U.S. patent application number 11/631390 was filed with the patent office on 2009-01-29 for phosphor, light-emitting device using same, image display and illuminating device.
This patent application is currently assigned to Mitsubishi Chemical Corporation. Invention is credited to Naoto Kijima, Yasuo Shimomura.
Application Number | 20090026920 11/631390 |
Document ID | / |
Family ID | 35785055 |
Filed Date | 2009-01-29 |
United States Patent
Application |
20090026920 |
Kind Code |
A1 |
Shimomura; Yasuo ; et
al. |
January 29, 2009 |
Phosphor, light-emitting device using same, image display and
illuminating device
Abstract
The present invention relates to a phosphor represented by the
following general formula (I), comprising: a composite oxide
containing a divalent and trivalent metal elements as a host
crystal; and at least Ce as an activator element in said host
crystal, wherein the phosphor has a maximum emission peak in a
wavelength range of from 485 nm to 555 nm in the emission spectrum
at room temperature: M.sup.1.sub.aM.sup.2.sub.bM.sup.3.sub.cO.sub.d
(I) wherein M.sup.1 represents an activator element containing at
least Ce; M.sup.2 represents a divalent metal element; M.sup.3
represents a trivalent metal element; a is a number within a range
of 0.0001.ltoreq.a.ltoreq.0.2; b is a number within a range of
0.8.ltoreq.b.ltoreq.1.2; c is a number within a range of
1.6.ltoreq.c.ltoreq.2.4; and d is a number within a range of
3.2.ltoreq.d.ltoreq.4.8. Further, a light emitting device
comprising said phosphor and a display and a lighting system having
said light emitting device as a light source are disclosed. In
accordance with the present invention, a phosphor which can be
easily produced and can provide a light emitting device having a
high color rendering, a light emitting device comprising the
phosphor, and a display and a lighting system comprising the light
emitting device as a light source can be provided.
Inventors: |
Shimomura; Yasuo; (Kanagawa,
JP) ; Kijima; Naoto; (Kanagawa, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Mitsubishi Chemical
Corporation
Minato-ku
JP
|
Family ID: |
35785055 |
Appl. No.: |
11/631390 |
Filed: |
June 30, 2005 |
PCT Filed: |
June 30, 2005 |
PCT NO: |
PCT/JP05/12100 |
371 Date: |
June 1, 2007 |
Current U.S.
Class: |
313/504 ;
252/301.4R; 252/301.6R; 313/483 |
Current CPC
Class: |
H01L 2224/48257
20130101; H05B 33/14 20130101; H01L 2224/48091 20130101; H01L
2924/181 20130101; H01L 2924/00014 20130101; H01L 2924/00012
20130101; H01L 33/502 20130101; H01L 2224/48247 20130101; H01L
2224/48091 20130101; C09K 11/7768 20130101; H01L 2924/181
20130101 |
Class at
Publication: |
313/504 ;
313/483; 252/301.4R; 252/301.6R |
International
Class: |
H01J 63/04 20060101
H01J063/04; H01J 1/62 20060101 H01J001/62; C09K 11/78 20060101
C09K011/78 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2004 |
JP |
2004-194508 |
Claims
1-13. (canceled)
14: A phosphor represented by general formula (I), which comprises
a composite oxide containing divalent and trivalent metal elements,
as a host crystal, and at least Ce as an activator element in said
host crystal, wherein said phosphor has a maximum emission peak in
a wavelength range of from 485 mm to 555 nm in the emission
spectrum at room temperature:
M.sup.1.sub.aM.sup.2.sub.bM.sup.3.sub.cO.sub.d (I) wherein M.sup.1
represents an activator element containing at least Ce; M.sup.2
represents a divalent metal element; M.sup.3 represents a trivalent
metal element; a is a number within a range of
0.0001.ltoreq.a.ltoreq.0.2; b is a number within a range of
0.8.ltoreq.b.ltoreq.1.2; c is a number within a range of
1.6.ltoreq.c.ltoreq.2.4; and d is a number with in a range of
3.2.ltoreq.d.ltoreq.4.8.
15: The phosphor as described in claim 14 wherein said activator
element M.sup.1 in general formula (I) contains at least Ce and at
least one element selected from the group consisting of Cr, Mn, Fe,
Co, Ni, Cu, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm and Yb.
16: The phosphor as described in claim 14, wherein said divalent
metal element M.sup.2 in general formula (I) is at least one metal
element selected from the group consisting of Mg, Ca, Zn, Sr, Cd
and Ba.
17: The phosphor as described in claim 14, wherein said trivalent
metal element M.sup.3 in general formula (I) is at least one metal
element selected from the group consisting of Al, Sc, Ca, Y, In,
La, Cd and Lu.
18: The phosphor as described in claim 14, which comprises at least
Sc as trivalent metal element M.sup.3 in general formula (I).
19: The phosphor as described in claim 18, wherein 50 mol % or more
of said trivalent metal elements M.sup.3 is Sc.
20: The phosphor as described in claim 14, wherein said host
crystal of said phosphor is a crystal represented by the
composition formula M.sup.2M.sup.3.sub.2O.sub.4, in which M.sup.2
represents a divalent metal element and M.sup.3 represents a
trivalent metal element.
21: The phosphor as described in claim 14, wherein said host
crystal of said phosphor has any of space groups Pnma, Fd3(-)m,
P2.sub.1/n, P2.sub.1, P6.sub.3 or P2.sub.1/c.
22: The phosphor as described in claim 14, which has a maximum
emission peak in a wavelength range of from 500 nm to 535 nm in the
emission spectrum at room temperature.
23: A light emitting device comprising a phosphor which is a
wavelength conversion material, and a semiconductor light emitting
device which emits light in a wavelength range of from ultraviolet
to visible light, wherein said light emitting device contains at
least a phosphor described in claim 14 as said phosphor.
24. An electroluminescence light emitting device comprising a
phosphor described in claim 14.
25: A display comprising a light emitting device described in claim
23 as a light source.
26: A lighting system comprising a light emitting device described
in claim 23 as a light source.
27: A display comprising a light emitting device described in claim
24 as a light source.
28: A lighting system comprising a light emitting device described
in claim 24 as a light source.
Description
TECHNICAL FIELD
[0001] In recent years, a white light-emitting device comprising in
combination a gallium nitride (GaN)-based light emitting diode
(LED) as a semiconductor light emitting device and a phosphor as a
wavelength conversion material has been noted as a light source for
display or lighting system by making the use of its characteristics
of small power consumption and prolonged life.
[0002] The present invention concerns a cerium (Ce)-activated oxide
phosphor which can emit light in the range of from red to blue when
excited with electron ray, X-ray, ultraviolet ray, visible light or
the like. In particular, the present invention concerns a phosphor
which can absorb light in the range of from near ultraviolet to
bluish green through blue to efficiently emit light in a longer
wavelength range such as from green to red through yellow, which
phosphor can be used as a wavelength conversion material for
absorbing light from a semiconductor light emitting device such as
light-emitting diode (LED) and laser diode (LD) which emits light
in the range of from near ultraviolet to blue to constitute a light
emitting device having a high color rendering, particularly a white
light-emitting device (hereinafter referred to as "white LED").
Further, the present invention concerns a light emitting device and
an electroluminescence light emitting device comprising the
phosphor and a display and a lighting system having such a light
emitting device as a light source.
BACKGROUND ART
[0003] As disclosed in Patent Reference 1, a white light-emitting
device comprising in combination a GaN-based blue light-emitting
diode and a phosphor has been noted as a light source for display
or lighting system by making the use of its characteristics of
small power consumption and prolonged life. Referring to this light
emitting device, the phosphor incorporated therein absorbs visible
light in the blue range emitted by the GaN-based blue
light-emitting diode to emit yellow light, and the blue light from
the diode which has not been absorbed by the phosphor and the
yellow light emitted by the phosphor are then mixed with each other
to attain emission of white light.
[0004] As the phosphor there has been typically known a phosphor
comprising a yttrium-aluminum composite oxide
(Y.sub.3Al.sub.5O.sub.12) as a host crystal and cerium (Ce)
incorporated as an activator element in said host crystal. Further,
it has been known that the tone of light emitted by this phosphor
can be adjusted by replacing some of yttrium (Y) atoms by
gadolinium (Gd) or the like or replacing some of aluminum (Al)
atoms by gallium (Ga) or the like (Non-patent Reference 1).
However, there were problems that in order to produce efficiently
this phosphor as a single phase, the material must be calcined at
extremely high temperature that makes it difficult to produce the
phosphor, and a phosphor which is uniform in emission intensity,
chromaticity, particle diameter, etc. can be difficulty
produced.
[0005] Also, a light emitting device comprising a blue
light-emitting diode and a yellow light-emitting phosphor in
combination was disadvantageous in that the emission of light in
the range of from bluish green to green is short, giving
deteriorated color rendering. In order to improve color rendering,
a method has been proposed which comprises combining a blue
light-emitting diode with a green phosphor and a red phosphor, and
Non-patent Reference 2, for example, discloses a white LED
comprising in combination a blue light-emitting diode, a green
phosphor SrGa.sub.2S.sub.4:Eu.sup.2+ and a red phosphor ZnCdS:Ag,
Cl. However, the phosphor used was disadvantageous in that it is a
sulfide, can be difficulty produced and lacks stability in use.
[0006] On the other hand, as a phosphor which is produced at a
relatively low calcining temperature and thus can be relatively
easily produced there is disclosed a Ce-activated
calcium-scandium-silicon composite oxide
(Ca.sub.3Sc.sub.2Si.sub.3O.sub.12) in Patent Reference 2. This
phosphor contains calcium oxides and silicon oxides that form a
low-melting compound when calcined, and a calcined powder is
extremely firmly sintered although the calcining temperature can be
lowered. Further, this phosphor had a high emission intensity, and
it was difficult to obtain a phosphor having particle diameters
which are as uniform as about 1 .mu.m to 20 .mu.m.
