JP4979187B2 - Aluminum nitride phosphor and method for producing the same - Google Patents

Description

  The present invention relates to a novel aluminum nitride phosphor and a method for producing the same.

  Phosphors include various display devices such as VFD (fluorescent display tube), FED (field emission display), high brightness CRT (cathode ray tube), PDP (plasma display panel), etc., and light emitting elements such as white LEDs (light emitting diodes). Widely used.

In these light emitting elements, the light emitting part is composed of a phosphor coating film containing a phosphor. The phosphor coating film can be obtained by applying a powdered phosphor together with a binder. This makes it easy to form a light emitting portion on a large-area substrate or on a surface having a complicated shape.

These phosphor coating films are manufactured by coating and molding a powdered phosphor together with a binder mainly on a glass or plastic film substrate.
Regarding phosphor coating films, various types of phosphors (fluorescent compounds) have been conventionally used depending on the desired emission color.

  For powder phosphors based on sulfides, yellow-orange to green, Cu-doped zinc sulfide (ZnS: Blue-green fluorescence is obtained in the Cu) system. In addition, ZnS: Ag, ZnS: Ag, Al, ZnS: Cu, Al, (Zn, Cd) S: Cu, Al, and the like are known as sulfide-based phosphors.

In the powder phosphor using the oxide as a base material, red in (Y, Gd) BO ₃ : Eu, Y ₂ O ₃ : Eu, SrTiO ₃ : Pr, Y ₂ O ₂ S: Eu, etc., BaAl ₁₂ O ₁₉ : Mn, Zn ₂ SiO ₄ : Mn, Zn (Ga, Al) ₂ O ₄ : Mn, Y ₃ (Al, Ga) ₅ O ₁₂ : Tb, Y ₂ SiO ₅ : Tb, ZnGa ₂ O ₄ : Mn, green It is known that blue fluorescent light emission can be obtained in BaMgAl ₁₄ O ₂₃ : Eu, Y ₂ SiO ₅ : Ce, and the like. In addition, for example, ZnO: Zn is known as an oxide phosphor.

  These phosphors emit light by converting energy given by electron beams, ultraviolet rays, etc. into visible light, but the conversion efficiency is usually about 30%, and energy that has not been converted into visible light is transferred to the phosphor. Absorbed.

  In recent years, fluorescent coating films for displays and the like are required to emit fluorescent light with higher brightness. In particular, for a phosphor coating film for PDP whose screen size is increasing, a method using powdered phosphor as a paint has become the mainstream because of ease of processing. For this reason, it is necessary to form a phosphor coating film with high brightness from these phosphors.

  However, when the applied energy is increased, the energy absorbed by the phosphor is also increased, and the damage proceeds due to the destruction of the structure of the phosphor, and there is a problem that stability over time cannot be obtained.

  As a phosphor capable of exhibiting sufficiently high luminance and long life characteristics, for example, a phosphor containing zinc sulfide as a base material and containing an activator and a coactivator (for example, Patent Document 1), sulfide-based or oxide-based A powder phosphor (for example, Patent Document 2) is known.

  However, these phosphors inevitably release sulfur, sulfide gas, oxygen, etc. when their structure is destroyed, and corrode or deteriorate peripheral parts such as electron sources and filaments used in display devices. Cause.

  As phosphors other than sulfides or oxides, there are gallium nitride phosphors (for example, Patent Document 3 and Patent Document 4). Gallium nitride phosphors do not release sulfur, sulfide gas, oxygen, etc., but they can only obtain the same brightness as sulfide or oxide phosphors even when the applied energy is increased. The raw material is expensive. Moreover, the forbidden band width of gallium nitride is about 3.4 eV, and high luminous efficiency cannot be expected for vacuum ultraviolet light excitation.

  On the other hand, an aluminum nitride-based phosphor obtained by doping aluminum nitride with a luminescent center impurity element has a large forbidden band width of about 6.2 eV, and has high luminous efficiency against ultraviolet light excitation in the vacuum ultraviolet region. It is advantageous in that it has high mechanical and chemical stability and does not deteriorate even when strongly excited, and high brightness can be obtained. Aluminum nitride is also attracting attention as an environmentally friendly material because it is composed of elements that are abundant in resources, non-toxic and corrosive, and highly compatible with ecosystems.

  As a method for producing such a material, for example, a method of treating Al—Mn mixed powder at 1000 ° C. and 1000 psi (about 7 MPa) in a nitrogen atmosphere is known (eg, Non-Patent Document 1).

