WO2011108740A1 - Li含有α-サイアロン系蛍光体粒子とその製造方法、照明器具ならびに画像表示装置 - Google Patents
Li含有α-サイアロン系蛍光体粒子とその製造方法、照明器具ならびに画像表示装置 Download PDFInfo
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- WO2011108740A1 WO2011108740A1 PCT/JP2011/055176 JP2011055176W WO2011108740A1 WO 2011108740 A1 WO2011108740 A1 WO 2011108740A1 JP 2011055176 W JP2011055176 W JP 2011055176W WO 2011108740 A1 WO2011108740 A1 WO 2011108740A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/26—Materials of the light emitting region
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/0883—Arsenides; Nitrides; Phosphides
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
- C09K11/7728—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing europium
- C09K11/77348—Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/50—Wavelength conversion elements
Definitions
- the present invention relates to an optical functional material having a function of converting a part of irradiated light into light having a different wavelength, and a method for manufacturing the same.
- the present invention relates to a sialon-based phosphor particle activated with a rare earth metal element suitable for an ultraviolet to blue light source.
- the present invention also relates to a method for producing the sialon phosphor particles, a light emitting device and an image display device using the same.
- LEDs blue light emitting diodes
- white LEDs using these blue LEDs have been vigorously developed.
- White LEDs have lower power consumption and longer life than existing white light sources, and are therefore being used for backlights for liquid crystal panels, indoor and outdoor lighting devices, and the like.
- the white LED that has been developed is one in which YAG (yttrium, aluminum, garnet) doped with Ce is applied to the surface of a blue LED.
- YAG yttrium, aluminum, garnet
- the fluorescence wavelength of YAG doped with Ce is in the vicinity of 530 nm. If this fluorescent color and the light of a blue LED are mixed to form white light, white light with strong bluish light is obtained, and good white color cannot be obtained.
- ⁇ -sialon is also required to emit various colors of fluorescence that can produce white light sources of various color temperatures. Therefore, a sialon-based phosphor that can emit fluorescence having a shorter wavelength is desired.
- Non-Patent Document 1 in the ⁇ -sialon phosphor containing Ca, the fluorescence intensity decreases when the fluorescence wavelength is shorter than 595 nm. For this reason, it has been difficult to produce a sialon-based phosphor that emits short-wavelength fluorescence suitable for producing a high-brightness daylight white or daylight color LED in combination with a blue LED.
- Patent Document 2 discloses a Li (lithium) -containing ⁇ -sialon-based phosphor.
- This sialon can emit fluorescence having a shorter wavelength than the Ca-containing ⁇ -sialon phosphor.
- the fluorescent light having the same fluorescence wavelength as that of Ca-containing ⁇ -sialon can be emitted, the applicable color range is wide and the phosphor is very convenient.
- it is produced in a pressurized nitrogen-containing atmosphere.
- it is commercially preferred to produce in an atmospheric atmosphere in terms of device safety and cost.
- a high fluorescence intensity cannot be easily obtained in a nitrogen-containing atmosphere at normal pressure. This is considered to be because Li-containing ⁇ -sialon is caused by the fact that the evaporation of Li increases in the production process, and thus the crystal site of Eu, which is a light emitting element, is not stable.
- the present invention has been made to solve the above-described problems of sialon-based phosphors.
- a white light emitting diode of daylight or daylight color is produced in combination with a blue LED with high fluorescence intensity.
- An object of the present invention is to provide a phosphor that emits a fluorescent color that can be used.
- the present invention also provides an illumination device such as a white LED that emits a daylight white or daylight color using an ultraviolet or blue LED as a light source by providing a Li-containing ⁇ -sialon-based phosphor with high fluorescence intensity. Objective.
- an object of the present invention is to provide a novel method for producing a sialon-based phosphor capable of emitting the fluorescent color as described above with high intensity and with high yield.
- the present inventors have studied the fluorescence intensity of an ⁇ -sialon-based phosphor containing Li and Eu (europium), and further mixed and fired a Li source to the Li-containing ⁇ -sialon once produced. Thus, the inventors have found that the fluorescence intensity is greatly improved and have completed the present invention. Moreover, it discovered that the Li containing alpha-sialon produced in that way exhibited a special form.
- Li-containing ⁇ -sialon phosphor particles having a sialon surface layer having a concavo-convex surface microstructure formed by sialon in the form of fine particles [2] Li-containing ⁇ -sialon phosphor particles according to [1], wherein 0 ⁇ and 0.3 ⁇ x / m ⁇ 0.9. [3] The Li-containing ⁇ -sialon phosphor particles according to [1] or [2], wherein the lithium-containing ⁇ -sialon phosphor particles have an average particle diameter of 0.5 to 30 ⁇ m.
- Li source comprising powder of silicon nitride or nitrogen-containing silicon compound, aluminum source material containing AlN, and Li nitride, oxynitride, oxide or precursor material that becomes oxide by thermal decomposition And an Eu source made of Eu nitride, oxynitride, oxide, or precursor material that becomes oxide by thermal decomposition, and in an inert gas atmosphere containing nitrogen at atmospheric pressure, 1500 to 1800 ° C.
- a lithium-containing ⁇ -sialon powder as an intermediate, an additional lithium source is added to the powder, and the temperature is lower than the firing temperature in an inert gas atmosphere containing atmospheric nitrogen Or a method for producing Li-containing ⁇ -sialon phosphor particles, which is refired at 1100 ° C. or more and less than 1600 ° C.
- the x / m is at least x / m as compared with the lithium-containing ⁇ -sialon phosphor particles as the intermediate.
- the lithium-containing ⁇ -sialon phosphor particles as the intermediate have the light absorptance of 65% or more in a wavelength region near 450 nm, according to any one of [6] to [8] Of producing Li-containing ⁇ -sialon phosphor particles.
- the additional lithium source is 0.05 to 1.6 mol in terms of metallic Li with respect to 1 mol of the lithium-containing ⁇ -sialon powder as the intermediate, [6] to [9]
- the manufacturing method of Li containing alpha-sialon fluorescent substance particle in any one of.
- Li-containing ⁇ -sialon-based phosphor of the present invention (hereinafter referred to as “Li-containing ⁇ -sialon-based phosphor as a final product”) is a Li-containing ⁇ -sialon (hereinafter referred to as “intermediate product”). Li-containing ⁇ -sialon-based phosphor ”)) can be obtained by re-diffusion of Li to obtain a Li-containing ⁇ -sialon exhibiting high fluorescence intensity that has not been obtained in the past.
- An illumination device such as a white LED that emits a daylight white color or a daylight color can be provided.
- FIGS. 1A to 1B are scanning electron microscope (SEM) photographs of the sample (particles) of Example 1.
- FIG. FIG. 2 is an EDS analysis result of the sample of Example 1.
- FIG. 3 is a photograph of the particle morphology observed by SEM for the sample (particles) with reduced fluorescence intensity due to re-diffusion of Li at 1600 ° C. shown in Comparative Example 10.
- FIG. 4 is a photograph of the particle morphology observed by SEM for the sample (particles) whose fluorescence intensity has been improved by re-diffusion of Li at 1600 ° C. shown in Example 9.
