USOO9023240B2
(12) United States Patent (10) Patent No.: US 9,023,240 B2 Fujinaga et al. (45) Date of Patent: *May 5, 2015
(54) SILICON NITRIDE POWDER FOR 11/7761; C09K11/7774; C09K11/7792; SILICONNITRIDE PHOSPHOR, CAALSIN, C01P 2004/03: C01P 2004/61; C01P 2004/06; PHOSPHORUSING SAME, SRSIN C01P 2006/80; C01P 2002/54; C01P 2004/52; PHOSPHORUSING SAME, (SR, CA)ALSIN, C01P 2006/12: C04B 35/584: CO4B PHOSPHORUSING SAME, LASIN 2235/3878; C04B 2235/5409; C04B PHOSPHORUSING SAME, AND METHODS 223.5/5436; C04B 2235/723; H01L 23/15; FOR PRODUCING THE PHOSPHORS H01L 23/3731; H01L 33/504; C01B 21/0602; C01B 21/068; Y02B 20/181 (75) Inventors: Masataka Fujinaga, Yamaguchi (JP); USPC ...... 252/301.4 F, 301.4 R, 301.6 F; 428/325, Takayuki Ueda, Yamaguchi (JP); 428/402, 698,704 Takuma Sakai, Yamaguchi (JP); See application file for complete search history. Shinsuke Jida, Yamaguchi (JP) (56) References Cited (73) Assignee: UBE Industries, Ltd. (JP) U.S. PATENT DOCUMENTS (*) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 6,682,663 B2 1/2004 Botty et al. 8, 147,715 B2 * 4/2012 Hirosaki ...... 252/301.4 F U.S.C. 154(b) by 0 days. 2002/0164475 A1* 11/2002 Imamura et al. ... 428/325 2005/0094381 A1* 5/2005 Imamura et al...... 361/750 This patent is Subject to a terminal dis 2006/0033083 A1 2/2006 Sakane et al...... 252/301.4F claimer. 2009/0134775 A1* 5, 2009 Watanabe et al...... 313,503 2009, O250663 A1* 10, 2009 Oshio ...... 252/3014 R (21) Appl. No.: 13/813,596 2010.0085728 A1* 4/2010 Seto et al...... 362/84 2011/O121234 A1* 5, 2011 Hirosaki .... 252/301.4 F (22) PCT Filed: Jul. 29, 2011 2011/0272187 A1* 1 1/2011 Kaga et al...... 174,260 2012/0305958 A1* 12/2012 Seibel et al...... 257/98 (86). PCT No.: PCT/UP2011/067467 FOREIGN PATENT DOCUMENTS S371 (c)(1), (2), (4) Date: Feb. 25, 2013 CN 1839.192 A 9, 2006 CN 10.1090953. A 12/2007 (87) PCT Pub. No.: WO2012/017949 (Continued) PCT Pub. Date: Feb. 9, 2012 OTHER PUBLICATIONS (65) Prior Publication Data Hoppe, H.A., et al. “Luminescence in EU2+-doped Ba2Si3N8: fluo US 2013/O140490 A1 Jun. 6, 2013 rescence, thermoluminescence, and upconversion'. Journal of Phys ics and Chemistry of Solids, 2000, vol. 61, pp. 2001-2006. (30) Foreign Application Priority Data Van Krevel, J.W.H., "On new rare-earth doped M. Si–Al-O N materials Luminescence properties and oxidation resistance'. TU Aug. 4, 2010 (JP) ...... 2010-175724 Eindhoven, 2000, ISBN 90-386-2711-4, pp. 29-40. Aug. 30, 2010 (JP) ...... 2010-1921.92 Hirosaki, Naoto et al., “Synthesis and Crystal Structure of Red Nitride Phosphor, CaAlSiN3:Eu2+”. The 65th Meeting of The Japan Aug. 30, 2010 (JP) ...... 2010-192209 Society of Applied Physics, Lecture notes, 2004, p. 1283. Aug. 30, 2010 (JP) ...... 2010-192252 English translation of the International Preliminary Report on Pat entability which issued in connection with corresponding Interna (51) Int. Cl. tional Application No. PCT/JP2011/067467. C09K II/08 (2006.01) C09K II/77 (2006.01) COIB 2/068 (2006.01) Primary Examiner — Carol M Koslow COIB 2/06 (2006.01) Assistant Examiner — Lynne Edmondson (52) U.S. Cl. (74) Attorney, Agent, or Firm — Clark Hill PLC CPC ...... COIB 21/068 (2013.01); Y10T 428/2982 (2015.01); COIB 21/0602 (2013.01); COIP (57) ABSTRACT 2002/54 (2013.01); COIP 2004/03 (2013.01); COIP 2004/61 (2013.01); COIP 2006/12 Provided are a crystalline silicon nitride powder for a silic (2013.01); COIP 2006/80 (2013.01); C09K onitride phosphors, which is used as a starting material for II/0883 (2013.01); C09K II/7734 (2013.01); producing a siliconitride phosphor containing a silicon ele C09K II/7774 (2013.01); C09K II/7792 ment and a nitrogen element but no oxygen element as a (2013.01); COIP 2004/62 (2013.01) constitutent element, an oxygen content of the silicon nitride (58) Field of Classification Search phosphor being 0.2-0.8 wt %; a CaAlSiN. phosphor, an CPC ...... C09K11/083; C09K11/0883; C09K Sr-SisNs phosphor, an (Sr, Ca)AlSiN phosphor and an 1 1/643; C09K11/7703: C09K11/7706; LaSiN phosphor, each using the silicon nitride powder; C09K11/7715; C09K11/7718; C09K and a method for producing the phosphors. 11/7721; C09K11/7728; C09K11/7734; C09K11/7746; C09K11/7749; C09K 6 Claims, 1 Drawing Sheet US 9,023,240 B2 Page 2
