INVESTIGATIONS OF NONSUPERCONDUCTING PHASES IN HGBA2CACU2O6+X BULK SUPERCONDUCTING MATERIALS

The HgBa2CaCu2O6+x high temperature superconducting materials are synt hesized under a high pressure of 30 kbar at 850 degrees C for 4 h. The zero resistance temperature of the materials measured by a four-probe method is 123 K. Using XRD, SEM, TEM and EDS the morphologies and fea tures of the non-superconducting phases in the materials, such as phas e stabilities, structure uniformities and transformations, were invest igated. The decomposition of the CaHgO2 phase under electron beam heat ing and bombardment was observed in-situ and an orientation evolution of the CaHgO2 during decomposition was analysed. The special structure s in some non-superconducting phases, such as the mosaic structure and the tweed structure in CaO and Ba2Cu3O5+x grains respectively, were i nvestigated.