抄録
Dependence of residual carbons in YBa2Cu3Ox powders prepared through sol⋅gel method on the heating conditions and their effects on superconducting properties of the powders were studied. Carbons were left 2.4-0.02wt% in the powders calcined at the various heating conditions that the holding temperatures were 600°C to 950°C and the flow gases were pure oxygen and air. The carbon content of the powders prepared through sol⋅gel method could be lower than that of the powders prepared by solid state reaction of powders of the mixed oxides. From the result of XPS and FT-IR analysis it was found that the residual car-bon existed as the state of carbonates and concentrated at the surface of the powders.
The powders whose carbon contents were lower than 0.4wt% could show superconducting transition. Magnetic susceptibitities and Tc(onset) of these powders were improved in proportion to decrease of the carbon contents, but Tc(onset) properties could not keep on growing up, being less than 0.04wt% of carbon contents.
