Production of oxide superconductors having large magnetic levitation force

A method for producing an RE--Ba--Cu--O oxide superconductor having large magnetic levitation force, where RE is a rare earth element selected from the group consisting of Y, Sm, Eu, Gd, Dy, Ho, Er, and Yb, which involves:

• providing a starting feed comprising a raw material mixture in powdered form,
• heating said raw material mixture for partial melting, followed by cooling and solidification of the partially melted raw material mixture to a solid,
• pulverizing said solid to achieve pulverized powders,
• mixing said pulverized powders to achieve mixed powders,
• shaping said mixed powders into a given shape,
• heating said shape for partial melting to achieve a partial melt,
• cooling said partial melt to a temperature at which a superconducting phase starts to form, followed by slow cooling, whereby a superconducting phase is formed and grown from a nucleation site,
• wherein the method further comprises placing or embedding nucleants on or in said shape at any point between completion of said sharing and just prior to said slow cooling.