Compositions – Inorganic luminescent compositions – Compositions containing halogen; e.g. – halides and oxyhalides
Reexamination Certificate
2001-03-28
2003-06-10
Koslow, C. Melissa (Department: 1755)
Compositions
Inorganic luminescent compositions
Compositions containing halogen; e.g., halides and oxyhalides
C313S582000, C313S584000, C313S495000, C313S486000
Reexamination Certificate
active
06576157
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vacuum ultraviolet ray-excited light-emitting phosphor. The present invention also relates to a phosphor suitable for vacuum ultraviolet ray-excited light-emitting devices such as a plasma display panel (hereinafter, abbreviated to as “PDP”), rare gas lamp and the like, and a vacuum ultraviolet ray-excited light-emitting device obtained by using said phosphor.
2. Description of the Related Art
Recently, there are wide-spread developments of vacuum ultraviolet ray-excited light-emitting devices having a mechanism in which a phosphor is excited by vacuum ultraviolet ray radiated by rare gas discharge to emit light. The typical example thereof is a development of PDP. In cathode-ray tubes and color liquid crystal displays, increase in size of images is difficult, on the other hand, PDP is a flat panel display enabling it, and expected to be used for indication or as a large screen television in public spaces. PDP is a display element constituted by placing a large number of fine discharging spaces (hereinafter, sometimes abbreviated as “display cell”) into matrix form. A discharge electrode is provided in each display cell and a phosphor is applied on the inner wall of each display cell. A space in each display cell is filled with a rare gas such as He—Xe, Ne—Xe, Ar and the like and by applying voltage on a discharge electrode, discharge occurs in the rare gas and vacuum ultraviolet ray is radiated. The phosphor is excited by this vacuum ultraviolet ray and emits visible ray. Images are displayed by allotting positions of display cells which emit light. By use of phosphors emitting three primary colors, blue, green and red, full color display can be carried out.
As the vacuum ultraviolet ray-excited light-emitting device other than PDP, a rare gas lamp is used. The rare gas lamp is a lamp emitting light by a mechanism in which vacuum ultraviolet ray is generated by discharge in a rare gas, and the vacuum ultraviolet ray is converted into visible ray by a phosphor. Rare gas lamps are noticed from the standpoint of environmental problems since they do not use mercury.
Phosphors excited by vacuum ultraviolet ray radiated by discharge in a rare gas have been already suggested, and as the blue phosphor, BaMgAl
10
O
17
:Eu is exemplified, as the green phosphor, Zn
2
SiO
4
:Mn is exemplified, and as the redphosphor, (Y, Gd)BO
3
:Eu is exemplified. For full-color PDP, improvement in brilliance of phosphors is desired. Particularly, improvement in brilliance of a blue phosphor is desired strongly.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a blue phosphor having high light-emitting brilliance for vacuum ultraviolet ray-excited light-emitting devices such as PDP and the like, and a vacuum ultraviolet ray-excited light-emitting device using the same.
The present inventors have intensively studied to solve the above-mentioned problems under such conditions, and resultantly found that the specific aluminate among aluminate-based phosphors containing Eu as an activator is useful as a vacuum ultraviolet ray-excited light-emitting phosphor, particularly as a blue phosphor, and have completed the present invention.
Namely, the present invention provides a vacuum ultraviolet ray-excited light-emitting phosphor comprising a compound represented by formula (Ba
x
M
1−x
)
1−0.25y
Mg
1−y
Al
10+y
O
17+0.25y
as a substrate, and Eu as an activator, wherein M represents Ca, Sr or Ca and Sr, x and y satisfy the following relations, 0.5≦x≦1, and 0.05≦y≦0.15. Further, the present invention provides a vacuum ultraviolet ray-excited light-emitting device using the said phosphor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will be illustrated in detail below.