(56) References Cited JP 2003-112977 4/2003 JP 3837588 1, 2006 JP 2007-291352 11, 2007 FOREIGN PATENT DOCUMENTS JP 2008-088362 4/2008 JP 2009-218422 9, 2009 CN 1.01171321 A 4/2008 JP 2010-070773 4/2010 CN 1.01434839. A 5, 2009 WO 2006/080535 8, 2006 JP 09-040406 2, 1997 WO WO 2007066733 A1 * 6, 2007 JP 2000-208815 T 2000 JP 2002-097005 4/2002 * cited by examiner U.S. Patent May 5, 2015 US 9,023,240 B2
FG.
US 9,023,240 B2 1. 2 SILICON NITRIDE POWDER FOR various values) as a mother skeleton, or Patent Literature 3, SILICONNITRIDE PHOSPHOR, CAALSIN, i.e., a phosphor having M.Si.N.:Eu (M-Ca,Sr, Ba, Zn; Z–2/ PHOSPHORUSING SAME, SRSIN, 3x+4/3y) as a mother skeleton is known. However, with exci PHOSPHORUSING SAME, (SR, CA)ALSIN, tation by blue-color visible light, the red light emission inten PHOSPHORUSING SAME, LASIN sity remains insufficient. PHOSPHORUSING SAME, AND METHODS Recently, a white-light emitting diode having near ultra FOR PRODUCING THE PHOSPHORS violet to blue-light emitting diode as an excitation source is actively studied. Thus, a phosphor emitting strong yellow RELATED/PRIORITY APPLICATION light in response to Such excitation wavelength is waited for. 10 As a yellow-color luminescent material, YAl30:Ce has This application is a National Phase filing regarding inter been conventionally used. However, as disclosed in Patent national Application No. PCR/JP2011/067467, filed on Jul. Literature 4, LaSiN is also known. 29, 2011, which relies upon Japanese Application No. Accordingly, those nitride phosphors can be used for a JP2010-175724, filed on Aug. 4, 2010, Japanese Patent vacuum fluorescent display (VFD), a field emission display Application No. 2010-192252, filed on Aug. 30, 2010, Japa 15 (FED), a plasma display panel (PDP), a cathode ray tube nese Patent Application No. 2010-192209, filed on Aug. 30. (CRT), a white-light emitting diode (LED), or the like, and 2010, and Japanese Patent Application No. 2010492192, filed their use as a phosphor having low luminance degradation is on Aug. 30, 2010, for priority. expected. TECHNICAL FIELD CITATION LIST
The present invention relates to a silicon nitride powder for Patent Literatures a siliconitride phosphor having higher fluorescent intensity which is used for a display, a back light of liquid crystal, a Patent Literature 1: JP 2000-208815 A fluorescent lamp, a white-light emitting diode, or the like, a 25 Patent Literature 2: JP 3837588 B1 CaAlSiN. phosphor, a Sr. SiN. phosphor, a (Sr, Ca)AlSiN Patent Literature 3: U.S. Pat. No. 6,682,663 phosphor, and a LaSiN phosphor, each using the silicon Patent Literature 4: JP 2010-70773 A nitride powder, and methods for producing the phosphors. Non-Patent Literatures BACKGROUND ART 30 Non-Patent Literature 1: Journal of Physics and Chemistry of Recently, in response to realized application of a blue-light Solids, Vol. 61 (2000) pages 2001 to 2006 emitting diode, a white-light emitting diode having this diode Non-Patent Literature 2: The 65th Meeting of The Japan as a light source is actively studied. Since the white-light Society of Applied Physics, Lecture notes, page 1283. emitting diode is lightweight, does not use mercury, and has 35 Non-Patent Literature 3: “On new rare-earth doped M-Si long lifetime, a rapidly rising demand is expected for it in Al-O N materials”, written by J. W. H. van Krevel, TU future. In general, as a white-light emitting diode, those Eindhoven 2000, ISBN 90-386-2711-4 obtained by coating paste of a mixture containing YAG (YA10:Ce) powder activated by cerium and epoxy resin SUMMARY OF INVENTION on a blue-light emitting device are used (Patent Literature 1). 