  However, this method requiring a high-pressure atmosphere is not suitable for production on an industrial scale because of safety and cost.

  In addition, a method of doping an aluminum nitride powder with an emission center impurity element by thermal diffusion (for example, Non-Patent Document 2) has also been proposed.

However, the doping amount of the luminescent center impurity element required for obtaining sufficient light emission intensity is usually 0.1 atomic% or more, but such amount cannot be doped by thermal diffusion. is there. In order to dope an element of several atomic%, there is a method (for example, Non-Patent Document 2) in which MnCl ₂ is added to expensive (NH ₄ ) ₃ AlF ₆ and reacted in a toxic NH ₃ atmosphere. It is not a suitable method for production on an industrial scale.

For this reason, the present situation is that aluminum nitride is only used for producing a thermoluminescent material (for example, Patent Document 5) on an industrial scale.
Japanese Patent Laid-Open No. 8-183954 JP-A-9-260060 JP 2002-309249 A JP 2002-356676 A JP-A-5-263075 J. electrochemical society 109 (11) 1962 Czechoslovakia J. Physics B, vol. 22 (1972), 847

  Accordingly, a main object of the present invention is to provide an aluminum nitride phosphor on an industrial scale.

  As a result of intensive studies in view of the problems of the prior art, the present inventor has found that the above object can be achieved by producing aluminum nitride powder by a specific process, and has completed the present invention.

  That is, the present invention relates to the following aluminum nitride phosphor and a method for producing the same.

1.1) At least one transition element of Ti, V, Cr, Mn, Co, Cu and Zn and its compound and 2) At least one rare earth element of Sm, Eu, Gd, Tb, Dy and Er and its An aluminum nitride-based fluorescent material in which a part or all of the transition element and the rare earth element are dissolved in aluminum nitride by burning and synthesizing a raw material containing at least one kind of compound and aluminum in an atmosphere containing nitrogen A method of manufacturing a body.
2. Item 2. The method according to Item 1, wherein the raw material further contains 3) boron.
3. Item 2. The method according to Item 1, wherein a part or all of the raw material is an alloy or a compound containing at least two of the transition element, the rare earth element, and aluminum.
4). Some or all of the ingredients
a) the transition element,
b) the rare earth element,
Item 3. The production method according to Item 2, which is an alloy or compound containing at least two of c) boron and d) aluminum.

  According to the production method of the present invention, since the aluminum nitride-based phosphor containing the second element can be produced by combustion synthesis, the film-like phosphor can be provided on an industrial scale.

  In addition, the phosphor obtained by the present invention has a high emission intensity equal to or higher than that of conventional phosphors, and also has characteristics (such as high thermal conductivity) of aluminum nitride because the matrix is made of aluminum nitride. Combined, overall, it can exhibit properties superior to conventional materials.

1. Method for Producing Aluminum Nitride-Based Phosphor The production method of the present invention comprises 1) transition elements and compounds thereof and 2) a raw material containing aluminum and at least one rare earth element and compounds thereof in an atmosphere containing nitrogen. This is a method for producing an aluminum nitride phosphor.

(1) Raw materials The raw materials are collectively referred to as 1) transition elements and compounds thereof and 2) rare earth elements and at least one of the compounds (hereinafter referred to as 1) and 2) as “second elements”. ) And aluminum. That is, the raw material contains at least one second element composed of 1) and 2) and aluminum as essential components.

As the transition element, at least one of Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Ag, and Zn is particularly preferable. As the rare earth element, at least one of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb is particularly preferable.
Furthermore, in the present invention, for the purpose of increasing the emission intensity, at least one of a boron group element selected from boron, gallium, indium, and thallium and a compound thereof (hereinafter, these are also collectively referred to as “third element”). May be included.

  The compounds of these second and third elements include inorganic acid salts (nitrates, sulfates, carbonates, chlorides, etc.), organic acid salts (acetates, oxalates, etc.), oxides, nitrides, In addition to carbides and borides, metal organic compounds containing these elements can be used. Among these, oxides can be preferably used.

In the present invention, as a part or all of the raw material,
a) transition elements,
b) rare earth elements,
It is also possible to use an alloy or compound containing c) at least one boron group element consisting of boron, gallium, indium and thallium and d) at least two kinds of aluminum. In addition, the alloy in this invention is the concept containing an intermetallic compound. Thus, for example, a) an alloy or compound containing a second element and aluminum, b) an alloy or compound containing a third element and aluminum, c) an alloy or compound containing a second element, a third element and aluminum, etc. It can also be used in combination.

