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Publication numberUS20070018567 A1
Publication typeApplication
Application numberUS 10/561,264
PCT numberPCT/JP2004/012135
Publication dateJan 25, 2007
Filing dateAug 18, 2004
Priority dateAug 22, 2003
Also published asCN1839193A, CN1839193B, DE112004001533T5, US8007684, US8147718, US8394295, US20080265748, US20110175519, US20120099291, WO2005019376A1
Publication number10561264, 561264, PCT/2004/12135, PCT/JP/2004/012135, PCT/JP/2004/12135, PCT/JP/4/012135, PCT/JP/4/12135, PCT/JP2004/012135, PCT/JP2004/12135, PCT/JP2004012135, PCT/JP200412135, PCT/JP4/012135, PCT/JP4/12135, PCT/JP4012135, PCT/JP412135, US 2007/0018567 A1, US 2007/018567 A1, US 20070018567 A1, US 20070018567A1, US 2007018567 A1, US 2007018567A1, US-A1-20070018567, US-A1-2007018567, US2007/0018567A1, US2007/018567A1, US20070018567 A1, US20070018567A1, US2007018567 A1, US2007018567A1
InventorsNaoto Hirosaki
Original AssigneeNational Institute For Material Science
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Oxynitride phosphor and light-emitting instrument
US 20070018567 A1
Abstract
The invention has for its object the provision of an oxynitride fluorescent material has higher emission luminance than conventional rare earth element-activated sialon fluorescent materials.
To this end, an oxynitride fluorescent material is designed in such a way as to contain as the primary constituent a JEM phase represented by a general formula MA1(Si6−zAlz)N10−zOz wherein M is one or two or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. For instance, this fluorescent material has a fluorescent spectrum maximum emission wavelength of 420 nm to 500 nm inclusive and an excitation spectrum maximum emission excitation wavelength of 250 nm to 400 nm inclusive.
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Claims(29)
1. An oxynitride fluorescent material, which contains as a main component a JEM phase represented by a general formula MA1(Si6−zAlz)N10−zOz wherein M is one or two or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.
2. The oxynitride fluorescent material according to claim 1, which comprises a JEM phase as a mother crystal with M1 as a luminescence center, wherein M1 is one or two or more elements selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb and Lu.
3. The oxynitride fluorescent material according to claim 1, which contains at least La and an element M1 wherein M1 is one or two or more elements selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb and Lu.
4. The oxynitride fluorescent material according to claim 1, which contains at least Ce.
5. The oxynitride fluorescent material according to claim 3, which contains at least Eu.
6. The oxynitride fluorescent material according to claim 3, which contains at least Tb.
7. The oxynitride fluorescent material according to claim 3, which contains at least Ce and Tb.
8. An oxynitride fluorescent material, which contains elements M, Si, Al, O and N where M is one or two or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb and Lu, and which has a composition represented by a compositional formula MaSibAlcOdNe where a=1, and satisfying all conditions:

b=(6−zf  (i)
c=(1+zg  (ii)
d=z×h  (iii)
e=(10−zi  (iv)
0.1≦z≦3  (v)
0.7≦f≦1.3  (vi)
0.7≦g≦3  (vii)
0.7≦h≦3  (viii)
0.7≦i≦1.3  (ix)
9. The oxynitride fluorescent material according to claim 8, wherein f=g=h=i=1.
10. The oxynitride fluorescent material according to claim 8, wherein z=1.
11. The oxynitride fluorescent material according to claim 8, wherein M is Ce.
12. The oxynitride fluorescent material according to claim 8, wherein M contains at least two elements La and Ce.
13. The oxynitride fluorescent material according to claim 8, wherein M contains at least two elements La and Eu.
14. The oxynitride fluorescent material according to claim 8, wherein M contains at least two elements La and Tb.
15. The oxynitride fluorescent material according to claim 8, wherein M contains at least three elements La, Ce and Tb.
16. The oxynitride fluorescent material according to claim 1, which contains at least two elements La and Ce, wherein a ratio of La and Ce (a ratio of the number of atoms in the composition) is 0.01≦Ce/La≦10.
17. The oxynitride fluorescent material according to claim 1, which contains at least two elements La and Eu, wherein a ratio of La and Eu (a ratio of the number of atoms in the composition) is 0.001≦Eu/La≦1.
18. The oxynitride fluorescent material according to claim 1, which contains at least two elements La and Tb, wherein a ratio of La and Tb (a ratio of the number of atoms in the composition) is 0.01≦Tb/La≦10.
19. The oxynitride fluorescent material according to claim 1, which contains at least three elements La, Ce and Tb, wherein a ratio of La, Ce and Tb (a ratio of the number of atoms in the composition) is 0.01≦(Ce+Tb)/La≦10.
20. The oxynitride fluorescent material according to claim 4, wherein a fluorescence spectrum has a maximum emission wavelength of 420 nm to 500 nm inclusive and an excitation spectrum has a maximum excitation wavelength of 250 nm to 400 nm inclusive.
21. The oxynitride fluorescent material according to claim 6, wherein a fluorescence spectrum has a maximum emission wavelength of 480 nm to 560 nm inclusive and an excitation spectrum has a maximum excitation wavelength of 200 nm to 300 nm inclusive.
22. The oxynitride fluorescent material according to claim 1, which comprises a mixture of the JEM phase and other crystal phase or an amorphous phase, wherein said mixture has a JEM content of 50% by mass or greater.
23. A lighting device, comprising an emission light source and a fluorescent material, wherein a fluorescent material as recited in claim 1 is at least used.
24. The lighting device according to claim 23, wherein said emission light source is an LED that emits light having a wavelength of 330 nm to 420 nm.
25. The lighting device according to claim 23, wherein said emission light source is an LED that emits light having a wavelength of 330 nm to 420 nm, and a fluorescent material as recited in any one of claims 1 to 22, a green fluorescent material that emits light having a wavelength of 520 nm to 570 nm inclusive in response to excitation light of 330 run to 420 nm and a red fluorescent material that emits light having a wavelength of 570 nm to 770 nm inclusive in response to excitation light of 330 nm to 420 nm are used to mix together red light, green light and blue light, emitting white light.
26. The lighting device according to claim 23, wherein said emission light source is an LED that emits light having a wavelength of 330 nm to 420 nm, and a fluorescent material as recited in any one of claims 1 to 22 and a yellow fluorescent material that emits light having a wavelength of 550 nm to 600 nm inclusive in response to excitation light of 330 nm to 420 nm are used to mix together yellow light and blue light, emitting white light.
27. The lighting device according to claim 26, wherein said yellow fluorescent material is a Ca-α-sialon with Eu in the form of a solid solution.
28. An image display comprising an excitation source and a fluorescent material, wherein a fluorescent material as recited in claim 1 at least used.
