| Oxygen Deficient YBa 2 Cu 3 O 7-δ : Two Superconducting Phases |
| J. Stankowski a , A. Ślązak a , W. Kempiński a , B. Andrzejewski a , B. Reichel b and G. Plesch c a Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland b Faculty of Applied Physics and Mathematics, Technical University of Gdańsk, Narutowicza 11/12, 80-952 Gdańsk, Poland c Department of Inorganic Chemistry, Faculty of Natural Sciences Comenius University, 842 15 Bratislava, Slovakia |
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| Received: October 6, 2003; revised version December 19, 2003 |
| A set of oxygen deficient powder and granular samples of YBa 2 Cu 3 O 7-δ ceramics was studied by means of thermogravimetric and magnetically modulated microwave absorption methods. Especially the last method has turned out to be a powerful method, which was used to determine the dependence of critical temperature T c on the oxygen parameter δ. Using these methods it has been shown that the removing of oxygen evokes the inhomogeneous oxygen distribution in the samples and a change in carrier concentration till to the loss of superconducting properties. A superconducting phase with T_c=60 K, which occurs in oxygen deficient YBa 2 Cu 3 O 7-δ sample, is an unstable phase. |
| DOI: 10.12693/APhysPolA.105.287 PACS numbers: 74.72.-h, 74.62.Bf, 74.62.-c, 74.25.Nf |