JP4879567B2 - Method for producing sialon phosphor and lighting apparatus using phosphor obtained thereby - Google Patents

Description

The present invention relates to a method for producing a sialon phosphor that is excited by ultraviolet or blue light and emits visible light, a phosphor obtained by the method, and a lighting device using the phosphor, particularly a white LED.

As phosphors, silicates, phosphates, aluminates, and sulfides are used as a base material, and transition metals or rare earth metals are used as emission centers. On the other hand, white LEDs that are excited by an excitation source having high energy such as ultraviolet light or blue light to emit visible light have been attracting attention and are being developed. However, the above-described conventional phosphor has a problem in that the luminance of the phosphor decreases as a result of exposure to the excitation source. Nitride and oxynitride phosphors have recently attracted attention as phosphors with low luminance reduction because they have a stable crystal structure and can shift excitation light and light emission to the longer wavelength side.

As nitride and oxynitride phosphors, α-sialons in which specific rare earth elements are activated are known to have useful fluorescence characteristics, and application to white LEDs and the like has been studied (patents) References 1 to 5 and Non-Patent Reference 1).
JP 2002-363554 A JP 2003-336059 A JP 2003-124527 A JP 2003-206481 A JP 2004-186278 A J. et al. W. H. van Krebel "On new rare-earth doped M-Si-Al-O-N materials", TU Eindhoven, The Netherlands, p. 145-161 (1998)

Moreover, it has been found that Ca ₂ (Si, Al) ₅ N ₈ , CaSiAlN ₃ or β-sialon activated with rare earth elements also has similar fluorescent properties (Patent Document 6, Non-Patent Document 2). , 3).
JP 2004-244560 A Proceedings of the 65th JSAP Academic Lecture Meeting (September 2004, Tohoku Gakuin University) 3 p. 1282-1284 Proceedings of the 52nd Applied Physics Related Lecture Meeting (March 2005, Saitama University) 3 p. 1615

In addition, a phosphor using a nitride or oxynitride such as aluminum nitride, magnesium magnesium nitride, calcium calcium nitride, silicon barium nitride, gallium nitride, or silicon zinc nitride as a base material has been proposed.

α-type sialon is a solid solution of α-type silicon nitride, and specific elements (Ca and LI, Mg, Y, or lanthanide metals excluding La and Ce) enter the solid solution between crystal lattices. In order to maintain this, the Si—N bond is partially substituted with an Al—N bond and an Al—O bond. Fluorescence characteristics are manifested by using a rare earth element as a light emission center for a part of the intruding solid solution element.

The α-sialon is obtained by firing a mixed powder composed of silicon nitride, aluminum nitride, aluminum oxide if necessary, and oxides of intruding solid solution elements at a high temperature in nitrogen. Various fluorescent characteristics can be obtained depending on the ratio of silicon nitride and aluminum compound, the type of element that enters and dissolves, the ratio of the element that becomes the emission center, and the like.

β-type sialon is a solid solution of β-type silicon nitride, in which Al is substituted at the Si position of O and silicon is substituted at the N position. Since there are two formula quantities of atoms in the unit cell, Si _{6 -Z} Al _Z O _Z N _8-Z is used as a general formula. Here, the composition Z is 0 to 4.2, the solid solution range is very wide, and the molar ratio of (Si, Al) / (N, O) needs to be maintained at 3/4. Therefore, as a raw material, β-sialon can be obtained by heating by adding silicon oxide and aluminum nitride, or aluminum oxide and aluminum nitride in addition to silicon nitride.

When Eu ion is sufficiently dissolved in the crystal structure of β-sialon, it is excited by ultraviolet to blue light and emits green to yellow light of 500 to 550 nm.

By the way, the white light of a white LED requires a combination of a plurality of colors unlike a monochromatic light, and a general white LED is a fluorescent light that emits visible light using an ultraviolet LED or a blue LED and their light as an excitation source. Consists of a combination with the body. Therefore, if there is variation in the color tone of the light emitted from the phosphor, the color tone of the white light emitted from the LED also varies.

Unlike colored light used for signal lights and marker lights, white light is often used as illumination light to illuminate objects brightly. If there is a variation in the color tone of white light, the color of the illuminated object will also vary, and the color of the object cannot be projected correctly. Therefore, when using white LED as a lighting fixture, it becomes an important subject to eliminate variation in color tone.

