Process for prorducing thallium-containing high-T.sub.c superconductors in flowing gas atmospheres

A process for producing high-T.sub.c superconductors containing thallium, calcium, barium and copper, and optionally lead and/or strontium, comprising

• preparing a thallium-free precursor in a first reaction step by mechanically triturating a mixture of compounds of the metals Ba, Ca and Cu, and optionally Pb and/or Sr, having a metal content in the numerical ratio of atoms desired in the particular case, heating the mixture to temperatures in the range from 700.degree. to 950.degree. C. and heat treating the mixture for a period of at least 3 hours, and then, optionally cooling the mixture to ambient temperature, grinding the mixture and subsequently heat treating the mixture at temperatures of from 400.degree. to 500.degree. C. in a stream of pure oxygen, said first reaction step being conducted using alkaline earth metal hydroxides, and
• tritrating the precursor with Tl.sub.2 O.sub.3 optionally, shaping the precursor into a shaped part, and oxidatively firing the precursor triturated with Tl.sub.2 O.sub.3 in a flowing gas atmosphere.