Atomic zip in SrNbO3.4. (a) HAADF STEM image taken before irradiation. The irradiation area is marked by a red open rectangle. (b) HAADF STEM image taken after the electron irradiation for ~300 s showing changes in atomic structure in the irradiated region. The zigzag-like slab in the rectangle is transformed to a chain-like connected structure, resulting in atomic merging of the two neighboring chain-like slabs. The new phase has adopted the structure of SrNbO3. The phase transformation can be well controlled with atomic precision.