40 However, as the fluorescent color of YAG:Ce is present Technical Problem near x=0.41, y=0.56 of CIE color coordinates, when admixed with excitation light with blue color of 460 nm, the color is Since the fluorescent intensity of those nitride phosphors is controlled on a line which connects the color coordinates of not sufficient yet, development of a phosphor having higher the blue-light emitting diode and the color coordinates of 45 luminance is in need. In this regard, an object of the present YAG, and as a result, white color mixed with greenish blue invention is to provide a silicon nitride powder for siliconi color is obtained instead of white color. For such reasons, a tride phosphor having high luminance, which can be used for problem arises in that only white color with insufficient red a vacuum fluorescent display (VFD), a field emission display color can be achieved. To deal with such poor color problem, (FED), a plasma display panel (PDP), a cathode ray tube YAG:Ce phosphor powder is admixed with a separate phos 50 (CRT), a light emitting diode (LED), or the like, a CaAlSiN phor powder exhibiting red color for color control. phosphor, a Sr-SisNs phosphor, a (Sr, Ca)AlSiN. phosphor, However, there are only very few reports regarding a phos and a LaSiN phosphor, each using the silicon nitride pow phor which absorbs blue-color light and emits red-color fluo der, and methods for producing the phosphors. rescence. As a specific example, BaSisNs activated by europium (Eu) has been reported in Non-Patent Literature 1. 55 Solution to Problem Further, CaAlSiN activated by Eu, which exhibits higher light output than BaSisNs, is recently found (Non-Patent The inventors of the present invention conducted intensive Literature 2). Further, Patent Literature 2 discloses an studies to solve the aforementioned problems, and as a result, example in which a powder of crystalline silicon nitride hav found that a CaAlSiN phosphor, a Sr-SisNs phosphor, a (Sr, ing average particle diameter of 0.5 um and oxygen content 60 Ca)AlSiN phosphor, and a LaSiN phosphor having high 0.93% by weight is used as a raw material and compositional fluorescent intensity can be obtained by using powder con ratio and sites for CaAlSiN are modified to control flores taining specific crystalline silicon nitride particles as a raw cence characteristics. material, and completed the invention accordingly. Further, as a phosphor having ASiSNs crystal structure Namely, the present invention relates to a crystalline sili that is activated rare earth element, a red-light emitting mate 65 con nitride powder for siliconitride phosphors, which is used rial as disclosed in Non-Patent Literature 3, i.e., a phosphor as a raw material for producing a siliconitride phosphor com having M.Si.N. (M-Ca, Sr, Ba, or Zn; x, y, and Z may have prising a silicon element and a nitrogen element but no oxy US 9,023,240 B2 3 4 gen element as a constituent element, an oxygen content of powder including the silicon nitride powder for the siliconi said silicon nitride powder being 0.2% by weight to 0.9% by tride phosphors, a LaN powder and a CeN powder at 1400 to weight. 