The particularities of infinite-layer compounds Sr(1-x)Ln(x)CuO(2-delta) (Ln = La, Pr, Nd, Eu)

The superconducting phases with general formula Sr(1-x)Ln(x)CuO(2-delta) wi th Ln = La (T-c= 24...40K); Pr (T-c =30... 44 K); Nd (T-c =8K...40 K); Eu ( T-c =40 K) and non-superconducting phases of CaCuO2 -type structure were pr epared by high-pressure synthesis. The products were examined by X-ray powd er diffraction. For the determination of composition Rietveld method was us ed. Structure investigations have shown that non-superconducting phases hav e oxygen vacancies. Within the Cu formal charge range from 1.81 to 1.93 the infinite layer cuprates exhibit superconductivity. Coexistence of both sup erconducting and non-superconducting phases of the CaCuO2-type structure in samples with Ln Nd and Eu was found.