  On the other hand, the aluminum used in the present invention is not particularly limited, and commercially available products can also be used. Moreover, the thing by well-known manufacturing methods, such as an atomizing method and a shred method, can be used.

  The purity of aluminum is not particularly limited, but it is generally preferable to use aluminum having a purity of 99% or more, and more preferably 99.9% or more. Although there is no limitation on the upper limit value of purity, it may be usually about 99.999%.

  The ratio of the second element in the raw material may be appropriately determined according to the type of the second element to be used, the composition of the target product, etc., but generally the second element is 0% in the aluminum nitride phosphor. It is desirable to set it to be 0.05 to 10 atomic%, particularly 0.1 to 5 atomic%. By setting within this range, better emission intensity can be obtained.

  The ratio of the third element in the raw material may be appropriately determined according to the type of the third element to be used, the composition of the target product, etc., but generally the third element is 0% in the aluminum nitride phosphor. It is desirable to set it to be 0.05 to 10 atomic%, particularly 0.1 to 5 atomic%. By setting within this range, better emission intensity can be obtained.

  The form of the raw material used in the present invention is not limited, but it is particularly desirable to use it in powder form. In this case, the average particle diameter of the raw material is usually about 100 μm or less, preferably 50 μm or less. In particular, the average particle size of the aluminum powder is usually 1 to 100 μm, preferably 5 to 50 μm. By setting the average particle size of the aluminum powder within the above range, it is possible to more surely perform uniform dispersion of the second element serving as the emission center in the obtained aluminum nitride phosphor.

  The average particle size of the powder of the second element and the third element (in the case of the compound of the second element and the third element, the powder of the compound) is usually 50 μm or less, particularly 20 μm or less, and more preferably 5 μm or less. preferable. When the average particle size of the second element and the third element is 50 μm or less, more excellent dispersibility can be obtained, which contributes to the improvement of the fluorescence characteristics. The lower limit of the average particle size of the powders of the second element and the third element is not particularly limited, but it is usually about 0.1 μm for industrial use.

(2) Combustion synthesis reaction An aluminum nitride-based phosphor is obtained by combustion synthesis of the above raw materials and nitriding the raw materials (particularly aluminum).

  The reaction conditions and operation procedures for combustion synthesis may be the same as those for known combustion synthesis reactions. For example, a raw material is arrange | positioned in nitrogen gas atmosphere, a combustion reaction is started by heating a part of raw material, and reaction can be completed by supplying nitrogen gas continuously.

  In the combustion synthesis of the present invention, usually, the combustion reaction part instantaneously becomes a high temperature of 3000 K or more, and at the same time, aluminum nitride is synthesized, and at the same time, any one or more elements of transition elements and rare earth elements serving as luminescence centers. Part or all of it is dissolved in aluminum nitride.

  After that, the part where the combustion synthesis is completed is rapidly cooled to near room temperature, so that part or all of one or more of the transition elements or rare earth elements serving as the luminescence center are in solid solution (in some cases non-equilibrium) Thus, an aluminum nitride phosphor having a solid solution in a large amount) can be obtained.

  The nitrogen gas concentration in the atmosphere is preferably 20% by volume or more (particularly 50% by volume or more), and the gas pressure is preferably about 0.2 to 3 MPa. Within this range, an appropriate reaction rate can be secured, and safety management is also preferable.

  In addition, for the purpose of adjusting the reaction temperature, commercially available aluminum nitride (powder) or aluminum nitride (powder) according to the present invention can be added to the raw material.

  The reaction product obtained by the combustion synthesis reaction can be used as a phosphor as it is, but after the reaction product is pulverized, it is preferably adjusted to an average particle size of about 1 to 20 μm by classification or the like The aluminum nitride-based phosphor is used. The pulverization may be performed by a known method, and may be performed by either dry pulverization or wet pulverization using an organic solvent or the like as a dispersion medium.

  When producing a phosphor coating film from the aluminum nitride phosphor of the present invention, a phosphor coating film can be produced by molding a mixture containing an aluminum nitride phosphor. More specifically, for example, the phosphor of the present invention is used, mixed with a resin binder or the like to prepare a paste, and the paste is applied or printed on the substrate so as to have a desired pattern. .

