The Quantum Cutting of Tb³⁺ in Ca₆Ln₂Na₂(PO₄)₆F₂ (Ln = Gd, La) under VUV−UV Excitation: with and without Gd³⁺

Abstract

The VUV-vis spectroscopic properties of Tb(3+) activated fluoro-apatite phosphors Ca(6)Ln(2-x)Tb(x)Na(2)(PO(4))(6)F(2) (Ln = Gd, La) were studied. The results show that phosphors Ca(6)Gd(2-x)Tb(x)Na(2)(PO(4))(6)F(2) with Gd(3+) ions as sensitizers have intense absorption in the VUV range. The emission color of both phosphors can be tuned from blue to green by changing the doping concentration of Tb(3+) under 172 nm excitation. The visible quantum cutting (QC) via cross relaxation between Tb(3+) ions was observed in cases with and without Gd(3+). Though QC can be realized in phosphors Ca(6)La(2-x)Tb(x)Na(2)(PO(4))(6)F(2), we found that Gd(3+)-containg phosphors have a higher QC efficiency, confirming that the Gd(3+) ion indeed plays an important role during the quantum cutting process. In addition, the energy transfer process from Gd(3+) to Tb(3+) as well as (5)D(3)-(5)D(4) cross relaxation was investigated and discussed in terms of luminescence spectra and decay curves.

Novel Emitting‐Color Tunable Phosphors Ba3Y2(BO3)4:Ce3+,Tb3+ with Efficient Energy Transfer for Near‐UV Light‐Emitting Diodes

“…In a suitable host lattice, Ce 3+ and activator can lead to their different emission intensity ratio; hence the emission color of phosphor can also be tuned in certain range to satisfy the different practical applications. Tb 3+ ion is an important rare earth ion, which can emit strong green light with high doping contents (>5%) and blue light with low doping contents (<1%) due to transitions of 5 D 4 → 7 F J and 5 D 3 → 7 F J ( J = 6, 5, 4, and 3), respectively . It is understandable that the tunable emission in visible region can be obtained in an appropriate host lattice co‐activated Ce 3+ and Tb 3+ ions under UV light excitation, which can match well with the UV InGaN‐based LEDs .…”

Luminescence and energy transfer of Eu2+/Tb3+/Eu3+ in LiBaBO3 phosphors with tunable-color emission

“…Generally, the Tb 3+ ion is used as an activator in green phosphors, whose emission is mainly due to transitions of 5 D 3 → 7 F J in the blue region and 5 D 4 → 7 F J in the green region ( J = 6, 5, 4, 3, 2) depending on its doping concentration [22] . In order to show the tunable luminescence, we can co-dope different rare earth ions by varying their concentrations [23] . In our experiment, we not only added yTb 3+ ions into LiBaBO 3 :Eu 3+ host, but also added xEu 3+ ions into LiBaBO 3 :Tb 3+ host.…”

Interionic cross relaxation and tunable color luminescence in KY3F10:Tb3+ nano/microcrystals synthesized by hydrothermal approach

“…Therefore, Tb 3+ activated phosphors with tunable emitting colors can be achieved by choosing a low phonon frequency host. We summarize the reported tunable color luminescence in Tb 3+ doped materials [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41], as shown in Table 1. The approximate values of the phonon frequency in some oxides containing ionic complexes and fluoride compounds have been reported, such as borates ($1300 cm À1 ), phosphates ($1200 cm À1 ), silicates ($1050 cm À1 ), tungstates ($900 cm À1 ), aluminates ($850 cm À1 ), fluorides ($450 cm À1 ).…”

“…Fig. 3 shows the PL spectra of KY 3 F 10 :Tb 3+ with different Tb 3+ concentrations under 218 nm excitation, where the intensities of the blue Halide compounds Ca 6 Ln 2 Na 2 (PO 4 ) 6 F 2 (Ln = Gd, La) [34] Rb 2 KInF 6 [35] b-NaYF 4 [36] K 2 YF 5 [37] ZBLAN [38] a-GdOF [39] CsMgCl 3 [40] CsMgBr 3 [40] CsCdBr 3 [40,41] emission originating from 5 D 3 are normalized. At low concentrations of Tb 3+ , the blue emissions from the 5 D 3 level are dominant in the fluorescence spectra, indicating that the 5 D 3 level is effectively populated when excited at 4f 7 5d configuration.…”