Mn4+ and Cr3+ ions in red and deep red-emitting phosphors: Spectral analysis and Racah parameter determination

The luminescence properties of the Mn4+ and Cr3+-activated fluoride and oxide phosphors have been discussed in detail. The Mn4+ and Cr3+-activated fluoride and oxide phosphors can be classified into five types from an aspect of the different luminescence properties: F-Mn, F-Cr, O-Mn, O-Cr-A, and O-Cr-B. The representative phosphors considered here are: BaSiF6:Mn4+ (type F-Mn), K2NaScF6:Cr3+ (type F-Cr), Sr2MgGe2O7:Mn4+ (type O-Mn), MgAl2O4:Cr3+ (type O-Cr-A), and BaZrSi3O9: Cr3+ (type O-Cr-B). The photoluminescence (PL) and PL excitation spectra are analyzed based on the Franck Condon analysis model with considering the electron lattice vibration interaction (Huang Rhys factors). The Racah and crystal-field-related parameters of such phosphors are determined and plotted very well on the Tanabe Sugano energy-level diagram curve.