- a Li component is added to a Li-containing ⁇ -sialon-based phosphor (intermediate) once manufactured, and then refired.
- the Li-containing ⁇ -sialon-based phosphor particles as the final product of the present invention are represented by the general formula (1): Li x Eu y Si 12- (m + n) Al (m + n) On + ⁇ N 16-n- ⁇ Sialon.
- the Li-containing ⁇ -sialon-based phosphor (“Li-containing ⁇ -sialon-based phosphor as an intermediate”) before refiring is also represented by the general formula (1): Li x Eu y Si 12- (m + n) Al (m + n)
- a sialon represented by On + ⁇ N16 -n- ⁇ is preferred but not limited.
- x is smaller than 0.3, the fluorescence intensity is lowered, and when it is larger than 1.2, a heterogeneous phase is generated, and a single-phase ⁇ -sialon phosphor cannot be obtained.
- the Li-containing ⁇ -sialon phosphor as an intermediate is preferably a single-phase ⁇ -sialon phosphor.
- the composition range in which the fluorescence intensity is high is 0.4 ⁇ x ⁇ 1.2, and further 0.5 ⁇ x ⁇ 1.1.
- the fluorescence wavelength shifts to a shorter wavelength as the Li content increases, and can be changed in the range of 565 nm to 590 nm at the peak wavelength.
- Eu is an element that is a solid solution in the Li-containing ⁇ -sialon phosphor and becomes a light source, and y is preferably 0.001 ⁇ y ⁇ 0.2.
- a bright phosphor cannot be obtained because the number of light emitting sources with y less than 0.001 is reduced, and a sialon that emits short-wavelength fluorescence cannot be obtained when y is greater than 0.2.
- a more preferable range is 0.01 ⁇ y ⁇ 0.15, and a further preferable range is 0.01 ⁇ y ⁇ 0.15.
- M and n are 1.0 ⁇ m ⁇ 2.9 and 0.05 ⁇ n ⁇ 2.5.
- the solid solution penetrated.
- the number of Al atoms substituted by Si atoms in excess of the number of substituted Al atoms at the cation site corresponding to the number of metal elements (Li and Eu) is expressed as ⁇ (in the present invention, ⁇ > 0). ). If m is less than 1.0, the solid solution amount of the metal elements (Li and Eu) is so small that it is difficult to stabilize the sialon crystal, so that the fluorescence intensity of the phosphor may be lowered. When the m value is larger than 2.9, a crystal phase other than sialon is easily generated. n is a value related to the substitutional solid solution amount of oxygen in the Li-containing ⁇ -sialon phosphor.
- n value is smaller than 0.05 or (n + ⁇ ) is smaller than 0.1, the solid solution amount of the metal elements (Li and Eu) is small, and the sialon crystal is difficult to stabilize, so that the fluorescence intensity may decrease. There is.
- n value is larger than 2.5 or (n + ⁇ ) is larger than 3.2, the absorptance becomes small, which is not preferable, and a crystal phase other than sialon is easily generated. More preferable ranges are 1.0 ⁇ m ⁇ 2.2, 0.2 ⁇ n ⁇ 2.0, 0.8 ⁇ n + ⁇ ⁇ 2.5, and still more preferable ranges are 1.1 ⁇ m ⁇ 2. 2, 1.0 ⁇ n ⁇ 2.3 and 1.0 ⁇ n + ⁇ ⁇ 2.0.
- the heterogeneous phase refers to a crystal phase different from the crystal phase of the Li-containing ⁇ -sialon phosphor, and is a heterogeneous phase identified by a diffraction pattern of X-ray diffraction, which does not appear in X-ray diffraction, For example, glass is not included.
- a single phase means a single crystal phase in which there is no heterogeneous phase identified by a diffraction pattern of X-ray diffraction.
- Li-containing ⁇ -sialon In the production of Li-containing ⁇ -sialon, the evaporation of Li element that does not occur in other sialons becomes significant. Such evaporation is not a problem with, for example, Ca-containing ⁇ -sialon. Since the phosphor emits higher fluorescence as the crystal with higher integrity, the synthesis is usually performed at the highest possible temperature. However, in the case of Li-containing ⁇ -sialon, there is a problem that at such temperatures, the evaporation of Li becomes intense and the fluorescence intensity decreases. As an approach to this problem, it can be considered that a large amount of Li is charged into the raw material in consideration of the evaporation of Li. The inventors have taken such measures.
- a Li-containing ⁇ -sialon is produced by raising the firing temperature for the purpose of ignoring the evaporation of Li and creating a crystal skeleton.
- characteristics deteriorate due to Li defects due to evaporation of Li. Therefore, later, only Li is replenished to the crystal to form a more complete crystal.
- This is a method that makes use of the feature that Li element easily diffuses with a relatively small ion radius, and is a method that makes good use of the characteristics of Li element.
- Li-containing ⁇ -sialon phosphor particles are provided. Moreover, it can be inferred from the morphological features that there is a special diffusion effect rather than simple Li re-diffusion.
- the form of the phosphor particles of Li-containing ⁇ -sialon thus obtained is shown in FIG. It appears that fine particles are attached to the surface of the particles, forming an uneven surface (fine structure).
- FIG. 1 (b) the particle morphology of the intermediate sample before re-diffusion of Li was observed. In this case, fine particles (unevenness) were not observed on the surface. From this, it is certain that the addition of the Li source is involved in the generation of fine particulate matter on the surface.
- EDS energy dispersive X-ray spectroscopy
- the value of x is the value of Li-containing ⁇ -sialon phosphor particles as an intermediate.
- the range is 0.4 ⁇ x ⁇ 1.5, more preferably 0.5 ⁇ x ⁇ 1.4, and still more preferably 0.6 ⁇ x ⁇ 1.35.
- the fluorescence intensity of the Li-containing ⁇ -sialon phosphor as the final product is improved even when 0.4 ⁇ x ⁇ 1.2.
- the fluorescence intensity is low, and even if it is greater than 1.5, the fluorescence intensity cannot be increased.
- the composition range in which the fluorescence intensity increases is 0.5 ⁇ x ⁇ 1.5, and further 0.6 ⁇ x ⁇ 1.31.
- the fluorescence wavelength shifts to a shorter wavelength as the Li content increases, and can be changed in the range of 565 nm to 590 nm at the peak wavelength.
- the values of y, m, n, ⁇ , and (n + ⁇ ) are basically in the same range as the Li-containing ⁇ -sialon-based phosphor particles as an intermediate including the preferable range, but the upper limit of m is 2 .8.
- the Li-containing ⁇ -sialon-based phosphor particles as the final product of the present invention are characterized by ⁇ > 0, particularly ⁇ is 0.05 to 1.1, and the ratio of x and m It is more preferable that x / m is 0.3 to 0.9 because the fluorescence intensity increases. More preferably, ⁇ is 0.05 to 1.0 and the x / m ratio is 0.4 to 0.6.
