Fig. 4: Polarization and electronic structures of the LAO GB.
From: Engineering of atomic-scale flexoelectricity at grain boundaries
a Atomic structure and polarization of the GB from DFT calculations. Vectors denote the polarization direction for each unit cell. The strength of polarization is expressed as a color map, ranging from white (weak) to yellow (strong). In the red polyhedron, the displacement between the cations and oxygen atoms in the AlO octahedron is clearly visible with an upward component, accounting for the deviation between the polar vector and displacement vector. b O K-edges from the GB core (red) and grains (blue) indicating stronger hybridization of La–O interactions in the GB. c Al L-edges and La N-edges manifesting different local Al–O configurations in the GB. The corresponding Al L3 (yellow) and L2 (green)-edges are marked for clarity. d Calculated density of states of the GB core (red) and grains (blue). The valence band maximum (VBM) energies in the bulk and at the GB are set to zero.
