SUPERCONDUCTING PROPERTIES OF GRAIN-ALIGNED HGBA2CUO4+X

HgBa2CuO4+x(Hg 1:2:0:1) particles (15 wt%) were aligned in an applied magnetic field of 70 kG at room temperature in an epoxy resin. Magneti zation hysteresis loops were measured from 0 to 10 kG at 20 K for samp les oriented with their c axis either parallel or perpendicular to the applied field. The degree of anisotropy, characterized by the ratio o f DELTAM (H parallel-to c axis) to DELTAM (H perpendicular-to c axis), was found to be field dependent. A maximum value of 4.53 was observed at 0.5 kG; however, the anisotropy decreased dramatically with increa sing field and was isotropic above 3 kG. This behavior differs signifi cantly from grain-aligned YBa2Cu3O7-x, where the anisotropy is indepen dent of applied field, and may indicate that flux pinning is more isot ropic in Hg 1:2:0:1. The critical current density J(c) was estimated b y the Bean model to be approximately 7 X 10(4) A/cm2 at 8 kG, 20 K and was independent of Hg 1:2:0:1 sample orientation.