Far-red emitting Mg2La3NbO9:Mn4+ powder phosphor: Synthesis and luminescence properties

Luminescence enhancement of Mn4+‐activated double‐perovskite phosphors for LEDs through a co‐replacement strategy

“…The radii of Mg 2+ ion and Ta 5+ ion are 0.72 and 0.64 Å, respectively, and the coordination numbers are both 6 (CN = 6). The radius of the Mn 4+ ion is 0.53 Å (CN = 6), which is similar to the radius of the Ta 5+ ion, so Mn 4+ ions doped into the MLTO matrix tend to replace the Ta 5+ ions sites 36 . In general, the percentage difference between the radii of the doped and substituted ions should be within 30%.…”

“…The Tanabe–Sugano energy level diagram of the Mn 4+ ion is shown in Figure 3C. The outermost electron configuration of Mn 4+ is 3d 3 , and the energy level splitting is susceptible to the intensity of the crystal field 36 . To analyze the luminescence mechanism of Mn 4+ ions, the crystal field strength Dq and Racah parameters ( B and C ) of Mn 4+ ions in the MLTO matrix was calculated.…”

“…The radius of the Mn 4+ ion is 0.53 Å (CN = 6), which is similar to the radius of the Ta 5+ ion, so Mn 4+ ions doped into the MLTO matrix tend to replace the Ta 5+ ions sites. 36 In general, the percentage difference between the radii of the doped and substituted ions should be within 30%. The radius difference between Mn 4+ ions and Ta 5+ ions can be calculated by the following equation 37 :…”

“…The outermost electron configuration of Mn 4+ is 3d 3 , and the energy level splitting is susceptible to the intensity of the crystal field. 36 To analyze the luminescence mechanism of Mn 4+ ions, the crystal field strength Dq and Racah parameters (B and C) of Mn 4+ ions in the MLTO matrix was calculated. The value of Dq depends on the transition 4 T 2g → 4 A 2g and can be calculated using the following formula 43 :…”

Structure Analysis, Photoluminescence, and Non-linear/Linear Optical Parameters of Li-=SUB=-2-=/SUB=-Ge-=SUB=-4-=/SUB=-O-=SUB=-9-=/SUB=- : Mn-=SUP=-4+-=/SUP=- Transparent Glass-Ceramic

“…12 describes the GCs emission spectra doped with different Mn 4+ contents. Under 325-nm excitation wavelength, the PL spectra display a narrow red band at 668-nm wavelength ascribed to the Mn 4+ spin-forbidden 4 E g → 4 A 2g transition [13,62,63]. By increasing the Mn 4+ concentration, the emission spectra shape remain unaffected; nevertheless, a concentration quenching behavior is observed at Mn 4+ concentration higher than 0.5 mol.% (Fig.…”