JP2010174222A - White fluorophor, field emission display, field emission lamp and inorganic electroluminescent display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white fluorophor which generates white light having good color purity even at a relatively low electron accelerating voltage and low in environmental effect. <P>SOLUTION: This white fluorophor includes (Ma)(Mb)<SB>2</SB>S<SB>4</SB>as a crystal base material and Pr<SP>3+</SP>(praseodymium ion) as an emission center, wherein Ma is Sr (strontium) or an element in which a part or the whole of Sr (strontium) is substituted with Ca (calcium) and Mb is Ga (gallium) or an element in which a part or the whole of Ga (gallium) is substituted with Al (aluminum). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a white phosphor, and more particularly to a white phosphor that can be used for a display using cathodoluminescence.

  In recent years, field emission displays (FED) and field emission lamps (FEL) using so-called cathodoluminescence have attracted attention. Usually, the FED is used for a thin display or the like, and the FEL is used for a liquid crystal backlight, an illumination light source, or the like.

  The light emission principle of FED and FEL is the same as that of a conventional cathode ray tube (CRT) display. The phosphor contained in FED and FEL is excited by electron beam irradiation, and light emission (cathode) generated when this phosphor returns to the ground state. Luminescence) is used.

  However, in the case of a CRT display, the phosphor screen having the phosphor is irradiated with an electron beam at a high acceleration voltage (for example, about 30 kV), whereby light is emitted from the phosphor. On the other hand, in the case of FED and FEL, the phosphor is irradiated with an electron beam at a relatively low acceleration voltage (for example, 10 kV or less) (Non-patent Documents 1-3). In the case of FED and FEL, the distance between the electron source and the phosphor screen is relatively close (for example, about 0.5 mm), and when a high acceleration voltage of 10 kV or higher is applied between them, This is because there is no breakdown voltage in the structure of the lamp and the lamp, so that there is a high possibility that electric discharge occurs or dielectric breakdown occurs.

  However, suppression of the acceleration voltage of electrons may lead to deterioration of the light emission characteristics of the phosphor. For this reason, there is a demand for a phosphor exhibiting appropriate light emission characteristics even at a relatively low electron acceleration voltage, and various developments have been made on such phosphor materials. However, in the case of white phosphors in particular, there have been few reports on materials having good color purity at a relatively low electron acceleration voltage.

Although the application is different, Patent Document 1 discloses a white phosphor (CaGa ₂ S ₄ ; Pb) having CaGa ₂ S ₄ as a crystal base material and Pb (lead) as an emission center.

JP 2006-2115 A

F. -L. Zhang, S.M. Yang, C.I. Stoffers, J.A. Penczek, P.M. N. Yocom, D.M. Zaremba, B.M. K. Wagner, C.I. J. et al. Summers, Appl. Phys. Lett. vol. 72, p2226 (1998) K. Tanaka, S .; Okamoto, H .; Kominami, Y .; Nakanishi, X .; Du, A .; Yoshikawa, “Cathodolumescence properties of blue-emitting SrGa2S4”, J. Am. Appl. Phys. vol. 92, no. 834 (2002) E. J. et al. Chi, et al. , “Recent improvements in brightness and color gamut of carbon nanotube field emission display”, SID '06 Digest, vol. 63, no. 1, p1841 (2006)

Although the aforementioned Patent Document 1 shows that white photoluminescence can be obtained when a CaGa ₂ S ₄ ; Pb phosphor is irradiated with ultraviolet light having a wavelength of 350 nm, other excitation sources and excitation methods are disclosed. It is not shown about the light emission characteristic at the time of employ | adopting. In general, if the excitation source or the excitation method is changed, the light emission behavior of the light emitter changes. Therefore, it is unclear whether the phosphor described in Patent Document 1 can be applied to FED, FEL, etc. using cathodoluminescence. It is. Thus, although there are some researches and reports on white phosphors using photoluminescence as basic research, there are some reports on white phosphors applicable for FED and FEL using cathodoluminescence. rare.

