| abstract |
A high-temperature oxide superconducting material in a single crystal form or polycrystal form comprising a phase of LnR₂Cu₃O x wherein Ln is yttrium or a rare earth metal(s), R is at least one element selected from the group of barium, calcium and strontium and x is 6.5 to 7, and having a high critical current density, and containing oriented crystal grains or crystals free of any twins, is prepared by synthesizing said material in the presence of at least one element selected from the group consisting of alkali metals and bismuth to form said material. |