- the Li-containing ⁇ -sialon-based phosphor particles as the final product of the present invention have an increased x / m ratio x / m compared to the Li-containing ⁇ -sialon-based phosphor particles as the intermediate.
- the ratio x / m between x and m is preferably 0.3 or more, but may be less than 0.3. It may be 0.2 or even 0.15.
- the Li-containing ⁇ -sialon phosphor particle main body may be either a primary particle or a secondary particle, and its size is generally 0.5 to 30 ⁇ m, preferably 1 to 20 ⁇ m, more preferably 5 to 20 ⁇ m. It is. In the case of secondary particles, the size of the primary particles is preferably 0.5 to 8 ⁇ m, more preferably 1 to 5 ⁇ m.
- the particle diameter of the Li-containing ⁇ -sialon phosphor particles may be determined by measuring the longest diameter and the shortest diameter of each particle from an SEM photograph and obtaining an equivalent circular radius from an ellipse based on the longest diameter and the shortest diameter. it can.
- the average particle diameter may be a number average.
- the surface layer that covers the surface of such a Li-containing ⁇ -sialon phosphor particle body and has a concavo-convex microstructure is formed of sialon having a dimension (average diameter observed by SEM) of 1 ⁇ m or less, particularly Li-containing ⁇ -sialon. ing.
- the size of the particulate sialon present on the surface of the phosphor particle body can be 0.5 ⁇ m or less, 0.3 ⁇ m or less, or 0.2 ⁇ m or less. Although the minimum of a dimension is not specifically limited, Generally, it is 0.001 micrometer or 0.01 micrometer. As can be seen in FIG. 1A, such fine fine-particle sialon covers the surface of the Li-containing ⁇ -sialon particle main body almost entirely to form an uneven surface.
- the surface layer having a concavo-convex microstructure formed on the surface of the Li-containing ⁇ -sialon particles is a sialon phase and can be the same quality as the Li-containing ⁇ -sialon particle body.
- the homogeneous material is a sialon composed of at least the same constituent elements (Li, Eu, Si, Al, O, N), and preferably has a composition represented by the general formula (1). It is not limited. This is a sialon surface layer formed on the surface when the Li source is mixed with the Li-containing ⁇ -sialon particle main body as an intermediate and Li is diffused inside the particle to increase the Li content ratio of the particle.
- the constituent elements of the layer were the same as those of the Li-containing ⁇ -sialon particle main body, but it was sufficient that Li was internally diffused in the Li-containing ⁇ -sialon particle main body to increase the Li content of the main body. Is preferably the same sialon up to the body, crystal phase and composition, but it is not necessary.
- the concavo-convex microstructure formed on the surface is certainly due to the addition of Li, but sialon is generated on the surface with Li attached to the surface as the nucleus, or solid solution Li diffuses on the surface and new on the surface It is unclear at present whether it will form a sialon. If the former is considered to be attached to the surface as particles, the latter is captured as deformation of the parent sialon particles. The inventors think that the possibility of the latter is high because surface deposits are not observed as clear particles from the SEM photograph of FIG.
- FIG. 1A shows a sample fired at 1400 ° C.
- FIG. 4 shows the result of observing the surface of Example 9 treated at 1600 ° C. Here it clearly looks like particles.
- Li diffused at a low temperature gathers on the surface and forms irregularities on the surface, and further, they become particles and eventually evaporate. I am thinking about the process. In that sense, even if the deposit looks like particles, the particles do not come from the outside.
- the completeness of the crystallinity of the Li-containing ⁇ -sialon phosphor particles provided by the present invention is expressed by crystallographic indicators such as the half width of the X-ray diffraction peak.
- crystallographic indicators such as the half width of the X-ray diffraction peak.
- the absorptance of the Li-containing ⁇ -sialon phosphor particles in the vicinity of 450 nm is preferably 65% or more, more preferably 70% or more, and more preferably 80% or more. The higher the absorptance, the more pronounced the effect of Li re-diffusion. Below 65%, the effect of re-diffusion is reduced.
- the Li-containing ⁇ -sialon phosphor powder is composed of a silicon nitride powder, a material that becomes an aluminum source containing AlN, and a nitride material, oxynitride, oxide, or precursor material that becomes an oxide by thermal decomposition.
- Li source, and Eu source consisting of Eu nitride, oxynitride, oxide, or precursor material that becomes oxide by thermal decomposition so as to have a calculated Li-containing ⁇ -sialon-based phosphor composition Weigh and mix to obtain a mixture.
- the calculated Li-containing ⁇ - sialon-based phosphor composition is a composition represented by Li x Eu y Si 12- (m + n) Al (m + n) O n N 16-n, an excess of Li The composition added to may be sufficient.
- silicon nitride or nitrogen-containing silane compound powder As the raw material silicon nitride or nitrogen-containing silane compound powder, crystalline silicon nitride, nitrogen-containing silane compound and / or amorphous silicon nitride powder may be used.
- the nitrogen-containing silane compound and / or amorphous silicon nitride powder as the main raw material may be obtained by a known method, for example, by vaporizing silicon halide such as silicon tetrachloride, silicon tetrabromide, silicon tetraiodide and ammonia in the gas phase.
- a Si—N—H system precursor compound such as silicon diimide produced by reacting in a liquid phase can be obtained by thermal decomposition at 600 to 1200 ° C. in a nitrogen or ammonia gas atmosphere.
- the crystalline silicon nitride powder is obtained by firing the obtained nitrogen-containing silane compound and / or amorphous silicon nitride powder at 1300 ° C. to 1550 ° C.
- Crystalline silicon nitride can also be obtained by nitriding metal silicon directly in a nitrogen atmosphere, but this method requires a pulverization step to obtain a fine powder, so impurities are easily contained. It is preferable to employ a method of decomposing a precursor that easily obtains a pure powder.
- the nitrogen-containing silane compound and / or the amorphous silicon nitride powder and the crystalline silicon nitride powder are those having an oxygen content of 1 to 5% by mass. Those having an oxygen content of 1 to 3% by mass are more preferred.
- the oxygen content is less than 1% by mass, the formation of an ⁇ -sialon phase due to the reaction in the firing process becomes extremely difficult, and the residual crystal phase of the starting material and the generation of AlN polytypes such as 21R are not preferable.
- the oxygen content exceeds 5% by mass, the ⁇ -sialon production reaction is promoted, but the production rate of ⁇ -sialon and oxynitride glass increases.
- the nitrogen-containing silane compound and / or the amorphous silicon nitride powder preferably has a specific surface area of 80 to 600 m 2 / g. More preferably, 340 to 500 m 2 / g.
- a raw material having a specific surface area (BET specific surface area) of 1 m 2 / g to 15 m 2 / g is preferably used.
- Examples of the aluminum source include aluminum oxide, metal aluminum, and aluminum nitride. Each of these powders may be used alone or in combination.
- As the aluminum nitride powder a general powder having an oxygen content of 0.1 to 8% by mass and a specific surface area of 1 to 100 m 2 / g can be used.
- the lithium (Li) source is selected from Li nitrides, oxynitrides, oxides, or precursor materials that become oxides by thermal decomposition.