29. The image display according to claim 28, which is any one of a vacuum fluorescent tube (VFD), a field emission display (FED), a plasma display panel (PDP), and a cathode-ray tube (CRT).
Description
    ART FIELD
  • [0001]
    The present invention relates generally to a silicon oxynitride fluorescent material composed primarily of a JEM phase, and its applications. More specifically, the present invention is concerned with a lighting device used alone or in combination of image displays, which harnesses the properties of that fluorescent material, that is, its ability to emit fluorescence having a wavelength of 420 nm or longer.
  • BACKGROUND ART
  • [0002]
    Fluorescent materials are used for vacuum fluorescent display tubes (VFDs), field emission displays (FEDs), plasma display panels (PDPs), cathode-ray tubes (CRTs), white light-emitting diodes (LEDs), etc. To allow the fluorescent material to emit light in any application, energy for exciting it must be supplied to it. Upon excitation by an excitation source having high energy such as vacuum ultraviolet radiation, ultraviolet radiation, electron radiation, blue light or the like, the fluorescent material gives out visible light rays. A problem with the fluorescent material is, therefore, that its luminance drops as a result of exposure to such an excitation source as mentioned above. To overcome that problem, sialon fluorescent materials have been proposed as those having more limited luminance decreases than do prior art fluorescent materials based on silicates, phosphates, aluminates, and sulfides.
  • [0003]
    The sialon fluorescent material, for instance, has been prepared by mixing together silicon nitride (Si3N4), aluminum nitride (AlN) and europium oxide (Eu2O3) at a given molar ratio, and then subjecting the resulting mixture to hot-press firing wherein it is held at a temperature of 1,700° C. for 1 hour in nitrogen of 1 atm (0.1 MPa)(for instance, see patent publication 1). α-sialon with activated Eu ions, obtained by this method, has been reported to provide a fluorescent material that is excited by blue light of 450 to 500 nm, giving out yellow light of 550 to 600 nm. In situations where ultraviolet radiation such as one emitted out of an ultraviolet LED or lamp is used for an excitation source, however, a fluorescent material that is efficiently excited at a wavelength of 400 nm or lower is still in demand. Besides, fluorescent materials emitting not only yellow light but also blue light or green light are still in need. There are also demands for materials having ever higher emission luminance.
  • Patent Publication 1: JP(A)2002-363554 SUMMARY OF THE INVENTION Subject Matter of the Invention
  • [0004]
    The primary object of the invention is to provide an oxynitride fluorescent material that has higher emission luminance than conventional rare earth-activated sialon fluorescent materials.
  • How the Subject Matter is Achieved
  • [0005]
    Such being the case, we have made study after study about fluorescent materials that contain elements M, Si, Al, O and N, where M is one or two or more elements selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and consequently found out that a material having a specific composition domain range and a specific crystal phase can provide a fluorescent material that is excited by ultraviolet radiation, emitting light having high luminance. That is, we have found out that a JEM phase having a composition represented by a general formula MA1(Si6−zAlz)N10−zOz wherein M is one or two or more elements selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu can become a fluorescent material that is excited by ultraviolet irradiation, giving out light having high luminance.
  • [0006]
    The JEM phase is quite an unheard-of nitrogen-enriched substance confirmed by Jekabs Grins et al. that it occurs in the process of preparing α-sialon stabilized by rare earth metals, and before the filing of this application, its details have already been reported at reat length in academic literature (see non-patent publication 1). The report teaches that the JEM phase is a crystal phase having a composition represented by the aforesaid general formula, and it is a substance that has a unique atomic configuration structure and excellent heat resistance with z as a parameter. By definition, this substance has a unique crystal and atomic configuration structure characterized by a unique space group as well as sites occupied by atoms and their coordinates, as shown in Table 1 (the same as Table 3 at page 2003 of the aforesaid non-patent publication), given just below.
  • Non-Patent Publication 1
  • [0007]
    Jekabs Grins and Three Others, “Journal of Materials Chemistry”, 1995, Vol. 5, No. 11, pp. 2001-1006
    TABLE 1
    Atom Site Coordinates (x) Coordinates (y) Coordinates (z)
    (1) La 8 d 0.0553 0.0961 0.1824
    (2) Al 4 c 0 0.427 0.25
    (3) M (1) 8 d 0.434 0.185 0.057
    (4) M (2) 8 d 0.27 0.082 0.52
    (5) M (3) 8 d 0.293 0.333 0.337
    (6) X (1) 8 d 0.344 0.32 0.14
    (7) X (2) 8 d 0.383 0.21 0.438
    (8) X (3) 8 d 0.34 0.485 0.41
    (9) X (4) 8 d 0.11 0.314 0.363
    (10) X (5) 8 d 0.119 0.523 0.127
  • [0008]
    More specifically, the JEM phase shown in Table 1 is a substance characterized by (1) a specific Pbcn space group, (2) lattice constants (a=9.4225 Å, b=9.7561 Å and c=8.9362 Å), and (3) a specific atom site and atomic coordinates. The lattice constants vary with changes in the amounts of the constituent Ln and solid solution amount z, but (1) the crystal structure indicated by the Pbcn space group as well as (3) the atom positions given by the sites occupied by atoms and their coordinates remain invariable.
  • [0009]
    Given those fundamental data as shown in Table 1, the crystal structure of that substance is unequivocally determined, and the X-ray diffraction intensity (X-ray diffraction chart) that crystal structure has can be calculated on the basis of those data. Then, if the results of X-ray diffraction measured are in agreement with the calculated diffraction data, that crystal structure can be identified to be the same.
  • [0010]
    In this sense, Table 1 is a criterion for, and an important consideration to, the identification of the JEM phase. How to identify the substance on the basis of Table 1 is now briefly explained, because it will be described specifically with reference to Example 1, given later. In Table 1, it is noted that the site symbols are indicative of symmetry of the space group, and that the coordinates have values of zero to one with respect to the lattices x, y and z, with M standing for Si or Al and X for O or N, respectively.
  • [0011]
    As far as the process of research of sialon has gone, the JEM phase has been exclusively studied for its heat resistance; never until now is there any study about using it as a fluorescent material.
  • [0012]
    That the JEM phase can be used as a fluorescent material that is excited by ultraviolet or electron radiation, giving out light having high luminance, has been discovered by us for the first time. We have extended this finding to further research, resulting in a discovery of a unique light emission phenomenon having improved luminance properties in a specific wavelength range, as embodied in (1) to (29) below.
  • [0013]
    Having been made as a result of a series of researches on the basis of the aforesaid findings, the present invention successfully provides an oxynitride fluorescent material capable of emitting light with ever higher luminance, and a lighting devicet using the same, which is used alone or in combination with image displays.
  • [0014]
    (1) An oxynitride fluorescent material, characterized by containing as a main component a JEM phase represented by a general formula MA1(Si6−zAlz)N10−zOz wherein M is one or two or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.