[0007] On the other hand, a phosphor comprising thulium (Tm)
incorporated in a scandate of alkaline earth metal having the same
CaFe.sub.2O.sub.4 structure as that of the desired phosphor of the
present invention is disclosed in Patent Reference 3. However, this
phosphor shows emission of light having a narrow half width based
on 4f-4f transition when excited with electron ray and is quite
different in mechanism from that of cerium-derived emission from
the phosphor of the present invention, i.e., emission of light
having a wide half width based on 4f-5d transition. Further, this
thulium-containing phosphor is a material which does not emit light
when irradiated with ultraviolet ray or visible light, and it is
thus not easy to anticipate and produce the phosphor of the present
invention from the presence of this phosphor.
[0008] Moreover, phosphors comprising cerium incorporated in a
strontium yttrate (SrY.sub.2O.sub.4), which, too, each are a
crystal having CaFe.sub.2O.sub.4 structure, are disclosed in
Non-patent Reference 3 and Non-patent Reference 4, but these
phosphors do not show emission efficiently at room temperature.
Further, a phosphor comprising cerium incorporated in a strontium
thioyttrate (SrY.sub.2S.sub.4), which, too, is a crystal having
CaFe.sub.2O.sub.4 structure, is disclosed in Non-patent Reference
5, but this phosphor was a sulfide and thus was practically
disadvantageous in long-range stability, producibility, etc.
Patent Reference 1: JP-A-10-242513
Patent Reference 2; JP-A-2003-064358
Patent Reference 3: JP-A-6-100860
Non-patent Reference 1: Preprints of 264th Meeting, Phosphor
Research Society, pp. 5-14
[0009] Non-patent Reference 2: Journal of The Electrochemical
Society, Vol. 150 (2003), pp. H57-H60
Non-patent Reference 3: The Journal of Chemical Physics, vol. 47,
pp. 5139-5145 (1967)
Non-patent Reference 4: Journal of Luminescence, Vol. 102-103, pp.
635-637 (2003)
Non-patent Reference 5: Journal of The Electrochemical Society,
Vol. 139, pp. 2347-2352 (1992)
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0010] The present invention has been worked out to develop a
phosphor which can be easily produced and has a high emission
intensity and a uniform particle diameter and even a phosphor which
can provide a light emitting device having a high color rendering
in the light of the aforementioned related art techniques and is
intended to provide a phosphor which can be easily produced and
gives high color rendering, a light emitting device and an
electroluminescence device comprising the phosphor, and a display
and a lighting system comprising the light emitting device as a
light source.
Means for Solving the Problems
[0011] As a result of extensive studies of solution to the
aforementioned problems, the present inventors found that a
phosphor comprising a compound having a specific chemical
composition as a host crystal, containing at least trivalent cerium
(Ce.sup.3+) in said host crystal as an activator element and having
a maximum emission peak in a wavelength range of from 485 nm to 555
nm in the emission spectrum can accomplish the aforementioned
object. The present invention has been thus worked out and has the
followings as essence.
[0012] (1) A phosphor represented by the following general formula
(I), which comprises: a composite oxide containing divalent and
trivalent metal elements, as a host crystal; and at least Ce as an
activator element in said host crystal, wherein the phosphor has a
maximum emission peak in a wavelength range of from 485 nm to 555
nm in the emission spectrum at room temperature:
M.sup.1.sub.aM.sup.2.sub.bM.sup.3.sub.cO.sub.d (I)
wherein M.sup.1 represents an activator element containing at least
Ce; M.sup.2 represents a divalent metal element; M.sup.3 represents
a trivalent metal element; a is a number within a range of
0.0001.ltoreq.a.ltoreq.0.2; b is a number within a range of
0.8.ltoreq.b.ltoreq.1.2; c is a number within a range of
1.6.ltoreq.c.ltoreq.2.4; and d is a number within a range of
3.2.ltoreq.d.ltoreq.4.8.
[0013] (2) The phosphor as described in (1), wherein the activator
element M.sup.1 in the general formula (I) contains at least Ce and
at least one element selected from the group consisting of Cr, Mn,
Fe, Co, Ni, Cu, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm and Yb.
[0014] (3) The phosphor as described in (1) or (2), wherein the
divalent metal element M.sup.2 in the general formula (I) is at
least one metal element selected from the group consisting of Mg,
Ca, Zn, Sr, Cd and Ba.
[0015] (4) The phosphor as described in any one of (1) to (3),
wherein the trivalent metal element M.sup.3 in the general formula
(I) is at least one metal element selected from the group
consisting of Al, Sc, Ga, Y, In, La, Gd and Lu.
[0016] (5) The phosphor as described in any one of (1) to (4),
which comprises at least Sc as trivalent metal element M.sup.3 in
the general formula (I).
[0017] (6) The phosphor as described in (5), wherein 50 mol % or
more of the trivalent metal elements M.sup.3 is Sc.
[0018] (7) The phosphor as described in any one of (1) to (6),
wherein the host crystal of the phosphor is a crystal represented
by the composition formula M.sup.2M.sup.3.sub.2O.sub.4 (in which
M.sup.2 represents a divalent metal element and M.sup.3 represents
a trivalent metal element).
[0019] (8) The phosphor as described in any one of (1) to (7),
wherein the host crystal of the phosphor has any of space groups
Pnma, Fd3(-)m, P2.sub.1/n, P2.sub.1, P6.sub.3 or P2.sub.1/c.
[0020] (9) The phosphor as described in any one of (1) to (8),
which has a maximum emission peak in a wavelength range of from 500
nm to 535 nm in the emission spectrum at room temperature.
[0021] (10) A light emitting device comprising: a phosphor which is
a wavelength conversion material; and a semiconductor light
emitting device which emits light in a wavelength range of from
ultraviolet to visible light, wherein said light emitting device
contains at least a phosphor described in any one of (1) to (9) as
said phosphor.
[0022] (11) An electroluminescence light emitting device comprising
a phosphor described in any one of (1) to (9).
[0023] (12) A display comprising a light emitting device described
in (10) or (11) as a light source.
[0024] (13) A lighting system comprising a light emitting device
described in (10) or (11) as a light source.
ADVANTAGE OF THE INVENTION
[0025] In accordance with the present invention, a phosphor which
can be easily produced and can provide a light emitting device
having a high color rendering, a light emitting device comprising
said phosphor, and a display and a lighting system comprising said
light emitting device as a light source can be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is the powder X-ray diffraction pattern (X-ray
source=CuK.alpha.) of a phosphor obtained in Example 1 of the
present invention. FIG. 1 also depicts the standard diffraction
pattern of CaSc.sub.2O.sub.4 set forth in No. 72-1360 of JCPDS
card. It is shown that the diffraction pattern of the phosphor
obtained in Example 1 coincides well with said standard diffraction
pattern.
[0027] FIG. 2 is a diagram illustrating the emission spectrum
(solid line) and the excitation spectrum (dotted line) of the
phosphor obtained in Example 1 of the present invention.
[0028] FIG. 3 is a diagrammatic sectional view illustrating an
example of a light emitting device having a phosphor of the present
invention as a wavelength conversion material and a semiconductor
light emitting device.
[0029] FIG. 4 is a diagrammatic sectional view illustrating an
example of a planar light emitting lighting system having the light
emitting device shown in FIG. 3 incorporated therein.
DESCRIPTION OF REFERENCE NUMERALS AND SIGNS
[0030] 1: Light emitting device [0031] 2: Mount lead [0032] 3:
Inner lead [0033] 4: Semiconductor light emitting device [0034] 5:
Phosphor-containing resin portion [0035] 6: Electrically-conductive
wire [0036] 7: Molding member [0037] 8: Planar light emitting
lighting system [0038] 9: Diffusion panel [0039] 10; Retaining
case
BEST MODE FOR CARRYING OUT THE INVENTION
[0040] The phosphor of the present invention is a phosphor
represented by the following general formula (I), which comprises:
a composite oxide containing a divalent and trivalent metal
elements as a host crystal; and at least Ce as an activator element
in said host crystal, the phosphor having a maximum emission peak
in a wavelength range of from 485 nm to 555 nm in the emission
spectrum at room temperature:
M.sup.1.sub.aM.sup.2.sub.bM.sup.3.sub.cO.sub.d (I)
(wherein M.sup.1 represents an activator element containing at
least Ce; M.sup.2 represents a divalent metal element; M.sup.3
represents a trivalent metal element; a is a number within a range
of 0.0001.ltoreq.a.ltoreq.0.2; b is a number within a range of
0.8.ltoreq.b.ltoreq.1.2; c is a number within a range of
1.6.ltoreq.c.ltoreq.2.4; and d is a number within a range of
3.2.ltoreq.d.ltoreq.4.8).
[0041] Herein, M.sup.1 in the general formula (I) is an activator
element (luminescent center ion) contained in the host crystal
described later which contains at least Ce and may contain at least
one divalent to tetravalent element selected from the group
consisting of Cr, Mn, Fe, Co, Ni, Cu, Ce, Pr, Nd, Sm, Eu, Tb, Dy,
Ho, Er, Tm and Yb as a coactivator for the purpose of
phosphorescence, chromaticity adjustment, sensitization, etc. In
the case where a coactivator is incorporated, the amount of the
coactivator based on 1 mol of Ce is normally from 0.01 mol to 20
mol. In particular, when Pr is used as a coactivator, the emission
of light from Pr appears in the vicinity of 620 nm in addition to
the emission of light from Ce, making it possible to add the
emission of light of red component to advantage.