  Moreover, since Pb (lead) contained in the phosphor described in Patent Document 1 is toxic, there is a problem that the use of this phosphor is not preferable in terms of environment.

  The present invention has been made under such a background. In the present invention, a white phosphor having a good color purity is produced even at a relatively low electron acceleration voltage, and the environmental impact is small. The purpose is to provide.

In the present invention,
As a crystal matrix material, it has (Ma) (Mb) ₂ S ₄ ,
A white phosphor having Pr ³⁺ (praseodymium ion) as the emission center is provided. here,
Ma is an element in which Sr (strontium) or a part or all of Sr is replaced with Ca (calcium),
Mb is an element in which Ga (gallium) or a part or all of Ga is substituted with Al (aluminum).

In the white phosphor according to the present invention, the crystal base material may be SrGa ₂ S ₄ .

In addition, the white phosphor in the present invention may further have Ce ³⁺ (cerium ion) as the emission center.

Further, in the white phosphor of the present invention, the amount of ^{Ce 3+} (mol%) may be less than 1/10 of the amount of ^{Pr 3+} (mol%).

  Further, in the white phosphor according to the present invention, the content of the emission center with respect to the entire white phosphor may be in the range of 0.01 mol% to 20 mol%.

In the present invention, a field emission display having an electron source that emits electrons and a substrate on which a phosphor layer that emits light when the electrons collide is disposed,
The phosphor layer is provided with a field emission display having a white phosphor having the above-described characteristics.

In the present invention, a field emission lamp having an electron source that emits electrons and a substrate on which a phosphor layer that emits light when the electrons collide is disposed,
The phosphor layer is provided with a field emission lamp having a white phosphor having the above-described characteristics.

Further, in the present invention, an inorganic electroluminescent display having a voltage source for applying a voltage between two electrodes, and a phosphor layer that is installed between the electrodes and emits light when the voltage is applied,
The phosphor layer is provided with an inorganic electroluminescent display having a white phosphor having the above-described characteristics.

  According to the present invention, it is possible to provide a white phosphor that generates white light having a good color purity even at a relatively low electron acceleration voltage and has little influence on the environment. In addition, it is possible to provide various devices having such a white phosphor.

Is a type of white phosphor according to the present invention, SrGa 2 S _4; is a diagram showing an example of an emission spectrum due to electron beam excitation of the _Pr. It is the figure which showed the CIE chromaticity coordinate of the white fluorescent substance by this invention. It is the figure which showed the area | region of the white light in a CIE chromaticity coordinate. Is a type of white phosphor according to the present invention, SrGa 2 S 4; is a diagram showing an example of the emission spectrum by _Pr, electron beam excitation of _Ce. It is the figure which showed an example of the basic composition principle figure of the field emission display (FED) apparatus to which the white fluorescent substance by this invention is applied. It is the figure which showed an example of the basic composition principle figure of the field emission lamp (FEL) apparatus to which the white fluorescent substance by this invention is applied. It is the figure which showed an example of the fundamental structure principle diagram of the inorganic electroluminescent display (ELD) apparatus to which the white fluorescent substance by this invention is applied.

  Hereinafter, the present invention will be described in more detail.

  In recent devices such as field emission display (FED) and field emission lamp (FEL) using so-called “cathode luminescence”, the distance between the electron source and the phosphor screen having the phosphor may be too large. Since it is not possible (for example, about 0.5 mm) and there is no structural breakdown voltage, when a large acceleration voltage is used, discharge occurs or dielectric breakdown occurs. For this reason, the phosphor is irradiated with electrons at a relatively low acceleration voltage (for example, 10 kV or less). In the present application, “cathode luminescence” means a general term for phenomena in which phosphors are excited by the incidence of electrons and light is emitted.

