SYNTHESIS OF HGBA2CA2CU3O8-TEMPERATURE HIGH-PRESSURE CHAMBER(DELTA AND HGBA2CA3CU4O10+DELTA SUPERCONDUCTORS IN A PROGRAMMED)

Single-phase ceramic samples of high-order homologous phases in the Hg -Ba-Ca-Cu-O system were prepared in a programmed-temperature high-pres sure chamber allowing synthesis at pressures up to 7.0 GPa and tempera tures up to 1770 K. According to x-ray diffraction data, increasing sy nthesis temperature and/or duration favors the formation of the 1223 a nd 1234 phases, as well as higher order homologous structures, up to 1 256. All of the phases were found to be tetragonal, with the same a ce ll parameter throughout the range of synthesis pressures tested.