- Li nitrides lithium oxide (Li 2 O), lithium carbonate (Li 2 CO 3 ), lithium nitride (Li 3 N), and the like.
- Li 2 O lithium oxide
- Li 2 CO 3 lithium carbonate
- Li 3 N lithium nitride
- Most preferred is Li 2 O.
- Lithium carbonate is not preferred because it releases excess carbon dioxide. Since Li 3 N is oxidized in the atmosphere, it becomes difficult to handle.
- the Eu source is selected from Eu nitrides, oxynitrides, oxides or precursor materials that become oxides upon thermal decomposition, for example, europium oxide (Eu 2 O 3 ), europium carbonate (Eu 2 (CO 3 ) 3 ), europium nitride (EuN) and the like. Most preferred is Eu 2 O 3 . Europium carbonate is not preferred due to the release of excess carbon dioxide. Since EuN is oxidized in the atmosphere, it becomes difficult to handle.
- metal salts such as respective carbonates, oxalates, citrates, basic carbonates and hydroxides can be exemplified.
- the amount of metal impurities other than the constituent components of the Li-containing ⁇ -sialon phosphor is 0.01% by mass or less.
- the content of metal impurities is preferably 0.01% by mass or less, preferably 0.005% by mass or less, more preferably 0.001% by mass is used.
- the metal impurity content in the case of the oxide of the metal Li oxide or the precursor material that becomes an oxide by thermal decomposition and the metal Eu oxide or the precursor material that becomes an oxide by thermal decomposition is 0. It is preferable to use one having a mass of 0.01% by mass or less.
- the method for mixing each of the starting materials is not particularly limited.
- a method known per se for example, a dry mixing method, a wet mixing in an inert solvent that does not substantially react with each component of the starting material, and then the solvent is added.
- a removal method or the like can be employed.
- a V-type mixer, a rocking mixer, a ball mill, a vibration mill, a medium stirring mill, or the like is preferably used.
- the nitrogen-containing silane compound and / or amorphous silicon nitride powder is extremely sensitive to moisture and moisture, it is necessary to mix the starting materials in a controlled inert gas atmosphere. .
- the starting material mixture is fired at 1400 to 1800 ° C., preferably 1500 to 1800 ° C., more preferably 1600 to 1750 ° C. in a nitrogen-containing inert gas atmosphere at normal pressure, and the target Li-containing ⁇ -sialon phosphor A powder is obtained.
- the inert gas include helium, argon, neon, and krypton. In the present invention, these gases and a small amount of hydrogen gas can be mixed and used.
- the firing temperature is lower than 1400 ° C., it takes a long time to produce the desired Li-containing ⁇ -sialon phosphor powder, which is not practical.
- generation powder also falls.
- the firing temperature exceeds 1800 ° C., an undesirable situation occurs in which silicon nitride and sialon undergo sublimation decomposition and free silicon is generated.
- Li-containing ⁇ -sialon after firing differs from the charged composition due to evaporation of Li and the like.
- the heating furnace used for firing the powder mixture there are no particular restrictions on the heating furnace used for firing the powder mixture.
- a batch-type electric furnace, rotary kiln, fluidized firing furnace, pusher-type electric furnace, or the like using a high-frequency induction heating system or a resistance heating system is used. be able to.
- a BN crucible, a silicon nitride crucible, a graphite crucible, or a silicon carbide crucible can be used.
- the inner wall is preferably covered with silicon nitride, boron nitride or the like.
- Li-containing ⁇ -sialon and the diffusing Li source powder are weighed and mixed.
- a raw material to be a Li source the above-described materials such as a nitride, oxynitride, oxide, or oxide by thermal decomposition can be employed.
- Li-containing ⁇ -sialon and Li source are mixed using a mixer such as a vibration mill, and the mixture is put into a crucible such as an alumina crucible, BN crucible, silicon nitride crucible, carbon crucible or the like. Baking is performed in a nitrogen-containing atmosphere at normal pressure.
- the firing temperature may be any temperature that is lower than the firing temperature at the time of producing the Li-containing ⁇ -sialon as an intermediate, but generally 1100 to 1600 ° C. is employed.
- the temperature is preferably 1300 to 1500 ° C, more preferably 1350 to 1450 ° C. If it is less than 1100 ° C., the effect of improving the fluorescence intensity is small, and if it exceeds 1600 ° C., the evaporation of Li increases, and the effect of improving the fluorescence intensity is small, which may cause a decrease. Further, the firing temperature for re-diffusion of Li is additional if the firing temperature is within the range of 1100 to 1600 ° C.
- An inert gas can be used as a gas other than nitrogen in the nitrogen-containing atmosphere, and examples of the inert gas include helium, argon, neon, krypton, and the like. It is also possible to use a mixture with hydrogen gas.
- the holding time at the firing temperature is preferably 0.5 to 5 hours. If it is less than 0.5 hours, there is a possibility that sufficient reaction does not proceed. Even if it exceeds 5 hours, the effect of improving the fluorescence intensity is manifested, but a remarkable effect cannot be obtained, and the production cost increases, which is not preferable.
- the powder after firing is weakly fused after being taken out, it is crushed lightly, and if necessary, the glass layer attached to the particle surface is removed and evaluated as a phosphor.
- the heating furnace used for re-diffusion of Li is not particularly limited.
- a batch type electric furnace, a rotary kiln, a fluidized firing furnace, a pusher type electric furnace or the like using a high frequency induction heating method or a resistance heating method is used. be able to.
- the crucible for firing an alumina crucible, a BN crucible, a silicon nitride crucible, a graphite crucible, or a silicon carbide crucible can be used.
- the inner wall is preferably covered with silicon nitride, boron nitride or the like.
- the Li-containing ⁇ -sialon-based phosphor thus obtained has a glass layer attached to the surface, and in order to obtain a phosphor with higher fluorescence intensity, it is preferable to remove the glass layer.
- cleaning with an acid is easiest.
- the sialon particles are placed in an acid solution selected from sulfuric acid, hydrochloric acid or nitric acid to remove the glass layer on the surface.
- the concentration of the acid solution is 0.1 N to 7 N, preferably 1 N to 3 N. If the concentration is excessively high, the oxidation proceeds remarkably and good fluorescence characteristics cannot be obtained.
- sialon phosphor powder 5 wt% of sialon phosphor powder is added to the acid solution of which the concentration is adjusted, and the solution is kept for a desired time while stirring. After washing, the solution containing the sialon phosphor powder is filtered, washed with water, washed away with acid, and dried.
- the Li-containing ⁇ -sialon-based phosphor activated with rare earth elements of the present invention is kneaded with a transparent resin such as an epoxy resin or an acrylic resin by a known method to produce a coating agent, and the surface is coated with the coating agent.
- a transparent resin such as an epoxy resin or an acrylic resin
- a light emission source having a peak wavelength of excitation light in the range of 330 to 500 nm is suitable for a Li-containing ⁇ -sialon phosphor.
- the luminous efficiency of the Li-containing ⁇ -sialon-based phosphor is high, and a light-emitting element with good performance can be configured.