  • [0015]
    (2) The oxynitride fluorescent material according to (1) above, characterized by comprising a JEM phase as a mother crystal with M1 as a luminescence center, wherein M1 is one or two or more elements selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.
  • [0016]
    (3) The oxynitride fluorescent material according to (1) or (2) above, characterized by containing at least La and an element M1 wherein M1 is one or two or more elements selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.
  • [0017]
    (4) The oxynitride fluorescent material according to any one of (1) to (3) above, characterized by containing at least Ce.
  • [0018]
    (5) The oxynitride fluorescent material according to (3) above, characterized by containing at least Eu.
  • [0019]
    (6) The oxynitride fluorescent material according to claim 3, which contains at least Tb.
  • [0020]
    (7) The oxynitride fluorescent material according to (3) above, characterized by containing at least Ce and Tb.
  • [0021]
    (8) An oxynitride fluorescent material, characterized by containing s elements M, Si, Al, O and N where M is one or two or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and by having a composition represented by a compositional formula MaSibAlcOdNe where a=1, and satisfying all conditions:
    b=(6−zf  (i)
    c=(1+zg  (ii)
    d=z×h  (iii)
    e=(10−zi  (iv)
    0.1≦z≦3  (v)
    0.7≦f≦1.3  (vi)
    0.7≦g≦3  (vii)
    0.7≦h≦3  (viii)
    0.7≦i≦1.3  (ix)
  • [0022]
    (9) The oxynitride fluorescent material according to (8) above, characterized in that f=g=h=i=j=1.
  • [0023]
    (10) The oxynitride fluorescent material according to (8) or (9) above, characterized in that z=1.
  • [0024]
    (11) The oxynitride fluorescent material according to any one of (8) to (10), characterized in that M is Ce.
  • [0025]
    (12) The oxynitride fluorescent material according to any one of (8) to (10) above, characterized in that M contains at least two elements La and Ce.
  • [0026]
    (13) The oxynitride fluorescent material according to any one of (8) to (10) above, characterized in that M contains at least two elements La and Eu.
  • [0027]
    (14) The oxynitride fluorescent material according to any one of claims (8) to (10), characterized in that M contains at least two elements La and Tb.
  • [0028]
    (15) The oxynitride fluorescent material according to any one of (8), (9), (10), (12) and (14) above, characterized in that M contains at least three elements La, Ce and Tb.
  • [0029]
    (16) The oxynitride fluorescent material according to any one of (1), (2), (3), (4), (7), (8), (9), (10), (11) and (12) above, characterized by containing at least two elements La and Ce, wherein the ratio of La and Ce (the ratio of the number of atoms in the composition) is 0.01≦Ce/La≦10.
  • [0030]
    (17) The oxynitride fluorescent material according to any one of (1), (2), (3), (5), (8), (9), (10) and (13) above, characterized by containing at least two elements La and Eu, wherein the ratio of La and Eu (the ratio of the number of atoms in the composition) is 0.001≦Eu/La≦1.
  • [0031]
    (18) The oxynitride fluorescent material according to any one of (1), (2), (3), (6), (7), (8), (9), (10), (14) and (15) above, characterized by containing at least two elements La and Tb, wherein the ratio of La and Tb (the ratio of the number of atoms in the composition) is 0.01≦Tb/La≦10.
  • [0032]
    (19) The oxynitride fluorescent material according to any one of (1), (2), (3), (6), (7), (8), (9), (10), (14) and (15) above, characterized by containing at least three elements La, Ce and Tb, wherein the ratio of La, Ce and Tb (the ratio of the number of atoms in the composition) is 0.01≦(Ce+Tb)/La≦10.
  • [0033]
    (20) The oxynitride fluorescent material according to any one of (4), (11), (12) and (16) above, characterized in that a fluorescence spectrum has a maximum emission wavelength of 420 nm to 500 nm inclusive and an excitation spectrum has a maximum excitation wavelength of 250 nm to 400 nm inclusive.
  • [0034]
    (21) The oxynitride fluorescent material according to any one of (6), (7), (14), (15), (18) and (19) above, characterized in that a fluorescence spectrum has a maximum emission wavelength of 480 nm to 560 nm inclusive and an excitation spectrum has a maximum excitation wavelength of 200 nm to 300 nm inclusive.
  • [0035]
    (22) The oxynitride fluorescent material according to any one of (1) to (21) above, characterized by comprising a mixture of the JEM phase and other crystal phase or an amorphous phase, wherein said mixture has a JEM content of 50% by mass or greater.
  • [0036]
    (23) A lighting device, characterized by comprising an emission light source and a fluorescent material, wherein a fluorescent material as recited in any one of (1) to (22) above is at least used.
  • [0037]
    (24) The lighting device according to (23) above, characterized in that said emission light source is an LED that emits light having a wavelength of 330 nm to 420 nm.
  • [0038]
    (25) The lighting device according to (23) or (24) above, characterized in that said emission light source is an LED that emits light having a wavelength of 330 nm to 420 nm, and a fluorescent material as recited in any one of claims 1 to 22, a green fluorescent material that emits light having a wavelength of 520 nm to 570 nm inclusive in response to excitation light of 330 nm to 420 nm and a red fluorescent material that emits light having a wavelength of 570 nm to 770 nm inclusive in response to excitation light of 330 nm to 420 nm are used to mix together red light, green light and blue light, emitting white light.
  • [0039]
    (26) The lighting device according to (23) or (24) above, characterized in that said emission light source is an LED that emits light having a wavelength of 330 nm to 420 nm, and a fluorescent material as recited in any one of claims 1 to 22 and a yellow fluorescent material that emits light having a wavelength of 550 nm to 600 nm inclusive in response to excitation light of 330 nm to 420 nm are used to mix together yellow light and blue light, emitting white light.
  • [0040]
    (27) The lighting device according to (26) above, characterized in that said yellow fluorescent material is a Ca-α-sialon with Eu in the form of a solid solution.
  • [0041]
    (28) An image display, characterized by comprising an excitation source and a fluorescent material, wherein a fluorescent material as recited in any one of (1) to (22) above is at least used.
  • [0042]
    (29) The image display according to (28) above, characterized by bing any one of a vacuum fluorescent display tube (VFD), a field emission display (FED), a plasma display panel (PDP), and a cathode-ray tube (CRT).
  • ADVANTAGES OF THE INVENTION
  • [0043]
    The sialon fluorescent material obtained by the fabrication process of the invention has ever higher luminance and is much more reduced in material deterioration and luminance drop even upon exposure to excitation sources, as compared with conventional sialon fluorescent materials; it lends itself well to applications such as VFDs, FEDs, PDPs, CRTs and white LEDs. Thus, the invention provides a novel yet promising material for material designs in that technical art.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • [0044]
    FIG. 1 is an X-ray diffraction chart for one embodiment of the inventive oxynitride (Example 1).
