Improvement of pinning in Bi2212 ceramics by hot plastic deformation

Enhanced superconducting performance of melt quenched Bi2Sr2CaCu2O8 (Bi-2212) superconductor

“…Thus alignment of grains along c-axis will result in decrease of average coherence length of polycrystalline MQ sample, when field is applied along axis of preferred orientation, thereby, resulting in enhancement of its H c2 (0). The zero temperature 8 coherence length ξ(0) is estimated from µ o H c2 (0) using Ginzburg-Landau formula given by…”

“…As far as fabrication of superconducting wire and tapes is concerned, despite the growing popularity of high temperature superconducting thin films and single crystals, the polycrystalline bulk materials still holds importance [1] [2] [3] [4]. The high temperature cuprate superconductors (HTSc) offer highest superconducting critical temperatures values among all known classes of superconducting materials [5] [6] [7] [8]. This makes them most desired materials for various applications of superconducting properties at higher temperatures and even at higher applied magnetic fields [9].…”

Melting of Bi2Sr2CaCu2O8 + x Ceramics under Uniform Compression

“…This may facilitate the preparation of microstructures that are difficult to achieve at conventional, "low" temperatures and may allow one to produce radically new microstructures, possessing unique superconducting properties. For example, it was shown previously [4] that Bi-2212 ceramic samples deformed in the range 875-940°C had a sharper texture and higher current-carrying capability compared to ceramics prepared below 875°C.…”

“…One way of achieving a sharp texture and high currentcarrying capability in this material is via hot plastic deformation near its melting point [2,3]. Very recently, Daminov et al [4] reported that composite (uniaxial compression + torsion) deformation ensured a sharp texture and high critical current density in Bi-2212 ceramics. In addition, it was found that, under a quasihydrostatic pressure of about 10 MPa, the Bi-2212 phase in the central part of the samples persisted for several hours at 940 ° C, whereas, according to differential thermal analysis (DTA) results in air at normal pressure, this phase fully decomposes at 900 ° C. The mechanism of this effect was not investigated in [4].…”

Microstructure, texture and superconducting properties of Bi2212 ceramics, deformed by torsion under pressure

“…One of such procedures is torsion under pressure [15] where quasihydrostatic pressure prevents destruction of the material and torsion leads to deformation up to very high strains [16,17]. Recently it has been revealed that applying low quasi-hydrostatic pressure (slightly above 0.6 MPa) increases the onset temperature for melting of Bi2212 by almost 60°C, which essentially expands the useable temperature range for hot deformation [18].…”