Structure of LiCaAlF6. Li, Ca, Al, F atoms are represented by red, blue, green, and magenta balls, respectively.
Band structure of LiCaAlF6 calculated using PBE functionals. Note that the PBE band gap is smaller than the experimental values. However, the defect calculations reported in this paper were all performed using hybrid functionals, which give good band gap compared to the experimental value (see text).
Isosurface plot of the localized hole state in the small hole polaron. The isosurface density is −0.005 e/bohr3. Color scheme same as in Figure 1.
Isosurface plot of the localized deep level of F−. The isosurface density is 0.01 e/bohr3. The Li, Ca, and Al atoms that surround the fluorine vacancy are indicated.
Distances between Li, Ca, and Al atoms surrounding the fluorine vacancy in F+, F0, and F−, as well as in defect-free LiCAF. Units are in Å.
Optical absorption energies (ΔEopt) due to the F center. The F−→ F0 and F0 → F+ transitions involve exciting an electron from the F center to the conduction band, while the F+ → F0 and F0→ F− transitions involve exciting an electron from the valence band to the F center.
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