Fluorescent substance and light-emitting device employing the same

A light-emitting device, comprising:

• a light-emitting element (S1) giving off light in the wavelength range of 250 to 500 nm;
• a fluorescent substance (R) which is represented by the following formula (1):
• (M1−xECx)aSibAlOcNd (1)
• in which M is an element selected from the group consisting of the Group 1 elements, the Group 2 elements, the Group 3 elements, the Group 13 elements other than Al, rare earth elements, the Group 4 elements and the Group 14 elements other than Si;
• EC is an element selected from the group consisting of Eu, Ce, Mn, Tb, Yb, Dy, Sm, Tm, Pr, Nd, Pm, Ho, Er, Cr, Sn, Cu, Zn, As, Ag, Cd, Sb, Au, Hg, TI, Pb, Bi and Fe;
• and x, a, b, c and d are numbers satisfying the conditions of 0<x<0.4, 0.55<a<0.80, 2<b<3, 0<c≦0.6 and 4<d<5, respectively;
• which is in the form of crystals whose mean grain size is in the range of 20 to 100 μm and whose aspect ratio is in the range of 2 to 4;
• and which emits luminescence having a peak in the wavelength range of 580 to 660 nm under excitation by light given off from said light-emitting element (S1);
• and
• another fluorescent substance (G) which is represented by the following formula (2):
• (M′1−x′EC′x′)3−y′Al3+z′Si13−z′O2+u′N21−w′ (2)
• in which M′ is an element selected from the group consisting of the Group 1 elements, the Group 2 elements, the Group 3 elements, the Group 13 elements other than Al, rare earth elements, the Group 4 elements and the Group 14 elements other than Si;
• EC′ is an element selected from the group consisting of Eu, Ce, Mn, Tb, Yb, Dy, Sm, Tm, Pr, Nd, Pm, Ho, Er, Cr, Sn, Cu, Zn, As, Ag, Cd, Sb, Au, Hg, TI, Pb, Bi and Fe;
• and x′, y′, z′, u′ and w′ are numbers satisfying the conditions of 0<x′≦1, −0.1≦y′≦0.3, −3≦z′≦1 and −3<u′−w′≦1.5, respectively;
• and which emits luminescence having a peak in the wavelength range of 490 to 580 nm under excitation by light given off from said light-emitting element (S1).

A light-emitting device, comprising:

• a light-emitting element (S2) giving off light in the wavelength range of 250 to 430 nm;
• a fluorescent substance (R) which is represented by the following formula (1):
• (M1−xECx)aSibAlOcNd (1)
• in which M is an element selected from the group consisting of the Group 1 elements, the Group 2 elements, the Group 3 elements, the Group 13 elements other than Al, rare earth elements, the Group 4 elements and the Group 14 elements other than Si;
• EC is an element selected from the group consisting of Eu, Ce, Mn, Tb, Yb, Dy, Sm, Tm, Pr, Nd, Pm, Ho, Er, Cr, Sn, Cu, Zn, As, Ag, Cd, Sb, Au, Hg, TI, Pb, Bi and Fe;
• and x, a, b, c and d are numbers satisfying the conditions of 0<x<0.4, 0.55<a<0.80, 2<b<3, 0<c≦0.6 and 4<d<5, respectively;
• which is in the form of crystals whose mean grain size is in the range of 20 to 100 μm and whose aspect ratio is in the range of 2 to 4;
• and which emits luminescence having a peak in the wavelength range of 580 to 660 nm under excitation by light given off from said light-emitting element (S2);
• another fluorescent substance (G) which is represented by the following formula (2):
• (M′1−x′EC′x′)3−y′Al3+z′Si13−z′O2+u′N21−w′ (2)
• in which M′ is an element selected from the group consisting of the Group 1 elements, the Group 2 elements, the Group 3 elements, the Group 13 elements other than Al, rare earth elements, the Group 4 elements and the Group 14 elements other than Si;
• EC′ is an element selected from the group consisting of Eu, Ce, Mn, Tb, Yb, Dy, Sm, Tm, Pr, Nd, Pm, Ho, Er, Cr, Sn, Cu, Zn, As, Ag, Cd, Sb, Au, Hg, TI, Pb, Bi and Fe;
• and x′, y′, z′, u′ and w′ are numbers satisfying the conditions of 0<x′≦1, −0.1≦y′≦0.3, −3≦z′≦1 and −3<u′−w≦1.5, respectively;
• and which emits luminescence having a peak in the wavelength range of 490 to 580 nm under excitation by light given off from said light-emitting element (S2);
• and
• still another fluorescent substance (B) which emits luminescence having a peak in the wavelength range of 400 to 490 nm under excitation by light given off from said light-emitting element (S2).

A process for production of a fluorescent substance which is represented by the following formula (1):

• (M1−xECx)aSibAlOcNd (1)
• in which M is an element selected from the group consisting of the Group 1 elements, the Group 2 elements, the Group 3 elements, the Group 13 elements other than Al, rare earth elements, the Group 4 elements and the Group 14 elements other than Si;
• EC is an element selected from the group consisting of Eu, Ce, Mn, Tb, Yb, Dy, Sm, Tm, Pr, Nd, Pm, Ho, Er, Cr, Sn, Cu, Zn, As, Ag, Cd, Sb, Au, Hg, TI, Pb, Bi and Fe;
• and x, a, b, c and d are numbers satisfying the conditions of 0<x<0.4, 0.55<a<0.80, 2<b<3, 0<c≦0.6 and 4<d<5, respectively;
• which is in the form of crystals whose mean grain size is in the range of 20 to 100 μm and whose aspect ratio is in the range of 2 to 4;
• and which emits luminescence having a peak in the wavelength range of 580 to 660 nm under excitation by light in the wavelength range of 250 to 500 nm;
• comprising the steps of:
• mixing materials including nitride or carbide of said M;
• nitride, oxide or carbide of Al;
• nitride, oxide or carbide of Si;
• and oxide, nitride or carbonate of said EC;
• and
• firing the mixture for a firing time of not more than 4 hours.