Molten Salt Synthesis, Characterization and Luminescence Properties of BaAl_1.4Si_0.6O_3.4N_0.6:Eu²⁺Green Phosphors

Abstract

Green emitting BaAl 1.4 Si 0.6 O 3.4 N 0.6 :Eu 2+ phosphors with a uniform sphere-like morphology were successfully prepared via molten salt synthesis (MSS) method using NaNO 3 as the reaction medium. The obtained phosphors exhibited a broad excitation spectrum ranging from 250 to 460 nm and a strong green emission peak at 510 nm due to the 4f 6 5d 1 -4f 7 ( 8 S 7/2 ) transition of Eu 2+ ions. Under excitation at 365 and 450 nm, the optimal emission intensities of the sample obtained by using molten salt are 17% and 13% higher than those of the sample prepared via conventional solid state (SSR) method, respectively. The quenching concentration of Eu 2+ ions is 5 mol%, and dipole-dipole interaction is responsible for the concentration quenching of Eu 2+ ions in this type of phosphor. The mechanism of thermal quenching is discussed by using the configuration coordinate model and thermal quenching temperature is ∼200 • C. Elemental mapping and energy dispersive X-ray spectroscopy (EDS) spectra proved the formation of the desired BaAl 1.4 Si 0.6 O 3.4 N 0.6 :Eu 2+ materials.

Photoluminescence properties of novel Ba2Lu5B5O17:Eu3+ red emitting phosphors with high color purity for near-UV excited white light emitting diodes

“… 40,66 The PL spectra profile slightly changed due to a decrease in the peak intensities as the temperature was raised above 403 K. It can be noted that the normalized PL intensities at 423 K still remained 38.2% of their initial intensities at 303 K. This implied that the thermal stability of Ba 2 Lu 4.48 Eu 0.5 La 0.02 B 5 O 17 phosphor further needs to be enhanced. In order to further investigate the relationship between PL intensity and the temperature, the activation energy (Δ E a ) for thermal quenching can be described via the Arrhenius equation as follows: 67,68 where I o is the initial PL intensity and I ( T ) represents the PL intensity at various temperature, k B is the Boltzmann constant (8.629 × 10 −5 eV K −1 ) and A is a constant. Furthermore, the eqn (6) can be rearranged as the following equation: 66,69,70 …”