  However, in general, the emission characteristics of the phosphor tend to decrease as the acceleration voltage of the electrons decreases. Therefore, there is a demand for a phosphor that exhibits good light emission characteristics, particularly light emission color with good color purity, even at a low acceleration voltage. In particular, a phosphor that emits white light with good color purity under a low acceleration voltage condition (hereinafter referred to as “white phosphor”) has hardly been reported. There is also a demand for safer phosphors with less environmental impact.

As a result of earnest research and development in view of such a background, the inventors of the present application can achieve the above object by using a phosphor having thiogallate SrGa ₂ S ₄ as a crystal base material and Pr ³⁺ as an emission center. And found the present invention.

That is, the present invention provides a white phosphor characterized by having (Ma) (Mb) ₂ S ₄ as a crystal matrix material and Pr ³⁺ (praseodymium ion) as a luminescence center. Here, Ma is an element in which part or all of Sr (strontium) or Sr (strontium) is replaced with Ca (calcium), and Mb is Ga (gallium) or a part of Ga (gallium). Alternatively, all elements are replaced by Al (aluminum).

In the thiogallate SrGa ₂ S ₄ containing Sr, even if at least part of Sr is replaced with Ca and / or at least part of Ga is replaced with Al, the cathodoluminescence characteristics of the phosphor are substantially reduced. It is well known that no effect occurs. Therefore, in the present invention, Ma is Sr (strontium), or an element in which part or all of Sr (strontium) is replaced by Ca (calcium), and Mb is Ga (gallium) or Ga (gallium). When a part or all of the element is substituted with Al (aluminum), the crystal base material of the white phosphor is represented by (Ma) (Mb) ₂ S ₄ .

As in the present invention, a white phosphor (hereinafter referred to simply as “()) having (Ma) (Mb) ₂ S ₄ as a crystal matrix material and Pr ³⁺ (praseodymium ion) as a luminescent center. In the present invention (referred to as “white phosphor”), white light emission with good color purity can be obtained by electron beam excitation even at a relatively low acceleration voltage of about 10 kV.

  In addition, the white phosphor according to the present invention does not contain a harmful substance such as Pb (lead) and can provide an environment-friendly white phosphor.

Furthermore, in the white phosphor according to the present invention, only a single material (Ma) (Mb) ₂ S ₄ is used as a crystal matrix material. That is, in the present invention, in order to obtain white light emission, a method of forming a single phosphor by mixing a plurality of light emitting materials exhibiting each light emission such as blue, red, and green is not employed. Therefore, the present invention has features that it is not necessary to consider the interaction between the light emitting materials and that the manufacturing is relatively simple.

Here, the white phosphor according to the present invention may contain Ce ³⁺ ions as emission center ions in addition to Pr ³⁺ ions. Ce ³⁺ ions are known as phosphors that emit blue light. By adding a small amount of Ce ³⁺ ions as the emission center, the color rendering property of the emission color (that is, white) is improved. Usually, the Ce ³⁺ ion content (mol%) contained in the white phosphor according to the present invention is 1/10 or less of the Pr ³⁺ ion content (mol%). This is because when Ce ³⁺ ions are further added to the white phosphor, the blue color in the light emission becomes too strong, and a white color with good color purity may not be obtained.

The content of the emission center (if not containing ^{Ce 3+} ions is the content of ^{Pr 3+} ions, if it contains ^{Ce 3+} ions, the sum of the content of ^{Pr 3+} ions and ^{Ce 3+} ions) is particularly limited However, for example, it is preferably in the range of 0.01 mol% to 20 mol%, more preferably in the range of 0.01 mol% to 3 mol%, with respect to the total amount of the phosphor. When the content of the luminescent center is less than 0.01 mol%, the luminance is lowered. On the other hand, when the content of the emission center is more than 20 mol%, concentration quenching occurs and the luminance decreases.

