Incommensurate structure of InAl1 − x Ti x O3 + x/2 [x = 0.701 (1)]: comparison between modulated and composite models

Abstract

The structure of the monoclinic phase of the compound InAl1 − x Ti x O3 + x/2 with x = 0.701 (1) has been analyzed within the (3 + 1)-dimensional superspace formalism. Two different models were refined describing the structure as an incommensurate modulated layer and modulated composite, respectively. Both models include the same composition–structure relation. In the composite approach it is derived from the mismatching between the two subsystems. In the incommensurate modulated system, it is derived from a closeness condition between O atomic domains. The distribution and coordination of the cations is discussed and compared with previously proposed models for similar compounds.