Effect of fluorite phase on the electrical conductivity of (Sm1 − xDyx)2Zr2O7 pyrochlore

A single pyrochlore phase for x = 0 to 0.4 in (Sm1 − xDyx)2Zr2O7 was obtained and a fluorite phase for x = 0.5 to 1.0. The occupancy of oxide ion on the 8b site which is originally a vacant site in Fd 3 ¯ m increased linearly from x = 0 to 0.4. The substitution of Dy3 + for Sm3 + increased the electrical conductivity and showed an abrupt decrease at x = 0.5 and further substitution decreased the conductivity. The Raman spectra for x = 0.4 showed a possibility for fluorite symmetry to exist in addition to a pyrcohlore whereas XRD patterns a single pyrochlore phase. A small amount of Al2O3 addition eliminated the fluorite phase observed by XRD and stabilized the pyrochlore phase. Additionally, the Al2O3 addition improved the electrical conductivity of 6.6 × 10− 3 Scm− 1 at 1073 K.