Structural Studies on the ZrO2–Y2O3 System by Electron Diffraction and Electron Microscopy III

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Abstract
The oxygen-ion displacements in modulated structures for 10–50 mol% Y2O3–ZrO2 can be assigned in terms of the frozen in distortions of the molecular vibrational modes of an oxygen ion cube. This assignment clarifies that the displacement of the 10 mol% Y2O3–ZrO2 structure type (a deformed fluorite structure) decreases and that of the Y2O3 structure type increases as the amount of Y2O3 increases. The displacement of the Y2O3 type already occupies 75% in 20 mol% Y2O3–ZrO2 and 97% in 50 mol% Y2O3–ZrO2 in the microdomains of modulated structures. The decrease of the ionic conductivity with the content of Y2O3 can be attributed to an increase in the volume of microdomains with the Y2O3-type displacement. The arc-shaped diffuse scattering observed in 20 and 40 mol% Y2O3–ZrO2 originates from the presence of various orientations and different intervals of the periodic antiphase boundaries.