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Crossover to nearly constant loss in ac conductivity of highly disordered pyrochlore-type ionic conductors

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Díaz Guillén, M. R. and Díaz Guillén, J. A. and Fuentes, A. F. and Santamaría Sánchez-Barriga, Jacobo and León Yebra, Carlos (2010) Crossover to nearly constant loss in ac conductivity of highly disordered pyrochlore-type ionic conductors. Physical review B, 82 (17). ISSN 1098-0121

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Official URL: http://dx.doi.org/10.1103/PhysRevB.82.174304


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http://journals.aps.org/Publisher


Abstract

We report on ac conductivity measurements of oxide ion conductors with composition Gd_(2)(Zr_(y)Ti_(1−y)_(2)O_(7), at temperatures between 170 and 500 K and in the frequency range 1 Hz–3MHz, and show that a crossover from a sublinear power law to a linear frequency dependence (or nearly constant loss behavior) in the ac conductivity can be clearly observed in a wide temperature range. This crossover is found to be thermally activated, and its activation energy ENCL to be much lower than the activation energy Edc for the dc conductivity. We also found that the values of ENCL are almost independent of composition, and therefore of the concentration of mobile oxygen vacancies, unlike those of Edc. Moreover, for each composition, the values of ENCL=0.67 +/- 0.04 are very similar to those estimated for the energy barrier for the ions to leave their cages, Ea=0.69 +/- 0.05. These results support that the nearly constant loss behavior, ubiquitous in ionic conductors, is originated from caged ion dynamics.


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© 2010 The American Physical Society. This work has been supported by Mexican CONACYT Grant No. SEP-2003-C02-44075, by Spanish MICINN under Projects No. MAT2008-6517-C02 and CONSOLIDER INGENIO 2010 No. CSD2009-00013 IMAGINE, and by CAM under PHAMA Grant No. S2009/MAT-1756. M.R.D.-G. thanks CONACYT for a grant to stay at Universidad Complutense.

Uncontrolled Keywords:Electrical relaxation; Glasses; Melts; Behavior; Solids; Temperature; Frequency; Crystals; Dynamics; Systems.
Subjects:Sciences > Physics > Electricity
Sciences > Physics > Electronics
ID Code:30271
Deposited On:26 May 2015 09:09
Last Modified:10 Dec 2018 14:58

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