Fig. 4: Defect dipoles.
A Electron paramagnetic resonance (EPR) spectra of the pristine, Fe-doped, and Mn-doped KTN crystals at 100 K. B The O 1s X-ray photoelectron spectra (XPS) of the pristine, Fe-doped, and Mn-doped samples. S1/S2 is the ratio of the integrated area of oxygen vacancy \(({{{\rm{V}}}}_{{{\rm{O}}}}^{\cdot\cdot})\) and lattice oxygen peaks. C The schematic structure used in DFT simulation. The [100]C, [010]C, and [001]C crystallographic directions are given, and the spontaneous polarization Ps in the pristine KTN is along the [011]C direction. In the doped lattices, a Fe or Mn ion substitutes a Nb ion, and a \({{{\rm{V}}}}_{{{\rm{O}}}}^{\cdot \cdot }\) is created at one of the nearest neighboring oxygen ion sites of the dopant. D The (100)C-section views of differential charge density (DCD) of the pristine KTN lattice, the KTN lattice with \({{{\rm{V}}}}_{{{\rm{O}}}}^{\cdot \cdot }\), the KTN lattice with \({({{\mathrm{F}}}{{{\mathrm{e}}}^{{{\prime\prime}}}}_{{{\mathrm{B}}}}{-}{{{\mathrm{V}}}}_{{{\mathrm{O}}}}^{\cdot \cdot})}^{\times }\), and the KTN lattice with \({({{\mathrm{M}}}{{{\mathrm{n}}}^{{{\prime}}}}_{{{\mathrm{B}}}}{-}{{{\mathrm{V}}}}_{{{\mathrm{O}}}}^{\cdot\cdot })}^{\cdot}\), respectively, in the inside dotted box of (C). The Bader charges of the B-site cations and oxygen ion immediately adjacent to the vacancy site are marked. E Box charts of deviation angles of dipole moments from the [011]C direction in the octahedra within the (100)C sections containing the defect dipoles, statistically obtained from Fig. S8. F Two-dimensional contour plots of the electron localization function (ELF) on the (100)C sections.