  • [0045]
    FIG. 2 is a spectral diagram for excitation and emission spectra of one embodiment of the inventive oxy-nitride (Example 1).
  • [0046]
    FIG. 3 is a spectral diagram for excitation and emission spectra of another embodiment of the inventive oxy-nitride (Example 3).
  • [0047]
    FIG. 4 is a spectral diagram for excitation and emission spectra of yet another embodiment of the inventive oxy-nitride (Example 5).
  • [0048]
    FIG. 5 is a spectral diagram for excitation and emission spectra of a further embodiment of the inventive oxy-nitride (Example 8).
  • [0049]
    FIG. 6 is illustrative of emission spectra of the inventive oxynitrides (Examples 14-24).
  • [0050]
    FIG. 7 is illustrative in schematic of one embodiment of the inventive lighting device (LED lighting device).
  • [0051]
    FIG. 8 is illustrative in schematic of one embodiment of the inventive image display (plasma display panel).
  • EXPLANATION OF THE REFERENCE NUMERALS
  • [0000]
    • 1: Mixture of the inventive red fluorescent material (Ex. 1) with a yellow fluorescent material or a blue fluorescent material plus a green fluorescent material,
    • 2: LED chip,
    • 3, 4: Electrically conductive terminals,
    • 5: Wire bond,
    • 6: Resin layer,
    • 7: Vessel,
    • 8: Inventive red fluorescent material (Ex. 1),
    • 9: Green fluorescent material,
    • 10: Blue fluorescent material,
    • 11, 12, 13: Ultraviolet emitting cells,
    • 14, 15, 16, 17: Electrodes,
    • 18, 19: Dielectric layers,
    • 20: Protective layer, and
    • 21, 22: Glass substrates.
  • BEST MODE FOR CARRYING OUT THE INVENTION
  • [0066]
    Some embodiments of the invention are now recounted with reference to the examples.
  • [0067]
    The fluorescent material of the invention contains as the main component the JEM phase that is represented by the general formula MA1(Si6−zAlz)N10−zOz wherein M is one or two or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. From considerations of emitting fluorescence in the invention, it is desired that the JEM phase that is a constituent of that oxynitride fluorescent material be contained with high purity and as much as possible, and whenever possible, it be composed of a single phase. However, the JEM phase could be mixed with other crystal phase or an amorphous phase within the range that its properties do not become worse. To obtain high luminance in this case, the content of the JEM phase should preferably be 50% by mass or greater. In other words, the fluorescent material of the invention should contain as the main component the JEM phase in a content of at least 50% by mass.
  • [0068]
    For JEM phase formation, it is an essential requirement to use one or two or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu as M in the general formula MA1(Si6−zAlz)N10−zOz. Among others, La, Ce and Nd are preferable because the JEM phase can be formed from a wide compositional range.
  • [0069]
    If the JEM phase is used as a matrix crystal and M1 where M1 is one or two or more elements selected from Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu is allowed to form a solid solution with the JEM matrix, then these elements work as luminescence centers, enabling fluorescent properties to show up. However, the element for forming the matrix could be the same as the element for the luminescence center. For instance, there is a JEM phase consisting of Ce alone. This JEM phase of Ce can provide a fluorescent material by itself with no addition of the luminescence center (M1).
  • [0070]
    Using La as the main element for JEM phase formation is preferable because of providing a fluorescent material of high luminance. In this case, selection is made from compositions that contain at least La and an element M1 where M1 is one element selected from Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu or a mixture of two or more such elements, and form the JEM phase. In particular, fluorescent materials comprising the JEM phase of La as the matrix crystal and the luminescence center (1) Ce, (2) Eu, (3) Tb, and (4) Ce plus Tb with Tb working as the luminescence center are found to have high luminance and emit light in various colors depending on compositions; they may be selectively combined with applications in mind.
  • [0071]
    In the invention, the type of composition is not critical on condition that the composition is a substance that has a JEM-phase crystal structure and is composed of M where M is one or two or more elements selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu as well as Si, Al, O and N. However, the following substance is desired because of ensuring a high JEM-phase content, and a fluorescent material of high luminance as well.
  • [0072]
    More specifically, that substance is composed of elements M, Si, Al, O and N where M is one or two or more elements selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and has a composition represented by a compositional formula MaSibAlcOdNe indicative of the ratio of the number of atoms forming that substance. It is here noted that products with the subscripts a, b, c, d and e multiplied by any number, too, have the same composition. In the invention, therefore, the following conditions are determined on the values obtained by re-calculation of a, b, c, d and e such that a=1. In the invention, the values of b, c, d, e and f are selected from those that satisfy all the conditions:
    b=(6−zf  (i)
    c=(1+zg  (ii)
    d=z×h  (iii)
    e=(10−zi  (iv)
    0.1≦z≦3  (v)
    0.7≦f≦1.3  (vi)
    0.7≦g≦3  (vii)
    0.7≦h≦3  (viii)
    0.7≦i≦1.3  (ix)
    Here, f, g, h, i and j are indicative of deviations from the general formula MA1(Si6−zAlz)N10−zOz for JEM. In that formula, the value of a is the content of the metal element M where M is one or two or more elements selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; it is indicative of the total amount of these elements contained in the fluorescent material. In the invention, let the value of a be 1.
  • [0073]
    The value of b is the content of Si given by b=(6−z)×f, where z is the amount given by 0.1≦z≦3 and f is the amount given by 0.7≦f≦1.3, respectively. Preferably, f=1. Any deviation of the value of b from this range will fail to yield a stable JEM phase, leading to an emission intensity drop.
  • [0074]
    The value of c is the content of Al given by c=(1+z)×g, where z is the amount given by 0.1≦z≦3 and g is the amount given by 0.7≦g≦3, respectively. Preferably, g=1. Any deviation of the value of c from this range will fail to yield a stable JEM phase, leading to an emission intensity drop.
  • [0075]
    The value of d is the content of O given by d=z×h, where z is the amount given by 0.1≦z≦3 and h is the amount given by 0.7≦g≦3, respectively. Preferably, h=1. Any deviation of the value of h from this range will fail to yield a stable JEM phase, leading to an emission intensity drop.
  • [0076]
    The value of e is the content of N given by e=(10−z)×i, where z is the amount given by 0.1≦z≦3 and i is the amount given by 0.7≦i≦1.3, respectively. Preferably, i=1. Any deviation of the value of i from this range will fail to yield a stable JEM phase, leading to an emission intensity drop.