[0042] The concentration a of the activator element M.sup.1 is
within a range of 0.0001.ltoreq.a.ltoreq.0.2. When the value of a
is too small, the amount of the luminescent center ion present in
the host crystal of phosphor is too small, giving a tendency that
the emission intensity decreases. On the other hand, when the value
of a is too large, a tendency is given that concentration quenching
causes the decrease of emission intensity. Accordingly, a is
preferably number within a range of 0.0005.ltoreq.a.ltoreq.0.1,
most preferably within a range of 0.002.ltoreq.a.ltoreq.0.04 from
the standpoint of emission intensity. Further, since as the
concentration of Ce rises, the emission peak wavelength shifts
toward longer range to show a relative increase of the amount of
emission of green light, with which a high visual sensitivity is
given, a is preferably within a range of
0.004.ltoreq.a.ltoreq.0.15, more preferably within a range of
0.008.ltoreq.a.ltoreq.0.1, most preferably within a range of
0.02.ltoreq.a.ltoreq.0.08 from the standpoint of balance between
emission intensity and emission peak wavelength.
[0043] M.sup.2 in the general formula (I) is a divalent metal
element and is preferably at least one metal element selected from
the group consisting of Mg, Ca, Zn, Sr, Cd and Ba from the
standpoint of emission efficiency and more preferably contains at
least one metal element of Mg, Ca and Sr. Herein, the green
phosphor preferably contains much Ca as M.sup.2, and it is most
desirable that 50 mol % or more of M.sup.2 elements is Ca. Further,
the bluish green phosphor preferably contains much Sr as M.sup.2,
and it is most desirable that 50 mol % or more of M.sup.2 elements
is Sr.
[0044] M.sup.3 in the general formula (I) is a trivalent metal
element and is preferably at least one metal element selected from
the group consisting of Al, Sc, Ga, Y, In, La, Gd, Yb and Lu for
the same reason as for M.sup.2, more preferably Al, Sc, Y, Yb or
Lu. It is particularly desirable that at least Sc is contained as
M.sup.3 element, and for example, M.sup.3 element is preferably Sc
singly, or in combination with Y, Al or Lu, more preferably Sc
singly, or in combination with Y. Further, it is particularly
desirable that 50 mol % or more, preferably 60 mol % or more, more
preferably 70 mol % or more of M.sup.3 elements is Sc. When Sc is
contained as M.sup.3 element, the emission intensity is further
enhanced to advantage.
[0045] The host crystal of the phosphor of the present invention is
normally a crystal represented by the composition formula
M.sup.2M.sup.3.sub.2O.sub.4 composed of M.sup.2 as divalent metal
element, M.sup.3 as trivalent metal element and oxygen and the
chemical composition ratio of b, c and d in the general formula (I)
are thus normally 1, 2 and 4, respectively, but in the present, it
may be not likely that b, c and d in the general formula (I) can be
1, 2 and 4, respectively, depending on which Ce, which is an
activator element, substitutes on metal element M.sup.2 or M.sup.3
in the position of crystal lattice or in the interstitial.
[0046] Accordingly, in the present invention, b is a number within
a range of 0.8.ltoreq.b.ltoreq.1.2, c is a number of within a range
of 1.6.ltoreq.c.ltoreq.2.4, and d is a number of within a range of
3.2.ltoreq.d.ltoreq.4.8. In particular, b and c are preferably a
number within a range of 0.9.ltoreq.b.ltoreq.1.1 and a range of
1.8.ltoreq.c.ltoreq.2.2, respectively, and d is a number within a
range of 3.6.ltoreq.d.ltoreq.4.4. Further, a, b, c and d are
numbers determined respectively, such that the charge balance of
the phosphor of the present invention becomes neutral.
[0047] Further, M.sup.2 and M.sup.3 represent a divalent metal
element and a trivalent metal element, respectively, but M.sup.2
and/or M.sup.3 can be extremely partly a metal element having a
valence of 1, 4 or 5 to adjust the charge balance and may contain a
slight amount of anion such as halogen element (F, Cl, Br, I),
nitrogen, sulfur and selenium.
[0048] The host crystal of the phosphor of the present invention is
a crystal represented by the composition formula
M.sup.2M.sup.3.sub.2O.sub.4 comprised of M.sup.2 as divalent metal
element, M.sup.3 as trivalent metal element and oxygen as
previously mentioned. In general, a crystal of the composition
ratio represented by this formula has any one of space groups:
[0049] Pnma, Fd3(-).sub.m, P2.sub.1/n, P2.sup.1, P6.sub.3,
P2.sub.1/c
depending on the difference of constituent metal elements. By
employing a structure having the space group Pnma among these space
groups, i.e., CaFe.sub.2O.sub.4 structure, a phosphor showing a
high brightness green emission can be obtained to advantage.
[0050] Further, the phosphor of the present invention is a phosphor
having a maximum emission peak in a wavelength range of from 485 nm
to 555 nm in the emission spectrum at room temperature. The room
temperature in the present invention is 25.degree. C. In the case
where there is a maximum emission peak wavelength in a wavelength
range shorter than 485 nm, when this phosphor is excited by a blue
LED having a wavelength of from 420 nm to 485 nm, the emission
wavelength of the phosphor overlaps that of the blue LED, making it
difficult to obtain good color rendering. Further, when the maximum
emission peak exceeds 555 nm, emission components ranging from
bluish green to green are insufficient, making it difficult to
obtain good color rendering. Accordingly, it is preferred that
there is a maximum emission peak in a wavelength range of from 485
nm to 545 nm, particularly preferably from 500 nm to 535 nm.
[0051] Further, even when some of oxygen atoms in the host crystal
are substituted by sulfur to an extent such that the properties of
the present invention are not impaired, a phosphor adapted for the
object of the present invention can be obtained, but the
substitution by a large amount of sulfur causes the deterioration
of the phosphor to disadvantage.
[0052] The aforementioned phosphor of the present invention can be
synthesized by an ordinary solid state reaction method. For
example, the phosphor of the present invention can be produced by
preparing a ground mixture by
[0053] a dry method which comprises grinding raw compounds such as
activator element M.sup.1 source compound, divalent metal element
M.sup.2 source compound and trivalent metal element M.sup.3 source
compound in the aforementioned general formula (I) using a dry
grinder such as hammer mill, roll mill, ball mill and jet mill,
mixing these materials using a mixer such as a ribbon blender,
V-shape blender or Henshell mixer, or mixing these raw compounds,
and then grinding the mixture using a dry grinder; or
[0054] a wet method which comprises adding these raw compounds to a
medium such as water, grinding or mixing these raw compounds using
a wet grinder such as medium-agitated grinder or grinding these raw
compounds using a dry grinder, adding the ground raw compounds to a
medium such as water to prepare a slurry, drying the slurry using a
spray drier to prepare a ground mixture,
and then subjecting the ground mixture thus obtained to heat
treatment so that it is calcined.
[0055] In particular, referring to activator element source
compounds, it is necessary that a small amount of these compounds
be entirely uniformly mixed and dispersed, and it is thus preferred
that a liquid medium be used, and preferred among the
aforementioned grinding/mixing methods is wet method because other
element source compounds can be also entirely uniformly mixed.
[0056] Further, during the preparation of the aforementioned ground
mixture, additives for accelerating the crystal growth of the
particulate phosphor during heat treatment (normally referred to as
"flux") can be added. As the flux there can be used ammonium halide
such as NH.sub.4C.sub.1 and NH.sub.4F.HF, alkaline carbonate such
as NaCO.sub.3 and LiCO.sub.3, alkali halide such as LiCl, NaCl and
KCl, halide of alkaline earth metal such as CaCl.sub.2, CaF.sub.2
and BaF.sub.2, borate compound such as B.sub.2O.sub.3,
H.sub.3BO.sub.3 and NaB.sub.4O.sub.7, phosphate such as
Li.sub.3PO.sub.4 and NH.sub.4H.sub.2PO.sub.4 or the like.
Particularly preferred among these fluxes are CaF.sub.2 and
H.sub.3BO.sub.3.
[0057] The heat treatment is carried out by heating in a heat
resistant vessel such as crucible and tray made of alumina, quartz,
silicon carbide and platinum normally at a temperature of from
1,200.degree. C. to 1,800.degree. C. in the air or in gases such as
oxygen, carbon monoxide, carbon dioxide, nitrogen, hydrogen and
argon, singly or in admixture, for 10 minutes to 24 hours. As the
heat resistant vessel there is preferably used a vessel made of
alumina having a high purity or platinum, more preferably platinum,
because such vessels have a low reactivity with the mixture of raw
materials, and a phosphor having a high purity and a high
luminescence can be obtained. Further, a vessel made of metal such
as molybdenum and tungsten or a vessel made of boron nitride or the
like can be used. The calcining temperature is normally from
1,200.degree. C. to 1,800.degree. C. When the calcining temperature
is lower than 1,200.degree. C., the solid state reaction of raw
materials in the mixture proceeds insufficiently, making it
unlikely that the target phosphor can be synthesized. On the other
hand, when the calcining temperature is higher than 1,800.degree.
C., an expensive calcining furnace is needed and it is likely that
unnecessary calcination energy can be consumed. Therefore, the
calcining temperature is preferably from 1,400.degree. C. to
1,700.degree. C., more preferably from 1,500.degree. C. to
1,650.degree. C. As the calcining atmosphere there is normally
employed air or gases such as oxygen, carbon monoxide, carbon
dioxide, nitrogen, hydrogen and argon, singly or in admixture, but
a reducing atmosphere is desirable to activate Ce.sup.3+ ion in the
host crystal stably and enhance luminescence, and in particular, a
nitrogen atmosphere containing hydrogen is more desirable because
body color of the host crystal assumes a clear green color to
provide a remarkably enhanced luminescence. Further, when the
material which has once been calcined in an oxidizing atmosphere or
neutral atmosphere is again subjected to heat treatment in a
reducing atmosphere, it is also effective for the stabilization of
trivalent Ce, which is an activator element, in the host crystal as
luminescence center ion. Further, the heating in a reducing
atmosphere by a plurality of times, too, is effective for the
enhancement of properties. The material thus heat-treated is
subjected to washing, drying, classification, etc. as necessary.
