Effect of mechanical stirring of YBaCuO mixed powder during heat treatment on superconductive properties

This paper deals with a new apparatus for the simultaneous processing of mechanical stirring and calcining of superconductive powder materials to achieve a simpler process for the fabrication of superconductive oxides. As the first step, the change of the mechanical motion of a powder bed at elevated temperature was visualized by use of a transparent mixing tube. Consequently, it was possible to analyze the effect of temperature on the dynamic motion of the powder bed. From the analysis, it was found that there was less increase in cohesiveness of mixed powder of Y2O3, BaCO3 and CuO below 400°C. Above this temperature, the cohesiveness increased considerably, which produces a negative effect of mechanical stirring. Furthermore, the powder calcined in the tumbling bed at the lowering temperature step of calcining showed better superconductive properties than that calcined in the fixed bed.