  • [0077]
    Within the above compositional range, there are obtained fluorescent materials capable of emitting light with high luminance; however, much higher luminance is obtained with:
      • (1) Compositions wherein M is Ce,
      • (2) Compositions wherein M includes at least two elements La and Ce, especially with compositions wherein the ratio of La and Ce (the ratio of the number of atoms therein) is 0.01≦Ce/La≦10,
      • (3) Compositions wherein M includes at least two elements La and Eu, especially with compositions wherein the ratio of La and Eu (the ratio of the number of atoms therein) is 0.001≦Eu/La≦10,
      • (4) Compositions wherein M includes at least two elements La and Tb, especially with compositions wherein the ratio of La and Tb (the ratio of the number of atoms therein) is 0.01≦Tb/La≦10, and
      • (5) Compositions wherein M includes at least three elements La, Ce and Tb, especially with compositions wherein M includes at least three elements La, Ce and Tb, and the ratio of La, Ce and Tb (the ratio of the number of atoms therein) is 0.01≦(Ce+Tb)/La≦10.
        Thus, by make a selection from those compositions, there can be obtained a fluorescent material having much higher luminance.
  • [0083]
    In the fluorescent material of the invention, there is a difference between excitation spectra and fluorescent spectra depending on a difference in the composition that forms the fluorescent material, and by suitable combinations of these, it is possible to obtain a fluorescent material having various emission spectra as desired.
  • [0084]
    How that fluorescent material is designed could be determined on the spectra necessary for the intended applications. A CeJEM phase, or a LaJEM phase activated with Ce can provide a fluorescent material that has a maximum emission wavelength of 420 nm to 500 nm inclusive and emits blue light upon excitation by ultraviolet radiation having a maximum excitation wavelength of 250 nm to 400 nm inclusive in an excitation spectrum.
  • [0085]
    A LaJEM phase activated with Tb can provide a fluorescent material that has a maximum emission wavelength of 480 nm to 560 nm inclusive and emits green light upon excitation by ultraviolet radiation having a maximum excitation wavelength of 200 nm to 300 nm inclusive in an excitation spectrum.
  • [0086]
    In the invention, the fluorescent material should preferably be composed of a single JEM phase as the crystal phase; however, that JEM phase could be mixed with other crystal phase or an amorphous phase in such a range that its properties do not become worse. To obtain high luminance in this case, the content of the JEM phase should preferably be 50% by mass or greater.
  • [0087]
    In the invention, the quantitative range of the primary component is determined such that the content of the JEM phase is at least 50% by mass, as already mentioned. The proportion of the content of the JEM phase could be found from the ratio of the strongest peaks of the respective phases measured by X-ray diffractometry.
  • [0088]
    When the fluorescent material of the invention is used in situations where it is excited by electron radiation, the fluorescent material could be mixed with an electrically conductive inorganic material to give it electrical conductivity. The conductive inorganic material includes oxides, oxynitrides or nitrides containing one or two or more elements selected from Zn, Al, Ga, In and Sn, or their mixture.
  • [0089]
    The oxynitride fluorescent material obtained by the fabrication process of the invention is higher in luminance and more reduced in terms of a luminance drop upon exposure to an excitation source than a conventional sialon fluorescent material, so it lends itself well to VFDs, FEDs, PDPs, CRTs, white LEDs, etc.
  • [0090]
    The lighting device of the invention is built up of at least a light-emitting source and the fluorescent material of the invention. The lighting device includes an LED lighting device and a fluorescent lamp. For instance, the LED lighting device may be fabricated using the fluorescent material of the invention according to such methods and means as set forth in prior publications, for instance, JP(A)'s 5-152609 and 7-99345 and Japanese Patent No. 2927279. Preferably in this case, the light-emitting source used should emit light having a wavelength of 100 nm to 500 nm, and particular preference is given to an ultraviolet (violet) LED light-emitting element having a wavelength of 330 nm to 420 nm.
  • [0091]
    Some light-emitting elements are formed of nitride semiconductors such as GaN and InGaN, and if their composition is controlled, they can provide a light-emitting source capable of emitting light at a given wavelength.
  • [0092]
    When the lighting device is built up, the fluorescent material of the invention could be used alone or in combination with a fluorescent material having other emission properties. In this manner, a lighting device capable of emitting light in the desired color could be set up.
  • [0093]
    As an example, there is a combination of an ultraviolet or violet LED emission element of 330 nm 420 nm, a green fluorescent material that is excited at this wavelength to give out light having a wavelength of 520 nm to 570 nm inclusive, a red fluorescent material capable of emitting light of 570 nm to 700 nm inclusive and the fluorescent material of the invention.
  • [0094]
    Such green fluorescent materials include BaMgAl10O17:Eu, Mn, and such red fluorescent materials include Y2O3:Eu.
  • [0095]
    As the fluorescent materials in this lighting device are irradiated with ultraviolet radiation coming out of the LED, it allows red light, green light and blue light to be mixed together into white light.
  • [0096]
    There is another combination of an ultraviolet or violet LED emission device of 330 nm to 420 nm, a yellow fluorescent material that is excited at this wavelength to have an emission peak at a wavelength of 550 nm to 600 nm inclusive and the fluorescent material of the invention.
  • [0097]
    Such yellow fluorescent materials include (Y, Gd)2(Al, Ga)5O12:Ce as set forth in Japanese Patent No. 2927279, and α-sialon:Eu base material as set forth in JP(A)2002-363554. Among others, Ca-α-sialon with Eu in a solid solution form is preferred because of its high emission luminance. As the fluorescent materials in this lighting device are irradiated with ultraviolet or violet light coming from the LED, it allows blue light and yellow light to be mixed together into whitish or reddish light like one emitted out of an electric bulb.
  • [0098]
    Comprising at least an excitation source and the fluorescent material of the invention, the image display of the invention is embodied in the form of a vacuum fluorescent display tube (VFD), a field emission display (FED), a plasma display panel (PDP), a cathode-ray tube (CRT) or the like. The fluorescent material of the invention has already been found to emit light upon excitation with vacuum ultraviolet radiation of 100 nm to 190 nm, and ultraviolet or electron radiation of 190 nm to 380 nm. As described above, such an image display may be set up by a combination of these excitation sources with the fluorescent material of the invention.
  • [0099]
    Although the invention is now explained in further details with reference to specific examples, it is to be understood that they are given as an aid only to a better understanding of the invention, and the invention is never limited thereto.
  • EXAMPLE 1
  • [0100]
    To obtain a compound represented by compositional formula La0.2Ce0.8Si5Al2O1.5N8.7 (Table 3 shows the mixing composition of the starting powders; Table 4 parameters; and Table 5 a post-reaction calculated composition), weighing was done such that silicon nitride powders having an average particle diameter of 0.5 μm, an oxygen content of 0.93% by weight and an α-type content of 92%, aluminum nitride powders, lanthanum oxide and cerium oxide were at 48.66% by weight, 17.06% by weight, 27.12% by weight and 7.16% by weight, respectively, and a 2-hour mixing was carried out in a wet ball mill using n-hexane.