Further, a charge compensator may be further added to the white phosphor according to the present invention. Examples of the charge compensator include an alkali metal element, a metal element that becomes a +1 cation such as Ag ⁺ (silver ion), a halogen ion (Cl ⁻ , F ⁻ , I ⁻ ), and the like. The charge compensation material agent is preferably added in an amount equivalent to the content of the emission center ion, and the addition amount is, for example, in the range of 0.01 mol% to 20 mol%. In addition, when the amount of the charge compensation material agent exceeds 20 mol%, the luminance may be lowered.

FIG. 1 shows an example of the emission spectrum of the white phosphor according to the present invention. This emission spectrum is obtained when SrGa ₂ S ₄ ; Pr (Pr content 2.0 mol%) is used as a white phosphor material and irradiated with an electron beam with an acceleration voltage of 2 kV. It can be seen that emission peaks occur at wavelengths near 483 nm, 495 nm, 539 nm, 610 nm, 630 nm, and 653 nm.

FIG. 2 shows the CIE chromaticity coordinates of the obtained light emission. The chromaticity coordinates (x, y) of SrGa ₂ S ₄ ; Pr were x = 0.33, y = 0.40 (point A in the figure).

FIG. 3 shows each color region in the CIE chromaticity coordinates (Source: Television Image Information Engineering Handbook, Ohmsha, 1990). In FIG. 3, the chromaticity coordinates (x, y) of SrGa ₂ S ₄ ; Pr shown in FIG. 2 are also shown as x = 0.33 and y = 0.40.

  In general, if the CIE chromaticity coordinates of light emission are within the shaded area in FIG. 3, it can be said that the light emission is white light with good color purity. Therefore, it can be seen from this figure that white light with good color purity is obtained with the white phosphor according to the present invention.

Even if the Pr concentration contained in the white phosphor is changed from 0.01 mol% to 20 mol% with respect to the total amount of the phosphor, the CIE chromaticity coordinates (x, y) of light emission are (0.32). , 0.40) to (0.35, 0.41), there is almost no change. This is thought to be because the emission of Pr ³⁺ is a transition between 4f-4f electrons, and even if the amount of luminescent center ions increases, the transition behavior is not significantly affected.

  Therefore, the white phosphor according to the present invention has an additional feature that it exhibits sufficiently good luminescent properties even when the concentration of the luminescent center is not so strictly controlled during the preparation.

FIG. 4 shows an example of the emission spectrum of another white phosphor according to the present invention. This emission spectrum uses SrGa ₂ S ₄ ; Pr, Ce (Pr content 4.9 mol%, Ce content 0.30 mol% with respect to the whole phosphor) as a white phosphor material, and an electron beam with an acceleration voltage of 2 kV is used. It was obtained when irradiated. A light emission peak having the same intensity was obtained at the same position as the white phosphor SrGa ₂ S ₄ ; Pr described above. However, in the case of this illuminant, a luminescence peak that was probably caused by Ce was obtained in the vicinity of 440 nm.

Light emission in the vicinity of 440 nm corresponds to a blue component. Therefore, the color rendering property of white light is improved by adding Ce to the SrGa ₂ S ₄ ; Pr phosphor.

FIG. 2 described above also shows the CIE chromaticity coordinates of the light emission obtained in the SrGa ₂ S ₄ ; Pr, Ce phosphor. The chromaticity coordinates (x, y) of this white phosphor are x = 0.31, y = 0.36 (point B in the figure), and it can be seen that white light with good color purity is obtained. .

In the white phosphor according to the present invention, when the amount of Ce ³⁺ is increased with respect to Pr ³⁺ , the CIE chromaticity coordinates of the luminescent color are on the line indicated by the broken line L in FIG. Move along. However, the inventors of the present application confirmed that when the Ce ³⁺ content (mol%) with respect to the Pr ³⁺ ion content (mol%) is 1/10 or less, the emission color remains in the white region. ing.

