The Particularities of Infinite‐Layer Compounds Sr1–xLnxCuO2–δ (Ln=La, Pr, Nd, Eu)

The superconducting phases with general formula Sr 1-x Ln x CuO 2-δ with 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 CaCuO 2 -type structure were prepared by high-pressure synthesis. The products were examined by X-ray powder diffraction. For the determination of composition Rietveld method was used. Structure investigations have shown that non-superconducting phases have oxygen vacancies. Within the Cu formal charge range from 1.81 to 1.93 the infinite layer cuprates exhibit superconductivity. Coexistence of both superconducting and non-superconducting phases of the CaCuO 2 -type structure in samples with Ln = Nd and Eu was found.