The variation in the color tone of the sialon phosphor that causes the variation in the color tone of the white LED is largely due to the variation in the composition of the sialon phosphor. As a method for reducing this composition variation, conventionally, a method for improving the uniformity of the raw material powder mixing has been studied. For example, it is a wet mixing method that improves the uniformity of mixing by using ceramic balls or the like as a movable mixing medium and dispersing the raw material powder in a liquid dispersion medium such as an organic solvent. Ball mill mixing method or wet vibration mill mixing method.

While these methods are effective for improving the uniformity of the raw material mixing, they are wet mixing, so that the raw material needs to be dried before filling the container and performing the heat treatment in a nitrogen atmosphere or a non-oxidizing atmosphere. Become. The raw material powder easily aggregates during this drying, but even if the aggregated powder is then crushed, the specific elements in the components are locally concentrated when heat treatment is performed in a nitrogen atmosphere or a non-oxidizing atmosphere. So-called segregation is likely to occur. Due to this segregation, the composition of the obtained sialon phosphor varies, and there is a problem that the effect of uniform mixing of raw materials at the corners is impaired.

In order to prevent the harmful effects of drying the raw material, a dry ball mill mixing method or a dry vibration mill mixing method using only a movable mixing medium is used as a dry method without using a liquid dispersion medium. In these methods, the uniformity of mixing is inferior to the wet method, but since the heat treatment can be performed as it is without drying, segregation of the component elements hardly occurs. However, when a dry and movable mixed medium is used, the energy of collision between the media during mixing increases, so that the components of the medium are easily mixed into the raw material as impurities. These impurities have a problem of deteriorating the light emission characteristics of the phosphor.

The present invention is intended to solve the above-described problems of the prior art, and as a result of various studies on the mixing method of sialon raw material powder, it has been found that the problems of the prior art can be solved by mixing the raw materials by a specific method. The present invention has been completed.

The present invention relates to a sialon powder obtained by heating a raw material powder obtained by mixing a silicon nitride powder, an aluminum nitride powder, an Eu-containing compound, an aluminum oxide powder or a Ca-containing compound in a nitrogen atmosphere or a non-oxidizing atmosphere. The raw material powder is mixed by a dry method without using a movable mixing medium, then passed through a sieve having an opening of 250 μm or less, and crushed to 45 μm. The phosphor is classified into the following sizes, and further mixed to classify to a size of 45 μm or less.

The present invention is a phosphor obtained by the method for producing a phosphor, wherein the sialon powder has a general formula: (Ca, Eu) _{m / 2} (Si) _{12- (m + n)} (Al) _{m + n} (O) _n (N) It is made of α-sialon represented by _16-n , and variation coefficients of Si, Al, O, and N are 1% or less, 3% or less, 20% or less, and 1% or less, respectively. Preferably, the phosphor is characterized in that the coefficient of variation of Ca and Eu is 5% or less and 20% or less, respectively.

The present invention is a phosphor obtained by the above-described phosphor manufacturing method, wherein the sialon powder is a base material of β-sialon represented by the general formula: Si _6-Z Al _Z O _Z N _8-Z It is a phosphor in which Eu is dissolved as a light emission center, and variation coefficients of Si, Al, O, and N are 1% or less, 15% or less, 20% or less, and 1% or less, respectively. Preferably, the phosphor is characterized in that the coefficient of variation of Eu is 20% or less.

The present invention is a luminaire comprising the above-mentioned phosphor in a luminaire composed of a light-emitting light source and a phosphor. Preferably, ultraviolet light or visible light is used as the light-emitting light source. It is said lighting fixture.

The phosphor production method of the present invention can increase the uniformity in the production lot by using a phosphor powder composed of sialon which is easily affected by composition fluctuations in a simple and low-cost manner. Therefore, it is possible to provide an inexpensive and powdery sialon phosphor with little variation.

The phosphor of the present invention is a phosphor composed of α-sialon containing Eu obtained by applying the above production method, and Eu functions as an emission center because of the unique crystal structure of α-sialon. It is efficiently excited by ultraviolet rays or visible light, and stably emits light having a peak in the yellow visible light region of 550 to 600 nm, and is a white LED having various light fixtures, particularly blue LEDs and ultraviolet LEDs as light sources. It is suitable for.

The phosphor of the present invention is a phosphor made of β-sialon containing Eu obtained by applying the above manufacturing method, and Eu functions as a light emission center because of the unique crystal structure of β-sialon. Efficiently excited by ultraviolet light or visible light, and stably emits light having a peak in the green to yellow visible light region of 500 to 550 nm. Various light fixtures, particularly blue LEDs and ultraviolet LEDs are used as light sources. Suitable for white LED.

