The conductivity of Ln2+xZr2−xO7−x/2 (Ln = Sm to Gd) solid solutions, prepared from mechanically activated Ln2O3 and ZrO2, was shown to be related to their structural properties. In all 3 systems, x-T regions were determined within which electrical transport was dominated by O-ion conduction. In the Sm2O3-ZrO2 system, ionic conductivities of 5 x 10−4 to 6 x 10−3S/cm at 740C were found in Sm2+xZr2−xO7−x/2 with 26.6, 33.3, 35.5, 37 or 40mol%Sm2O3; prepared at 1450, 1530 and 1600C. Also, Eu2+xZr2−xO7−x/2 and Gd2+xZr2−xO7−x/2 containing 33.3 to 37mol%Ln2O3 exhibited 740C ionic conductivities of 10−3 to 7.5 x 10−3 and 10−3 to 7 x 10−3S/cm, respectively. The activation energy for conduction in Ln2+xZr2−xO7−x/2 (Ln = Sm-Gd), 0.84 to 1.04eV, increased with the atomic number of Ln and with x. The highest ionic conductivity was exhibited by stoichiometric Ln2Zr2O7 (Ln = Sm-Gd) pyrochlores prepared at 1600C. This was due to the optimum concentration (5 to 22%) of LnZr+ZrLn antistructure pairs. The grain size of the samples ranged from 0.5 to 2 µm.

Ionic Conductivity of Ln2+xZr2−xO7−x/2 (Ln = Sm-Gd) Solid Solutions. A.V.Shlyakhtina, I.V.Kolbanev, A.V.Knotko, M.V.Boguslavskii, S.Y.Stefanovich, O.K.Karyagina, L.G.Shcherbakova: Inorganic Materials, 2005, 41[8], 854-63