INFLUENCE OF AG ADDITIONS ON THE SUPERCONDUCTING PROPERTIES OF HGBA2CUO4- HOLE DOPING AND SURFACE-BARRIER EFFECTS(DELTA MATERIALS )

A series of superconducting HgBa2CuO4+delta materials, containing Ag-x additions with molar fraction x up to 0.5, has been studied, The proc essing with Ag at elevated temperatures led to changes in superconduct ing properties; the properties are consistently interpreted in terms o f the superconducting hole density, as obtained from the London penetr ation depth lambda measured on the same materials, The irreversible ma gnetic properties are well described in terms of thermally activated t unneling of pancake vortices through a surface barrier.