  • [0101]
    n-Hexane was evaporated off in a rotary evaporator, and the ensuing mixture was molded in a mold at a pressure of 20 MPa into a compact of 12 mm in diameter and 5 mm in thickness.
  • [0102]
    That compact was placed in a boron nitride crucible, which was then set in an electric furnace of the graphite resistance-heating mode. Firing operation was started with evacuation of a firing atmosphere with a diffusion pump. Then, the compact was heated from room temperature up to 800° C. at a heating rate of 500° C. per hour, and at 800° C. nitrogen with a purity of 99.999% by volume was admitted into the furnace to bring the pressure to 1 MPa. Finally, the temperature was brought up to 1,700° C. at a rate of 500° C. per hour, and at 1,700° C. the compact was held for 2 hours.
  • [0103]
    After firing, the constituting crystals of the obtained sintered compact were identified in following manner. As a result, they were judged as a JEM phase. First, the synthesized sample was ground down to powders in an agate mortar for powder X-ray diffraction measurement using Kα radiation of Cu.
  • [0104]
    The ensuing chart showed a pattern of FIG. 1. As a result of indexing of this, the results reported in Table 2, below, were obtained. The lattice constants determined from FIG. 2 were a=9.4304 Å, b=9.7689 Å and c=8.9386 Å.
  • [0105]
    Using the lattice constants and the atomic coordinates shown in Table 1, X-ray diffraction pattern simulation was carried on Rietveld analysis computation software (RIETAN-2000 prepared by Fujio Izumi; “Actual Aspects of Powder X-Ray Analysis”, Asakura Shoten), and the result was in coincidence with the experimentally obtained X-ray diffraction pattern.
  • [0106]
    From these results, the substance of Example 1 was judged as a JEM phase. Referring specifically to FIG. 1, it was ascertained that the substance was a mixture containing the JEM phase as the primary component and β-sialon as the byproduct. The respective phases had the strongest peaks of 83 and 15, from which the proportion of the JEM phase was found to be 85%.
  • [0107]
    As a result of irradiation of the powder sample with 365-nm wavelength light coming from a lamp, it was found to emit blue light. As a result of measuring the emission spectrum and the excitation spectrum (FIG. 2) of the powder sample using a fluorescent emission spectrometer, it was found to be a fluorescent material having an excitation spectrum peak at 365 nm and a peak at 447-nm blue light in an emission spectrum upon excitation by 365-nm ultraviolet light.
  • [0108]
    The peak emission intensity was 1,787 counts. It is here to be noted that the count value varies with a measuring device and conditions, so it is given in an arbitrary unit. In other words, comparison is possible among inventive examples alone or comparative examples alone measured under the same conditions.
  • [0109]
    Emission properties of the powder sample upon excitation by electron radiation were observed under an SEM equipped with a cathode luminescence (CL) detector. With this system, visible light generated by irradiation with electron radiation is guided through an optical fiber to a photomultiplier located outside it, so that the emission spectra of light emitted upon excitation by electron radiation can be measured.
  • [0110]
    It was ascertained that the inventive fluorescent material was excited by electron radiation to emit blue light of 430 nm in wavelength.
    TABLE 2
    h k l d I
    1 1 0 13.052 6.7776 41
    1 1 1 16.401 5.4001 29
    2 0 0 18.820 4.7113 13
    0 0 2 19.854 4.4681 3
    0 2 1 20.728 4.2817 4
    1 1 2 23.833 3.7304 34
    0 2 2 27.040 3.2949 7
    2 0 2 27.489 3.2420 37
    2 2 1 28.139 3.1686 93
    1 2 2 28.679 3.1102 10
    1 3 1 30.732 2.9069 100
    3 1 1 31.528 2.8353 39
    1 1 3 32.815 2.7270 30
    2 2 2 33.151 2.7001 40
    3 0 2 34.888 2.5695 26
    3 2 1 35.415 2.5325 38
    1 2 3 36.580 2.4545 44
    0 4 0 36.820 2.4390 7
    0 4 1 38.218 2.3530 10
    2 3 2 39.205 2.2960 10
  • EXAMPLES 2-12
  • [0111]
    As in Example 1, oxynitride powders were prepared with the exception that the compositions shown in Tables 3, 4 and 5 were used. As a result, high-luminance fluorescent materials excited by ultraviolet radiation were obtained as set out in “Examples 2-12” in Table 6.
  • [0112]
    In Example 3 (Ce1Si5Al2O1.5N8.7), only Ce was contained as the rare earth element, and the obtained fluorescent material emitted 468-nm blue light, with spectra shown in FIG. 3. In Example 5 (La0.8Eu0.2Si5Al2O1.5N8.7), Eu worked as a luminescence center, and the obtained fluorescent material emitted green light of 510 to 550 nm with spectra shown in FIG. 4.
  • [0113]
    In Example 8 (La0.5Tb0.5Si5Al2O1.5N8.7), Tb worked as a luminescence center, and the obtained fluorescent material emitted green light with spectra shown in FIG. 5.
  • COMPARATIVE EXAMPLE 13
  • [0114]
    Oxynitride powders were prepared as in Example 1 with the exception that the composition shown in Table 3 was used. The fluorescent material obtained herein had a high JEM content, but its luminance was low.
