We report on the results of a comparative investigation of highly dense bulk MgB2 samples prepared by three methods: (i) hot deformation; (ii) high pressure sintering; and (iii) mechanical alloying of Mg and B powders with subsequent hot compaction. All types of samples were studied by ac-susceptibility, dc-magnetization and resistivity measurements in magnetic fields up to μ0H=160 kOe. A small but distinct anisotropy of the upper critical field Hc2a,b/Hc2c∼1.2 connected with some texture of MgB2 grains was found for the hot deformed samples. The samples prepared by high pressure sintering as well as by mechanical alloying show improved superconducting properties, including high upper critical fields Hc2 (μ0Hc2(0)∼23 T), irreversibility fields Hirr which are strongly shifted towards higher values Hirr(T)∼0.8Hc2(T) and high critical current Jc (Jc=105 A/cm2 at 20 K and 1 T).
@article{arxiv.cond-mat/0206513,
title = {Comparative Study of Dense Bulk MgB$_2$ Materials Prepared by Different Methods},
author = {V. N. Narozhnyi and G. Fuchs and A. Handstein and A. Gümbel and J. Eckert and K. Nenkov and D. Hinz and O. Gutfleisch and A. Wälte and L. N. Bogacheva and I. E. Kostyleva and K. -H. Müller and L. Schultz},
journal= {arXiv preprint arXiv:cond-mat/0206513},
year = {2016}
}
Comments
3 pages including 6 figures. Presented at SCRM2002 conference. Submitted to the J. Supercond.: Inc. Novel Magnetism