磁场下Ca2+掺杂对YBCO超导体输运特性的影响

uperconducting properties such as transportation behavior and magnetization characteristic of the Ca-doped Y1-xCaxBa2Cu3O7-δ sintered bulk were studied under magnetic fields. Experimental results show that Ca-doping result in fine microstructure of the bulk, and critical current density Jc is obviously enhanced within the weak magnetic field H<Hc2J. On the contrary, under high magnetic field H>>Hc2J, not any improvement of Jc was observed for the doping sample. The magnetization of the doping sample is also decreased lower than the un-doping sample. Due to the fine structure of the material, which is induced by doping, the “clean” boundaries increased in the bulk. Those “clean” boundaries could carry higher superconducting current than the weak-link boundaries do, and make the doping bulk with higher critical current than the un-doped one. However, those “clean” boundaries will lost their superconductivity and came back to Josephson weak-link type when external magnetic field is highe