Luminescence of Nanocrystalline Tb[sub 3]Al[sub 5]O[sub 12]:Ce[sup 3+] Phosphors Synthesized by Nitrate-Citrate Gel Combustion Method

Abstract

Ce 3+ -doped nanocrystalline terbium aluminum garnet ͑Tb 3 Al 5 O 12 :Ce 3+ , TAG:Ce 3+ ͒ phosphors were successfully synthesized in low temperature by nitrate-citrate gel combustion method using microwave irradiation as a heating source. The pure TAG phase was obtained after calcining at 800°C for 6 h. The prepared nanocrystalline phosphors showed a broad peak at 551 nm, and the maximum doping concentration of Ce 3+ for the highest emission intensity was 0.8 mol % at 551 nm. The temperature dependence on photoluminescence properties of the prepared TAG:Ce 3+ phosphors was investigated from 25 to 275°C, and the activation energies ͑⌬E͒ for thermal quenching was determined by Arrhenius fitting. The experimental results clearly indicate that prepared nanocryatalline TAG:Ce 3+ has great potentials for a down-conversion yellow phosphor in white light emitting diodes.

Thin Film Deposition of Tb3Al5O12:Ce by Pulsed Laser Ablation and Effects of Low-temperature Post-annealing

“…Completely crystallized pure TAG phase was obtained after post-annealing at 800℃ for 2 hrs as shown in (d). This post-annealing temperature is somewhat similar to that of citrate-complex derived TAG:Ce powders [5], and significantly lower than that of the conventional solid-state reaction process [15]. Figure 2 shows the surface morphologies of the TAG:Ce films (a) as-deposited and (b) post-annealed at 800℃ for 2 hrs.…”

“…The starting TAG:Ce powder was synthesized by a citrate complex method with a optimum Ce doping concentration of 0.8 mol% [5]. A bulk target was prepared by compressing the prepared TAG:Ce powder under a uni-axial pressure of 300 MPa and then sintering at 1500℃ for 3 hrs.…”

“…As an alternative for YAG:Ce, Tb 3 Al 5 O 12 :Ce (TAG:Ce) has emerged as an excellent phosphor material for white LEDs, because the TAG:Ce is capable of absorbing radiation in the range from near UV to blue, and emitting a broad spectrum of visible light in the range from approximately 490 nm to approximately 770 nm [5]. It is well known that when compared with YAG:Ce, the spectrum of the TAG:Ce is slightly shifted to red range, which is advantageous to resolve the problem of the high temperature of YAG:Ce LEDs [6].…”

Influence of Ce ion Concentration on Fluorescence Properties of Ce:TAG‐Al2O3 Eutectic Mixed Crystals

“…The emission peak of Ce 3+ in the Tb 3+ site is slightly shifted (comparatively to that in YAG) to the red region due to reduced crystal field strength . The broad emission spectra range from 480 nm to 650 nm, which are attributed to the well‐known transition from the lowest 5d 1 (2D) configuration to the unresolved ground states 4f 1 (2F 5/2 , 2F 7/2 ) of the Ce 3+ ion . With higher concentration of Ce 3+ doping, the emission intensity gradually increases and shows a maximum at 2.0%.…”

Synthesis and luminescence properties of novel Sr3Gd(PO4)3:Dy3+ phosphor

“…According to the above Eq. (3), the activation energy ΔE for thermal quenching is calculated to be 0.13 eV, while TAG:Ce and YAG:Ce are calculated to be 0.213 eV and 0.272 eV [28,29], respectively. It is generally known that activation energy signifies the energy gap between the lowest excited state level of Dy 3 þ and the bottom of the conduction band, which is closely related to the thermally activated energy transfer processes.…”