    TABLE 3
    Starting Composition (% by weight)
    Si3N4 La2O3 CeO2 Eu2O3 Tb4O7 AlN LaN
    Ex. 1 48.66 27.12 7.16 0 0 17.06 0
    2 47.55 0 0 35.79 0 16.67 0
    3 47.93 0 35.27 0 0 16.8 0
    4 48.38 16.85 17.8 0 0 16.96 0
    5 48.58 27.07 0 7.31 0 17.03 0
    6 48.19 16.79 0 18.13 0 16.89 0
    7 48.36 26.95 0 0 7.73 16.95 0
    8 47.65 16.6 0 0 19.04 16.71 0
    9 49 15.93 7.21 0 0 17.18 10.68
    10 48.92 15.9 0 7.36 0 17.15 10.66
    11 48.7 15.83 0 0 7.78 17.07 10.61
    12 48.85 15.88 3.6 0 3.9 17.12 10.65
    CE 13 48.85 34.03 0 0 0 17.12 0

    CE: comparative example
  • [0115]
    TABLE 4
    Parameters
    a b c d e f g h i z
    Ex. 1 1 5 2 1.5 8.67 1 1 1.5 0.96 1
    2 1 5 2 1.5 8.67 1 1 1.5 0.96 1
    3 1 5 2 1.5 8.67 1 1 1.5 0.96 1
    4 1 5 2 1.5 8.67 1 1 1.5 0.96 1
    5 1 5 2 1.5 8.67 1 1 1.5 0.96 1
    6 1 5 2 1.5 8.67 1 1 1.5 0.96 1
    7 1 5 2 1.5 8.67 1 1 1.5 0.96 1
    8 1 5 2 1.5 8.67 1 1 1.5 0.96 1
    9 1 5 2 1 9 1 1 1 1 1
    10 1 5 2 1 9 1 1 1 1 1
    11 1 5 2 1 9 1 1 1 1 1
    12 1 5 2 1 9 1 1 1 1 1
    CE 13 1 5 2 1.5 8.67 1 1 1.5 0.96 1

    CE: comparative example
  • [0116]
    TABLE 5
    Product Composition (atm %)
    Si La Ce Eu
    Ex. 1 27.523 4.4037 1.1009 0
    2 27.523 0 0 5.5046
    3 27.523 0 5.5046 0
    4 27.523 2.7523 2.7523 0
    5 27.523 4.4037 0 1.1009
    6 27.523 2.7523 0 2.7523
    7 27.523 4.4037 0 0
    8 27.523 2.7523 0 0
    9 27.778 4.4444 1.1111 0
    10 27.778 4.4444 0 1.1111
    11 27.778 4.4444 0 0
    12 27.778 4.4444 0.5556 0
    CE 13 27.523 5.5046 0 0
    Tb Al O N
    Ex. 1 0 11.009 8.2569 47.706
    2 0 11.009 8.2569 47.706
    3 0 11.009 8.2569 47.706
    4 0 11.009 8.2569 47.706
    5 0 11.009 8.2569 47.706
    6 0 11.009 8.2569 47.706
    7 1.009 11.009 8.2569 47.706
    8 2.7523 11.009 8.2569 47.706
    9 0 11.111 5.5556 50
    10 0 11.111 5.5556 50
    11 1.111 11.111 5.5556 50
    12 0.5556 11.111 5.5556 50
    CE 13 0 11.009 8.2569 47.706

    CE: comparative example
  • [0117]
    TABLE 6
    Byproduct Proportion of JEM Phase (%)
    Ex. 1 β-sialon 85
    2 β-sialon 79
    3 β-sialon 71
    4 β-sialon 83
    5 β-sialon 77
    6 β-sialon 62
    7 β-sialon 70
    8 β-sialon 86
    9 β-sialon 92
    10 β-sialon 88
    11 β-sialon 93
    12 β-sialon 90
    CE 13 La2Si6O3N8 93
    Light Emission Excitation
    Wavelength Intensity wavelength Intensity
    nm Arbitrary unit nm Arbitrary unit
    Ex. 1 447 1787 365 1788
    2 592 81 472 81
    3 468 822 375 826
    4 445 1521 363 1523
    5 533 189 432 189
    6 514 47 426 47
    7 516 2613 257 1378
    8 510 2936 262 2508
    9 440 1769 350 1750
    10 499 200 360 205
    11 550 3010 254 3025
    12 545 3342 260 3335
    CE 13 No Fluorescent Properties
  • EXAMPLES 14-32
  • [0118]
    The starting powders used herein were silicon nitride powders (having an average particle diameter of 0.5 μm, an oxygen content of 0.93% by weight and an α-type content of 92%), aluminum nitride powders (having a specific area of 3.3 m2/g and an oxygen content of 0.79%), lanthanum oxide powders (with a 99.9% purity), europium oxide powders (with a 99.9% purity), aluminum oxide powders (with a 99.9% purity), lanthanum nitride powders obtained by synthesis by nitriding of metallic lanthanum (with a 99.9% purity) in ammonia, cerium nitride powders obtained by synthesis by nitriding of metallic cerium in ammonia, and europium nitride powders obtained by synthesis by nitriding of metallic europium in ammonia.
  • [0119]
    These starting powders were weighed in such a way as to have compositions as shown in Table 7. The composition was mixed in a mortar with an agate pestle for 30 minutes. Then, the resulting mixture was passed through a 500-μm sieve, and allowed to fall gravitationally down into a boron nitride crucible, thereby filling it with the powders. The bulk density (packing density by volume) of the powders was about 20 to 30%.
  • [0120]
    Why the bulk density was kept at up to 30% was that as there was a free space around the starting powders, it allowed the reaction product to grow crystallographically in the free space at the next firing step, so that there was lesser contact of crystals with each other, resulting in synthesis of crystals having lesser surface defects. When the sample to be prepared contained lanthanum nitride powders, cerium nitride powders and europium nitride powders, the steps of weighing, mixing and packing the powders were all carried out in a globe box capable of keeping a nitrogen atmosphere having a moisture of up to 1 ppm and an oxygen content of up to 1 ppm.
  • [0121]
    The powdery mixture was placed in a boron nitride crucible, which was then set in an electric furnace of the graphite resistance-heating mode. Firing operation was started with evacuation of a firing atmosphere by a diffusion pump. Then, the compact was heated from room temperature up to 800° C. at a heating rate of 500° C. per hour, and at 800° C. nitrogen with a purity of 99.999% by volume was admitted into the electric furnace to bring the pressure to 1 MPa. Then, the compact was heated to 1,900° C. at a heating rate of 500° C. per hour, and at 1,900° C. the compact was held for 2 hour. After firing, the obtained fired compact was crushed, manually pulverized in a crucible and mortar formed of sintered silicon nitride, and passed through a 30-μm sieve to obtain powders. The thus obtained synthesized powders were pulverized in an agate mortar for powder X-ray diffraction measurement using Kα radiation of Cu. As a result, every sample contained the JEM phase as the primary component at a proportion of at least 50%.
  • [0122]
    The emission spectra and the excitation spectra of the powder samples were measured with a fluorescent emission spectrometer, with the results set out in Table 8. The emission spectra for Examples 14-24 are illustrated in FIG. 6. The results of fluorescent measurement have indicated that the fluorescent materials of these examples are capable of emitting blue or green light peaking at a wavelength of 400 nm to 450 nm.