The luminaire of the present invention uses the phosphor made of the sialon. However, since the sialon is thermally and chemically stable, the luminance of the phosphor is small even when used at a high temperature, and the lifetime is long. There is the feature that it is. In the case of a phosphor made of α-sialon, when a blue LED capable of emitting visible light having a wavelength of 440 to 480 nm is used as a light-emitting light source, a combination of the light from the light-emitting light source and the fluorescence emitted by the α-sialon is used. In the case of a β-type sialon phosphor, a blue LED capable of emitting visible light with a wavelength of 440 to 480 nm and an ultraviolet LED capable of emitting ultraviolet light with a wavelength of 350 to 410 nm can be provided. Used as a light-emitting light source, it has the feature that it can easily provide white light by combining the light from the light-emitting light source with β-type sialon phosphor and, if necessary, red or blue phosphor, and can be applied to various applications is there.

The phosphor production method of the present invention comprises a raw material powder obtained by mixing a silicon nitride powder, an aluminum nitride powder, an aluminum oxide powder as required, and an Eu-containing compound and, if necessary, a Ca-containing compound. The present invention relates to a phosphor made of sialon powder that is heated in a nitrogen atmosphere or a non-oxidizing atmosphere. However, this is because the sialon phosphor obtained by the manufacturing method has a problem of preventing the light emission characteristics from changing by reflecting subtle composition fluctuations. In the present invention, the raw material powder is blended, mixed in a dry method without using a movable mixing medium, and then passed through a sieve having an opening of 250 μm or less in a dry method. It is possible to obtain the effect that the composition fluctuation is extremely small and the phosphor powder having substantially no variation in emission characteristics can be provided at low cost.

Specific methods of mixing raw materials without using a movable mixing medium include rolling mixers such as V-type mixers, W-corn type mixers, rocking mixers, ribbon blenders, and Henschel mixers. However, since a dead space does not occur and mixing is easy evenly, a rolling mixer is particularly preferable.

The raw material powder is granulated at the time of mixing, but if heat treatment is performed as it is to obtain sialon, the granulated particles are sintered. At the time of sintering, a liquid phase is formed by components mainly containing oxygen in the raw material and moves actively at a high temperature, so that the liquid phase is easily segregated, and as a result, the composition of the fired product tends to vary. In the present invention, the mixed powder is passed through a sieve having a mesh size of 250 μm or less before heat treatment, but the granulated particles are thereby crushed, which makes it difficult to sinter during the heat treatment and segregates the liquid phase. And variations in the composition of the fired product resulting therefrom are less likely to occur.

On the other hand, if the wet-mixed raw material is also dried and passed through a sieve in a dry manner, the granulation is crushed, but the primary particles of the raw material powder are secondary agglomerated during drying. Since this cohesive force is stronger than that of dry mixing, strong secondary agglomeration remains even if the granulated particles are crushed with a sieve. Variations in composition are likely to occur. In the present invention, for the reason described above, the dry process is selected in the mixing process as well as the process using the sieve.

Hereinafter, the present invention will be described in detail with the intention of manufacturing a phosphor made of α-type sialon and a phosphor made of β-type sialon.

The composition of the α-type sialon phosphor is represented by the general formula: (Ca, Eu) _{m / 2} (Si) _{12- (m + n)} (Al) _{m + n} (O) _n (N) _16-n. In order to achieve expression, it is preferable that the Eu content is 0.1 to 0.35 at% because light emission characteristics can be reliably obtained.

The α-sialon phosphor powder composed of many kinds of elements also varies in color tone of the emitted light in relation to the variation in composition. The inventor investigates the relationship between composition variation and emission color variation, and as a result, variation coefficient indicating variation in content (% by mass) of each element in a predetermined amount of powder (production lot) that determines the average quality. For Si, Al, O, and N, the variation in emission color tone of the sialon phosphor can be suppressed when the content is 1% or less, 3% or less, 20% or less, and 1% or less, respectively. It has been found that when the coefficient of variation is 5% or less and 20% or less, the effect can be achieved more remarkably, and the present invention has been achieved. In calculating the coefficient of variation, it is preferable to standardize the total of the components as 100% by mass because errors such as analysis can be excluded from consideration.

Similarly, the composition of the β-sialon phosphor, the general _formula: is shown in _{Si 6-Z Al Z O Z} N 8-Z, in order to express fluorescent properties, Eu content is from 0.05 to 0. If it is 3 at%, since the light emission characteristic is obtained reliably, it is preferable.

