Sialon phosphor, process for producing the same, and illuminator and luminescent element employing the same

Abstract

Phosphor that can provide white LED that uses a blue LED or an ultraviolet LED as a light source and that has superior luminous efficiency. This phosphor includes, as a main component, α-type sialon represented by a general expression: (M1)x(M2)y(Si,Al) 12 (O,N) 16 (where M1 is one or more types of elements selected from a group consisting of Li, Mg, Ca, Y, and lanthanide element (except for La and Ce) and M2 is one or more types of elements selected from a group consisting of Ce, Pr, Eu, Tb, Yb, and Er, and 0.3≦X+Y≦1.5 and 0<Y≦0.7 are established and the sialon phosphor consists of a powder having a specific surface area of 0.2 to 0.5 m 2 /g.

1 . A sialon phosphor that includes, as a main component, α-type sialon represented by a general expression: (M1)x(M2)y(Si,Al) 12 (O,N) 16 , wherein M1 is one or more types of elements selected from a group consisting of Li, Mg, Ca, Y, and lanthanide element (except for La and Ce) and M2 is one or more types of elements selected from a group consisting of Ce, Pr, Eu, Tb, Yb, and Er, and 0.3≦X+Y≦1.5 and 0<Y≦0.7 are established, and the sialon phosphor is a powder having a specific surface area of 0.2 to 0.5 m 2 /g,
 said α-type sialon has a lattice constant a in a range from 0.780 to 0.788 nm and a lattice constant c in a range from 0.565 to 0.573 nm, and 
 when powders consisting of said α-type sialon are evaluated based on an X-ray diffraction method, crystal phases other than that of the α-type sialon have diffraction intensities that are all 10% or less to a diffraction line intensity of a face (102) of the α-type sialon. 
 
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . The sialon phosphor according to  claim 1 , wherein the M1 includes at least Ca. 
     
     
         5 . The sialon phosphor according to  claim 1 ,
 wherein the M2 includes at least Eu and 0<Y≦0.1 is established and, when ultraviolet light or visible light having wavelengths in a range from 250 to 500 nm is emitted as an excitation source to the sialon phosphor, the sialon phosphor shows a light emission characteristic having a peak in a wavelength range from 540 to 600 nm.   
     
     
         6 . A method of manufacturing sialon phosphor that includes, as a main component, α-type sialon represented by a general expression: (M1)x(M2)y(Si,Al) 12 (O,N) 16 , wherein M1 is one or more types of elements selected from a group consisting of Li, Mg, Ca, Y, and lanthanide metal (except for La and Ce) and M2 is one or more types of elements selected from a group consisting of Ce, Pr, Eu, Tb, Yb, and Er, and 0.3≦X+Y≦1.5 and 0<Y≦0.7 are established,
 wherein starting raw material is filled in a crucible made of boron nitride material having a density 1.75 g/cm 3  or higher and burned in nitrogenous atmosphere. 
 
     
     
         7 . The method of manufacturing sialon phosphor according to  claim 6 ,
 wherein starting raw material includes α-type sialon in an amount of 5 to 30 mass %.   
     
     
         8 . The method of manufacturing sialon phosphor according to  claim 7 ,
 wherein the starting raw material includes the α-type sialon having a specific surface area in a range from 0.5 to 2 m 2 /g.   
     
     
         9 . The method of manufacturing sialon phosphor according to  claim 6 ,
 wherein the crucible consists of pyrolytic boron nitride.   
     
     
         10 . An illuminator consists of the sialon phosphor according to any of  claims 1 ,  4 , and  5  and a light-emitting light source emitting light having a predetermined wavelength. 
     
     
         11 . The illuminator according to  claim 10 ,
 wherein the light has a wavelength in a range from 250 to 500 nm.   
     
     
         12 . An illuminator consisting of phosphor obtained by the method of manufacturing sialon phosphor according to any of  claims 6  to  9  and light-emitting light source emitting light having a predetermined wavelength. 
     
     
         13 . The illuminator according to  claim 12 ,
 wherein the light has a wavelength in a range from 250 to 500 nm.   
     
