MERCURY SUPERCONDUCTOR CRYSTAL-GROWTH UNDER HIGH-PRESSURE AND HIGH-TEMPERATURE INFLUENCED BY CRUCIBLE COMPOSITION

We have investigated the influence of Al2O3, Y2O3, BaZrO3 crucibles on the crystal growth of the Hg family of high temperature superconducto rs (HTSCs), as accomplished by the high pressure, high temperature (HP -HT) gas method. We present an approach of p-T-x conditions of synthes is for Hg - containing oxide superconductors. The rich complexity of t his system is correlated with a variety of chemical reactions among th e melted flux and the crucible and/or substrate or seed immersed in it . SEM and EDX investigations of chemical reactions among a complex flu x containing Hg, Pb, Ba, Ca, Cu, oxides and their different phases obt ained during high pressure crystallization (p = 1GPa, T = 1020-1080 de grees C) and the crucible wail are presented. The importance of CaHgO2 and BaCuO2 phases and their influences on growing Hg - based supercon ductors is presented. To date, the BaZrO3 crucible appears to be the m ost passive for high pressure, high temperature processing of the Hg - based compounds. (C) 1997 Academic Press Limited.