Magnetoresistive effects in Bi-2212 melt textured bulk with MgO additions
The magnetoresistive (MR) effect in Bi-2212+MgO composites with proportions 6, 15 and 20 wt% of MgO was observed and compared with the MR effect of pure Bi-2212 and previously reported Bi-2212+USr2CaO6. The resistivity of melt textured Bi-2212+MgO composites is characterized by a high sensitivity to an applied magnetic field over an increasing temperature range with increasing MgO addition. X-ray results show that the MgO phase is compatible with the Bi-2212 matrix, stable during the melt texturing process and shows little adverse effect on the superconducting transition temperature. A cryogenic sensor was built using Bi-2212+20 wt% MgO as an active component and tested at 77 K in cycling fields from 0 to 1 T. It showed a high sensitivity and no hysteresis.