fig4

Figure 4. A-E: Representative BF TEM images obtained along [001] zone axis of the BTO sample during in situ heating process. The scale bars are 500 nm; F: the plot shows temperature (T) vs. time, with points A-E highlighted at different temperatures, corresponding to BF-TEM images labeled A-E. T: Tetragonal; R: rhombohedral phases; O: orthorhombic; TEM: transmission electron microscopy; BTO: BaTiO3; BF: bright-field; DW: domain wall.