Structural disorder and superconductivity suppression in NdBa2Cu3Oz (z similar to 7)статья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Structural features of a low-T-c nearly; stoichiometric Nd1+xBa2-xCu3Oz phase (x less than or equal to 0.05, z similar to 6.9, a = 3.897-3.899 Angstrom, b = 3.902-3.908 Angstrom, c = 11.707-11.719 Angstrom) have been investigated for the first time by XRD, EXAFS structure refinement techniques and Raman spectroscopy. It has been found that the abnormal lattice parameters and the low superconductivity transition temperature (55 K) of such a phase are related to structural disorder in the Ba and Nd sites resulting in oxygen disordering which cannot be avoided by a standard oxidation procedure. It is shown that longer annealing at high temperatures is an important factor for reducing the oxygen disordering and hence enhancing superconducting properties after oxidation. (C) 2000 Elsevier Science B.V. All rights reserved.