SYNTHESIS OF BISMUTH STRONTIUM/CALCIUM/COPPER AND YTTRIUM/BARIUM/COPPER OXIDE SYSTEMS FROM MALONATE PRECURSORS/

Malonate salts of the above metals dissolved in a glycerol/malonic aci d polyester have been found to form amorphous oxide systems at relativ ely low temperatures. Mixtures of the appropriate stoichiometry rapidl y form the corresponding 2212 BSCCO and tetragonal YBCO oxide systems on heating to temperatures in the range 750-850 degrees C. In the case of YBCO, the formation of crystalline barium carbonate can be largely suppressed by an appropriate thermal programme, but whereas the tetra gonal YBCO6.5 phase can be readily obtained as the sole crystalline ph ase, oxygen diffusion into this phase is remarkably difficult. This ap pears to be due to the presence of amorphous intergranular material.