An evaluation was made of the effect of Gd substitution upon the dc activation

energy and ionic conductivity of this pyrochlore-type zirconate, P-Gd2Zr2O7.

Several compositions with the general formulae, Gd2−yLnyZr2O7 (Ln = Er3+, Y3+,

Dy3+, Sm3+, Nd3+ and La3+) were prepared by mechanically milling and firing

stoichiometric mixtures of the corresponding elemental oxides, and their electrical

properties were analyzed as a function of frequency and temperature by using

impedance spectroscopy. Whereas Gd replacement in P-Gd2Zr2O7 by smaller

lanthanides induced a pyrochlore-to-fluorite phase transition, the use of larger

dopant cations yielded partially disordered pyrochlores. Despite higher structural

disorder, the ionic conductivity values measured for the fluorite-type materials

were lower than those observed for pyrochlores whereas the activation energies for

oxygen migration in the series decreased monotonically as the average size of the

A cation increased.

The Effect of Homovalent a-Site Substitutions on the Ionic Conductivity of

Pyrochlore-Type Gd2Zr2O7. J.A.Díaz-Guillén, A.F.Fuentes, M.R.Díaz-Guillén,

J.M.Almanza, J.Santamaría, C.León: Journal of Power Sources, 2009, 186[2], 349-

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