Modulated fluorite-type structure of materials from the (1-x)Y0.5Zr0.5O1.75-xY0.75Nb0.25O1.75 (0≤x≤1) system

The microstructures of different high-temperature prepared oxides of the (1-x)Y0.5Zr0.5O1.75-xY(0.75)Nb(0.25)O(1.75) (0 less than or equal to x less than or equal to 1) system have been studied by selected-area electron diffraction and high-resolution transmission electron microscopy. The materials show a modulated fluorite-type structure mainly due to a partial or short-range ordering of the oxygen vacancies. The modulation is related to the pyrochlore-type structure in the Y0.75Nb0.25O1.75 A short-range ordering of the oxygen vacancies related to the C-type structure is observed in the Y0.5Zr0.5O1.75. Gradual transition from the pyrochlore to the C-type structures is established with the variation of the composition.