fig4
Figure 4. Novel ferroelectricity in brownmillerite structure. (A) Atomic structural features of perovskite and brownmillerite. Tetrahedral chain of brownmillerite can be distorted up and downward. (B) Experimental measurements in brownmillerite SrFeO2.5 thin film. Polarization and junction current as a function of electric field (left) and PFM measurements (right). Reproduced with permission[78]. Copyright 2019, WILEY-VCH Verlag Gmbh & Co. KGaA, Weinheim.