2. Aluminum nitride phosphor The phosphor of the present invention contains 0.05 to 10 atomic% of at least one transition element and rare earth element. In particular, the phosphor of the present invention is an aluminum nitride phosphor obtained by the production method of the present invention, and is an aluminum nitride phosphor containing 0.05 to 10 atomic% of at least one transition element and rare earth element. It is desirable.

  The type of the second element is not limited and can be appropriately selected according to desired fluorescence characteristics and the like. In the present invention, as the transition element, at least one of Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Ag, and Zn is particularly preferable. As the rare earth element, at least one of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb is particularly preferable.

  The second element is desirably 0.05 to 10 atomic%, particularly 0.1 to 5 atomic% in the phosphor of the present invention. By setting to such a range, better emission intensity and the like can be obtained.

  The phosphor of the present invention may have a configuration in which part or all of the second element is dissolved in the aluminum nitride matrix. The degree of solid solution of the second element with respect to the aluminum nitride base is not limited, and may be set as appropriate so as to obtain desired fluorescence characteristics.

  The phosphor of the present invention may further contain the third element for the purpose of increasing the emission intensity. The third element is desirably 0.05 to 10 atomic%, particularly 0.1 to 5 atomic% in the phosphor of the present invention. By setting to such a range, better emission intensity and the like can be obtained.

  Although the form of the phosphor of the present invention is not limited, it is usually preferable to be in a powder form. In this case, the average particle size of the powder is generally about 0.5 to 100 μm, and particularly preferably 1 to 50 μm. By setting it in such a range, more excellent dispersibility and the like can be obtained.

  The phosphor of the present invention can be used for the same applications as conventional phosphors, and can be suitably used for production of a film-like phosphor. For example, a film-like phosphor can be formed by applying a paste containing the phosphor of the present invention and a resin binder to a substrate. The resulting film-like phosphors are VFD (fluorescent display tube), FED (field emission display), high brightness CRT (cathode ray tube), PDP (plasma display panel) as a light emitting element, and white LED (light emitting diode). It can be used widely.

  Hereinafter, examples and comparative examples will be shown to clarify the features of the present invention. However, the present invention is not limited to these examples.

  Each physical property in the present invention was measured as follows.

(1) Average particle diameter It measured by the laser diffraction method using "LA-500 type" by Horiba.

(2) Transition element / rare earth element content Measured by ICP emission spectroscopy or flame analysis.

(3) Luminescent characteristics Spectrophotometer (UV light of 254 nm of helium cadmium laser device (“PCLN-U10R” manufactured by USHIO INC.), 12 mW output, and 6 W mercury lamp (irradiated 10 cm away) as an excitation source ( Hamamatsu Photonics "PMA-50").

(4) Stability over time A laser beam having an output of 0.6 mW and a wavelength of 325 nm was condensed to 0.5 mm and irradiated on the sample in the atmosphere.

<Comparative Example 1>
When a commercially available (Cu, Al) -added zinc sulfide green powder phosphor coating film for CRT was irradiated with ultraviolet rays (wavelengths of 325 nm and 254 nm), light emission with a central wavelength of about 530 nm (green) was observed.

<Example 1>
Aluminum powder (average particle size 40 μm) and MnO ₂ powder (average particle size 5 μm) were shaken and mixed in a resin container for 10 minutes to obtain a uniform mixed powder. In this case, the ratio of aluminum to Mn was Al: Mn = 99.7 atomic%: 0.3 atomic%.
20 g of the obtained mixed powder was placed in the center of a 10 cm × 12 cm graphite plate, and this graphite plate was placed in a reaction vessel.

  As a combustion reaction ignition source, a carbon ribbon heater is brought into contact with one end of the mixed powder, degassed to 50 Pa, nitrogen gas is introduced, and when the internal pressure of the container reaches 0.8 MPa, 2. The combustion synthesis reaction was started by energizing at 25 KW for 15 seconds and igniting.

  After completion of the combustion reaction, the synthesized reaction product was pulverized by a vibration mill, and a powdered aluminum nitride-based phosphor (average particle size 10 μm) was obtained by pulverization and sieving. The Mn content in the aluminum nitride phosphor was 0.3 atomic%.

When the obtained aluminum nitride phosphor was irradiated with ultraviolet rays (wavelengths of 325 nm and 254 nm), light emission with a central wavelength of about 600 nm (orange near red) was observed. The emission spectrum is shown in FIG. 1 (“MnO ₂ 0.3%”).

