A New Class of Pyrochlore Solid Solution Formed by Chemical Intercalation of Oxygen

Abstract

Oxygen intercalation into a pyrochlore at room temperature is reported. A simple chemical route was employed. Previously only perovskite or a few closely related phase have demonstrated an ability to act as hosts for such intercalation. The specific system studied was the interstitial solid solution Ce 2 Zr 2 O 7+x (0 e x e 0.36). Neutron diffraction reveals that interstitial oxygen enters the tetrahedral 8b sites (space group Fd3 hm), which are empty in stoichiometric pyrochlore, but displacement of existing oxygen from the tetrahedral 8a sites also occurs. The lattice contracts on intercalation due to oxidation of Ce 3+ . The changes in structure and the diffusion pathways for oxygen are discussed.

Oxygen potential measurements of Am0.5Pu0.5O2−x by EMF method

“…Some oxygen potential plots are diverged from the flat line at À360 kJ mol À1 and around x = 0.23. This indicates that the oxygen potential data contained not only those of the equilibrium phase but also those of the non-equilibrium phase, because the coulometric titration method can insert and extract oxide ions into and out of an oxide lattice even if it is in a non-equilibrium state [6].…”

Chemoselective Hydrogenation of Cinnamaldehyde over Pd/CeO2–ZrO2 Catalysts

“…At intermediate compositions, various phases (t, t 0 , t 00 , j and t*) have been identified [22][23][24]. Oxygen deficient structures, such as the pyrochlore structure (A 2 B 2 X 7 ) may also be formed [25][26][27][28][29]. For ceria-zirconia mixed oxides, the pyrochloric structure is generally reported to be formed under severe reduction conditions.…”

Sol–Gel Synthesis of Tunable Cerium Titanate Materials

“…These values yield a ratio of 1.72, which is within the tolerated range 1.46-1.8 for the pyrochlore structure. [10] Nevertheless, the oxidation of Ce…”