When the phosphor is washed with an acid, impurity phases other
than host crystal such as flux attached to the surface of the
phosphor can be removed to improve the luminescence to advantage.
Further, as surface treatment, a ultrafine particulate material
such as silica, alumina and calcium phosphate can be attached to
the surface of the phosphor to improve the powder properties
(agglomeration, dispersibility and precipitation behavior in
solution, etc.). Referring to treatment after heat treatment, any
techniques which are publicly known concerning known phosphors,
e.g., those for use in cathode ray tube, plasma display panel,
fluorescent lamp, fluorescent display tube, x-ray-intensifying
screen, etc., are available, and it can be properly selected
depending on the purpose, usage, etc.
[0058] As M.sup.1 source compound, M.sup.2 source compound and
M.sup.3 source compound there may be exemplified oxides,
hydroxides, carbonates, nitrates, sulfates, oxalates, carboxylates,
halides, etc. of M.sup.1, M.sup.2 and M.sup.3, and they are
selected from these examples taking into account their reactivity
to composite oxide, whether or not NOx, SOx, etc. can be produced
during calcination, etc.
[0059] Specific examples of Ce source compounds concerning Ce
contained in the activator element M.sup.1 include Ce.sub.2O.sub.3,
CeO.sub.2, Ce(OH).sub.3, Ce(OH).sub.4, Ce.sub.2 (CO.sub.3).sub.3,
Ce(NO.sub.3).sub.3, Ce.sub.2(SO.sub.4).sub.3, Ce(SO.sub.4).sub.2,
Ce.sub.2(OCO).sub.6, Ce(OCOCH.sub.3).sub.3, CeCl.sub.3, CeCl.sub.4,
etc.
[0060] Specifically exemplifying M.sup.2 source compounds
concerning the aforementioned Mg, Ca and Sr, which are desirable as
divalent metal element M.sup.2, examples of Mg source compounds
include MgO, Mg(OH).sub.2, MgCO.sub.3,
Mg(OH).sub.2.3MgCO.sub.3.3H.sub.2O, Mg(NO.sub.3).sub.2.6H.sub.2O,
MgSO.sub.4, Mg(OCO).sub.2.2H.sub.2O,
Mg(OCOCH.sub.3).sub.2.4H.sub.2O, MgCl.sub.2, etc., examples of Ca
source compounds include CaO, Ca(OH).sub.2, CaCO.sub.3,
Ca(NO.sub.3).sub.2.4H.sub.2O, CaSO.sub.4.2H.sub.2O,
Ca(OCO).sub.2.H.sub.2O, Ca(OCOCH.sub.3).sub.2.H.sub.2O, CaCl.sub.2,
etc., and examples of Sr source compounds include SrO, Sr
(OH).sub.2, SrCO.sub.3, Sr(NO.sub.3).sub.2, Sr(OCO).sub.2,
Sr(OCOCH.sub.3).sub.2, SrCl.sub.2, etc.
[0061] Further, specifically exemplifying M.sup.3 source compounds
concerning the aforementioned Sc, Lu, Y and Al, which are desirable
as trivalent metal element M.sup.3, examples of Sc source compounds
include Sc.sub.2O.sub.3, Sc(OH).sub.3, Sc.sub.2(CO.sub.3).sub.3,
Sc(NO.sub.3).sub.3, Sc.sub.2(SO.sub.4).sub.3, Sc.sub.2(OCO).sub.6,
Sc(OCOCH.sub.3).sub.3, ScCl.sub.3, etc., examples of Lu source
compounds include Lu.sub.2O.sub.3, Lu.sub.2(SO.sub.4).sub.3,
LuCl.sub.3, etc., examples of Y source compounds include
Y.sub.2O.sub.3, Y(OH).sub.3, Y.sub.2(CO.sub.3).sub.3, Y
(NO.sub.3).sub.3, Y.sub.2(SO.sub.4).sub.3, Y.sub.2(OCO).sub.6,
Y(OCOCH.sub.3).sub.3, YCl.sub.3, etc., and examples of Al source
compounds include Al.sub.2O.sub.3, Al(OH).sub.3, AlOOH,
Al(NO.sub.3).sub.3.9H.sub.2O, Al.sub.2(SO.sub.4).sub.3, AlCl.sub.3,
etc.
[0062] The particle diameter of the phosphor of the present
invention produced by the aforementioned production method is
normally from not smaller than 0.1 .mu.m to not greater than 50
.mu.m, but the lower limit of the particle diameter of the phosphor
of the present invention is preferably 1 .mu.m or more, more
preferably 2 .mu.m or more and the upper limit of the particle
diameter of the phosphor of the present invention is preferably 30
.mu.m or less, more preferably 15 .mu.m or less.
[0063] By subjecting the phosphor to necessary classification or
crushing such that the particle diameter falls within this range, a
more desirable phosphor can be obtained. As the classification
there may be used any means such as wet classification, e.g.,
levigation and air flow classification, e.g., cyclone and inertia
classifier. Further, concerning the crushing, too, the process is
not limited and ball mill treatment or the like may be used.
[0064] The aforementioned particle diameter of phosphor means the
particle diameter measured by a laser diffraction particle diameter
distribution measuring device such as Model LA-300 produced by
HORIBA, Ltd.
[0065] The phosphor of the present invention can be synthesized
also by a spray pyrolysis method. For example, firstly, compounds
containing the constituent elements of the phosphor to be produced
are dissolved in a solvent such as water to prepare a raw material
solution. The solvent for the raw material solution is not limited
so far as it is a liquid the viscosity of which is low enough to
form a droplet at the subsequent procedure but is preferably water
taking into account cost and safety of exhaust gas.
[0066] As the compounds containing the constituent elements of said
phosphor there may be used any raw materials which can be dissolved
in the solvent used and reacted to decompose to oxides when heated
to high temperature.
[0067] In order to obtain good luminescence property, these raw
material compounds and raw material solutions are preferably those
having little impurity elements such as iron and nickel which act
as killer center.
[0068] The raw material solution may comprise various additives
incorporated therein besides the constituent elements of the
phosphor. For example, alkaline metal salts, halides and borates of
various metals, etc. can be expected to exert a fluxing effect of
accelerating crystal growth and a polyacid such as citric acid, a
polyol such as ethylene glycol, etc. have an effect on the uniform
mixing of the raw material metals and control over the particulate
form of the obtained phosphor, and these additives can be thus
added.
[0069] The content ratio of the raw material metals in the raw
material solution is preferably the composition ratio of the target
phosphor.
[0070] There is a tendency that when the total concentration of the
aforementioned constituent elements in the raw material solution is
raised, the phosphor thus obtained has a raised secondary particle
diameter, and on the contrary, when the total concentration of the
aforementioned constituent elements in the raw material solution is
reduced, the phosphor thus obtained has a reduced secondary
particle diameter. Further, when the concentration of solute is too
small, the amount of the solvent to be evaporated rises, requiring
unnecessary energy to disadvantage. On the other hand, when the
concentration of solute is too great, it is made difficult to form
a droplet. Accordingly, in order to synthesize a good phosphor, the
total number of moles of the constituent elements of the phosphor
contained in the raw material solution is preferably from not
smaller than 0.01 mol/l to not greater than 10 mol/l.
[0071] Subsequently, droplets are formed from the raw material
solution thus obtained. The formation of droplets can be carried
out by various spray methods. For example, there may be employed a
method which comprises spraying a liquid while being sucked up by
compressed air to form droplets having a particle diameter of from
1 .mu.m to 50 .mu.m, a method which comprises utilizing an
ultrasonic wave having a frequency of about 2 MHz from a
piezoelectric crystal to form droplets having a particle diameter
of from 4 .mu.m to 10 .mu.m, a method which comprises supplying a
liquid at a predetermined speed into an orifice having a hole
diameter of from 10 .mu.m to 20 .mu.m which is being oscillated by
an oscillator so that the liquid is discharged from the hole of
orifice in a predetermined amount at a time, depending on the
frequency to form droplets having a particle diameter of from 5
pinto 50 .mu.m, a method which comprises dropping a liquid at a
predetermined rate onto a rotating disc so that droplets having a
particle diameter of from 20 .mu.m to 100 .mu.m are formed from the
liquid by centrifugal force, a method which comprises applying a
high voltage to the surface of a liquid to form droplets having a
particle diameter of from 0.5 .mu.m to 10 .mu.m, etc. For the
production of a phosphor having a uniform particle diameter on the
order of submicron to micron which can be used for cathode ray
tube, fluorescent lamp, FED, etc., a spray method involving the
utilization of ultrasonic wave that can form droplets having a
particle diameter as relatively uniform as 4 .mu.m to 10 .mu.m is
desirable.
[0072] The droplets thus formed can be converted into a particulate
phosphor by heating such as introducing into a pyrolysis reaction
furnace by a carrier gas. In this pyrolysis reaction furnace,
factors affecting the heating speed such as kind of solution, kind
of carrier gas, flow rate of carrier gas and temperature in the
pyrolysis reaction furnace cause the production of particles having
various forms such as hollow particle, porous particle, solid
particle and crushed particle and various surface conditions.
