(Sm1−xDyx)2Zr2O7 (0 ≤ x ≤ 1) ceramics were prepared by a solid state reaction process at 1973K for 10 h in air. (Sm1−xDyx)2Zr2O7 (0 ≤ x ≤ 0.3) ceramics exhibited a single phase of pyrochlore-type structure, while (Sm1−xDyx)2Zr2O7 (0.5 ≤ x ≤ 1.0) possess a defective fluorite-type structure. The full width at half-maxima in the Raman spectra increases with increasing Dy content, which indicated that the degree of structural disorder increases as the Dy content increases. The ionic conductivity of (Sm1−xDyx)2Zr2O7 ceramics was investigated by impedance spectroscopy over a frequency range of 0.2 Hz to 8 MHz in the temperature range of 873–1173K in air and hydrogen atmospheres, respectively. The ionic conductivity had a maximum near the phase boundary between the pyrochlore- and the defective fluorite-type phases under identical temperature levels. The ionic conductivity was determined by the degree of structural disorder or unit cell free volume, which was depending on the Dy content. As the ionic conductivity in the hydrogen atmosphere was almost the same as that obtained in air, the conduction of (Sm1−xDyx)2Zr2O7 was purely ionic with negligible electronic conduction.

Order–Disorder Transformation and Enhanced Oxide-Ionic Conductivity of (Sm1−xDyx)2Zr2O7 Ceramics. X.L.Xia, Z.G.Liu, J.H.Ouyang: Journal of Power Sources, 2011, 196[4], 1840-6