- the luminous efficiency is high, and a good light-white to daylight light-emitting element can be configured by combining the yellow fluorescence of the Li-containing ⁇ -sialon phosphor and the blue excitation light.
- the daylight white color or the daylight color can be controlled to a warm light bulb color region.
- a light-emitting element having a light bulb color can be widely used for general household lighting.
- day white means a correlated color temperature of 4600 to 5500 K according to JIS
- daylight color means a correlated color temperature of 5700 to 7100 K.
- an image display element using a Li-containing ⁇ -sialon phosphor.
- the light-emitting element described above can be used, but it is also possible to directly emit light by exciting the Li-containing ⁇ -sialon-based phosphor using an excitation source such as an electron beam, an electric field, or ultraviolet light.
- an excitation source such as an electron beam, an electric field, or ultraviolet light.
- it can be used on the principle of a fluorescent lamp.
- Such a light emitting element can also constitute an image display device.
- Li-containing sialon having various compositions was prepared. A specific manufacturing method is shown as an example.
- the number was assumed to be trivalent at the time of the raw material).
- the weighed raw materials were mixed in a nitrogen atmosphere using a dry vibration mill to obtain a mixed powder. This powder is put in a crucible made of silicon nitride, charged in an electric furnace, heated in a normal pressure atmosphere while flowing nitrogen, held at the holding temperature shown in Table 1 for 12 hours, and fired. - ⁇ -sialon was obtained.
- the composition of the Li- ⁇ -sialon thus obtained is different from the charged composition.
- the powder taken out was washed with a 2N nitric acid solution and the surface glass layer was removed.
- Oxygen nitrogen was measured using an oxygen-nitrogen simultaneous analyzer manufactured by LECO, and other elements.
- the composition of sialon was calculated from the analysis results and shown in Table 1.
- Eu has a valence of 2.
- ICP analysis is as follows. For Li, after subjecting the sample to pressure acid decomposition with nitric acid and hydrofluoric acid, the mixture was heated and concentrated until white smoke was generated by adding sulfuric acid, and hydrochloric acid was added thereto. After dissolution by heating, quantitative analysis was performed by ICP-AES method using SPS5100 model manufactured by SII Nanotechnology. For Si, the sample was melted by heating with sodium carbonate and boric acid, then dissolved in hydrochloric acid, and quantitative analysis was performed according to the coagulation weight method. For Al and Eu, the filtrate obtained by the pretreatment for the quantitative analysis of Si was collected and subjected to quantitative analysis by ICP-AES.
- S1-5 was a sialon single phase, but S6-7 was a 12H type crystal which is a polymorph of AlN as a different phase in addition to sialon.
- S6 to 7 do not represent the sialon composition, but are the results when the entire composition is assumed to be sialon. Therefore, the composition of S6 to 7 has no physical meaning.
- the calculated ⁇ was positive, and Li was insufficient and Al was excessive as compared with ordinary Li- ⁇ -sialon.
- Lithium oxide Li 2 O, high-purity chemistry, 99.0%
- Li- ⁇ -sialon Li- ⁇ -sialon shown in Table 1, and mixed using a vibration mill.
- the obtained powder was put into an alumina crucible and heated under the firing conditions shown in Table 2 at a heating rate of 300 ° C./h. After calcination, acid washing was performed with a 2N nitric acid solution, and composition measurement and fluorescence measurement were performed by the methods described above. The results are shown in Table 2. It can be seen that the fluorescence intensity is greatly improved.
- the results of composition analysis are also shown in Table 2.
- the amount of change shown in Table 2 is a value obtained by dividing the amount of increase in the fluorescence intensity ratio by the fluorescence intensity ratio of the used sialon (S1 to S7) (that is, the change ratio of the fluorescence intensity ratio).
- An SEM photograph of the sialon particles obtained is shown in FIG. Since the surface deposits of the parent sialon particles are not observed as distinct particles, the surface deposits are considered to be deformations of the parent sialon particles.
- Comparative Examples 1 and 2 Li was re-diffused in the same manner as in Example 1 except that sialon (S6, S7) shown in Table 2 was used. As a result, it was confirmed that there was little improvement in fluorescence intensity by Li re-diffusion.
- the absorption rate of the raw material sialon (S6, S7) used in Comparative Examples 1 and 2 is lower than 65%, and the Li re-diffusion effect cannot be obtained for Li- ⁇ -sialon having such a low absorption rate.
- Comparative Examples 3-7 Li re-diffusion was performed in the same manner as in Example 1 except that sialons (S3 to S5) shown in Table 3 were used and the treatment temperature was 1000 ° C.
- the fluorescence intensity is improved as in Examples 3 to 5.
- the amount to be improved is small, and as a result, absolute fluorescence intensity is not obtained.
- the absorption rate of the raw material is smaller than 65%. Under such conditions, the effect of re-diffusion of Li cannot be obtained at all.
- Examples 6-8 Li re-diffusion was performed in the same manner as in Example 1 except that sialons (S3 to S5) shown in Table 3 were used and the treatment temperature was extended to 5 hours. An improvement in fluorescence properties is seen. However, the improvement is almost the same as in Examples 3-5. In the treatment, temperature is more important than time.
- Comparative Examples 8 and 9 Li re-diffusion was performed in the same manner as in Example 1 except that the sialon (S6, S7) shown in Table 3 was used and the treatment temperature was extended to 5 hours. As a result, it was confirmed that there was little improvement in fluorescence intensity by Li re-diffusion.
- the absorption rate of the raw material sialon (S6, S7) used in Comparative Examples 8 and 9 is lower than 65%. With regard to Li- ⁇ -sialon having such a low absorption rate, even if the re-diffusion time of Li is extended, Li The effect of re-diffusion cannot be obtained.
- Example 9 Li re-diffusion was performed in the same manner as in Example 1 except that the treatment temperature was changed to 1600 ° C. using sialon (S3) shown in Table 3. As shown in Table 3, the fluorescence intensity was improved as in Example 3.
- Comparative Examples 10 and 11 Li re-diffusion was performed in the same manner as in Example 1 except that the treatment temperature was changed to 1600 ° C. using sialon (S4, S5) shown in Table 3.
- the absorptivity of the used sample was 65% or more, and there was an effect at 1300 ° C. as in Examples 4 and 5.
- the effect of improving the fluorescence intensity was not seen at 1600 ° C.
- the processing temperature is raised, there is a tendency that the effect cannot be obtained.
- Comparative Example 12 Using the sialon (S3) shown in Table 3, firing was performed in the same manner as in Example 1 except that Li addition was set to zero. There was no improvement in fluorescence intensity. It can be seen that the effect of this patent is brought about by the addition of Li.
- Examples 10 and 11 Li re-diffusion was performed in the same manner as in Example 1 except that the addition amount of Li was changed using sialon (S3) shown in Table 3. An improvement in fluorescence intensity was observed. It has been found that a sufficiently large effect can be obtained even when the amount of Li 2 O added is 0.03 mol. On the other hand, even if the amount of Li 2 O added was increased to 0.75 mol, the amount of change did not increase compared to Example 3. It can be seen that the improvement in fluorescence intensity does not increase as the amount of addition increases.
