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

Abstract

In this study, the microstructures and superconducting properties of Bi, Pb-2223 thin films on SrTiO 3 (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 × 10 5 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.

Microstructure and substrate dependent enhanced critical current density in Pb-substituted Bi-based high temperature superconducting thin films

“…SEM measurements were performed on the bulk and the thin film samples to get more insight into the JC value with the decrease in the dimensionality of the sample. Figures 3(a In the case of the thin films grown by the PLD technique, the values of J C obtained in the present study were found to be comparable to those reported in the literature [28][29][30][31]. The enhancement in the value of J C with the decrease in the dimensionality of the sample from bulk to thin-film can be related to the microstructure of the superconductor.…”

Enhancing Phase Purity of CSD Bi-2223 Thin Films Through Protected Sintering Method

“…The critical current density (J C ) of commercial Bi-2223 tape has exceeded 50 kA•cm −2 at 77 K and self-field [4]. Recently, it was reported that Bi-2223 thin film allows a higher J C of 0.9 MA•cm −2 (77 K, 0 T) [5]. So there is a plenty of room to improve the J C of Bi-2223 tapes through thin film technology.…”

“…Bi-2223 thin films were successfully fabricated by several methods, such as chemical vapor deposition (CVD) [6], pulsed laser decomposition (PLD) [7], molecular beam epitaxy (MBE) [8], and sputtering [5], [9]- [11]. However, few studies investigated the preparation of Bi-2223 thin films by nonvacuum method [12] because of the volatilization of elements during sintering, which leads to impure mixture of Bi-2212, Bi-2223 and some other cuprates.…”

“…It was reported that Pb was not found in the RF sputtered Bi-2223 film even though the targets contained enough Pb. But the Pb content could be observed after annealing the deposited film with Bi-2223 pellets and powders [5]. We have fabricated Bi-2212 thin films by CSD method [13].…”

Effect of Annealing DC-Sputtered Bi,Pb-2223 Thin Films

“…Other studies of Bi-2223 thin films have reported J c values of over 2.0 × 10 5 A/cm 2 at 77 K, which are in fact much higher than those obtained with tape conductors [28]. The fabrication of Bi,Pb-2223 thin films with very high J c (∼10 6 A/cm 2 at 77 K in a self-field) and zero-resistance T c (typically around 100 K) has also 00been achieved through a refined three-step (deposition + annealing + post-annealing) process [29]. Building on this work, this study explores the possibility of fabricating Bi,Pb-2223 thin films using DC sputtering, and how the J c value is affected by the temperature of subsequent heat treatment.…”