원문정보
초록
영어
The effects of the heat treatment temperature (600℃-1050℃) on the formation of MgB2 and the superconducting properties have been examined. The self-synthesized MgB4 and commercial Mg powders were used as raw materials for the formation of MgB2. The superconducting critical temperatures (Tcs) of MgB2 bulk superconductors prepared at 600℃-850℃ were as high as 37-38 K regardless of the heat treatment temperature. However, because MgB4 is more stable than MgB2 at above 850℃, no superconducting signals were detected in the susceptibility-temperature curves of the samples prepared above 850℃. As for the critical current density (Jc), the sample heat-treated at a low temperature (600℃) for a prolonged period (40 h) showed a Jc higher than those prepared at 650℃-850℃ for a short period (1 h). The FWHM (full width at half maximum) result showed that the grain size of MgB2 of the 600℃ sample was smaller than that of the other samples. The high Jc of the 600℃sample is attributed to the presence of large numbers of grain boundaries, which can act as flux pinning centers of MgB2.
목차
1. INTRODUCTION
2. EXPERIMENTAL PROCEDURE
3. RESULTS AND DISCUSSION
4. CONCLUSIONS
ACKNOWLEDGMENT
REFERENCES