[0073] As the carrier gas there can be used hydrogen, nitrogen,
argon, oxygen, air or the like, or a mixture thereof, but in order
to obtain good luminescence properties, nitrogen, argon, a mixture
of nitrogen and hydrogen, or a mixture of argon and hydrogen is
desirable, and nitrogen or a mixture of nitrogen and hydrogen is
more desirable from the standpoint of cost. The mixing ratio of
hydrogen in the mixture of hydrogen and nitrogen or argon is
preferably 10% or less, more preferably 5% or less, particularly
preferably not greater than 4%, which is the lower limit of
explosibility of hydrogen gas, from the standpoint of safety. On
the other hand, the mixing ratio of hydrogen is preferably high,
more preferably 1% or more, even more preferably 2% or more from
the standpoint of enhancement of reducing ability.
[0074] The heating temperature is normally predetermined such that
the lower limit is 1,200.degree. C. or more and the upper limit is
1,900.degree. C. When this pyrolysis reaction temperature is too
low, the crystallinity is low and the activator elements such as Ce
cannot be effectively dispersed in the crystal, giving a tendency
toward lower luminescence property. On the other hand, when the
pyrolysis reaction temperature is too high, it not only causes the
consumption of unnecessary energy but also the evaporation of
constituent components of phosphor and the sudden condensation of
constituent components of phosphor during cooling, making it easy
to deteriorate luminescence property. From this standpoint of view,
the lower limit and upper limit of heating temperature are
preferably 1,500.degree. C. or more and 1,700.degree. C. or less,
respectively.
[0075] The pyrolysis reaction is normally carried out for a
reaction time of from not shorter than 0.1 seconds to not longer
than 10 minutes, i.e., residence time in the pyrolysis reaction
furnace. Among these reaction time periods, the reaction time
period of from not shorter than 1 second to not longer than 1
minute is preferably used to carry out the reaction. When the
reaction time is too short, the phosphor thus obtained has a low
crystallinity and the activator elements such as Ce cannot be
activated in the crystal, giving a tendency toward lower
luminescence property. On the other hand, it goes without saying
that when the reaction time is too long, it merely causes the
consumption of unnecessary energy but the drop of productivity,
giving a tendency that an unexpected reaction such as decomposition
of phosphor occurs to cause easily the drop of brightness.
[0076] While the method for synthesis of the phosphor of the
present invention has been described with reference to solid state
reaction method and spray pyrolysis method, the synthesis method is
not limited thereto, and ordinary methods known as method for
synthesis of inorganic compound powder can be used. For example,
the phosphor of the present invention can be produced by preparing
a precursor material comprising raw materials uniformly mixed
therein by a sol-gel method, a complex polymerization method, a
uniform precipitation method or the like, and then subjecting the
precursor material to heat treatment. The heat treatment method in
this case can be carried out by a method which is almost the same
as the heat treatment method in the aforementioned solid state
reaction method, but a precursor having metals in raw materials
uniformly mixed therein can be used to synthesize a phosphor having
excellent properties at a lower temperature than in the case of
solid phase reaction method.
[0077] The light emitting device of the present invention has the
aforementioned phosphor as a wavelength conversion material and a
semiconductor light emitting device such as LED and LD. It is a
high color rendering light emitting device, which absorbs light in
the wavelength range of from ultraviolet to visible light emitted
by the semiconductor light emitting device to emit visible light in
a longer wavelength range and thus can be suitably used as a light
source for display such as color liquid crystal display comprising
back light unit and lighting system such as surface emitting. The
light emitting device may contain other phosphors besides the
phosphor of the present invention. Further, impurity compounds
produced with the production of the phosphor of the present
invention may be incorporated to an extent such that the properties
cannot be impaired.
[0078] The light emitting device of the present invention will be
hereinafter described in connection with the drawings. FIG. 3 is a
diagrammatic sectional view illustrating an example of a light
emitting device having a phosphor of the present invention as a
wavelength conversion material and a semiconductor light emitting
device, FIG. 4 is a diagrammatic sectional view illustrating an
example of a surface emitting lighting system having the light
emitting device shown in FIG. 3 incorporated therein, and in FIGS.
3 and 4, the numeral 1 indicates a light emitting device, the
numeral 2 indicates a mount lead, the numeral 3 indicates an inner
lead, the numeral 4 indicates a semiconductor light emitting
device, the numeral 5 indicates a phosphor-containing resin
portion, the numeral 6 indicates an electrically-conductive wire,
the numeral 7 indicates a molding member, the numeral 8 indicates a
surface emitting lighting system, the numeral 9 indicates a
diffusion plate, and the numeral 10 indicates a retaining case.
[0079] The light emitting device 1 of the present invention, as
shown in FIG. 3, is in an ordinary shell-type form and has a
semiconductor light emitting device 4 made of a GaN-based blue
light-emitting diode or the like provided in the upper cap of the
mount lead 2, and the semiconductor light emitting device 4 is
covered and fixed at the upper part thereof by a
phosphor-containing resin portion 5 formed by mixing a wavelength
conversion material containing at least a phosphor of the present
invention with a binder such as epoxy resin and acrylic resin so
that it is dispersed in the binder, and then pouring the dispersion
into a cap. On the other hand, the semiconductor light emitting
device 4 and the mount lead 2, and the semiconductor light emitting
device 4 and the inner lead 3 are electrically connected to each
other with the electrically-conductive wire 6, and they are
entirely covered and protected by the molding member 7 made of
epoxy resin or the like.
[0080] Further, the surface emitting lighting system 8 having this
light emitting device 1 incorporated therein, as shown in FIG. 4,
has a large number of light emitting devices 1 provided on the
bottom surface of a rectangular retaining case 10, the inner
surface of which is opaque such as white smooth, a power supply and
a circuit (not shown) for driving the light emitting device 1
provided there outside and a diffusion plate 9 such as semiopaque
acryl sheet fixed at the position corresponding to the cover
portion of the retaining case 10 for uniformalizing light
emission.
[0081] When the surface emitting lighting system 8 is driven and a
voltage is applied to the semiconductor light emitting device 4 of
the light emitting device 1, blue light, etc. are emitted. These
emissions are partly absorbed by the phosphor of the present
invention which is a wavelength conversion material in the
phosphor-containing resin portion 5 to emit light having a longer
wavelength. On the other hand, the longer wavelength light is mixed
with blue light, which have not been absorbed by the phosphor to
obtain emission having high color rendering. This light passes
through the diffusion plate 9 and is then emitted upward as viewed
on FIG. 4 to obtain lighting having in-plain uniform brightness in
the diffusion plate 9 of the retaining case 10.
[0082] Further, the phosphor obtained in the present invention can
be used not only for the aforementioned light emitting device
utilizing emission of semiconductor light emitting device but also
as green wavelength conversion material for use in full-color
inorganic electroluminescence device as proposed in "Proceedings of
The 10th International Display Workshops", pp. 1109-1112 (2003). In
other words, for example, the full-color electroluminescence light
emitting device of the present invention has a blue light-emitting
electroluminescence light emitting device, the aforementioned
phosphor as a green wavelength conversion material and an arbitrary
red wavelength conversion material and has minute blue, green and
red light-emitting regions formed therein the emission intensity of
which are electrically controlled to make full-color display.
Further, the full-color electroluminescence light emitting device
having the aforementioned constitution can be used as a surface
emitting light emitting device showing emission of white color or
specific color tone so that it can be used as a backlight unit for
color liquid crystal display to constitute a display or surface
emitting lighting system. The electroluminescence light emitting
device may comprise other phosphors incorporated therein besides
the phosphor of the present invention.
[0083] Further, the phosphor obtained in the present invention can
emit light when irradiated with not only ultraviolet rays or
visible light but also cathode ray, X-ray or the like or under
electric field and thus can be used as a phosphor utilizing these
excitating means.
[0084] Moreover, the phosphor of the present invention can be used
also for a display having a light source (excitation source) and a
phosphor. Examples of the display include vacuum fluorescent
display (VFD), field emission display (FED), plasma display panel
(PDP), cathode ray tube (CRT), etc. Further, the phosphor of the
present invention can be used also for backlight for display.
EXAMPLE
[0085] The present invention will be further described hereinafter
in the following examples, but the present invention is not limited
thereto so far as the essence thereof is not exceeded. The
measurement of emission spectrum, excitation spectrum and emission
intensity in the following examples and comparative examples were
effected at room temperature (25.degree. C.).
Example 1
[0086] Raw material powders were measured out such that CeO.sub.2
as M.sup.1 source compound, CaCO.sub.3 as M.sup.2 source compound
and Sc.sub.2O.sub.3 as M.sup.3 source compound were incorporated in
an amount of 0.01 mols, 0.99 mols and 1 mol, respectively, based on
1 mol of phosphor to give a phosphor chemical composition
Ce.sub.0.01Ca.sub.0.99Sc.sub.2O.sub.4. These raw material powders
were wet-ground and mixed with ethanol as a dispersion medium in a
powder mixer, and the dispersion medium was then evaporated away to
obtain a dried mixture of ground raw material powders. The dried
ground mixture thus obtained was heated at 1,600.degree. C. at
maximum in a nitrogen atmosphere containing 4% of hydrogen in a
platinum crucible for 3 hours so that it was calcined, and then
subsequently subjected to washing with water, drying and
classification to produce a phosphor powder.