     
         14 . A sialon phosphor, wherein the phosphor is α-type sialon represented by a general expression: (M1) X (M2) Y (Si) 12-(m+n) (Al) m+n (O) n (N) 16-n , wherein M1 is one or more types of elements selected from a group consisting of Li, Mg, Ca, Sr, Y, and lanthanide metal (except for La and Ce) and M2 is one or more types of elements selected from Ce, Pr, Eu, Tb, Yb, and Er, and 0.3≦X+Y≦1.5, 0<Y≦0.7, 0.6≦m≦3.0, 0≦n≦2.5, X+Y=m/(average valence of M1 and M2),
 the constituent particles of said phosphor have an average circularity degree of 0.75 or more, the phosphor has a particle size distribution D 50  of 5 to 30 μm and D 10  of 2.0 μm or more, 
 the particles of said phosphor includes light emission-related elements that have a low concentration in the interior of the particle and that have a high concentration at the outer periphery of the particle, and 
 the light emission-related element at the outer periphery of the phosphor particle has a concentration 1.2 times or more higher than that of the light emission-related element at the interior of the particle. 
 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . The sialon phosphor according to  claim 14 ,
 wherein the M1 is Ca and the M2 is Eu.   
     
     
         19 . A sialon phosphor,
 wherein the phosphor is composed of host material of β-type sialon represented by a general expression of Si 6-z Al z O z N 8-z  (wherein 0.01≦z≦4.2) and includes 0.01 to 10 atm % of a metal element M3, wherein M3 is one or more types of elements selected from among Mn, Ce, and Eu,   the constituent particles of said phosphor have an average circularity degree of 0.75 or more, a particle size distribution D 50  of 5 to 30 μm, and D 10  of 2.0 μm or more,   the particles of said phosphor includes light emission-related elements that have a low concentration in the interior of the particle and that have a high concentration at the outer periphery of the particle, and   the light emission-related element at the outer periphery of the phosphor particle has a concentration 1.2 times or more higher than that of the light emission-related element at the interior of the particle.   
     
     
         20 . The sialon phosphor according to  claim 19 ,
 wherein 0.1≦z≦0.5 is established in the general expression and M3 is Eu and has a content from 0.03 to 0.3 atm %.   
     
     
         21 . A method of manufacturing sialon phosphor, comprising:
 a step of mixing silicon-containing material, aluminum-containing material, and raw material including M1 (one or more types of elements selected from a group consisting of Li, Mg, Ca, Sr, Y, and lanthanide metal (except for La and Ce)), M2 (one or more types of elements selected from Ce, Pr, Eu, Tb, Yb, and Er) to prepare granulated powders; and   a step of heating the powders in a nitrogen gas atmosphere at 1500 to 2100 degrees C. to obtain α-type sialon phosphor,   said step of preparing granulated powder includes:   mixing said raw material, solvent, and a binder to prepare slurry,   recovering said slurry by a spray drier to make granulated powder, and   removing the binder from said recovered granulated powder.   
     
     
         22 . The method of manufacturing sialon phosphor according to  claim 21 ,
 wherein previously-synthesized α-type sialon phosphor is added to the raw material and mixed with the raw material.   
     
     
         23 . A method of manufacturing sialon phosphor, comprising:
 a step of mixing silicon-containing material, aluminum-containing material, and raw material including M3 (one or more types of elements selected from a group consisting of Mn, Ce, and Eu) to prepare granulated powders; and   a step of heating the powders in a nitrogen gas atmosphere at 1500 to 2100 degrees C. to obtain β-type sialon phosphor,   said step of preparing granulated powder includes:   mixing said raw material, solvent, and a binder to prepare slurry,   recovering said slurry by a spray drier to make granulated powder, and   removing the binder from said recovered granulated powder.   
     
     
         24 . The method of manufacturing sialon phosphor according to  claim 23 ,
 wherein previously-synthesized β-type sialon phosphor is added to the raw material and mixed with the raw material.   
     
     
         25 . A luminescent element, comprising, as constituting elements:
 the sialon phosphor according to any of  claims 14 ,  18 ,  19 , and  20 ; and   a light-emitting diode having the maximum intensity in light emission wavelengths in a range from 240 to 480 nm.   
     
     
         26 . The method of manufacturing sialon phosphor as set forth in  claim 21 , wherein
 the particle diameter of said granulated powder is 10 to 35 μm.   
     
     
         27 . The method of manufacturing sialon phosphor as set forth in  claim 23 , wherein the particle diameter of said granulated powder is 10 to 35 μm.