EFFECTS OF RE-DOPING ON MICROSTRUCTURE AND SUPERCONDUCTIVITY OF HGBA2CA2CU3O8+DELTA

In order to study the solubility of Re in HgBa2Ca2Cu3O8+delta and the influence of Re-doping on microstructure and superconductivity, sample s of Hg1-xRexBa2Ca2Cu3O8+delta with x = 0.05, 0.10, 0.15, 0.20, 0.25 a nd 0.30, have been synthesized. Grain size and shape change with nomin al Re content while the intra-grain microstructure which is dominated by stacking faults remains the same. Both, EDX and X-ray diffraction ( XRD) measurements suggest a change of solubility of Re in HgBa2Ca2Cu3O 8+delta at about x = 0.10-0.15 towards lower solubility. For x greater than or equal to 0.15 a Re-rich secondary phase appears. The critical temperature, T-c, of the Re-doped samples is above 130 K and the magn etic hysteresis, Delta M, shows a maximum for x = 0.15. (C) 1998 Elsev ier Science B.V. All rights reserved.