<Example 2>
Aluminium powder (average particle diameter 40 μm) and Eu ₂ O ₃ powder (average particle diameter 1 μm) were used and mixed so that the ratio of aluminum to Eu was Al: Eu = 97 atomic%: 3 atomic%. In the same manner as in Example 1, a powdered aluminum nitride phosphor (average particle size 8 μm) was produced. The Eu content in the obtained aluminum nitride phosphor was 3 atomic%.

When the obtained aluminum nitride phosphor was irradiated with ultraviolet rays (wavelengths of 325 nm and 254 nm), light emission with a center wavelength of about 530 nm (green) was observed. The emission spectrum is shown in FIG. 1 (“Eu ₂ O ₃ 3.0%”) and FIG.

<Example 3>
Aluminium powder (average particle diameter 40 μm) and Sm ₂ O ₃ powder (average particle diameter 1 μm) were used and mixed so that the ratio of aluminum to Sm was Al: Sm = 99 atomic%: 1 atomic%. In the same manner as in Example 1, a powdered aluminum nitride phosphor (average particle size 8 μm) was produced. The Sm content of the obtained aluminum nitride based phosphor was 1 atomic%.

When the obtained aluminum nitride phosphor was irradiated with ultraviolet rays (wavelengths of 325 nm and 254 nm), light emission with a central wavelength of about 700 nm (infrared) was observed. The emission spectrum is shown in FIG. 1 (“Sm ₂ O ₃ 1.0%”).

<Example 4>
Aluminium powder (average particle diameter 40 μm) and Tb ₄ O ₇ powder (average particle diameter 1 μm) were used and mixed so that the ratio of aluminum to Tb was Al: Tb = 99 atomic%: 1 atomic%. In the same manner as in Example 1, a powdered aluminum nitride phosphor (average particle size 8 μm) was produced. The Tb content in the obtained aluminum nitride phosphor was 1 atomic%.

When the obtained aluminum nitride phosphor was irradiated with ultraviolet rays (wavelengths of 325 nm and 254 nm), light emission with a central wavelength of about 550 nm (green) was observed. The emission spectrum is shown in FIG. 1 (“Tb ₄ O ₇ ” 1.0%).

<Example 5>
Aluminum powder (average particle diameter 40 μm), Eu ₂ O ₃ powder (average particle diameter 1 μm) and BN powder (average particle diameter 2 μm) were used, and the ratio of aluminum to Eu and B was Al: Eu: B = 92 atomic%. A powdered aluminum nitride phosphor (average particle size of 8 μm) was produced in the same manner as in Example 1 except that the mixing was carried out so that the concentration was 3 atom% and 5 atom%. The resulting aluminum nitride phosphor had an Eu content of 3 atomic% and a B content of 5 atomic%.

  When the obtained aluminum nitride phosphor was irradiated with ultraviolet rays (wavelengths of 325 nm and 254 nm), light emission with a center wavelength of about 530 nm (green) was observed. The emission spectrum is shown in FIG.

<Test Example 1>
The time-dependent stability of a) the zinc sulfide powder phosphor of Comparative Example 1, b) the aluminum nitride phosphor obtained in Example 1, and c) the aluminum nitride phosphor obtained in Example 2 were measured. The results are shown in FIGS.

It is a spectrum figure of the fluorescent substance obtained in Examples 1-4. It is a spectrum figure of the fluorescent substance obtained in Example 2 and 5. It is a figure which shows the result of having measured the temporal stability of the zinc sulfide powder fluorescent substance of the comparative example 1. FIG. It is a figure which shows the result of having measured temporal stability of the aluminum nitride-type fluorescent substance obtained in Example 1. FIG. It is a figure which shows the result of having measured temporal stability of the aluminum nitride-type fluorescent substance obtained in Example 2. FIG.

Claims (4)

1) at least one transition element of Ti, V, Cr, Mn, Co, Cu and Zn and a compound thereof; and 2) at least one rare earth element of Sm, Eu, Gd, Tb, Dy and Er and a compound thereof, An aluminum nitride-based phosphor in which a part or all of the transition element and the rare earth element are dissolved in aluminum nitride by burning and synthesizing a raw material containing at least one of aluminum and aluminum in an atmosphere containing nitrogen. How to manufacture. The manufacturing method according to claim 1, wherein the raw material further contains 3) boron. The manufacturing method according to claim 1, wherein a part or all of the raw material is an alloy or a compound containing at least two of the transition element, the rare earth element, and aluminum. Some or all of the ingredients
a) the transition element,
b) the rare earth element,
The production method according to claim 2, which is an alloy or compound containing at least two of c) boron and d) aluminum.

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