Judd–Ofelt parameters and X-ray irradiation results of MNb₂O₆:Eu³⁺ (M = Sr, Cd, Ni) phosphors synthesized via a molten salt method

Abstract

SEM micrographs and PL–RL emissions of MNb2O6: Eu3+ (M = Sr, Cd, Ni) phosphors.

Boron doping effect on the structural, spectral properties and charge transfer mechanism of orthorhombic tungsten bronze β-SrTa2O6:Eu3+ phosphor

“…The parameter U 4 is related to the electron density of the surrounding ligands, where an increase in U 4 parameter indicates a decreased electron density. 28,29 The trend of the U 4 parameter is SrTa 2 O 6 :xEu 3+ , 0.1B 3+ > SrTa 2 O 6 :-xEu 3+ wherein B 3+ co-doped phosphors have relatively weak ligand density. The relatively high value of the U 4 parameter may be ascribed to the reduced charge transfer from the ligand ions to the Eu 3+ ion, which supports the effect of boron to decrease the formation of CTB or the reduction of Eu 3+ to Eu 2+ and increase the 5 D 0 / 7 F 2 transition intensity.…”

“…3.3 Judd-Ofelt analysis of SrTa 2 O 6 :xEu 3+ and SrTa 2 O 6 :xEu 3+ , 0.1B 3+ phosphors Judd-Ofelt (JO) theory explains the intensity of electron transitions in 4f shell of rare-earth ions using three parameters and describes their spectral properties. 26,27 The JO intensity parameters U J (J = 2, 4, 6) from emission spectrum for Eu 3+ can be determined by eqn (1): 28,29…”

“…For all electric dipole (ED) transitions originating from the 5 D 0 level, the reduced matrix elements are zero except for the 5 D 0 / 7 F 2 (U 2 = 0.0032), 5 D 0 / 7 F 4 (U 4 = 0.0023) and 5 D 0 / 7 F 6 (U 6 = 0.0002) transitions. 28,29 The 5 D 0 / 7 F J (J = 1, 2, 4, 6) transitions are used for the determination of the radiative transition probabilities while 5 D 0 / 7 F J (J = 0, 3, 5) transitions are prohibited, and are not included JO calculation. The 5 D 0 / 7 F 6 transition related to U 6 parameter was not included in the calculation because it could not be detected by PL in infrared region.…”

“…However, the effect of this transition on the calculation is negligible, which has been reported in some studies. 28,29 The spontaneous transition probability (A) is related to its dipole strength which can be expressed as eqn (2):…”

Influence of europium doping on the crystallization, morphology, and the cathodoluminescent properties of PbNb2O6:Eu3+ phosphors

“…Trivalent lanthanide (Ln 3+ ) ions exhibiting 4f-4f inner-shell transitions have certain properties such as high luminescence efficiency, narrow emission line, and long decay time constant. Due to their advantages, such as reliability and environmental friendliness, they have attracted great attention as new generation solid-state lighting sources in recent years (1)(2)(3)(4)(5)(6)(7)(8)(9). Among these materials, trivalent europium, which is used as a dopant in the production of inorganicbased red light emitting phosphors (LEDs), is known as an effective activator due to its characteristic 5 F0 → 7 FJ (J = 0, 1, 2, 3, 4, 5) band transitions.…”