Physical property characterization of Fe-tube encapsulated and vacuum annealed bulk MgB2

Abstract

We report phase formation, and detailed study of magnetization and resistivity under magnetic field of MgB 2 polycrystalline bulk samples prepared by Fe-tube encapsulated and vacuum (10 -5 torr) annealed (750 0 C) route. Zero-field-cooled magnetic susceptibility (χ ZFC ) measurements exhibited sharp transition to superconducting state with a sizeable diamagnetic signal at 39 K (T c ). The measured magnetization loops of the samples, despite the presence of flux jumps, exhibited a stable current density (J c ) of around 2.4 x 10 5 A/cm 2 in up to 2 T (Tesla) field and at temperatures (T) up to 10 K. The upper critical field is estimated from resistivity measurements in various fields and shows a typical value of 8 T at 21 K. Further, χ FC measurements at an applied field of 0.1 T reveal paramagnetic Meissner effect (PME) that is briefly discussed.

Fluxoid jump coupled high critical current density of nano-Co3O4doped MgB2

“…We believe the aligned thin films of nano-particle doped MgB 2 are warranted to study the effective distribution of pinning centers. The fluxiod jumps are seen only for higher J c samples and are commented on earlier in some reports [7,11].…”

“…As far as the volume fraction of the superconductivity is concerned, it is difficult to ascertain the same in the presence of possible high pinning and the PME phenomenon in the present samples. Worth noting is the fact that in various earlier reports [7][8][9][10][11], a similar behavior of FC magnetization in terms of either very weak diamagnetism or PME phenomenon is seen in highly pinned nano-particles doped MgB 2 compounds. as their density, to let them act as effective pinning centers.…”

“…Further these jumps could be nearly stabilized if the fields intervals applied are small [11]. The importance of intrinsic fluxiod jumps and high J c are discussed earlier in detail in ref.…”

“…A/cm 2 ) coupled with fluxiodjumps for a vacuum-annealed and Mg-turnings added MgB 2 [11]. Interestingly this compound consisted reasonable amount of Mg/MgO in it [11].…”

“…Interestingly this compound consisted reasonable amount of Mg/MgO in it [11]. Not only the amount of added Mg turnings but the heating rate also controls the amount of Mg/MgO in the end product.…”