Preparation of Hg based superconducting wire by solution spinning method.

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We have studied the preparation of Hg based superconducting wire by solution spinning method.Long precursor filaments were prepared by dry spinning through a homogeneous aqueous solution mixed acetates of Ba, Sr, Ca and Cu, ammonium perrhenate, poly (vinyl alcohol) and organic acids. The as-drawn filament with a diameter of 250 mum was pyrolyzed to remove volatile components and then calcined. The filaments reacted in an evacuated fused quartz with a pellet of Hg_1 (Ba, Sr) _2Ca_1Cu_2Re_<0.1>O_x or Hg_1 (Ba, Sr) _2Ca_2Cu_3Re_<0.2>O_x. A single phase of filamentary Hg1212 (1) or Hg1223 (2) superconductor is prepared with Re addition by controlling the heating condition. The T_c of the (1) and (2) filaments is 93 K and 127 K and J_c at 77K and 0 T is 2300A/cm^2 and 1000A/cm^2, respectively.A superconducting F-doped Hg_xBa_2Cu_3Re_<0.2>O_y filament was examined to enhance the J_c by using a pellet containing BaF_2. The J_c of the specimens was enhanced by post-annealing up to 350ﾟC in O_2 flow. The influence of fluorine on the transport J_c of the F-doped Hg1223 filament at 77K was examined in magnetic fields of up to 10 T.F-doping resulted in a formation of dense liquidus texture and marked improvement in the field dependence of J_c for the filament. A J_c of more than 10^2A/cm^2 was maintained at 77 K in a field of 10 T.By controlling the heating condition and addition of a trace HgCl_2, a maximum J_c value of 10^4A/cm^2 at 77 K and 0 T was measured.