2000° C. under a nitrogen-containing inert gas atmosphere. Further, the present invention relates to a method for pro ducing a CaAlSiN. phosphor by using the silicon nitride 5 Advantageous Effects of Invention powder for the siliconitride phosphors, the method compris ing: mixing the silicon nitride powder for the siliconitride As described above, according to the invention, silicon phosphors, a material as an aluminum Source, a material as a nitride powder for siliconitride phosphor having high lumi calcium source, and a material as an europium source to have nance, which can be used for a vacuum fluorescent display the general formula of (Eu,Ca)AlSiN., and calcining the 10 (VFD), a field emission display (FED), a plasma display mixture at 1400 to 2000° C. under a nitrogen atmosphere of panel (PDP), a cathode ray tube (CRT), a light emitting diode O.05 MPa to 100 MPa. (LED), or the like, a CaAlSiN. phosphor, a Sr. SiN. phos Further, the present invention relates to a CaAlSiN phos phor, a (Sr, Ca)AlSiN. phosphor, and a LaSiN phosphor, phor using the silicon nitride powder for the siliconitride each using the silicon nitride powder, and methods for pro phosphors, which is represented by the general formula of 15 ducing them are provided. (Eu,Ca)AlSiN., and is obtained by calcining a mixture powder including the silicon nitride powder for the siliconi BRIEF DESCRIPTION OF DRAWINGS tride phosphors, a CaN powder, an AlN powder, and an EuN powder at 1400 to 2000°C. under a nitrogen-containing inert FIG. 1 is a Scanning electron microscope image illustrating gas atmosphere. the particles of a powder of crystalline silicon nitride accord Further, the present invention relates to a method for pro ing to Example 1. ducing a Sr-SisNs phosphor by using the silicon nitride pow FIG. 2 is a Scanning electron microscope image illustrating der for the siliconitride phosphors, the method comprising: the particles of a powder of crystalline silicon nitride accord mixing the silicon nitride powder for the siliconitride phos ing to Example 4. phors, a material as a strontium source, and a material as an 25 europium source to have the general formula of (EuSr.) DESCRIPTION OF EMBODIMENTS SisNs; and calcining the mixture at 1400 to 2000° C. under a nitrogen atmosphere of 0.05 MPa to 100 MPa. The silicon nitride powder for siliconitride phosphor Further, the present invention relates to a Sr-SisNo phos according to the invention is a raw material for producing a phor using the silicon nitride powder for the siliconitride 30 siliconitride phosphor containing a silicon element and a phosphors, which is represented by the general formula of nitrogen element but having no oxygen element as a constitu (EuSr.) SisNs, and is obtained by calcining a mixture pow ent element, and specifically it is a powder of crystalline der including the silicon nitride powder for the siliconitride silicon nitride for use as a raw material for producing a phosphors, a strontium nitride powder and an europium CaAlSiN phosphor, a Sr-SisNs phosphor, a (Sr, Ca)AlSiN nitride powder at 1400 to 2000°C. under a nitrogen-contain 35 phosphor, or a LaSiN phosphor. In the present invention, ing inert gas atmosphere. the crystalline silicon nitride is preferably a type silicon Further, the present invention relates to a method for pro nitride. ducing a (Sr, Ca)AlSiN phosphor by using the silicon nitride Oxygen content in the silicon nitride powder for siliconi powder for the siliconitride phosphors, the method compris tride phosphoraccording to the invention is 0.2% by weight to ing: mixing the silicon nitride powder for the siliconitride 40 0.9% by weight. Meanwhile, oxygen content in silicon nitride phosphors, a material as a strontium source, a material as a powder as a raw material for conventional phosphors is 1.0 by calcium source, a material as an europium source, and a weight to 2.0% by weight. In this regard, by using silicon material as an aluminum Source to have the general formula nitride powder with low oxygen content as described in the of (Eu,Sr.,Ca)AlSiN (with the proviso that, x+y+z=1); and present invention as a raw material for a phosphor, a siliconi calcining the mixture at 1400 to 2000° C. under a nitrogen 45 tride phosphor having higher fluorescent intensity than con atmosphere of 0.05 MPa