Fig. 4: STEM-ABF and IFFT images of the different TTB samples for the revelation of the Vo concentrations.

a CBN (T-sample). b red Ce:CSBN (R-sample). c black Ce:CSBN (B-sample). d red Ce:CSBN2 (R2-sample). In the ABF mode, heavier atoms provide a darker contrast. The solid red circles represent intact O columns, while the dashed red circles indicate columns containing Vo. The green, yellow, blue, and red balls represent the Ca, Sr/Ba/Ce, Nb, and O atoms, respectively. All images were recorded along the [001] zone axis.