The effect that La-incorporation might have upon the ionic conductivity of PGd2Zr2O7,

a pyrochlore-type fast oxygen ion conductor was analyzed. Single-phase

powder samples with differing La/Gd ratios were prepared in the pyrochlore-type

Gd2−yLayZr2O7 solid solution (0 ≤ y ≤ 1) system by mechanically milling

stoichiometric mixtures of the corresponding oxides. Electrical conductivity

measurements were performed for different compositions by using pressed pellets

sintered at 1500C, as a function of frequency and temperature. Despite increasing

structural ordering (decreasing number of mobile charge carriers), it was found that

oxide–ion conduction at intermediate temperatures was almost independent of the

La-content, for y ≤ 0.8, because of s decreasing dc activation energy (from 1.13 to

0.85eV). It was shown that these results could be explained in terms of weaker ion–

ion interactions in better ordered structures (i.e., rich La-content); highlighting the

importance of structural order/disorder in determining the dynamics of mobile

oxygen ions. High Ionic Conductivity in the Pyrochlore-Type Solid Solution (0≤y≤1). J.A.Díaz-

Guillén, M.R.Díaz-Guillén, K.P.Padmasree, A.F.Fuentes, J.Santamaría, C.León:

Solid State Ionics, 2008, 179[38], 2160-4