- Example 12 Li re-diffusion was performed in the same manner as in Example 1 except that sialon (S3) shown in Table 3 was used and lithium carbonate was added in an amount shown in Table 3 as a Li source. An improvement in fluorescence intensity was observed.
- sialon (S3) shown in Table 3 was used and lithium carbonate was added in an amount shown in Table 3 as a Li source. An improvement in fluorescence intensity was observed.
- Example 13 Using sialon (S3) shown in Table 3, lithium nitride was added in an amount shown in Table 3 as a Li source, mixed in a nitrogen box, and a raw material was prepared without touching oxygen. Other than that, Li was re-diffused in the same manner as in Example 1. An improvement in fluorescence intensity was observed.
- Sialon (S3) shown in Table 3 lithium nitride was added in an amount shown in Table 3 as a Li source, mixed in a nitrogen box, and a raw material was prepared without touching oxygen. Other than that, Li was re-diffused in the same manner as in Example 1. An improvement in fluorescence intensity was observed.
- Example 14 Using sialon (S3) shown in Table 3, Li was re-diffused in the same manner as in Example 1 except that a boron nitride crucible was used as the crucible. An improvement in fluorescence intensity was observed.
- the particulate material is in the Li 2 O without considered to be sialon.
Abstract
Description
〔1〕一般式(1):
LixEuySi12−(m+n)Al(m+n)On+δN16−n−δ (1)
(式中、0.4≦x≦1.5、0.001≦y≦0.2、1.0≦m≦2.8、0.1≦n+δ≦3.2であり、Euの平均価数をaとすると、x+ya+δ=mである。)
で表されるリチウム含有α−サイアロン蛍光体粒子であって、450nm付近の波長領域において光の吸収率が65%以上であり、前記リチウム含有α−サイアロン蛍光体粒子は、その表面に1μm以下の寸法の微粒子状のサイアロンによって形成された凹凸表面微細構造を有するサイアロン表面層を有する、Li含有α−サイアロン蛍光体粒子。
〔2〕0<δ、0.3≦x/m≦0.9である、〔1〕に記載のLi含有α−サイアロン蛍光体粒子。
〔3〕前記リチウム含有α−サイアロン蛍光体粒子の平均粒子径が0.5~30μmである、〔1〕又は〔2〕に記載のLi含有α−サイアロン蛍光体粒子。
〔4〕前記サイアロン表面層がリチウム含有α−サイアロンであり、前記サイアロン表面層の微粒子状サイアロンの寸法が0.01~0.8μmである、〔1〕~〔3〕のいずれか1に記載のLi含有α−サイアロン蛍光体粒子。
〔5〕励起光を入射することにより、波長560nmから590nmのピーク波長の蛍光を放出する、〔1〕記載のLi含有α−サイアロン系蛍光体粒子。
〔6〕窒化ケイ素又は含窒素ケイ素化合物の粉末と、AlNを含むアルミニウム源となる物質と、Liの窒化物、酸窒化物、酸化物または熱分解により酸化物となる前駆体物質からなるLi源と、Euの窒化物、酸窒化物、酸化物または熱分解により酸化物となる前駆体物質からなるEu源とを混合し、常圧の窒素を含有する不活性ガス雰囲気中、1500~1800℃で焼成して中間物としてのリチウム含有α−サイアロン粉末を得て、その粉末に追加のリチウム源を添加混合し、常圧の窒素を含有する不活性ガス雰囲気中、前記焼成温度よりも低い温度で又は1100℃以上1600℃未満で再焼成する、Li含有α−サイアロン蛍光体粒子の製造方法。
〔7〕前記再焼成により得られるリチウム含有α−サイアロン蛍光体粒子が、一般式(1):
LixEuySi12−(m+n)Al(m+n)On+δN16−n−δ (1)
(式中、0.4≦x≦1.5、0.001≦y≦0.2、1.0≦m≦2.8、0.1≦n+δ≦3.2であり、Euの平均価数をaとすると、x+ya+δ=mであり;0<δ、0.3≦x/m≦0.9である。)
で表されるリチウム含有α−サイアロン粒子であって、450nm付近の波長領域において光の吸収率が65%以上であり、前記リチウム含有α−サイアロン蛍光体粒子は、その表面に1μm以下の寸法の微粒子状のサイアロンによって形成された凹凸表面微細構造を有するサイアロン表面層を有する、〔6〕に記載のLi含有α−サイアロン蛍光体粒子の製造方法。
〔8〕前記の中間物としてのリチウム含有α−サイアロン蛍光体粒子が、一般式(1)
LixEuySi12−(m+n)Al(m+n)On+δN16−n−δ (1)
(式中、0.3≦x<1.2、0.001≦y≦0.2、1.0≦m≦2.9、0.1≦n+δ≦3.2であり、Euの平均価数をaとすると、x+ya+δ=mである。)
で表されるリチウム含有α−サイアロン粒子であり、前記再焼成により得られるリチウム含有α−サイアロン蛍光体粒子において前記の中間物としてのリチウム含有α−サイアロン蛍光体粒子と比べてx/mが少なくとも0.02増加している、〔6〕又は〔7〕に記載のLi含有α−サイアロン蛍光体粒子の製造方法。
〔9〕前記の中間物としてのリチウム含有α−サイアロン蛍光体粒子が、450nm付近の波長領域において光の吸収率が65%以上である、〔6〕~〔8〕のいずれか1項に記載のLi含有α−サイアロン蛍光体粒子の製造方法。
〔10〕前記追加のリチウム源が、前記の中間物としてのリチウム含有α−サイアロン粉末1モルに対し、金属Li換算で、0.05~1.6モルである、〔6〕~〔9〕のいずれかに記載のLi含有α−サイアロン蛍光体粒子の製造方法。
〔11〕前記再焼成により得られるLi含有α−サイアロン系蛍光体粒子が、励起光を入射することにより、波長560nmから590nmのピーク波長の蛍光を放出する、〔6〕~〔10〕のいずれかに記載のLi含有α−サイアロン系蛍光体粒子の製造方法。
