TEM and ED confirmation of conversion of 3D and 2D perovskite-type into fluorite-type structure

In this paper, we confirm the transformation of three-dimensional (3D) In-doped perovskite-like BaCe1−xInxO3−δ (x = 0.1; 0.2) and layered (two-dimensional) perovskite-related Sr2Ce1−xYxO4−δ (x = 0.1; 0.2) into corresponding fluorite-type Ce1−xMxO2−δ (M = In, Y) under CO2 mediated reaction at elevated temperature, respectively, using high-resolution transmission electron microscopy (HRTEM) and electron diffraction (ED) studies. HRTEM images confirmed expected nano-sized materials and ED study showed the formation of a single-phase fluorite-type CeO2 structure and absence of ED patterns resulting from the perovskite-like precursors and potential reaction by-products such as In2O3 and Y2O3 after the CO2 reaction, which is consistent with ex situ and in situ powder X-ray diffraction (PXRD), and strongly support the proposed structural transformation reactions.