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Título:
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Influence of thermally induced oxygen order on mobile ion dynamics in Gd_(2)(Ti_(0.65)Zr_(0.35))_(2)O_(7)
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Autores:
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Moreno, Karla J. ;
Fuentes, Antonio F. ;
Maczka, Miroslaw ;
Hanuza, Jerzy ;
Amador, Ulises ;
Santamaría Sánchez-Barriga, Jacobo ;
León Yebra, Carlos
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Tipo de documento:
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texto impreso
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Editorial:
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American Physical Society, 2007-05
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Dimensiones:
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application/pdf
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Nota general:
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info:eu-repo/semantics/openAccess
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Idiomas:
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Palabras clave:
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Estado = Publicado
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Materia = Ciencias: Física: Electricidad
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Materia = Ciencias: Física: Electrónica
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Tipo = Artículo
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Resumen:
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We report on the influence of oxygen order in the oxygen-ion dynamics in the ionic conductor Gd_(2)(Ti_(0.65)Zr_(0.35))_(2)O_(7). The metastable Gd_(2)(Ti_(0.65)Zr_(0.35))_(2)O_(7) powders prepared by mechanical milling present an anion-deficient fluorite type of structure, stable up to about 800 °C. Thermal treatments at higher temperatures facilitate the gradual rearrangement of the cation and anion substructures and the relaxation of mechanochemically induced defects. Interestingly, metastable pyrochlores showing a very unusual cation distribution were observed during the thermally induced defect-recovery process. We have found that the ionic conductivity due to mobile oxygen ions increases significantly with increasing sintering temperature from 800 to 1500 °C as a result of a systematic decrease in the activation energy for the dc conductivity from 1.23 to 0.78 eV. Electrical conductivity relaxation is well described by stretched exponentials of the form ?(t)=exp[-(t/?)^(1?n)], and the fractional exponent n decreases systematically from n=0.51 to 0.18 with increasing sintering temperature. These results are explained in terms of weaker ion-ion interactions in the increasingly ordered structure of the samples sintered at higher temperatures, and point to the importance of structural disorder in determining the dynamics of mobile oxygen ions.
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En línea:
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https://eprints.ucm.es/id/eprint/30542/1/LeonC48libre.pdf
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