Preparation of Bi-Based High-Tc Superconductors by the Polymer Gel Method

• Published in: KOBUNSHI RONBUNSHU Vol. 50; no. 8; pp. 599 - 604
• Main Authors: TATSUMI, Masakazu, IBI, Hidemi, YAMAMOTO, Seika
• Format: Journal Article
• Language: Japanese
• Published: Tokyo The Society of Polymer Science, Japan 01.01.1993; Tsukiji daisan nagaoka
• Subjects: (Bi, Pb) 2Sr2Ca2Cu3Oy; High-Tc Superconductor; Poly (acrylic acid); Poly (ethylene glycol); Polymer Gel Method; Precursor Gel
• ISSN: 0386-2186; 1881-5685
• DOI: 10.1295/koron.50.599

A high-Tc, superconductor with a nominal composition of Bi1.6Pb0.4Sr2.0Ca2.0Cu3.0Oy, was prepared by the polymer gel method. The precursor gel was produced by the reaction of metal nitrates with a stoichiometric amount of poly (acrylic acid) (PAA) in ethylene glycol (EG) or poly (ethylene glycol) (PEG) solution and was in the amorphous state. The high-Tc, phase was most predominantly formed in the specimen sintered at 850°C for 72h after calcination of the PAAPEG system at 860°C, and the critical temperature was 106K. However, the fraction of the high-Tc, phase in the case of the PAA-EG system did not increase significantly with sintering time. The polymer matrix is considered to be composed of networks of cross-linked polymer as a result of the interaction between carboxylate anions or ester linkages and metal cations. Experimental result ssuggest that the double oxide Ca2PbO4 formed before the formation of the superconducting phase may be the most important factor in the formation of the high-Tc, phase. In particular, the formation of Ca2PbO4 is controlled by the PAA-PEG system, leading to the growth of high-Tc phase during the calcination.