Oxygen fluorite-related phases

The parent structure of the anion-deficient fluorite structure phases is the cubic fluorite structure (Fig. 4.7). As in the case of the anion-excess fluorite-related phases, diffraction patterns from typical samples reveals that the defect structure is complex, and the true defect structure is still far from resolved for even the most studied materials. For example, in one of the best known of these, yttria-stabilized zirconia, early studies were interpreted as suggesting that the anions around vacancies were displaced along < 111 > to form local clusters, rather as in the Willis 2 2 2 cluster described in the previous section, Recently, the structure has been described in terms of anion modulation (Section 4.10). In addition, simulations indicate that oxygen vacancies prefer to be located as second nearest neighbors to Y3+ dopant ions, to form triangular clusters (Fig. 4.11). Note that these suggestions are not... 

Relationship between the surface structure and the intermediate phase The existence of oxygen deficient fluorite-related intermediate phases of the rare earth higher oxides is due to vacancy ordering. Fig. 3-28 demonstrates the relationship between the surface structure and the bulk superstructure... 

I synthesized the S phase and obtained information on the unit cell of the S phase by electron microscopy. Professor Eyring told me the story of the 8 phase in the terbium higher oxides. At that time the formula of the oxygen-deflcient fluorite-related homologous series of the rare earth higher oxides was R 02 -2, and that there are two families when n is odd the... 

Stable phases in the rare earth oxide systems are tabulated and discussed. New data on the structure of sesquioxides quenched from the melt are reported. The structural interrelations between the A, B, and C type sesquioxides and the fiuorite dioxides are pointed out. The sequences of several intermediate oxides in the CeO, PrO., and TbO, systems are observed to be related to the fluorite structure and the C form sesquioxide with respect to the metal atom positions. A hypothetical homologous series of the general formula Mn02n i, related to the fluorite structure and the A form sesquioxide with a more or less fixed oxygen lattice, is suggested. 

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