Flux pinning force in bulkMgB2with variable grain size

Abstract

We report temperature and magnetic-field dependence of flux pinning force in bulk MgB 2 with variable grain size. The samples are prepared by advanced methods, allowing minimizing effects of porosity, impurities, and inclusions of secondary phases. The effects of grain connectivity, flux-creep phenomena, and grain size on critical current density and flux pinning curves are analyzed. We have compared the field dependence of the pinning force for a range of samples with the predictions of theoretical models accounting for the effect of the grain size. There is qualitative agreement between grain-boundary pinning mechanism proposed by Hampshire and Jones ͓J. Phys. C 21, 419 ͑1987͔͒ and the experimentally observed grain-size dependence of pinning force in bulk MgB 2 .

Role of carbon in enhancing the performance of MgB2 superconductor

“…5 & fig. 6 at 20 K. The relationship between flux pinning force and critical current density could be described by [16,17].…”

Microscopic role of carbon on MgB2 wire for critical current density comparable to NbTi

“…17,18 Carbohydrates easily decompose at, or even below 650 1C, the melting temperature of magnesium, which enables low sintering temperature fabrication to suppress grain growth. Smaller grains are related to larger pinning force and higher critical current, [19][20][21][22] according to grain boundary pinning models. It is also claimed that more homogeneous mixing is possible than with other doping methods.…”

Synthesis and characterization of excess magnesium MgB2 superconductor under inert carbon environment

“…The relationship between flux pinning force and critical current density could be described by [49][50][51],…”