Abstract
Materials with the A2B2O7 pyrochlore structure have interesting ionic transport properties because of their crystallographic structure, which can be described as a stable array of corner-shared BO6 octahedra that is penetrated by a 3-dimensional tunnel configuration that is partly filled by the A2O sublattice. The pyrochlore stochiometry means that there are built-in intrinsic oxide ion vacancies in the crystal structure in comparison to the related fluorite type structure. These are in the A2O sublattice, so that the tunnels are only 75% occupied. The presence of these tunnels leads to the possibility of significant changes in the composition, and some ionic species in this sublattice exhibit high mobility.
The cubic pyrochlore Gd2Ti2O7 was doped in various ways to change its ionic and electronic transport properties. The total conductivity and partial ionic and electronic contributions were investigated by ac impedance and EMF measurement techniques.
The influence of either A or B site doping with aliovalent ions that occupy sites in the A2O and B2O6 sublattices was investigated. The results of these experiments are presented and discussed in relation to the crystal structure and defect chemistry of this family of oxides.
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Heider, U., Jörissen, L., Huggins, R.A. et al. Oxygen ion conductivity in doped Gd2Ti2O7 with the pyrochlore structure. Ionics 2, 7–11 (1996). https://doi.org/10.1007/BF02375861
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DOI: https://doi.org/10.1007/BF02375861