[0087] The median diameter of the thus obtained phosphor measured
by a Type LA-300 laser diffraction particle size distribution meter
(produced by HORIBA, Ltd.) was 14 .mu.m. The observation under
scanning electron microscope showed that this phosphor was an
agglomeration of primary particles having a diameter of about 3
.mu.m. Further, the powder X-ray diffraction pattern of this
phosphor was as shown in FIG. 1 and coincided with the diffraction
pattern set forth in JCPDS card No. 72-1360, demonstrating that
this phosphor is a compound having a crystal structure having the
same space group Pnma as CaSc.sub.2O.sub.4. Moreover, when this
phosphor was measured for emission spectrum and excitation spectrum
using a Type F-4500 fluorescence spectrophotometer (produced by
HITACHI, LTD.), the spectrum shown in FIG. 2 was obtained,
demonstrating that this phosphor comprises trivalent Ce
incorporated in the aforementioned host crystal. Further, it was
confirmed that this phosphor shows an emission peak wavelength of
516 nm and hence little variation of excitation intensity in a blue
wavelength range of from 450 nm to 465 nm and thus is efficiently
excited to emit green light when irradiated with light from a blue
LED which emits light in this wavelength range. Supposing that the
emission intensity of the phosphor of Comparative Example 1 is 100,
the fluorescence intensity of emission of this phosphor at the
emission peak wavelength developed when this phosphor is irradiated
with excitation light having a wavelength of 455 nm was 143,
demonstrating that this phosphor shows a remarkably high emission
intensity as compared with the conventional yellow phosphors.
[0088] When this phosphor was irradiated with blue light from a
GaN-based blue light-emitting diode (peak wavelength: 460 nm) to
adjust its irradiance, this phosphor absorbed the blue light to
emit green light which was then mixed with the blue light from the
diode which had not been absorbed by the phosphor to show emission
of bluish green light.
[0089] Further, this green phosphor and an Eu-activated CaS red
phosphor were mixed with an epoxy resin, spread over an InGaN-based
blue light-emitting diode (peak wavelength: 460 nm), heat-cured,
and then sealed in a transparent epoxy resin to prepare a
shell-type white LED. When this LED was electrically energized, it
showed a high luminous intensity and an average color rendering
index of 90 to great advantage. The Eu-activated CaS red phosphor
was obtained by mixing CaS and EuF.sub.3 at a molar ratio of
99.6:0.4, heating the mixture at 1,000.degree. C. in an alumina
crucible in a nitrogen atmosphere containing 4% of hydrogen for two
hours, and then subjecting the material to grinding and
classification.
Comparative Example 1
[0090] 1.05 mols of Y.sub.2O.sub.3, 0.39 mols of Gd.sub.2O.sub.3,
2.5 mols of Al.sub.2O.sub.3, 0.12 mols of CeO.sub.2, 0.25 mols of
BaF.sub.2 as a flux were ground and mixed with purified water in an
alumina vessel and a wet ball mill with beads, dried, and then
passed through a nylon mesh. The ground mixture thus obtained was
then heated to 1,450.degree. C. in the air in an alumina crucible
for two hours so that it was calcined. Subsequently, the material
was washed with water, dried, and then classified to obtain a
(Y.sub.0.7Gd.sub.0.26Ce.sub.0.04).sub.3Al.sub.5O.sub.12 phosphor.
The emission intensity of the phosphors of Examples 1 to 14 were
compared with that of this phosphor at an excitation wavelength of
455 .mu.m as 100. When this phosphor was irradiated with emission
of the aforementioned blue light-emitting diode, the emission of
this phosphor and the blue light from the diode which had not been
absorbed by this phosphor were mixed to give light that looked
white.
Examples 2 to 6
[0091] Phosphors were produced in the same manner as in Example 1
except that the material of the crucible and the calcining
temperature during the production of the phosphor were changed as
set forth in Table 1.
[0092] The phosphors thus obtained were each identified comprising
CaSc.sub.2O.sub.4 as a host crystal and having trivalent Ce as an
activator element in said host crystal by the analysis of powder
X-ray diffraction, emission spectrum, and excitation spectrum. The
emission peak wavelength and the emission intensity of the
phosphors thus obtained are also set forth in Table 1. For the
measurement of the emission spectrum of the phosphors of Example 2
and after, a high speed phosphor evaluation device produced by
JASCO Corporation was used. This device comprises a Xe lamp as a
light source and a Type C7041 multi-channel detector produced by
Hamamatsu Photonics K.K. as a light-receiving element.
[0093] The phosphors produced using a platinum crucible showed a
high emission intensity, and the phosphors obtained by calcining at
1,600.degree. C. within this temperature range showed the highest
emission intensity.
Examples 7 to 11
[0094] Phosphors were produced in the same manner as in Example 1
except that the formulation of mixing of raw materials Ce and Ca of
phosphor were changed as set forth in Table 2. The phosphors thus
obtained were each identified comprising CaSc.sub.2O.sub.4 as a
host crystal and having trivalent Ce as an activator element in
said host crystal by the analysis of powder X-ray diffraction,
emission spectrum, and excitation spectrum. The emission peak
wavelength and the emission intensity of the phosphors thus
obtained are also set forth in Table 2. The phosphors obtained by
adjusting the Ce mixing molar ratio to 0.01 showed the highest
emission intensity. Further, as the concentration of Ce increased,
the emission peak wavelength shifted toward a longer wavelength and
a higher color purity green emission was shown.
Examples 12 to 14
[0095] Phosphors were produced in the same manner as in Example 1
except that the formulation of raw material mixing was changed as
set forth in Table 3 such that some of Ca atoms in the phosphor
were replaced by Mg. However, MgCO.sub.3 was used as a Mg element
source in addition to the raw materials described in Example 1.
When identified by powder X-ray diffraction, the phosphors thus
obtained had the same space group as in Example 1 but showed
reduced lattice constants and further had a small amount of MgO
incorporated therein. Further, when measured for emission spectrum,
the phosphors showed an emission peak wavelength shifted toward a
longer wavelength. These facts showed that some of Mg atoms in the
raw material had been solid-dissolved in the host crystal. The
emission peak wavelength and the emission intensity of the
phosphors thus obtained are set forth in Table 3. The replacement
of Ca by Mg caused the drop of emission intensity, but the emission
peak wavelength shifted toward a longer wavelength to cause
desirable emission of green light.
Example 15
[0096] An aqueous solution of cerium nitrate, an aqueous solution
of calcium nitrate and an aqueous solution of scandium nitrate were
mixed such that the metal element ratio (molar ratio) of the raw
material solution were Ce:Ca:Sc=0.01:0.99:2, and then thoroughly
stirred. This mixed aqueous solution was dried in a platinum
vessel, and then heated to 1,400.degree. C. at highest in a
nitrogen atmosphere containing 4% of hydrogen for 3 hours so that
it was calcined to produce a phosphor.
[0097] The phosphor thus obtained was identified to be a compound
having a crystal structure having the same space group Pnma as
CaSc.sub.2O.sub.4 by the analysis using powder X-ray diffraction.
Further, when measured for emission spectrum and excitation
spectrum using a fluorescence spectrophotometer, this phosphor was
identified having trivalent Ce incorporated in the aforementioned
host crystal as an activator element. Further, this phosphor showed
an emission peak wavelength of 513 nm and little variation of
excitation intensity in a blue wavelength range of from 450 nm to
465 nm and thus was confirmed to be efficiently excited by light
from a blue LED which emits in this wavelength range to emit green
light. The intensity of fluorescence developed at the emission peak
wavelength when this phosphor was irradiated with an excitation
light having a wavelength of 455 nm was defined to be 100.
Example 16
[0098] A phosphor as produced in the same manner as in Example 15
except that an aqueous solution of manganese nitrate, an aqueous
solution of cerium nitrate, an aqueous solution of calcium nitrate
and an aqueous solution of scandium nitrate were used in such an
arrangement that the metal element ratio of the raw material
solution was molar ratio values set forth in Table 4.
[0099] The emission peak wavelength of the phosphor thus obtained
when irradiated with an excitation light having a wavelength of 455
nm and the emission intensity at the wavelength are set forth in
Table 4. However, this fluorescence intensity is represented
relative to the emission intensity of the phosphor of Example 15
thus obtained at the emission peak wavelength when irradiated with
an excitation light having a wavelength of 455 nm as 100.
[0100] As set forth in Table 4, the coactivation by Mn caused the
rise of the emission intensity of the phosphor.
Examples 17 to 30
[0101] A phosphor as produced in the same manner as in Example 15
except that an aqueous solution of nitrate of rare earth element as
coactivator, an aqueous solution of cerium nitrate, an aqueous
solution of calcium nitrate and an aqueous solution of scandium
nitrate were used in such an arrangement that the metal element
ratio of the raw material solution was molar ratio values set forth
in Table 4.
[0102] The emission peak wavelength of the phosphor thus obtained
when irradiated with an excitation light having a wavelength of 455
nm and the emission intensity at the wavelength are set forth in
Table 4. However, this fluorescence intensity is represented
relative to the emission intensity of the phosphor of Example 15
thus obtained at the emission peak wavelength when irradiated with
an excitation light having a wavelength of 455 nm as 100.
[0103] As set forth in Table 4, the coactivation by Pr, Tb, Dy or
Tm caused the rise of the emission intensity of the phosphor. In
particular, in the case where Pr was incorporated, emission derived
from Pr appeared with emission from Ce. Further, even when Nd, Sm,
Ho, Er and Yb were incorporated in a slight amount, no remarkable
drop of emission intensity was recognized.
Examples 31 to 44
[0104] A phosphor was produced in the same manner as in Example 15
except that nitrate of Mg, nitrate of Sr and nitrate of Ba were
incorporated in addition to the nitrates used in Example 15 such
that the metal element ratio in the raw material solution was as
set forth in Table 5 to prepare an aqueous solution of a mixture of
nitrates.
[0105] The emission peak wavelength of the phosphor thus obtained
when irradiated with an excitation light having a wavelength of 455
nm and the emission intensity at the wavelength are set forth in
Table 5. However, this fluorescence intensity is represented
relative to the emission intensity of the phosphor of Example 15
thus obtained at the emission peak wavelength when irradiated with
an excitation light having a wavelength of 455 nm as 100.