(Application example of white phosphor of the present invention)
Such a white phosphor of the present invention can be applied to various devices utilizing cathodoluminescence.

  FIG. 5 shows a basic configuration principle diagram of a field emission display (FED) device having a white phosphor according to the present invention.

  The FED device 100 (unit element) includes a glass substrate 120, a transparent electrode 130 formed on the glass substrate 120 and made of a transparent conductor such as ITO (indium tin oxide), and the transparent electrode. And a phosphor layer 140 disposed thereon. Further, the FED device 100 further includes an electron emission source 150 that is disposed so as to face the phosphor layer 140 apart from the phosphor layer 140. Here, the phosphor layer 140 includes the white phosphor 141 according to the present invention.

  Although not shown in FIG. 5, the space between the glass substrate 120 and the electron emission source 150 is sealed with a sealing material, and this sealed space is evacuated.

  In practice, a planar field emission display is configured by arranging a plurality of unit elements shown in FIG. 5 in a two-dimensional (vertical and horizontal) matrix.

  In the FED device 100 configured as described above, when a voltage is applied between the transparent electrode 130 and the electron emission source 150 by the voltage source 170, electrons 190 are emitted from the electron emission source 150 toward the phosphor layer 140. Radiated. When the electrons 190 collide with the white phosphor 141 according to the present invention included in the phosphor layer 140, white light 191 is generated from the white phosphor 141.

  Here, as described above, the white phosphor 141 has a feature that white light emission with good color purity can be obtained by electron beam excitation even at a relatively low acceleration voltage. Therefore, in the FED device 100, white light emission with good color purity can be obtained even when the acceleration voltage of the electrons 190 is a relatively low voltage of about 10 kV or less.

  Next, with reference to FIG. 6, another apparatus using cathodoluminescence to which the white phosphor of the present invention is applied will be described.

  FIG. 6 shows a basic configuration principle diagram of a field emission lamp (hereinafter referred to as “FEL device”) having a white phosphor according to the present invention.

  The FEL device 200 includes a first glass substrate 220, a first metal electrode 230 formed on the first glass substrate 220, and a phosphor layer installed on the first metal electrode 230. 240. Here, the phosphor layer 240 includes the white phosphor 241 according to the present invention.

  Further, the FEL device 200 further includes an electron emission source 250 disposed so as to face the phosphor layer 240 at a distance from the phosphor layer 240. The electron emission source 250 is disposed on the second substrate 260 provided with the second metal electrode 255 so as to be in contact with the second metal electrode 255.

  In the FEL device 200 configured as described above, when a voltage is applied between the first metal electrode 230 and the second metal electrode 255 by the voltage source 270, the electron emission source 250 applies to the phosphor layer 240. Electrons 290 are emitted toward it. When the electrons 290 collide with the white phosphor 241 according to the present invention included in the phosphor layer 240, white light is generated from the white phosphor 241 in each direction. In particular, in this structure, the generated white light is reflected by the first metal electrode 230 and the second metal electrode 255, whereby light emission can be propagated in the lateral direction. Also in the FEL device 200, when the first metal electrode 230 is made transparent like the above-described FED, it is possible to take out light emission upward.

  Here, as described above, the white phosphor 241 has a feature that white light emission with good color purity can be obtained by electron beam excitation even at a relatively low acceleration voltage. Therefore, in the FEL device 200, white light emission with good color purity can be obtained even when the acceleration voltage of the electrons 290 is a relatively low voltage of about 10 kV or less.

  The white phosphor of the present invention can also be applied to various display devices using systems other than cathodoluminescence. For example, the white phosphor of the present invention may be applied to a display device using electroluminescence.

  Hereinafter, an application example of the white phosphor according to the present invention to an electroluminescent display device will be described with reference to FIG.

  FIG. 7 shows a basic configuration principle diagram of an inorganic electroluminescent display (ELD) having the white phosphor of the present invention.

