Process for the preparation of superconducting compound materials

Claim 1

In a process for the preparation of a composite material containing a substrate and a metallic layer of a metastable or unstable phase strongly adhering to the substrate surface, the layer containing more than one elemental component, and being deposited onto the substrate from the gas or vapor phase to a desired thickness, the improvement comprising: (a) using very pure components for formation of the metastable or unstable phase, having respective impurity concentrations of less than 100 ppm, by weight; (b) effecting an initial deposition of the layer to a layer thickness of about 5 to 20 nm by simultaneously depositing the components on the substrate, while reducing the mobility of the components on the substrate to thereby promote germination of a subsequently deposited metastable or unstable phase formed by the components, the reduction of mobility being effected by adding a specific impurity, selected from the group consisting of oxygen and oxygen-containing compounds, to the components; and (c) providing the substrate containing the initially deposited layer with a temperature at which a metastable or unstable phase is formed and, after terminating the addition of the specific impurity, depositing the components for the remainder of the layer up to the desired thickness, from the gas or vapor phase onto the substrate to produce the subsequently deposited phase.