to 100 MPa. ventional phosphors can be obtained. The oxygen content in Further, the present invention relates to a (Sr, Ca)AlSiN silicon nitride powder is preferably 0.2% by weight to 0.8% phosphorusing the silicon nitride powder for the siliconitride by weight, and more preferably 0.2% by weight to 0.4% by phosphors, which is represented by the general formula of weight. Having oxygen content equal to or lower than 0.2% (Eu,Sr.,Ca)AlSiN (with the proviso that, x+y+z=1), and is 50 by weight is difficult to achieve in terms of production. On the obtained by calcining a mixture powder including the silicon other hand, even when the oxygen content is equal to or nitride powder for the siliconitride phosphors, a Sr.N. pow higher than 0.9% by weight, no significant improvement in der, a CaN powder, an EuN powder, and an AlN powder at fluorescence properties is observed, and therefore undesir 1400 to 2000°C. under a nitrogen-containing inert gas atmo able. Measurement of oxygen content was performed by sphere. 55 using the oxygen and nitrogen analyzer manufactured by Further, the present invention relates to a method for pro LECO Corporation. ducing a LaSiN phosphor by using the silicon nitride Average particle diameter of the silicon nitride powder powder for the siliconitride phosphors, the method compris according to the invention is preferably 1.0 Lum to 12 Lum. ing: mixing the silicon nitride powder for the siliconitride When it is used as a raw material for producing a CaAlSiN phosphors, a material as a lanthanum source, and a material as 60 phosphor or a Sr-SisNs phosphor, the average particle diam a cerium source to have the general formula of (Ce, La.) eter is more preferably 2.0 um to 12 um. Further, when it is SiN; and calcining the mixture at 1400 to 2000° C. under used as a raw material for producing a (Sr, Ca)AlSiN. phos a nitrogen atmosphere of 0.05 MPa to 100 MPa. phorora LaSiN phosphor, the average particle diameteris Further, the present invention relates to a LaSiN phos more preferably 1.0 um to 8 um. When the average particle phor using the silicon nitride powder for the siliconitride 65 diameter is less than 1.0 um, oxygen content tends to increase, phosphors, which is represented by the general formula of yielding lower effect resulting from fluorescent properties. (Ce, La.) SiN, and is obtained by calcining a mixture On the other hand, when the average particle diameteris more US 9,023,240 B2 5 6 than 12 um, production is difficult to achieve, and therefore oxygen content can be obtained. Lower the oxygen concen practically not useful. Meanwhile, the average particle diam tration in amorphous silicon nitride powder is, lower oxygen eter was measured from a scanning electron microscope content in resulting crystalline silicon nitride particles can be image according to the following procedures. Specifically, a obtained. circle is drawn on a scanning electron microscope image, a Next, by calcining the nitrogen-containing silane com maximum-size circle inscribed to a particle in contact with pound and/or amorphous silicon nitride powder in the tem the circle is determined for each particle, and average of the perature range of 1300 to 1700° C. under nitrogen or ammo particle diameter which is determined as the diameter of the nia gas atmosphere, crystalline silicon nitride powder is circle is obtained for the particles to calculate the average obtained. By controlling the condition for calcination (i.e., particle diameter of particles. Number of the particles as a 10 temperature and temperature increase rate), the particle diam subject for measurement was about 50 to 150. Specific surface area of the silicon nitride powder accord eter is controlled. According to the invention, to obtain crys ing to the invention is preferably 0.2 m/g to 4.0 m/g. When talline silicon