As the vacuum ultraviolet ray-excited light-emitting blue phosphor, BaMgAl
10
O
17
:Eu is widely known. The substrate oxide BaMgAl
10
O
17
is a compound having a structure of &bgr; alumina type wherein a part of aluminum ions of a spinel layer contained in the &bgr; alumina type structure is substituted with magnesium ions. A phosphor obtained by adding Eu as an activator to compounds represented by formula Ba
1−0.25y
Mg
1−y
Al
10+y
O
17+0.25y
having lower magnesium content and higher aluminum content than BaMgAl
10
O
17
, particularly to a compound in which y is 0.05 to 0.15 has high brilliance and is useful as a vacuum ultraviolet ray-excited light-emitting phosphor.
Since up to half of Ba in the above-mentioned composition formula can be substituted by Ca, Sr, or Ca and Sr, the phosphor of the present invention is a vacuum ultraviolet ray-excited light-emitting phosphor comprising a compound represented by formula (Ba
x
M
1−x
)
1−0.25y
Mg
1−y
Al
10+y
O
17+0.25y
(wherein, M represents Ca and/or Sr, 0.5≦x≦1, and 0.05≦y≦0.15) as a substrate, and Eu as an activator. Regarding the range of y, preferably 0.1≦y≦0.15.
The content of Eu is preferably from 1 to 30 mol %, more preferably from 5 to 20 mol %, further preferably from 8 to 15 mol % based on the total molar amount of Ba, M (M represents Ca, Sr or Ca and Sr) and Eu. When the content of Eu is less than 1 mol % or more than 30 mol % based on the total molar amount of Ba, M and Eu, high light-emitting brilliance may not be obtained sometimes.
The vacuum ultraviolet ray-excited light-emitting phosphor can also be applied to phosphors excited by ultraviolet ray, X-ray and electronbeam out of the vacuumultraviolet range, and to elements using the same.
The method for producing a phosphor of the present invention is not particularly restricted, and for example, a phosphor can be produced by known methods such as a method described in JP-A No. 10.153760. In general, raw materials can be compounded to give a given composition and calcined to produce a phosphor.
The phosphor of the present invention can be obtained by a method in which raw materials are weighed to give a given composition, mixed using a ball mill, V shape mixing machine, stirring apparatus or the like, then, calcined at temperatures from 900 to 1600° C. for 1 to 50 hours.
As aluminum source, there can be used alumina having high purity (purity: 99.9% or more) (the crystal form may be &agr; alumina or transition alumina), aluminum hydroxide, aluminum nitrate or aluminum halide having high purity (purity: 99% or more), and the like.
As barium source, there can be used those which can be decomposed at higher temperatures to become barium oxide such as barium hydroxide, barium carbonate, barium nitrate, barium halide or barium oxalate having high purity (purity: 99% or more) and the like, or barium oxide having high purity (purity: 99% or more).
As calcium source, there can be used those which can be decomposed at higher temperatures to become calcium oxide such as calcium hydroxide, calcium carbonate, calcium nitrate, calcium halide or calcium oxalate having high purity (purity: 99% or more) and the like, or calcium oxide having high purity (purity: 99% or more).
As strontium source, there can be used those which can be decomposed at higher temperatures to become strontium oxide such as strontium hydroxide, strontium carbonate, strontium nitrate, strontium halide or strontium oxalate having high purity (purity: 99% or more) and the like, or strontium oxide having high purity (purity: 99% or more).
As magnesium source, there can be used those which can be decomposed at higher temperatures to become magnesium oxide such as magnesium hydroxide, magnesium carbonate, magnesium nitrate, magnesium halide, magnesium oxalate or basic magnesium carbonate having high purity (purity: 99% or more) and the like, or magnesium oxide having high purity (purity: 99% or more).
As europium source, there can be used those which can be decomposed at higher temperatures to become europium oxide such as europium hydroxide, europium carbonate, europium nitrate, europium halide or europium oxalate having high purity (pur
Miyazaki Susumu
Ono Keiji
Koslow C. Melissa
Sumitomo Chemical Company Limited
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