SYNTHESIS AND OXYGEN STOICHIOMETRY OF BI2SR2CACU2O8+X

Bi2Sr2CaCu2O8+x (2212) was synthesized from freeze-dried precursors. T he oxygen content of 2212 was determined as a function of temperature and oxygen partial pressure and the variation of T(c) with oxygen cont ent was determined. It was found that 2212 without excess oxygen (x=0) is superconducting. This points to the role of the (Bi-O)infinity lay ers as a source for holes in 2212. It was also found that samples of 2 212 with the same oxygen content had different T(c)'s depending on the thermal history. This difference in T(c) is thought to arise from oxy gen occupying different sites in the lattice while maintaining the sam e total oxygen content.