nitride powder with a low oxygen content, it is it is used as a raw material for producing a CaAlSiN phos necessary to control the oxygen which is simultaneously con phor or a Sr-SisNs phosphor, the specific Surface area of the 15 tained in a nitrogen gas atmosphere used for calcining the silicon nitride powder is more preferably 0.2 m/g to 3.0m/g. nitrogen-containing silane compound to produce amorphous Further, when it is used as a raw material for producing a (Sr, silicon nitride. In order to obtain the crystalline silicon nitride Ca)AlSiN phosphor or a LaSiN phosphor, the specific powder with a large particle diameter, it is necessary to have surface area of the silicon nitride powder is more preferably slow temperature increase like 40° C./hour or less when 0.3 m/g to 3.0 m/g. The silicon nitride powder having the amorphous silicon nitride powder is calcined into a crystal specific surface area of less than 0.2 m/g is difficult to line silicon nitride powder. The crystalline silicon nitride achieve in terms of production, and therefore it is practically obtained after the process has large primary particles that are not useful and inconvenient for obtaining a device containing approximately in monodispersion state and has no aggregated it. On the other hand, when the specific surface area is more particles or fused particles, as illustrated in FIG. 2. The than 4.0 m/g, the effect resulting from fluorescent properties 25 obtained crystalline silicon nitride powder is a highly pure is lowered, and therefore it is preferably 0.2 m/g to 4.0 m/g. powder having metal impurities of 100 ppm or less. Further, The specific Surface area was measured by using an apparatus when the powder of crystalline silicon nitride is subjected to for measuring specific surface area, i.e., FLOW SORB 2300 a chemical treatment like acid washing, crystalline silicon manufactured by Shimadzu Corporation (BET method based nitride powder with a low oxygen content can be obtained. As on nitrogen gas adsorption). 30 a result, the silicon nitride powder for siliconitride phosphor The silicon nitride powder for siliconitride phosphor according to the invention, in which the oxygen content is according to the invention can be obtained by thermal degra 0.2% by weight to 0.9% by weight, can be obtained. dation of a nitrogen-containing silane compound and/or non Further, unlike the silicon nitride powder produced by crystalline (i.e., amorphous) silicon nitride powder. direct nitridation of metal silicon, the silicon nitride powder Examples of the nitrogen-containing compound include sili 35 as obtained above does not need strong pulverization. There con diimide (Si(NH)), silicon tetraamide, silicon nitrogen fore, the impurity amount is very small, i.e., it is 100 ppm or imide, and silicon chloroimide or the like. They are produced less. The impurities (Al, Ca, and Fe) contained in the silicon by a known method like a method of reacting in gas phase a nitride powder according to the invention are 100 ppm or less, silicon halide such as silicon tetrachloride, silicon tetrabro and preferably 20 ppm or less. Accordingly, a phosphor hav mide, or silicon tetraiodide with ammonia, a method of react 40 ing high fluorescent intensity can be obtained. ing silicon halide in liquid phase with liquid ammonia, or the Next, the method for producing a siliconitride phosphorby like. using the silicon nitride powder for siliconitride phosphor Further, as for the amorphous silicon nitride powder, a according to the invention will be described. powder produced by a known method like heating and First, explanations are given for the case in which the decomposing the aforementioned nitrogen-containing silane 45 siliconitride phosphor is a CaAlSiN phosphor. The compound in the temperature range of 1200 to 1460° C. under CaAlSiN