  The ELD device 300 (unit element) includes a glass substrate 320, and a transparent electrode 330, a first insulating layer 335, a phosphor layer 340, and a second insulating layer 350 are provided on the glass substrate 320. And the back electrode 360 are laminated in this order. The transparent electrode 330 and the back electrode 360 are formed of a transparent conductor such as ITO (Indium Tin Oxide). The phosphor layer 340 includes the white phosphor 341 according to the present invention.

  The ELD device 300 further includes an AC voltage source 370, and the AC voltage source 370 can apply an AC voltage between the transparent electrode 330 and the back electrode 360.

  In practice, a planar inorganic electroluminescent display is configured by arranging a plurality of unit elements having the configuration shown in FIG. 6 in a two-dimensional (vertical and horizontal) matrix.

  In the ELD device 300 configured as described above, when a voltage is applied between the transparent electrode 330 and the back electrode 360 by the AC voltage source 370, an electric field is generated in the phosphor layer 340. Accordingly, white light 391 is emitted from the white phosphor 341 according to the present invention included in the phosphor layer 340.

  Also in such an ELD apparatus 300, white light emission with good color purity can be obtained by the effect of the white phosphor according to the present invention.

(Method for producing white phosphor according to the present invention)
Next, an example of a method for producing a white phosphor according to the present invention will be described.

  The white phosphor according to the present invention can be manufactured in various forms such as a thin film and a powder. Therefore, first, a method for producing a thin-film white phosphor will be described.

(Method for producing film-like white phosphor)
Here, as a typical film forming technique, a method of manufacturing an SrGa ₂ S ₄ ; Pr, Ce white phosphor using a molecular beam epitaxy (Molecular Beam Epitaxy) method will be described.

First, four Kununsen cells (hereinafter referred to as “K cells”) are respectively solid Sr (strontium), Ga ₂ S ₃ (digallium trisulfide), PrCl ₃ (praseodymium trichloride), and CeCl ₃ (cerium trichloride). ). These K cells are arranged in a molecular beam epitaxy apparatus together with, for example, a glass deposition substrate.

  Next, after raising the deposition target substrate to a predetermined temperature, each of the four K cells is heated to a predetermined temperature.

On the deposition target substrate, a crystal base film of SrGa ₂ S ₄ grows by the following chemical reaction.

Sr + 2Ga ₂ S ₃ → SrGa ₂ S ₄ + 2GaS ↑ (1) Formula

Note that in (1), GaS, in order to re-evaporated on the substrate, does not remain in the host crystal film finally SrGa ₂ S _4.

Also, by heating PrCl ₃ and CeCl ₃ , Pr and Ce are incorporated into the host crystal of SrGa ₂ S ₄ , and finally a SrGa ₂ S ₄ ; Pr, Ce thin film is obtained.

In normal cases, the heating temperature of the film formation substrate is about 450 ° C. to 650 ° C. The heating temperature of Sr is in the range of 400 ° C. to 600 ° C., the heating temperature of Ga ₂ S ₃ is in the range of 700 ° C. to 900 ° C., and the heating temperature of PrCl ₃ and CeCl ₃ is 450 ° C. to 650 ° C. It is in the range of ° C. The film formation rate is in the range of 10 Å / min to 10000 Å / min.

It should be noted that the concentration of the luminescent center ions, that is, Pr ³⁺ and Ce ³⁺ ions in the white phosphor can be easily adjusted by adjusting the heating temperature of the PrCl ₃ and CeCl ₃ K cells. It will be obvious.

Through the above steps, a thin-film SrGa ₂ S ₄ ; Pr, Ce white phosphor can be obtained.

It will be apparent to those skilled in the art that white phosphors that do not contain Ce ³⁺ as the emission center can also be manufactured by the same method. In this case, the phosphor film is formed using three types of K cells except for CeCl ₃ .

