HG VAPOR-PRESSURE, PHASE-STABILITY, AND SYNTHESIS OF G1-XBA2CAN-1CUNO2N-LESS-THAN-OR-EQUAL-TO-3(2+DELTA WITH N)

The stability of Hg1-xBa2Can-1CunO2n+2+delta[Hg12(n - 1)n] and its com peting phase, HgCaO2, at synthesis temperatures were studied in terms of their equilibrium Hg vapor pressure P-Hg. It was found that the sta bility of Hg12(n - 1)n varies with n in a complex way. It was also obs erved that traces of moisture and/or carbon dioxide reduce the P-Hg of Hg HgCaO2, while partially substituting Re, Pb and Mo for Hg suppress es the P-Hg of Hg12(n - 1)n. Possible relationships between the benefi cial substitution effect, the change of cation valence, and the defect structures in Hg12(n - 1)n are proposed. (C) 1997 Elsevier Science B. V.