Superconductivity in New Pb-Based 1222 Layered Cuprates of (Pb0.75W0.25)Sr2(Eu2.0−xCex)Cu2Oz

• Published in: Journal of superconductivity and novel magnetism 2014, Vol.27 (1), p.5-8
• Main Authors: Sasakura, Hiroyuki, Akagi, Yoshiya, Tanaka, Masashi, Tsukui, Shigeki, Adachi, Motoaki
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Letter; Magnetic Materials; Magnetism; Physics; Physics and Astronomy; Strongly Correlated Systems; Superconductivity
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-013-2442-7

New Pb-based 1212 cuprates of (Pb 0.8 W 0.2 )Sr 2 (Nd 1− x Ca x )Cu 2 O 7− δ were synthesized. The sample with x =0.6 was reported to show superconductivity with an onset temperature up to 82 K. Interestingly, in order to obtain superconductivity of the sample, synthesis in N 2 was necessary, then synthesis in air or post-treatment in O 2 led to the disappearance of superconductivity. Recently, we have successfully synthesized new Pb-based 1222 cuprates for the composition range of 0.3≤ x ≤1.0 in the (Pb 0.75 W 0.25 )Sr 2 (Eu 2.0− x Ce x )Cu 2 O z system. The samples have a tetragonal crystal structure; the typical lattice parameters are a =0.3850 nm and c =2.889 nm. Among them, a sample with x =0.3 is discovered to show superconductivity with an onset of about 15 K. These cuprates have the same (Pb, W)O monolayers as the Pb-based 1212 cuprates described above. In these new cuprates, superconductivity appears when the samples are annealed not in air and under He atmosphere, but under high-pressure O 2 .