phosphor according to the invention indicates a atmosphere of nitrogen or ammonia gas, a method of reacting phosphor having CaAlSiN as a basic structure in which a part a silicon halide Such as silicon tetrachloride, silicon tetrabro of Ca is replaced with an activating element like Eu. The mide, or silicon tetraiodide with ammonia at high tempera method for producing a CaAlSiN phosphor according to the ture, or the like is used. Average particle diameter of the 50 invention includes mixing a powder of the silicon nitride amorphous silicon nitride powder and nitrogen-containing having oxygen content of 0.2% by weight to 0.9% by weight, silane compound is generally from 0.003 um to 0.05 um. a material like AlN as an aluminum source, a material like The nitrogen-containing silane compound and the amor CaN as a calcium source, and a material like EuN as an phous silicon nitride powder are easily hydrolyzed and oxi europium source to have the general formula of (Eu,Ca) dized. Thus, weighing of those raw powder materials is per 55 AlSiN and calcining the mixture at 1400 to 2000°C. under formed under inert gas atmosphere. With respect to the nitrogen atmosphere of 0.05 MPa to 100 MPa. materials, according to a known method for improving mate Examples of the material as an aluminum source include an rials of a reaction vessel and friction state between powder aluminum metal as well as aluminum nitride (AIN). and a metal in an apparatus for handling the powder, the metal Examples of the material as a calcium source include a cal impurities presentinamorphous silicon nitride powder can be 60 cium metal as well as CaN. Examples of the material as an lowered to 10 ppm or less. Further, the oxygen concentration europium source include a metal europium as well as EuN. in nitrogen gas purged into a heating furnace used for obtain The CaAlSiN phosphor according to the invention may ing amorphous silicon nitride powder can be controlled to the emit light even when Mn, Ce, Pr, Nd, Sm, or Yb is used as a range of from 0.0% by volume to 2.0% by volume. By setting light source instead of Eu. However, it is preferable to contain the oxygen concentration in atmosphere during thermal deg 65 Eu and it is desirably Eu. radation to 100 ppm or less, for example, or preferably 10 The obtained CaAlSiN phosphor is a phosphor repre ppm or less, amorphous silicon nitride powder having low sented by the general formula of (Eu,Ca)AlSiN and a part US 9,023,240 B2 7 8 of Ca in CaAlSiN is replaced with Eu. The replacement Next, explanations are given for the case in which the amount X is, although not specifically limited, within the siliconitride phosphor is a (Sr, Ca)AlSiN. phosphor. The (Sr, range of 0 TABLE 3 TABLE 4 Characteristics Characteristics of phosphor Silicon nitride raw material of phosphor Composition formula (nol Fluorescent intensity Specific Average Oxygen Fluorescent 25 Eu Sir Ca (relative intensity) Surface particle content intensity area diameter (% by (relative Example 30 0.008 0.794 O.1984 118 (m’g) (Lm) weight) intensity) Example 37 0.002 0.794 O.2044 120 Example 38 0.030 0.794 O.1764 119 Example 30 Example 4 1.O 3.0 0.72 118 Example 39 0.008 0.1 O.892 121 Example 31 Example 5 1.O 3.0 O.34 124 30 Example 40 0.008 0.5 O492 118 Example 32 Example 6 O.3 8.O 0.75 116 Example 33 Example 7 O.3 8.O O.29 128 Example 34 Example 8 3.0 1.0 0.73 108 Example 35 Example 9 3.0 1.O O.S3 115 Example 36 Example 10 3.0 1.O O.33 120 Production of LaSiN. Phosphor Comparative Comparative 10 O.2 1.34 88 Example 14 Example 1 35 Examples 41 to 47 and Comparative Comparative Comparative 3.0 1.O 1.65 90 Examples 19 to 23 Example 15 Example 2 Comparative Comparative 1.O 3.0 1.55 94 Example 16 Example 3 By using the powder of crystalline silicon nitride according Comparative Comparative O.3 8.O 1.42 98 to Examples 4 to 