Preparation of CaAlSiN3:Eu2+ phosphors by the self-propagating high-temperature synthesis and their luminescent properties

Divalent europium-doped nitride phosphors, Ca1-xEuxAlSiN3 (x = 0-0.2), were successfully prepared by the self-propagating high-temperature synthesis (SHS) by using Ca1-xEuxAlSi alloy powder as a precursor. The Rietveld refinement analysis was carried out on the CaAlSiN3 host lattice to elucidate the luminescence properties of dopant Eu2+ on the tetrahedrally coordinated site. For the Eu2+ 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, Ca0.98Eu0.02AlSiN3, gave the red emission peaking at 649 nm of which the intensity was competitive with the sample prepared from the metal nitride raw materials (Ca3N2, AlN, Si3N4, and EuN). The CIE chromaticity index (0.647, 0.347) with high color saturation indicated that it was a promising candidate as a red-emitting phosphor for the InGaN/GaN-based down-conversion white LEDs for general illumination or displays.