Preparation of CaAlSiN₃:Eu²⁺ Phosphors by the Self-Propagating High-Temperature Synthesis and Their Luminescent Properties

Abstract

Divalent europium-doped nitride phosphors, Ca 1-x Eu x AlSiN 3 (x ) 0-0.2), were successfully prepared by the self-propagating high-temperature synthesis (SHS) by using Ca 1-x Eu x AlSi alloy powder as a precursor. The Rietveld refinement analysis was carried out on the CaAlSiN 3 host lattice to elucidate the luminescence properties of dopant Eu 2+ on the tetrahedrally coordinated site. For the Eu 2+ doped samples, strong absorption peaking at about 460 nm was observed on the excitation spectra, which matched perfectly with the current blue light of InGaN/GaN light-emitting diodes (LEDs). The optimized sample, Ca 0.98 -Eu 0.02 AlSiN 3 , gave the red emission peaking at 649 nm of which the intensity was competitive with the sample prepared from the metal nitride raw materials (Ca 3 N 2 , AlN, Si 3 N 4 , and EuN). The CIE chromaticity index (0.647, 0.347) with high color saturation indicated that it was a promising candidate as a redemitting phosphor for the InGaN/GaN-based down-conversion white LEDs for general illumination or displays.

Inorganic Phosphor Materials for Lighting

“…shows 83 % of its initial (RT) emission efficiency at 150°C as compared to 60 % of RT emission efficiency for YAG:Ce 3? [186]. Furthermore, they have demonstrated that Ca 0.…”

“…As for thermal stability of CaAlSiN 3 :Eu 2? , Piao et al [186] indicated that the thermal quenching is inefficient as CaAlSiN 3 :Eu 2? shows 83 % of its initial (RT) emission efficiency at 150°C as compared to 60 % of RT emission efficiency for YAG:Ce 3?…”

Carbothermal Reduction Synthesis Using CaCN2 as Calcium and Carbon Sources for CaAlSiN3:Eu2+ Phosphor and Their Luminescence Properties

“…Meanwhile, carbothermal reduction and nitriding (CRN) by using carbon as a reducing agent for the raw materials, MCO 3 and Eu 2 O 3 , has been applied to produce Sr 2 Si 5 N 8 :Eu 2+ and other 2-5-8 type phosphors which provide good luminescence properties, but the resultant powders still contain unreacted carbon residue. This results in lowering the emission intensity because such carbon absorbs the blue light for exciting Eu 2+ ion and must be removed by reheating in a H 2 -containing gas.…”

“…3 and then drying in vacuo. Each mixed powder was put into a boron nitride (BN) crucible and heated in an electric furnace using a graphite heater at 1600°C for 57 h under normal pressure (0.1 MPa) of nitrogen gas (>99.999%).…”

“…2,3,7 The excitation peak at 444 nm is generally ascribed to the excitation of Eu 2+ ion via the 4f 7 ¼ 4f 6 5d 1 parity-allowed transition. Figure 3 shows the temperature-dependence curve of integrated emission intensity of CaAl 0.8 SiN 3 :Eu 2+ (3 atom %) phosphor, together with that of YAG:Ce 3+ (P46-Y3) phosphor.…”