In the β-type sialon phosphor powder composed of many kinds of elements, the color tone of the emitted light varies depending on the variation in composition. The inventor investigated the relationship between the variation in composition and the variation in emission color tone, and the variation coefficient indicating the variation in the content (% by mass) of each element in the production lot is 1 for each of Si, Al, O, and N. % Or less, 15% or less, 20% or less, and 1% or less, it is possible to suppress the variation of the light emission color tone of the illuminant, and the above effect is more remarkable when the variation coefficient of Eu is 20% or less. Thus, the present invention has been found to be achieved. In calculating the coefficient of variation, it is preferable to standardize the total of the components as 100% by mass because errors such as analysis can be excluded.

In the present invention, according to the desired composition of α sialon or β sialon, a silicon nitride powder, an aluminum nitride powder, an aluminum oxide powder as required, an Eu-containing compound, and a Ca as required. In order to suppress mixing of impurities after the above operation, the raw material powder obtained by blending and mixing the containing compound is kept in a container such as a crucible where at least the surface in contact with the raw material powder is made of boron nitride (BN). In a nitrogen atmosphere or a non-oxidizing atmosphere, α-sialon or β-sialon is obtained by heating at a temperature of 1600-1800 ° C. for β-sialon and 1820-2200 ° C. for β-sialon for a predetermined time.

The filling of the raw material powder into the container is desirably as bulky as possible for the purpose of suppressing sintering between particles during the heat treatment. Specifically, the filling rate of the raw material powder into the container is desirably 40% by volume or less.

As for the temperature of the heat treatment, in the case of α-sialon, if the temperature of the heat treatment is less than 1600 ° C., there are many unreacted products or insufficient particle growth, and 1800 ° C. If it exceeds, sintering between particles becomes remarkable. In the case of β-type sialon, Eu cannot be dissolved in the β-type sialon crystal structure below 1820 ° C., and if it exceeds 2200 ° C., high atmospheric pressure is required to suppress the decomposition of the raw material and β-type sialon. An apparatus having a container is required, which is industrially undesirable.

Regarding the heat treatment time, there are many unreacted products, insufficient solid solution of Eu, insufficient growth of primary particles, or sintering between particles. A time range in which such an inconvenience does not occur is selected. According to the study by the present inventors, 2 to 24 hours is a preferable range.

The α-type sialon and β-type sialon obtained by the above operation are loosely agglomerated lumps, so they are crushed and combined with a classification treatment as necessary to obtain a powder of a predetermined size, and further mixed if necessary. Thus, after making a production lot, it becomes a powdery phosphor applied to various uses.

Production lots that determine the average quality of powdered phosphors are often determined with the maximum amount that can be processed during powder production as the upper limit. For example, after the raw material mixing step, firing step and crushing, classification, mixing, etc. The powder produced through the treatment process is determined in lots based on one raw material mixing, one firing or one crushing, classification or mixing. Accordingly, the scale of the lot varies depending on the type of process used as a reference and the scale of equipment used.

Since sialon phosphor powders require strict quality, it is common to make production lots by the mixing process, which is the actual final process, and the scale of the production lot is also 1 to several kg for the convenience of quality control. It is relatively small.

The powder quality variation within the same production lot (hereinafter simply referred to as “lot”) is usually determined by the following method. First, samples for evaluation are collected from a plurality of locations in the lot, and all the samples are analyzed and evaluated. Next, an average value (m) and a standard deviation (σ) of analysis values and evaluation values are obtained, and a coefficient of variation (CV) is obtained by expressing a value obtained by dividing the standard deviation by the average value as a percentage.

Sampling can be performed according to JIS M 8100-1992 (powder mixture-general sampling method), Section 6.5.2 (increment reduction method). The number of samples is expanded to a predetermined thickness for the total amount of powder in one lot, and is equally divided into 10 categories according to the small sample in the same section, and sampling is performed from each category using a predetermined incremental reduction scoop. be able to.

Component analysis of the above samples is performed using a fluorescent X-ray analyzer (XRF) or inductively coupled plasma emission analyzer (ICP) for the metallic elements Ca, Eu, Si, and Al, and an oxygen nitrogen analyzer for O and N. Can be used. Although a measurement error occurs during analysis, it can be ignored because it is significantly smaller than the deviation caused by the variation between samples.

The α-type sialon phosphor is used in a lighting fixture composed of a light emission source and a phosphor, and in particular, by irradiating visible light containing a wavelength of 440 to 480 nm as an excitation source, a range of 550 to 600 nm. Since it has a light emission characteristic having a peak in wavelength, white light can be easily obtained by combination with a blue LED. In addition, α-sialon does not deteriorate even when exposed to high temperatures, has excellent heat resistance, and excellent long-term stability in an oxidizing atmosphere and moisture environment. It is characterized by high brightness and long life.