  In the above description, the method for producing the white phosphor according to the present invention using the molecular beam epitaxy method has been shown as a typical film forming technique. However, the white phosphor according to the present invention can be manufactured using other film forming methods such as an electron beam evaporation method, a sputtering method, a CVD method, and an ion plating method.

(Method for producing powdered white phosphor)
Next, a method for producing a powdered white phosphor will be described by taking the SrGa ₂ S ₄ ; Pr, Ce white phosphor according to the present invention as an example.

The SrGa ₂ S ₄ ; Pr, Ce white phosphor can be relatively easily manufactured by a sintering method using a solid phase reaction.

First, each raw material powder of Sr (strontium), Ga ₂ S ₃ (digallium trisulfide), S (sulfur), PrCl ₃ (praseodymium trichloride), and CeCl ₃ (cerium trichloride) has a stoichiometric composition. Weigh and mix well.

  Next, this mixed powder is placed in a heat-resistant container made of quartz glass, ceramics, or the like, and placed in an atmosphere adjustment furnace. After the furnace is filled with an atmosphere containing hydrogen sulfide, the mixed powder is fired at a high temperature for a predetermined time. The firing atmosphere may be, for example, an Ar (argon) atmosphere containing 1 vol% to 10 vol% (for example, 5 vol%) of hydrogen sulfide. The firing temperature and firing time are not particularly limited, but the firing temperature is, for example, in the range of 800 ° C. to 1000 ° C., and the firing time is, for example, in the range of 1 hour to 24 hours.

Thereafter, the obtained fired product is taken out from the furnace, pulverized, and refined to a desired particle size, whereby a SrGa ₂ S ₄ ; Pr, Ce white phosphor powder can be obtained.

In addition, SrGa ₂ S ₄ ; Pr white phosphor powder and the like that do not contain Ce as the luminescent center ion can be produced by the same method.

  Examples of the present invention will be described below.

Example 1
The white phosphor thin film according to the present invention was prepared by the following method, and the characteristics thereof were evaluated.

A SrGa ₂ S ₄ ; Pr thin film was formed on a glass substrate by molecular beam epitaxy.

First, three S cells were filled with solid Sr, Ga ₂ S ₃ , and PrCl ₃ , respectively. Hereinafter, the K cells containing each solid material are referred to as K cell 1, K cell 2, and K cell 3, respectively. These K cells and glass substrate were placed in a commercially available molecular beam epitaxy apparatus.

Next, the glass substrate was heated up to 550 ° C. and held at this temperature, and the three K cells were heated by a temperature controller and held at a predetermined temperature. At this time, K cell 1 (for Sr) is held at 500 ° C., K cell 2 (for Ga ₂ S ₃ ) is held at 800 ° C., and K cell 3 (for PrCl ₃ ) is held at 550 ° C. did.

Thereby, a SrGa ₂ S ₄ ; Pr thin film was obtained. The deposition rate was 100 Å / min. As a result of the analysis, the content of Pr contained in the SrGa ₂ S ₄ ; Pr thin film was 2.0 mol%. Hereinafter, the SrGa ₂ S ₄ ; Pr thin film thus produced is referred to as “white phosphor according to Example 1”.

  Next, the light emission characteristics of the white phosphor according to Example 1 were evaluated. The evaluation of the emission characteristics was carried out by measuring the emission spectrum generated when the white phosphor according to Example 1 was irradiated with electrons at an acceleration voltage of 2 kV.

  As a result of the measurement, the emission spectrum shown in FIG. 1 was obtained. Further, the CIE chromaticity coordinates of the obtained emission spectrum are indicated by point A (0.33, 0.40) in FIG.

(Example 2)
A SrGa ₂ S ₄ ; Pr, Ce thin film was formed on a glass substrate by the following method, and its characteristics were evaluated.

First, four K cells were filled with solid Sr, Ga ₂ S ₃ , PrCl ₃ and CeCl ₃ , respectively. Hereinafter, the K cells containing each solid material will be referred to as K cell 1, K cell 2, K cell 3, and K cell 4, respectively. These K cells and glass substrate were placed in a commercially available molecular beam epitaxy apparatus.

