Fig. 2: Ni enrichment of APBs in the pristine non-stoichiometric LSNT film.
a A STEM-HAADF image and the corresponding b La and c Ni EDS elemental map of a typical APB, indicating the Ni enrichment of the APB in the pristine non-stoichiometric 60 nm thick film. The atomic-resolution La EDS map confirms the proposed APD structure with the projected translation vector of a/2 [001]. d–f Atomic structure model of APB with the lattice translation vector of a/2 [011]. The yellow, navy, and orange spheres denote A-site (La/Sr), B-site (Ni/Ti) cations, and O ions, respectively. The gray octahedra represent the core-shared network in the matrix and APD; the blue octahedra represent the edge-shared network in the APB. The white dashed line denotes APB. The calculated segregation energy (Eseg1) of Ni to the B-site at the APB is shown in e which is −0.17 eV. The projection of the model along the [010] zone axis in f where the matrix, APD and APB are overlapped, was used for STEM image simulation. g Simulated STEM-HAADF image using the APB structural model. EEL spectra of h O-K edge and i Ti-L2,3 edge. The measurement locations for the matrix perovskite and the APBs are indicated by gray and blue triangular marks, respectively, in g. The blue and gray spectra represent the spectra obtained from the perovskite matrix and the APB, respectively. The red arrows highlight the difference between the matrix and the APB in fine structure of EEL spectra due to the oxygen deficiency and the related change of Ti valence state. Source data are provided as a Source Data file.
