Abstract: The invention relates to a method for producing special transition metal compounds, to novel transition metal compounds and to the use thereof for polymerizing olefins.

Abstract: The invention relates to a process for producing cylindrical or round parts of high-T.sub.c superconductor material comprising bismuth, strontium, calcium, copper and oxygen. In this process, a pre-prepared finely-divided oxide mixture with organic additives is first introduced at room temperature into a casting mold. The shaped mixture is then converted into the superconducting shaped part by subsequent thermal treatment.

Abstract: A description is given of a solid oxide-ceramic superconductor containing copper in the crystal lattice which is composed of crystals which are arranged essentially in parallel and intergrown with one another and which also contains, per 100 g of copper in the superconductor, 0.04 to 0.5 mol of CuF.sub.2 or KF, and of a sinter process for producing it. The copper-containing superconductor may be made up, for example, of bismuth, strontium, calcium or of bismuth, strontium, calcium, lead and also copper and oxygen.

Abstract: A compact superconductor of the empirical composition YBa.sub.2 Cu.sub.3 O.sub.7-x .times.zCuO, in which z is a number from 0.08 to 0.84, consists of elongated crystals grown together irregularly. It has a density of at least 5.9 g/cm.sup.3, in particular at least 6.02 g/cm.sup.3. It is prepared by mixing a fine-grained superconductor powder of the composition YBa.sub.2 Cu.sub.3 O.sub.7-x with 1 to 10% by weight of CuO, compressing the mixture under a pressure of at least 1 MPa to give a compact, and heating this compact at 940.degree.-985.degree. C. for at least 5 hours.