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Journal of Spectroscopy
Volume 2013 (2013), Article ID 217268, 13 pages
http://dx.doi.org/10.1155/2013/217268
Research Article

XPS Study of Mechanically Activated YBa2Cu3O6+δ and NdBa2Cu3O6+δ

1Institute of Metallurgy, Ural Branch of the Russian Academy of Sciences, 101 Amundsen Street, Ekaterinburg 620016, Russia
2Ural State Academy of Agriculture, Karl Liebknecht Street 42, Ekaterinburg 620075, Russia

Received 27 February 2013; Accepted 30 March 2013

Academic Editor: Kong-Thon Tsen

Copyright © 2013 A. V. Fetisov et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Oxides RBa2Cu3O6+δ (R=Y, Nd) subjected to mechanical activation in AGO-2 mill have been studied by X-ray photoelectron spectroscopy (XPS), thermal analysis, and magnetometry. It has been shown that mechanoactivation accelerates chemical degradation under the impact of H2O and CO2 in YBa2Cu3O6+δ samples. Degradation occurs in the standard way. Investigation of mechanically activated NdBa2Cu3O6+δ has revealed other results. It has been suggested that CO2 can diffuse into its structure more freely than in YBa2Cu3O6+δ; as a result, carbonization may proceed directly in the volume of NdBa2Cu3O6+δ and independently of the hydrolysis process. In addition, the mechanism of interaction between the oxide and water is not active and not “traditional” for the homologous series REBa2Cu3O6+δ (where RE = rare earth and Y)—the characteristic “color” phase (Nd2BaCuO5) is not formed during hydrolysis. It is known that high-temperature treatment of NdBa2Cu3O6+δ oxide results in partial substitution of cations Ba by Nd; which is accompanied by decrease in the superconducting transition temperature and formation of the impurity phase Ba2Cu3O5+y. According to our data, mechanical activation of the resulting solid solution Nd1+xBa2−xCu3O6+δ unexpectedly has led to the reverse redistribution of cations, which has been manifested in the complete disappearance of the impurity phase and increase in .