〔12〕発光源と、〔1〕~〔5〕のいずれかに記載のLi含有α−サイアロン系蛍光体粒子を含有する蛍光体とから構成される照明器具。
〔13〕前記発光源が330~500nmの波長の光を発光するLEDである、〔12〕に記載の照明器具。
〔14〕前記Li含有α−サイアロン系蛍光体粒子を600nm~650nmの赤色の蛍光体と組み合わせて、昼白色や昼光色の発光色を得る、〔12〕又は〔13〕に記載の照明器具。
〔15〕励起源と、〔1〕~〔5〕のいずれかに記載のLi含有α−サイアロン系蛍光体粒子を含有する蛍光体とから構成される、画像表示装置。
〔16〕前記励起源が電子線、電場、真空紫外、紫外線である、〔15〕に記載の画像表示装置。
図2は、実施例1の試料のEDS分析結果である。
図3は、比較例10に示した1600℃におけるLiの再拡散によって、蛍光強度が低下した試料(粒子)についてSEMにより観察した粒子形態の写真である。
図4は、実施例9に示した1600℃におけるLiの再拡散によって、蛍光強度が向上した試料(粒子)についてSEMにより観察した粒子形態の写真である。
本発明は、一旦製造したLi含有α−サイアロン系蛍光体(中間物)に対して、Li成分を添加して、再焼成を行う。
Li含有α−サイアロン系蛍光体粉末は、窒化ケイ素粉末と、AlNを含むアルミニウム源となる物質と、Liの窒化物、酸窒化物、酸化物、または熱分解により酸化物となる前駆体物質からなるLi源と、Euの窒化物、酸窒化物、酸化物、または熱分解により酸化物となる前駆体物質からなるEu源とを、計算されたLi含有α−サイアロン系蛍光体組成になるように秤量、混合し、混合物を得る。ここで、計算されたLi含有α−サイアロン系蛍光体組成とは、LixEuySi12−(m+n)Al(m+n)OnN16−nで表される組成であるが、Liを過剰に添加した組成であってもよい。
次に、作製したLi含有α−サイアロンと拡散するLi源粉末を秤量し、混合する。Li源となる原料としては、Liの窒化物、酸窒化物、酸化物、または熱分解により酸化物など前述したものを採用できる。Li含有α−サイアロンとLi源を、振動ミルなどの混合機を用いて混合し、混合物を、アルミナ製坩堝等、BN製の坩堝、窒化ケイ素製の坩堝、炭素製の坩堝などの坩堝に入れ、常圧の窒素含有雰囲気において焼成を行う。焼成温度は、中間物としてのLi含有α−サイアロンを作製する際の焼成温度より低い温度であればよいが、一般的には1100~1600℃が採用される。好ましくは1300~1500℃、より好ましくは1350~1450℃である。1100℃未満では蛍光強度改善の効果が小さくなり、1600℃を超えると、Liの蒸発が多くなり、蛍光強度の向上の効果が少なく、かえって低下を引き起こす恐れもある。また、Liを再拡散させる焼成温度は、中間物としてのLi含有α−サイアロンを作製する際の焼成温度より高い温度であっても、焼成温度が1100~1600℃の範囲内であれば、追加のLiを再拡散させる一定の効果を得ることができる。窒素含有雰囲気の窒素以外のガスとしては不活性ガスを用いることができ、不活性ガスとしては、ヘリウム、アルゴン、ネオン、クリプトンなどが例示されるが、本発明においては、これらのガスと少量の水素ガスとを混合して使用することも可能である。
はじめに、各種組成のLi含有サイアロンの作製を行った。具体的な作製方法を例示す。
実施例1~5
表1に示すLi−α−サイアロン1モルに対し、酸化リチウム(Li2O、高純度化学、99.0%)を表2に示す分量を添加し、振動ミルを用いて混合した。得られた粉末をアルミナ坩堝にいれ、300℃/hの昇温速度で、表2に示す焼成条件で加熱した。焼成後、2Nの硝酸溶液で酸洗浄し、組成の測定、蛍光測定を前述の方法で行った。結果を表2に示す。蛍光強度は大きく改善していることがわかる。組成分析の結果も表2に示した。その結果、Liと酸素が増加していることがわかる。蛍光特性の改善の理由のひとつとして、不足していたLiの増加が関与している可能性がある。なお、表2に示す変化量とは、蛍光強度比の増加量を、用いた原料のサイアロン(S1~S7)の蛍光強度比で割った値(すなわち、蛍光強度比の変化割合)である。
図1(a)に得られたサイアロン粒子のSEM写真を示す。母体のサイアロン粒子の表面付着物は明確な粒子として観察されないので、表面付着物は母体のサイアロン粒子の変形と考えられる。
表2に示すサイアロン(S6、S7)を用いる以外は実施例1と同じ方法でLiの再拡散を行った。その結果、Li再拡散によって、蛍光強度の改善が少ないことが確認された。比較例1,2に用いた原料サイアロン(S6、S7)の吸収率は65%よりも低く、このような低い吸収率のLi−α−サイアロンに関してはLi再拡散の効果を得ることはできない。
表3に示すサイアロン(S3~S5)を用い、処理温度を1000℃にする以外は、実施例1と同じ方法でLiの再拡散を行った。吸収率の高い試料では、実施例3~5と同じように蛍光強度の改善は見られる。しかし、改善する量は小さく結果として、絶対的な蛍光強度は得られていない。1000℃のような低い温度では、再拡散の効果を十分に得ることはできない。比較例6、7では、1000℃の焼成条件に加えて、原料の吸収率は65%よりも小さい。このような条件では、Liの再拡散の効果は全く得られない。
表3に示すサイアロン(S3~S5)を用い、処理温度を5時間に伸ばした以外は実施例1と同じ方法でLiの再拡散を行った。蛍光特性の改善は見られる。しかし、実施例3~5のものに比べ、改善量はほとんど変わらない。処理は温度のほうが、時間よりも重要である。
表3に示すサイアロン(S6,S7)を用い、処理温度を5時間に伸ばして以外は実施例1と同じ方法でLiの再拡散を行った。その結果、Li再拡散によって、蛍光強度の改善が少ないことが確認された。比較例8,9に用いた原料サイアロン(S6,S7)の吸収率は65%よりも低く、このような低い吸収率のLi−α−サイアロンに関しては、Liの再拡散時間を伸ばしてもLi再拡散の効果を得ることはできない。
表3に示すサイアロン(S3)を用いて、処理温度を1600℃にした以外は、実施例1と同じ方法でLiの再拡散を行った。表3に示すように、実施例3と同様に蛍光強度の改善が見られた。
表3に示すサイアロン(S4、S5)を用いて、処理温度を1600℃にした以外は、実施例1と同じ方法でLiの再拡散を行った。用いた試料の吸収率は65%以上であり、実施例4,5のような1300℃では効果があったが、1600℃になると蛍光強度改善の効果が見られなくなった。処理温度を上げると効果がえられない傾向がある。
表3に示すサイアロン(S3)を用いて、Liの添加を0にした以外は、実施例1と同じ方法で焼成を行った。蛍光強度改善は見られなかった。本特許の効果は、Liの添加によってもたらされていることがわかる。
表3に示すサイアロン(S3)を用いて、Liの添加量を変化させた以外は、実施例1と同じ方法でLiの再拡散を行った。蛍光強度の改善が見られた。Li2Oの添加量で0.03モルでも、十分に大きな効果が得られることがわかった。一方、Li2Oの添加量で0.75モルに増やしても、実施例3と比較して、変化量が大きくなることはなかった。添加の量が多くなっても蛍光強度の改善が大きくなることはないことがわかる。
