The effects of high energy milling on intra- and inter-granular superconducting properties of Ba(Fe0.92Co0.08)2As2 polycrystalline bulks
德田 進之介 （東京農工大）； 嶋田 雄介 （東北大）； 山本 明保 （東京農工大）
Abstract:In this study, Ba(Fe0.92Co0.08)2As2 polycrystalline bulk samples were prepared by sintering mechanically alloyed powder. High energy ball-milling is expected to change intra-granular Tc and Hc2 by introduction of lattice defects and to increase inter-granular Jc by refinement of grains. Ball-milling condition of elemental metals was systematically changed by using ball-milling energy (EBM) as a barometer. With increasing EBM, the slope of Hc2(T) monotonically increased up to 6.2 T/K. On the other hand, inter-granular J c increased up to 1.7×10^4 A/cm^2 (5 K, self-field) at medium EBM, but then decreased by an order of magnitude at higher EBM due to the formation of aggregates.