Figure 4.

PL spectra of a) KMnF₃; b) NaMnF₃ and c) CsMnF₃ at various temperatures ranging from 10 to 300 K; d–f) show variations of temperature‐dependent emission intensities of VIS and NIR emissions for KMnF₃, NaMnF₃, and CsMnF₃, respectively; g–i) crystal structures of KMnF₃, NaMnF₃, and CsMnF₃, respectively (for clarity, the alkali cations are omitted in the structures and only the MnF₆ octahedra are shown); and j) schematic representation of the most important sigma overlaps between the d orbitals of Mn²⁺ and the p orbital of ligand F⁻ with a bridging angle of 180°.