The ordering processes in Yb2Ti2O7 ceramics are studied by thermal analysis, IR spectroscopy, X-ray diffraction, SEM and electrical conductivity measurements. Yb2Ti2O7 was obtained by a co-precipitation method followed by freeze drying and thermal annealing at 3501670 degrees C. The existence of the fluorite-pyrochlore low-temperature transition near 800 degrees C and the pyrochlore-fluorite high-temperature transition near 1700 degrees C was established. The conductivity of Yb2Ti2O7 sintered at 1670 degrees C seems to be ionic in the range of 300-950 degrees C, with a bulk activation energy of 0.81 eV. Yb2Ti2O7 ceramics had a grain size of about 30 nm over a wide range of sintering temperatures (1400-1670 degrees C). (c) 2005 Elsevier B.V. All rights reserved.