表3に示すサイアロン(S3)を用いて、Li源として炭酸リチウムを表3に示す量を添加した以外は、実施例1と同じ方法でLiの再拡散を行った。蛍光強度の改善が見られた。
表3に示すサイアロン(S3)を用いて、Li源として窒化リチウムを表3に示す量を添加し、窒素ボックス中で混合し、酸素に触れないようにして原料を準備した。それ以外は、実施例1と同じ方法でLiの再拡散を行った。蛍光強度の改善が見られた。
表3に示すサイアロン(S3)を用いて、坩堝として窒化ホウ素の坩堝を用いた以外は、実施例1と同じ方法でLiの再拡散を行った。蛍光強度の改善が見られた。
実施例1の蛍光強度の改善した試料について、X線回折(XRD)を行い相の同定を行った。また、Liの再拡散前の試料(S1)についても同様のXRDを行い相の同定を行った。その結果、Liの再拡散前後で、サイアロンに関するXRDパターンの大きな変化はなかった。厳密には、組成の変化に伴う格子定数の変化は生じると考えられるが、通常のXRDパターンでは顕著な差はないと言える。新しいピークとしては、Liに由来する新たな結晶相、例えば、LiSi2N3のような結晶相が出現するが、ごく微量であった。
実施例1の試料について走査型電子顕微鏡(SEM)を用いて粒子の形態を観察した。比較として、Li再拡散前の試料(S1)についての粒子形態も観察した。結果をそれぞれ図1(a)及び図1(b)に示す。再拡散によって粒子の表面に1μm以下、具体的には0.2μm程度の微粒子状物による凹凸微細構造が観察された。処理前の試料では表面には微粒子状の凹凸微細構造はない。
Claims (16)
- 一般式(1):
LixEuySi12−(m+n)Al(m+n)On+δN16−n−δ (1)
(式中、0.4≦x≦1.5、0.001≦y≦0.2、1.0≦m≦2.8、0.1≦n+δ≦3.2であり、Euの平均価数をaとすると、x+ya+δ=mである。)
で表されるリチウム含有α−サイアロン蛍光体粒子であって、450nm付近の波長領域において光の吸収率が65%以上であり、前記リチウム含有α−サイアロン蛍光体粒子は、その表面に1μm以下の寸法の微粒子状のサイアロンによって形成された凹凸表面微細構造を有するサイアロン表面層を有する、Li含有α−サイアロン蛍光体粒子。 - 0<δ、0.3≦x/m≦0.9である、請求項1に記載のLi含有α−サイアロン蛍光体粒子。
- 前記リチウム含有α−サイアロン蛍光体粒子の平均粒子径が0.5~30μmである請求項1又は2に記載のLi含有α−サイアロン蛍光体粒子。
- 前記サイアロン表面層がリチウム含有α−サイアロンであり、前記サイアロン表面層の微粒子状サイアロンの寸法が0.01~0.8μmである、請求項1~3のいずれか1項に記載のLi含有α−サイアロン蛍光体粒子。
- 励起光を入射することにより、波長560nmから590nmのピーク波長の蛍光を放出する、請求項1記載のLi含有α−サイアロン系蛍光体粒子。
- 窒化ケイ素又は含窒素ケイ素化合物粉末と、AlNを含むアルミニウム源となる物質と、Liの窒化物、酸窒化物、酸化物または熱分解により酸化物となる前駆体物質からなるLi源と、Euの窒化物、酸窒化物、酸化物または熱分解により酸化物となる前駆体物質からなるEu源とを混合し、常圧の窒素を含有する不活性ガス雰囲気中、1500~1800℃で焼成して中間物としてのリチウム含有α−サイアロン粉末を得て、その粉末に追加のリチウム源を添加混合し、常圧の窒素を含有する不活性ガス雰囲気中、前記焼成温度よりも低い温度で又は1100℃以上、1600℃未満で再焼成する、Li含有α−サイアロン蛍光体粒子の製造方法。
- 前記再焼成により得られるリチウム含有α−サイアロン蛍光体粒子が、一般式(1):
LixEuySi12−(m+n)Al(m+n)On+δN16−n−δ (1)
(式中、0.4≦x≦1.5、0.001≦y≦0.2、1.0≦m≦2.8、0.1≦n+δ≦3.2であり、Euの平均価数をaとすると、x+ya+δ=mであり;0<δ、0.3≦x/m≦0.9である。)
で表されるリチウム含有α−サイアロン粒子であって、450nm付近の波長領域において光の吸収率が65%以上であり、前記リチウム含有α−サイアロン蛍光体粒子は、その表面に1μm以下の寸法の微粒子状のサイアロンによって形成された凹凸表面微細構造を有するサイアロン表面層を有する、請求項6に記載のLi含有α−サイアロン蛍光体粒子の製造方法。 - 前記の中間物としてのリチウム含有α−サイアロン蛍光体粒子が、一般式(1)
LixEuySi12−(m+n)Al(m+n)On+δN16−n−δ (1)
(式中、0.3≦x<1.2、0.001≦y≦0.2、1.0≦m≦2.9、0.1≦n+δ≦3.2であり、Euの平均価数をaとすると、x+ya+δ=mである。)
で表されるリチウム含有α−サイアロン粒子であり、前記再焼成により得られるリチウム含有α−サイアロン蛍光体粒子において前記の中間物としてのリチウム含有α−サイアロン蛍光体粒子と比べてx/mが少なくとも0.02増加している、請求項6又は7に記載のLi含有α−サイアロン蛍光体粒子の製造方法。 - 前記の中間物としてのリチウム含有α−サイアロン蛍光体粒子が、450nm付近の波長領域において光の吸収率が65%以上である、請求項6~8のいずれか1項に記載のLi含有α−サイアロン蛍光体粒子の製造方法。
- 前記追加のリチウム源が、前記の中間物としてのリチウム含有α−サイアロン粉末1モルに対し、金属Li換算で、0.05~1.6モルである、請求項6~9のいずれか1項に記載のLi含有α−サイアロン蛍光体粒子の製造方法。
- 前記再焼成により得られるLi含有α−サイアロン系蛍光体粒子が、励起光を入射することにより、波長560nmから590nmのピーク波長の蛍光を放出する、請求項6~10のいずれか1項に記載のLi含有α−サイアロン系蛍光体粒子の製造方法。
- 発光源と、請求項1~5のいずれか1項に記載のLi含有α−サイアロン系蛍光体粒子を含有する蛍光体とから構成される照明器具。
- 前記発光源が330~500nmの波長の光を発光するLEDである、請求項12に記載の照明器具。
- 前記Li含有α−サイアロン系蛍光体粒子を600nm~650nmの赤色の蛍光体と組み合わせて、昼白色や昼光色の発光色を得る、請求項12又は13に記載の照明器具。
- 励起源と、請求項1~5のいずれか1項に記載のLi含有α−サイアロン系蛍光体粒子を含有する蛍光体とから構成される、画像表示装置。
- 前記励起源が電子線、電場、真空紫外、紫外線である、請求項16記載の画像表示装置。
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US13/581,529 US8497624B2 (en) | 2010-03-01 | 2011-03-01 | Li-containing α-sialon-based phosphor particle, production method thereof, lighting device, and image display device |
KR1020127020679A KR101366866B1 (ko) | 2010-03-01 | 2011-03-01 | Li 함유 α-사이알론계 형광체 입자와 그의 제조 방법, 조명 기구 및 화상 표시 장치 |
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