SYNTHESIS OF HGBA2CUO4-GEL METHOD UNDER CONTROLLED OXYGEN-PRESSURE - ELECTRON AND THERMAL TRANSPORT-PROPERTIES(DELTA BY SOL)

Samples of mercury superconductor HgBa2CuO4+delta were prepared employ ing highly homogeneous and reactive precursor Ba2CuO3+x obtained by th e sol-gel method. Mixture of Mn3O4/Mn2O3 was used to adjust p(O-2) dur ing the synthesis. This approach allows to achieve the appropriate p(O -2) at the reaction temperature 720 degrees C and multizone furnace is not required. The enhancement of the thermal conductivity below T-c, measured for the first time in Hg-type superconductor, indicates unusu ally strong phonon-electron coupling. The enhancement is accompanied b y a sharp resistivity and thermopower decrease. (C) 1998 Elsevier Scie nce B.V. All rights reserved.