[0106] As set forth in Table 5, when the content of Ca was
decreased and the content of Mg or Sr were increased, the phosphors
having a small content of Mg or Sr showed an increase of emission
intensity, and these phosphors showed a gradual drop of emission
intensity with the rise of Mg content or Sr content. Further, when
the content of Sr was increased, the emission peak wavelength
shifted toward a shorter wavelength to increase the emission of
bluish green light. On the other hand, when the content of Ba was
increased, the emission intensity was monotonously decreased, but
even when the molar ratio of Ba was increased to 0.4, the emission
intensity was kept at about 30 or more.
Examples 45 to 55
[0107] A phosphor was produced in the same manner as in Example 15
except that nitrate of Al, nitrate of Y and nitrate of Lu were
incorporated in addition to the nitrates used in Example 15 such
that the metal element ratio in the raw material solution was as
set forth in Table 6 to prepare an aqueous solution of a mixture of
nitrates.
[0108] The emission peak wavelength of the phosphor thus obtained
when irradiated with an excitation light having a wavelength of 455
nm and the emission intensity at the wavelength are set forth in
Table 6. However, this fluorescence intensity is represented
relative to the emission intensity of the phosphor of Example 15
thus obtained at the emission peak wavelength when irradiated with
an excitation light having a wavelength of 455 nm as 100.
[0109] As set forth in Table 6, when the content of Sc was
decreased and the content of Al, Y or Lu were increased, the
phosphors having a small content of Al, Y or Lu showed an increase
of emission intensity, and these phosphors showed a drop of
emission intensity with the rise of Al content or Y content.
[0110] A tendency was shown that the emission peak wavelength
shifts toward a shorter wavelength with the rise of Al content. On
the other hand, the emission peak wavelength shifted toward a
longer wavelength with the rise of Y content or Lu content.
Examples 56 to 63
[0111] A phosphor was produced in the same manner as in Example 15
except that nitrate of Mg, nitrate of Sr, nitrate of Ba and nitrate
of Al were incorporated in addition to the nitrates used in Example
15 such that the metal element ratio in the raw material solution
was as set forth in Table 7 to prepare an aqueous solution of a
mixture of nitrates.
[0112] The emission peak wavelength of the phosphor thus obtained
when irradiated with an excitation light having a wavelength of 455
nm and the emission intensity at the wavelength are set forth in
Table 7. However, this fluorescence intensity is represented
relative to the emission intensity of the phosphor of Example 15
thus obtained at the emission peak wavelength when irradiated with
an excitation light having a wavelength of 455 nm as 100.
Examples 64 to 69
[0113] A phosphor was produced in the same manner as in Example 15
except that nitrate of Mg, nitrate of Sr, nitrate of Ba and nitrate
of Y were incorporated in addition to the nitrates used in Example
15 such that the metal element ratio in the raw material solution
was as set forth in Table 8 to prepare an aqueous solution of a
mixture of nitrates.
[0114] The emission peak wavelength of the phosphor thus obtained
when irradiated with an excitation light having a wavelength of 455
nm and the emission intensity at the wavelength are set forth in
Table 8. However, this fluorescence intensity is represented
relative to the emission intensity of the phosphor of Example 15
thus obtained at the emission peak wavelength when irradiated with
an excitation light having a wavelength of 455 nm as 100.
Examples 70 to 86
[0115] A phosphor was produced in the same manner as in Example 15
except that nitrate of Mg, nitrate of Sr, nitrate of Ba and nitrate
of Lu were incorporated in addition to the nitrates used in Example
15 such that the metal element ratio in the raw material solution
was as set forth in Table 9 to prepare an aqueous solution of a
mixture of nitrates.
[0116] The emission peak wavelength of the phosphor thus obtained
when irradiated with an excitation light having a wavelength of 455
nm and the emission intensity at the wavelength are set forth in
Table 9. However, this fluorescence intensity is represented
relative to the emission intensity of the phosphor of Example 15
thus obtained at the emission peak wavelength when irradiated with
an excitation light having a wavelength of 455 nm as 100.
Example 87
[0117] A precursor solution containing metal salts, respectively,
in the following concentrations was prepared.
TABLE-US-00001 Ca(NO.sub.3).sub.2 0.0495 mol/L Sc(NO.sub.3).sub.3
0.1 mol/L Ce(NO.sub.3).sub.3 0.0005 mol/L
[0118] This solution was put in an ultrasonic nebulizer equipped
with a 1.7 MHz oscillator to form minute droplets. The flow of a
nitrogen gas containing 4% of hydrogen caused these droplets to
pass the interior of the core tube of a longitudinal cylindrical
electric furnace. The electric furnace had a uniform temperature
region length of about 150 cm and the temperature of the electrical
furnace was set to 1,500.degree. C. The gas flow rate was set to 2
L/min. When passed through the electric furnace, the droplets were
dried to form a powder which was then recovered by an electric dust
collector. The powder was a CaSc.sub.2O.sub.4:Ce phosphor produced
by the reaction of the nitrate compounds contained in the precursor
solution. The phosphor thus obtained absorbed blue light to show
green light with good property. The luminescence properties are set
forth in Table 10. The emission intensity set forth in Table 10 is
a value relative to the emission intensity of the phosphor of
Comparative Example 1 as 100. When particle diameter of the
phosphor thus obtained was measured in the same manner as in
Example 1, the median particle diameter (D.sub.50) was found to be
1.0 .mu.m, demonstrating that the phosphor was a phosphor having a
sharp particle diameter distribution.
Example 88
[0119] A phosphor was synthesized by a spray pyrolysis method in
the same manner as in Example 87 except that the flowing gas was
nitrogen gas. The phosphor thus obtained was put in a crucible
wherein it was then heated (annealed) to 1,500.degree. C. in a
nitrogen atmosphere containing 4% of hydrogen. The phosphor thus
obtained absorbed blue light to show good emission of green light.
The luminescence properties are set forth in Table 10.
Examples 89 to 91
[0120] The procedure of Example 88 was followed except that the
annealing temperature was changed as set forth in Table 10 to
obtain a phosphor. The luminescence properties of this phosphor are
set forth in Table 10.
Examples 92, 93
[0121] Raw material compounds and a flux compound were fairly
compounded such that the formulation of Table 11 was attained, and
then subjected to heat treatment in the same manner as in Example 1
to obtain a phosphor. However, the calcining temperature was
1,550.degree. C. The molar ratio of flux was the number of mols of
the flux compound based on mol of phosphor CaSc.sub.2O.sub.4 to be
produced. The phosphor thus obtained was soaked around-the-clock in
a 1 normal hydrochloric acid to remove impurities such as excess
flux. Thereafter, an operation of solid-solution separation,
addition of water and agitation was repeated until the pH value of
the supernatant liquid reached 4 or more. The phosphor thus washed
was dried in a 120.degree. C. drier, and then sieved so that the
dried agglomerated material was loosened. The luminescence
properties of the phosphor thus obtained are set forth in Table 11.
The emission intensity was represented relative to that of the
phosphor of Comparative Example 1 as 100.
Comparative Example 2
[0122] 0.0297 mols of SrCO.sub.3, 0.03 mols of Y.sub.2O.sub.3 and
0.0003 mols of CeO.sub.2 were thoroughly wet-mixed with ethanol in
a mortar, and then dried. This mixture was put on a platinum foil
which was then heated to 1,450.degree. C. in a nitrogen atmosphere
containing 4% of hydrogen for two hours so that it was calcined to
obtain SrY.sub.2O.sub.4:Ce. It was confirmed by powder X-ray
diffraction that the material thus obtained has a crystal structure
reported as SrY.sub.2O.sub.4. The material thus obtained was an
orange color powder. The material thus obtained was irradiated with
excitation light having a wavelength of 254 nm, 365 nm and 460 nm
but showed no emission with light having any wavelength.
TABLE-US-00002 TABLE 1 Molar mixing ratio of Calcining Emission raw
material Crucible temperature Emission wavelength Example CeO.sub.2
CaCO.sub.3 Sc.sub.2O.sub.3 material .degree. C. intensity nm
Example 1 0.01 0.99 1 Platinum 1,600 143 516 Example 2 0.01 0.99 1
Alumina 1,600 134 516 Example 3 0.01 0.99 1 Platinum 1,500 133 516
Example 4 0.01 0.99 1 Alumina 1,500 130 516 Example 5 0.01 0.99 1
Platinum 1,400 114 514 Example 6 0.01 0.99 1 Alumina 1,400 111
514
TABLE-US-00003 TABLE 2 Molar mixing ratio Calcining Emission of raw
material Crucible temperature Emission wavelength Example CeO.sub.2
CaCO.sub.3 Sc.sub.2O.sub.3 material .degree. C. intensity nm
Example 7 0.0005 0.9995 1 Platinum 1,600 62 512 Example 8 0.001
0.999 1 Platinum 1,600 80 512 Example 9 0.003 0.997 1 Platinum
1,600 111 513 Example 1 0.01 0.99 1 Platinum 1,600 143 516 Example
10 0.03 0.97 1 Platinum 1,600 103 521 Example 11 0.05 0.95 1
Platinum 1,600 79 527
TABLE-US-00004 TABLE 3 Molar mixing ratio of raw Calcining Emission
material Crucible temperature Emission wavelength Example CeO.sub.2
CaCO.sub.3 MgCO.sub.3 Sc.sub.2O.sub.3 material .degree. C.
