Nonstoichiometry in A2B2O7 Pyrochlores

Abstract

Energies associated with deviations from stoichiometry for an extensive series of A2B2O7 pyrochlores have been predicted. A3+ cations range in size from Lu to La and B4+ cations from Ti to Pb. Results are presented in the form of contour maps as a means of conveying large quantities of data as well as predicting characteristics for pyrochlore compounds not explicitly modeled. These contour maps indicate that the BO2 excess nonstoichiometry in the pyrochlore structure is distinct from solid‐solution fluorite. Within the limitations of this methodology, the contour maps provide a means to understand and predict distinct compositional variations. Defect cluster formation is discussed.