    TABLE 7
    Starting Composition (% by weight)
    Si3N4 La2O3 CeO2 Eu2O3
    Ex. 14 48.85 33.35 0.69
    15 48.85 33.69 0.34
    16 48.85 33.92 0.11
    17 48.85 33.99 0.34
    18 48.85 34.02 0.01
    19 48.82 33.33 0.74
    20 48.83 33.68 0.37
    21 48.84 33.91 0.12
    22 48.85 33.99 0.04
    23 48.85 34.02 0.01
    24 48.84 32.89 1.14
    25 59.13
    26 54.16 11.43
    27 49.19 22.84
    28 59.09
    29 54.11 11.42
    30 49.15 22.83
    31 44.19 33.18 1.11
    32 39.25 33.15 1.11
    Al2O3 LaN CeN EuN AlN
    Ex. 14 17.12
    15 17.12
    16 17.12
    17 17.12
    18 17.12
    19 17.12
    20 17.12
    21 17.12
    22 17.12
    23 17.12
    24 17.12
    25 31.26 0.97 8.64
    26 20.5 12.94
    27 9.76 17.24
    28 31.23 1.05 8.63
    29 20.48 1.05 12.94
    30 9.75 1.05 17.23
    31 21.52
    32 3.56 22.93
  • [0123]
    TABLE 8
    Excitation Emission Intensity
    Wavelength (nm) Wavelength (nm) Arbitrary unit
    Ex. 14 352 418 3617
    15 351 415 3397
    16 351 411 1923
    17 349 407 1225
    18 349 407 1300
    19 285 469 641
    20 328 492 658
    21 336 471 739
    22 341 468 610
    23 340 465 447
    24 354 423 4177
    25 358 434 2000
    26 354 424 2215
    27 356 440 2293
    28 300 539 159
    29 296 496 415
    30 329 506 524
    31 290 493 573
    32 323 495 545
  • [0124]
    The lighting device using the fluorescent material comprising the nitride according to the invention is now explained. FIG. 7 is illustrative in schematic of the structure of a white LED working as a lighting device.
  • [0125]
    A 405-nm violet LED 2 is used as a light-emitting element. The fluorescent material of inventive Example 24 and a Ca-α-sialon:Eu base yellow fluorescent material composed of Ca0.75Eu0.25Si8.625Al3.375O1.125N14.875 dispersed in a resin layer is applied over the LED 2. This device functions as a lighting device in which, upon conduction of currents to an electrically conductive terminal, the LED 2 emits 405-nm light that in turn excites the blue fluorescent material and the yellow fluorescent material to give out blue light and yellow light, so that they are mixed together to emit white light.
  • [0126]
    In an alternative embodiment of the lighting device, a formulation different from the aforesaid one is designed. First, a 380-nm violet LED is used as a light-emitting element. The fluorescent material of inventive Example 24, a green fluorescent material (BaMgAl10O17:Eu, Mn) and a red fluorescent material (La2O2S:Eu) dispersed in a resin layer are applied over the violet LED. This device functions as a lighting device in which, upon conduction of currents to an electrically conductive terminal, the LED emits 380-nm light that in turn excites the red, green and blue fluorescent materials, giving out red, green, and blue light, which are then mixed together into white light.
  • [0127]
    One exemplary image display design using the fluorescent material of the invention is now explained. FIG. 8 is illustrative in schematic of the principles of a plasma display panel working as that image display. The fluorescent material of inventive Example 24, a green fluorescent material (Zn2SiO4:Mn) and a blue fluorescent material (BaMgAl10O17:Eu) are coated on the inner surfaces of the associated cells 11, 12 and 13, respectively. Conduction of currents to electrodes 14, 15, 16 and 17 causes vacuum ultraviolet radiation to occur by Xe discharge, whereby the fluorescent materials are excited, generating red, green, and blue visible light to be observed from outside through a protective layer 20, a dielectric layer 19 and a glass substrate 22; This way, the image display works.
  • [0128]
    The fluorescent material of the invention, because of emitting blue or green light upon irradiation with electron radiation, also functions as a fluorescent material for CRTs or field emission displays.
  • [0129]
    As recounted above, the invention provides a fluorescent material having quite an unheard-of composition and its fabrication process, so it can provide an improved fluorescent material capable of maintaining high luminance and free of any deterioration.
  • Possible Applications to the Industry
  • [0130]
    Much concern is now growing about fluorescent materials and their utilization. The present invention provides a novel nitride fluorescent material, which is capable of emitting light with higher luminance and is lesser likely to decrease in luminance and deteriorate as compared with conventional sialon or oxynitride fluorescent materials, and so lends itself well to VFDs, FEDs, PDPs, CRTs, white LEDs and so on. From now on, this fluorescent material will have wide applications in material designs for lighting devices including various image displays, etc.
Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US6670748 *Jul 26, 2002Dec 30, 2003Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbHIllumination unit having at least one LED as light source
US20030094893 *Jul 26, 2002May 22, 2003Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen MbhIllumination unit having at least one LED as light source
US20030168643 *Apr 8, 2003Sep 11, 2003National Institute For Materials ScienceOxynitride phosphor activated by a rare earth element, and sialon type phosphor
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
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US7553056 *Jun 30, 2009Lg Display Co., Ltd.Backlight unit
US7780872Aug 24, 2010National Institute For Materials ScienceFluorescent substance, method for manufacturing the same and image display device
US7851988 *Sep 24, 2004Dec 14, 2010Osram Gesellschaft mit beschränkter HaftungGreen-emitting LED
US7965031Sep 24, 2004Jun 21, 2011Osram Gesellschaft mit beschränkter HaftungWhite-emitting LED having a defined color temperature
US8057704Feb 22, 2007Nov 15, 2011National Institute For Materials SciencePhosphor, method for producing same, and light-emitting device
US8114313Dec 7, 2006Feb 14, 2012National Institute For Materials SciencePhosphor, process for producing the same, and luminescent device
US8142685Jan 11, 2008Mar 27, 2012National Institute For Materials ScienceFluorescent material, process for producing the same, and luminescent device
US8147715Dec 7, 2006Apr 3, 2012National Institute For Materials SciencePhosphor, process for producing the same, and luminescent device
US8398892Sep 1, 2008Mar 19, 2013Showa Denko K.K.Phosphor, method for producing the same and light-emitting device using the same
US8550645Nov 25, 2009Oct 8, 2013Showa Denko K.K.Illumination device for display device, and display device
US8608980Feb 12, 2013Dec 17, 2013National Institute For Materials SciencePhosphor, method for producing the same and light-emitting device using the same
US8946981Aug 26, 2011Feb 3, 2015National Institute For Materials SciencePhosphor, lighting fixture, and image display device
US9062252Nov 30, 2012Jun 23, 2015National Institute For Materials SciencePhosphor, manufacture thereof, light-emitting device, and image display device
US9279079May 29, 2008Mar 8, 2016Sharp Kabushiki KaishaMethod of manufacturing phosphor, light-emitting device, and image display apparatus
US9359551Nov 30, 2012Jun 7, 2016National Institute For Materials SciencePhosphor, manufacture thereof; light-emitting device, and image display device utilizing phosphor
US20060186377 *Feb 22, 2006Aug 24, 2006Sharp Kabushiki KaishaOxynitride phosphor and semiconductor light-emitting device
US20060289878 *Sep 24, 2004Dec 28, 2006Herbert BrunnerWhite-emitting led having a defined color temperature
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US20070034885 *Sep 24, 2004Feb 15, 2007Bert BrauneGreen-emitting led
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Dec 19, 2005ASAssignment
Owner name: NATIONAL INSTITUTE FOR MATERIALS SCIENCE, JAPAN
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Effective date: 20050725