Oxygen defect in non-stoichiometric europium orthoniobate, EuxNbO4-1.5(1-x)

The crystal chemistry of non-stoichiometric europium orthoniobate, EuxNbO4- 1.5(1-x), prepared using Rb2CO3 flux, was studied. The lattice parameters v ary clearly with the rare earth content of the orthoniobate specimens. In t he Eu2O3-Nb2O5 system without a flux, the non-stoichiometric compound could not be synthesized as a single phase. With the use of flux, europium-defic ient non-stoichiometric solid solution appears to form in which oxygen vaca ncies are the predominant defects. These non-stoichiometric compounds have the potential to act as new oxide ion conductors. (C) 2000 Elsevier Science B.V. All rights reserved.