Critical current density enhancement of Bi, Pb-2223 thin film fabricated by RF sputtering and post-annealing processes

In this study, the microstructures and superconducting properties of Bi, Pb-2223 thin films on SrTiO₃(100) fabricated by radio-frequency (RF) sputtering and annealing have been investigated. Most of the as-deposited films fabricated by RF sputtering did not exhibit a superconducting transition, due to low crystallinity, deviation from the composition of Bi-2223, and low intergrain connectivity. The as-deposited films did not contain Pb. To obtain the Bi, Pb-2223 phase, we annealed the film with Bi, Pb-2223 pellets and powder. After annealing, we confirmed that the thin film contained Pb. A zero-resistance transition temperature of 100 K was obtained in the Bi, Pb-2223 thin film after post-annealing. We observed strong 00l peaks and a sharp quadrupole in x-ray θ–2θ and ϕ-scan measurements. These results suggested that this film consists of a single phase of Bi, Pb-2223 and has a biaxial orientation. The Bi, Pb-2223 thin film had a maximum critical current density of 0.9 × 10⁵ A cm⁻² at 77 K in a self-field. Furthermore, Bi, Pb-2223 exhibited very strong anisotropy in its critical current density–magnetic field angle characteristics. (paper)