Reversible Oxidation/Reduction in the CeTaO_4+δ System: a TEM and XRD Study

Author： Drew G. Withers R.L. Larsson A-K. Schmid S.

ISSN： 0022-4596

Source： Journal of Solid State Chemistry, Vol.140, Iss.1, 1998-10, pp. : 20-28

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Abstract

A detailed TEM and XRD study has been made of the basic crystallography (unit cells, space group symmetries, and twin relationships) of each of the three oxidized phases which occur in the CeTaO_4+δ system, their structural relationship to stoichiometric Ce^+IIITaO₄, and their temperature-dependent redox reactions. Such crystallographic knowledge is essential to understand the structural relationships between the various phases and to gain insight into the oxidation/reduction mechanisms allowing the formation of the oxidized phases. Twinning is found to be endemic in stoichiometric Ce^+IIITaO₄ as well as in each of the oxidized Series 2, 3, and 4 phases; the twin plane relating the twin variants is derived in each case.