Investigations of non-superconducting phases in HgBa2CaCu2O6+x bulk superconducting materials

The HgBa 2 CaCu 2 O 6+ x high temperature superconducting materials are synthesized under a high pressure of 30 kbar at 850 °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 features of the non-superconducting phases in the materials, such as phase stabilities, structure uniformities and transformations, were investigated. The decomposition of the CaHgO 2 phase under electron beam heating and bombardment was observed in-situ and an orientation evolution of the CaHgO 2 during decomposition was analysed. The special structures in some non-superconducting phases, such as the mosaic structure and the tweed structure in CaO and Ba 2 Cu 3 O 5+ x grains respectively, were investigated.