) due to Nd substitution within a narrow temperature range, is of great scientific andtechnological significance.