Next, the glass substrate was heated up to 550 ° C. and held at this temperature, and the four K cells were heated by a temperature controller to be held at a predetermined temperature. At this time, K cell 1 (for Sr) is held at 500 ° C., K cell 2 (for Ga ₂ S ₃ ) is held at 800 ° C., and K cell 3 (for PrCl ₃ ) is held at 550 ° C. K cell 4 (for CeCl ₃ ) was kept at 530 ° C.

Thus, a glass _{substrate, SrGa 2 S 4; Pr,} Ce thin film is formed. The film formation rate was 100 Å / min. As a result of analysis, the content of Pr contained in the SrGa ₂ S ₄ ; Pr, Ce thin film was 4.85 mol%, and the content of Ce was 0.30 mol%. The SrGa ₂ S ₄ ; Pr, Ce thin film obtained through the above steps is referred to as “white phosphor according to Example 2”.

  Next, the light emission characteristics of the white phosphor according to Example 2 were evaluated by the same method as in Example 1 described above.

  As a result of the measurement, the emission spectrum shown in FIG. 4 was obtained. In addition, the CIE chromaticity coordinates of the obtained emission spectrum are indicated by point B (0.31, 0.36) in FIG.

  As described above, it was found that the white phosphors according to Example 1 and Example 2 can obtain white light with good color purity.

  The present invention can be applied to various display devices and / or illumination lamps that emit light by using cathodoluminescence or electroluminescence.

DESCRIPTION OF SYMBOLS 100 FED apparatus 120 Glass substrate 130 Transparent electrode 140 Phosphor layer 141 White phosphor 150 Electron emission source 170 Voltage source 190 Electron 191 White light 200 FEL apparatus 220 First glass substrate 230 First metal electrode 240 Phosphor layer 241 White Phosphor 250 Electron emission source 255 Second metal electrode 260 Second substrate 270 Voltage source 290 Electron 300 ELD device 320 Glass substrate 330 Transparent electrode 335 First insulating layer 340 Phosphor layer 341 White phosphor 350 Second insulation Layer 360 Back electrode 370 AC voltage source 391 White light

Claims (8)

As a crystal matrix material, it has (Ma) (Mb) ₂ S ₄ ,
White phosphor having Pr ³⁺ (praseodymium ion) as the emission center:
here,
Ma is an element in which Sr (strontium) or a part or all of Sr is replaced with Ca (calcium),
Mb is an element in which Ga (gallium) or a part or all of Ga is substituted with Al (aluminum). The white phosphor according to claim 1, wherein the crystal base material is SrGa ₂ S ₄ . The white phosphor according to claim 1, further comprising Ce ³⁺ (cerium ion) as a light emission center. The white phosphor according to claim 3, wherein the amount of Ce ³⁺ (mol%) is 1/10 or less of the amount of Pr ³⁺ (mol%).   The white phosphor according to any one of claims 1 to 4, wherein the content of the emission center with respect to the entire white phosphor is in the range of 0.01 mol% to 20 mol%. A field emission display having an electron source that emits electrons, and a substrate on which a phosphor layer that emits light when the electrons collide is disposed,
The field emission display, wherein the phosphor layer includes the white phosphor according to any one of claims 1 to 5. A field emission lamp having an electron source that emits electrons and a substrate on which a phosphor layer that emits light when the electrons collide is disposed,
6. The field emission lamp according to claim 1, wherein the phosphor layer has the white phosphor according to any one of claims 1 to 5. An inorganic electroluminescent display comprising: a voltage source that applies a voltage between two electrodes; and a phosphor layer that is installed between the electrodes and that emits light when the voltage is applied.
The inorganic electroluminescent display, wherein the phosphor layer includes the white phosphor according to any one of claims 1 to 5.

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