intensity nm Example 1 0.01 0.99 1 Platinum 1,600 143 516 Example
12 0.01 0.693 0.297 1 Platinum 1,600 98 520 Example 13 0.01 0.495
0.495 1 Platinum 1,600 92 523 Example 14 0.01 0.297 0.693 1
Platinum 1,600 69 524
TABLE-US-00005 TABLE 4 Coactivator Emis- Kind sion of wave- ele-
Molar Element ratio Emission length Example ment ratio Ce Ca Sc
intensity nm Example 15 0.01 0.99 2 100 513 Example 16 Mn 0.003
0.01 0.987 2 126 514 Example 15 0.01 0.99 2 100 513 Example 17 Pr
0.003 0.01 0.987 2 111 513 Example 15 0.01 0.99 2 100 513 Example
18 Nd 0.003 0.01 0.987 2 97 513 Example 15 0.01 0.99 2 100 513
Example 19 Sm 0.003 0.003 0.994 2 91 512 Example 15 0.01 0.99 2 100
513 Example 20 Tb 0.003 0.003 0.994 2 122 514 Example 21 Tb 0.01
0.003 0.987 2 133 514 Example 22 Tb 0.003 0.01 0.987 2 117 515
Example 23 Tb 0.01 0.01 0.98 2 106 514 Example 15 0.01 0.99 2 100
513 Example 24 Dy 0.003 0.01 0.987 2 121 514 Example 25 Dy 0.01
0.01 0.98 2 103 514 Example 15 0.01 0.99 2 100 513 Example 26 Ho
0.003 0.003 0.994 2 88 513 Example 15 0.01 0.99 2 100 513 Example
27 Er 0.003 0.01 0.987 2 88 514 Example 15 0.01 0.99 2 100 513
Example 28 Tm 0.003 0.01 0.987 2 125 513 Example 29 Tm 0.01 0.01
0.98 2 89 514 Example 15 0.01 0.99 2 100 513 Example 30 Yb 0.01
0.01 0.98 2 84 514
TABLE-US-00006 TABLE 5 Emis- M.sup.2 element sion other than Ca
wave- Kind of Molar Element ratio Emission length Example element
ratio Ce Ca Sc intensity nm Example 15 0.01 0.99 2 100 513 Example
31 Mg 0.10 0.01 0.89 2 125 514 Example 32 Mg 0.20 0.01 0.79 2 97
515 Example 33 Mg 0.40 0.01 0.59 2 58 514 Example 15 0.01 0.99 2
100 513 Example 34 Sr 0.10 0.01 0.89 2 156 509 Example 35 Sr 0.20
0.01 0.79 2 139 509 Example 36 Sr 0.30 0.01 0.69 2 123 507 Example
37 Sr 0.40 0.01 0.59 2 123 503 Example 38 Sr 0.60 0.01 0.39 2 127
499 Example 39 Sr 0.70 0.01 0.29 2 97 497 Example 40 Sr 0.90 0.01
0.09 2 99 491 Example 41 Sr 0.99 0.01 2 79 485 Example 15 0.01 0.99
2 100 513 Example 42 Ba 0.20 0.01 0.79 2 56 515 Example 43 Ba 0.30
0.01 0.69 2 42 513 Example 44 Ba 0.40 0.01 0.59 2 33 510
TABLE-US-00007 TABLE 6 Emis- M.sup.3 element sion other than Sc
wave- Kind of Molar Element ratio Emission length Example element
ratio Ce Ca Sc intensity nm Example 15 0.01 0.99 2.0 100 513
Example 45 Al 0.4 0.01 0.99 1.6 109 515 Example 46 Al 0.6 0.01 0.99
1.4 91 513 Example 47 Al 0.8 0.01 0.99 1.2 41 509 Example 15 0.01
0.99 2.0 100 513 Example 48 Y 0.2 0.01 0.99 1.8 109 515 Example 49
Y 0.8 0.01 0.99 1.2 69 546 Example 15 0.01 0.99 2.0 100 513 Example
50 Lu 0.6 0.01 0.99 1.4 102 512 Example 51 Lu 0.8 0.01 0.99 1.2 88
513 Example 52 Lu 1.0 0.01 0.99 1.0 60 518 Example 53 Lu 1.2 0.01
0.99 0.8 45 519 Example 54 Lu 1.4 0.01 0.99 0.6 41 522 Example 55
Lu 1.6 0.01 0.99 0.4 28 520
TABLE-US-00008 TABLE 7 M.sup.2 element M.sup.3 element other than
Ca other than Sc Kind Kind Emission of Molar of Molar Element ratio
Emission wavelength Example element ratio element ratio Ce Ca Sc
intensity nm Example 15 0.01 0.99 2 100 513 Example 56 Mg 0.3 Al
0.6 0.01 0.69 1.4 58 514 Example 15 0.01 0.99 2 100 513 Example 57
Sr 0.1 Al 0.2 0.01 0.89 1.8 77 512 Example 58 Sr 0.1 Al 0.6 0.01
0.89 1.4 52 512 Example 59 Sr 0.3 Al 0.2 0.01 0.69 1.8 79 511
Example 60 Sr 0.3 Al 0.6 0.01 0.69 1.4 71 513 Example 61 Sr 0.5 Al
0.6 0.01 0.49 1.4 55 507 Example 15 0.01 0.99 2 100 513 Example 62
Ba 0.1 Al 0.2 0.01 0.89 1.8 69 514 Example 63 Ba 0.1 Al 0.6 0.01
0.89 1.4 67 513
TABLE-US-00009 TABLE 8 M.sup.2 element M.sup.3 element other than
Ca other than Sc Kind Kind Emission of Molar of Molar Element ratio
Emission wavelength Example element ratio element ratio Ce Ca Sc
intensity nm Example 15 0.01 0.99 2 100 513 Example 64 Mg 0.3 Y 0.2
0.01 0.69 1.8 49 529 Example 15 0.01 0.99 2 100 513 Example 65 Sr
0.1 Y 0.2 0.01 0.89 1.8 77 513 Example 66 Sr 0.3 Y 0.2 0.01 0.69
1.8 79 502 Example 67 Sr 0.3 Y 0.6 0.01 0.69 1.4 56 517 Example 68
Sr 0.5 Y 0.2 0.01 0.49 1.8 70 497 Example 15 0.01 0.99 2 100 513
Example 69 Ba 0.1 Y 0.2 0.01 0.89 1.8 67 519
TABLE-US-00010 TABLE 9 M.sup.2 element M.sup.3 element other than
Ca other than Sc Kind Kind Emission of Molar of Molar Element ratio
Emission wavelength Example element ratio element ratio Ce Ca Sc
intensity nm Example 15 0.01 0.99 2 100 513 Example 70 Mg 0.1 Lu
0.2 0.01 0.89 1.8 83 519 Example 71 Mg 0.1 Lu 0.6 0.01 0.89 1.4 53
513 Example 72 Mg 0.1 Lu 1.0 0.01 0.89 1.0 68 516 Example 73 Mg 0.3
Lu 0.2 0.01 0.69 1.8 99 522 Example 74 Mg 0.3 Lu 0.6 0.01 0.69 1.4
72 520 Example 75 Mg 0.3 Lu 1.0 0.01 0.69 1.0 81 524 Example 76 Mg
0.5 Lu 0.2 0.01 0.49 1.8 60 523 Example 15 0.01 0.99 2 100 513
Example 77 Sr 0.1 Lu 0.6 0.01 0.89 1.4 55 507 Example 78 Sr 0.1 Lu
1.0 0.01 0.89 1.0 52 507 Example 79 Sr 0.3 Lu 0.2 0.01 0.69 1.8 85
502 Example 80 Sr 0.3 Lu 0.6 0.01 0.69 1.4 118 501 Example 81 Sr
0.3 Lu 1.0 0.01 0.69 1.0 101 495 Example 82 Sr 0.5 Lu 0.2 0.01 0.49
1.8 82 494 Example 83 Sr 0.5 Lu 0.6 0.01 0.49 1.4 114 489 Example
84 Sr 0.5 Lu 1.0 0.01 0.49 1.0 121 486 Example 15 0.01 0.99 2 100
513 Example 85 Ba 0.1 Lu 0.6 0.01 0.89 1.4 89 512 Example 86 Ba 0.1
Lu 1.0 0.01 0.89 1.0 72 514
TABLE-US-00011 TABLE 10 Emission Element ratio Atmospheric gas for
Spray Annealing Emission wavelength Example Ce Ca Sc spray
pyrolysis temp. temp. intensity nm Example 87 0.01 0.99 2 Nitrogen
+ 4% hydrogen 1,500 52 514 Example 88 0.01 0.99 2 Nitrogen 1,500
1,500 118 518 Example 89 0.01 0.99 2 Nitrogen 1,500 1,300 91 516
Example 90 0.01 0.99 2 Nitrogen 1,500 1,200 53 512 Example 91 0.01
0.99 2 Nitrogen 1,500 1,100 42 514
TABLE-US-00012 TABLE 11 Calcining Emission Element ratio Kind of
Molar ratio temp. Emission wavelength Example Ce Ca Sc flux of flux
.degree. C. intensity nm Example 92 0.01 0.99 2 CaF.sub.2 0.03
1,550 148 517 Example 93 0.01 0.99 2 H.sub.3BO.sub.3 0.03 1,550 149
515
[0123] While the present invention has been described in detail and
with reference to specific embodiments thereof, it will be apparent
to one skilled in the art that various changes and modifications
can be made therein without departing from the spirit and scope
thereof.
[0124] The present invention is based on Japanese Patent
Application (Japanese Patent Application 2004-194508) filed on Jun.
30, 2004 and the contents thereof are hereby incorporated therein
by reference.
INDUSTRIAL APPLICABILITY
[0125] In accordance with the present invention, a phosphor which
can be easily produced and can provide a light emitting device
having a high color rendering, a light emitting device comprising
the phosphor, and a display and a lighting system comprising the
light emitting device as a light source can be provided.
* * * * *