10 and Comparative Examples 1 to 5, Example 17 Example 4 40 siliconitride phosphors according to Examples 41 to 47 and Comparative Comparative 10 O.2 O.93 1OO Comparative Examples 19 to 23 were prepared. Specifically, Example 18 Example 5 a silicon nitride powder, a lanthanum nitride powder, and a cerium nitride powder were weighed in a nitrogenbox to have composition of Ceo Lao SiN. These raw materials were Example 37 45 mixed for one hour using a shaking mill under a nitrogen gas atmosphere. The obtained mixture was added to a crucible By using the powder of crystalline silicon nitride according made of boron nitride. Next, the crucible was set on a pres to Example 4 (the specific surface area was 1.0 m/g, the Surized type electric heating furnace. After having vacuum average particle diameter was 3.0 Lim, and the oxygen content using a rotary oil pump, nitrogen with purity of 99.999% was was 0.72% by weight), a silicon nitride powder, a strontium 50 added to have pressure of 0.8 MPa, and the temperature was nitride powder, a calcium nitride powder, an europium nitride increased to 1000° C. for one hour, to 1200° C. for one hour, powder, and an aluminum nitride powder were weighed in a and to 1950° C. for three hours, that is, total five hours to nitrogen box to have composition of Euloo. 1950° C. After maintaining for 2 hours at 1950° C., the Sr., Cao. AlSiN. Other than that, a (Sr, Ca)AlSiN furnace was cooled and the crucible was removed. The syn phosphor in which a part of (Sr, Ca) is replaced with Eu was 55 thesized sample was briefly pulverized and subjected to pow produced in the same manner as Examples 30 to 36. The der X ray diffraction measurement (XRD). As a result, it was results are listed in Table 4. found to be a LaSiN phosphor in which a part of La is replaced with Ce. Example 38 The powder was pulverized by using an agate mortar and 60 pestle, a dry type pulverizer, and a wet type pulverizer. After A silicon nitride powder, a strontium nitride powder, a pulverization to a pre-determined particle diameter, the fluo calcium nitride powder, an europium nitride powder, and an rescence characteristics were evaluated at excitation of 450 aluminum nitride powder were weighed to have composition nm by using FP-6500 equipped with an integrating sphere, of EuloosSrozos Cao. 1764AlSiN. Other than that, a (Sr, manufactured by JASCO Corporation. Ca)AlSiN phosphor in which a part of (Sr, Ca) is replaced 65 In Table 5, a specific Surface area and an oxygen content of with Eu was produced in the same manner as Examples 30 to the powder of crystalline silicon nitride as a raw material, and 36. The results are listed in Table 4. also the relative fluorescence intensity of the obtained US 9,023,240 B2 19 20 LaSiN phosphor when the fluorescence intensity of Com 3. A method for producing a Sr-SisNs phosphorby using as parative Example 23 is 100 are summarized. a raw material a crystalline silicon nitride powder for the siliconitride phosphors comprising a silicon element and a TABLE 5 nitrogen element but no oxygen element as a constituent 5 element, an oxygen content of said silicon nitride powder Characteristics being 0.2 by weight to 0.8% by weight, wherein the silicon Silicon nitride raw material of phosphor nitride powder has an average particle diameter of 1.0 to 12 Specific Average Oxygen Fluorescent um, and a specific Surface area of 0.2 or more and less than 3.0 Surface particle content intensity m/g, the method comprising: area diameter (% by (relative mixing the silicon nitride powder for the siliconitride phos (m/g) (Lm) weight) intensity) 10 phors, a material as a strontium source, and a material as Example 41 Example 4 1.O 3.0 0.72 118 an europium source to have the general formula of (Eu, Example 42 Example 5 1.O 3.0 O.34 135 Sr.) SisNs (with the proviso that, 0.01