Synthesis, Characterization, and Fabrication of High Temperature Superconducting Oxides

Abstract

The authors report the results of an extensive set of investigations on superconducting compounds in the BaO-Y{sub 2}O{sub 3}-CuO system. Two new synthetic procedures, a nitrate coprecipitation and a sol-gel technique, are described. A possible new superconducting phase, which may be a distorted 2:1:3, is partially characterized. It is shown that superconductivity is insensitive to a number of processing parameters, and, to some extent, to microstructure. A microstructural screening technique is used to quantify the proportions of different phases present in phase impure samples. A systematic thermal analysis of the 2:1:3 phase is presented, showing the effects of oxygen partial pressure on the defect structure and on the crystal structure, and providing evidence for the existence of two phase transitions.