Nitride phosphor, CaAlSiN3:Eu2+, was efficiently synthesized without any impurity phase by the directnitriding
method using metal hydride fine powders of (Ca0.97Eu0.03)AlSiHx and/or CaH2 in a particle size
range below 20 lm as starting materials under atmospheric pressure heating conditions in a stream of N2
gas. High-quality powders of CaAlSiN3:Eu2+(3 at%) phosphor were obtained from such metal hydride
powder mixed with a large excess amount of CaH2 powder (>30 wt%) as a flux and gave an intense red
emission band peaking at 650 nm under the excitation of 450 nm, of which the relative integrated
emission intensity was about 110% versus that of a commercially-available YAG:Ce3+ (P46-Y3) standard
phosphor. Also, the thermal quenching effect was as low as the CaAlSiN3:Eu2+ phosphors prepared by the
other methods (6% at 150 C), so that this direct-nitriding method was noted as one of excellent
procedures to produce the high-quality nitride phosphors for white-LED illumination lamps.