RT Journal Article
T1 Cation size effects in oxygen ion dynamics of highly disordered pyrochlore-type ionic conductors
A1 Díaz Guillén, M. R.
A1 Moreno, K. J.
A1 Díaz Guillén, J. A.
A1 Fuentes, A .F.
A1 Naval, K. L. Ngai
A1 Garcia Barriocanal, Javier
A1 Santamaría Sánchez-Barriga, Jacobo
A1 León Yebra, Carlos
AB In this work we evaluate the effect of cation size on the dc activation energy needed for oxygen ion migration, E_(dc), in highly disordered pyrochlore-type ionic conductors A_(2)B_(2)O_(7). Twenty six compositions with the general formula, Ln_(2)Zr_(2−y)Ti_(y)O_(7), Ln_(1.7)Mg_(0.3)Zr_(2)O_(7) (Ln=Y, Dy, and Gd), and Gd_(2−y)La_(y)Zr_(2)O_(7), were prepared by mechanical milling, and their electrical properties were measured by using impedance spectroscopy as a function of frequency and temperature. By using the coupling model we also examine the effect of cation radii R_(A) and R_(B) on the microscopic potential-energy barrier, E_(a), which oxygen ions encounter when hopping into neighboring vacant sites. We find that, for a fixed B-site-cation radius R_(B), both activation energies decrease with increasing A-site-cation size, R_(A), as a consequence of the increase in the unit-cell volume. In contrast, for a given R_(A) size, the E_(dc) of the Ln_(2)Zr_(2−y)Ti_(y)O_(7) series increases when the average R_(B) size increases. This behavior is associated with enhanced interactions among mobile oxygen ions as the structural disorder increases with R_(B).
PB American Physical Society
SN 1098-0121
YR 2008
FD 2008-09
LK https://hdl.handle.net/20.500.14352/51401
UL https://hdl.handle.net/20.500.14352/51401
LA eng
NO © 2008 The American Physical Society. This work has been carried out with the financial support of Mexican Conacyt  Grant No. SEP-2003-C02-44075 and Spanish MCYT  Contracts No. MAT2005-06024-C02 and No. MAT2008-06517-C02. M.R.D.G. thanks Conacyt for financial support. K.L. Ngai was supported in part by ONR under Program Element and Project 61153N.
NO Mexican Conacyt
NO Spanish MCYT
NO Conacyt ONR under Program Element
DS Docta Complutense
RD 8 abr 2025