Commercial-quality powders were consolidated by using 2 shock-consolidation methods: the single-stage propellant gun method and the underwater shock consolidation method. The samples exhibited anisotropic resistance–temperature features. The narrowest resistive transition width was observed along the directions of shock loading. The onset temperatures were independent of the direction or method. No grain orientation previously observed would have resulted from the consolidation processes using a duration of about 1μs. The samples exhibited a higher diamagnetism than that of a cold isostatically pressed sample in a field of 1Oe. However, the diamagnetism degraded relatively with increasing field and eventually became much less than that of the CIPed sample. This was attributed to thick highly-distorted grain boundaries that could behave as weak links in high fields.

Anisotropic Grain Connectivity in Shock Consolidated MgB2 Bulk Samples. H.Tamaki, W.Ohashi, H.Kitazawa, H.Matsuzawa, Y.Takano, T.Atou, K.Fukuoka, M.Kikuchi, M.Kawasaki, E.Kakimoto, K.Dohke: Superconductor Science and Technology, 2004, 17, 799-803