In addition, the β-type sialon phosphor is used in a lighting fixture composed of a light source and a phosphor, and in particular, by irradiating ultraviolet light or visible light containing a wavelength of 350 to 500 nm as an excitation source, 500 Since it has a light emission characteristic having a peak at a wavelength in the range of ˜550 nm, there is a feature that white light can be easily obtained by combining with an ultraviolet LED or a blue LED and, if necessary, a red and / or blue phosphor. In addition, β-sialon does not deteriorate even when exposed to high temperatures, has excellent heat resistance, and has excellent long-term stability in an oxidizing atmosphere and moisture environment. It is characterized by high brightness and long life.

Since the main use of the luminaire that emits white light is emission of light that illuminates an object, a stable color tone is required to correctly reflect the color of the object. For this reason, not only a blue LED as a light emission source but also an α-type sialon or β-type sialon as a phosphor is required to have a stable emission color tone with little variation.

The color tone of the phosphor can be measured according to JIS Z 8724-1997 (color measurement method-light source color) and item 4 (spectral colorimetry method). By measuring the emission spectral distribution of the phosphor by this method, further obtaining the chromaticity coordinate value (x, y), and comparing them, the variation in color tone can be known.

The luminaire of the present invention is configured using at least one light-emitting light source and the phosphor of the present invention. The lighting fixture of the present invention includes an LED, a fluorescent lamp, etc., for example, by a known method described in JP-A-5-152609, JP-A-7-99345, JP-A-2927279, etc. An LED can be manufactured using the phosphor of the present invention. In this case, it is preferable to use an ultraviolet LED or a blue LED that emits light with a wavelength of 350 to 500 nm, particularly preferably a blue LED that emits light with a wavelength of 440 to 480 nm, as these light emitting elements. GaN, InGaN, and other nitride semiconductors can be used, and by adjusting the composition, a light emitting source that emits light of a predetermined wavelength can be obtained.

In addition to the method of using the α-sialon phosphor of the present invention alone in a lighting fixture, a lighting fixture that emits a desired color can also be configured by using in combination with a phosphor having other light emission characteristics. . In particular, when a blue LED is used as an excitation source, white light emission with a wide color temperature is generated when the phosphor comprising the α-sialon of the present invention is combined with a phosphor exhibiting green to yellow light emission having a peak wavelength of 500 to 550 nm. It becomes possible. An example of such a phosphor is β-sialon in which Eu is dissolved. Further, by combining with a red phosphor such as CaSiAlN ₃ : Eu, an improvement in color rendering is achieved.

In addition, in addition to the method of using the phosphor of the present invention alone in a lighting fixture, a lighting fixture that emits a desired color can be configured by using it together with a phosphor having other light emission characteristics. In particular, when a blue LED is used as an excitation source, white light emission with a wide color temperature can be achieved by combining the phosphor of the present invention with a red phosphor such as CaSiAlN ₃ : Eu. In addition, when an ultraviolet LED is used as an excitation source, when combined with a phosphor that emits blue light and a red phosphor, an improvement in color rendering is achieved in addition to a wide color temperature.

(Example 1) α-type silicon nitride powder (9 FW grade) manufactured by Denki Kagaku Kogyo Co., Ltd. 69.9% by mass, aluminum nitride powder (F grade) manufactured by Tokuyama Co., Ltd., 17.1% by mass, calcium carbonate powder manufactured by Kanto Chemical Co., Inc. (special grade) Reagent) 6.7% by mass, Wako Pure Chemical Industries, Ltd. calcium fluoride powder (special grade reagent) 5.2% by mass, Shin-Etsu Chemical Co., Ltd. europium oxide powder (RU grade) 1.1% by mass in total 1.2 kg It mix | blended so that it might become. In this case, the Eu content is 0.14 at%.

This was mixed by a dry method for 60 minutes using a rocking mixer (RM-10, manufactured by Aichi Electric), and further passed through a stainless steel sieve having an opening of 150 μm to obtain a raw material powder for synthesizing α-sialon.

This was filled in two rectangular boron nitride containers with lids of 19.5 cm wide × 19.5 cm deep × 6.2 cm high in internal dimensions, and 1750 in a nitrogen atmosphere at atmospheric pressure with an electric furnace of a carbon heater. Heat treatment was carried out at 16 ° C. for 16 hours. The obtained product was crushed with an alumina mortar except for a strong sintered portion produced in a small amount near the upper surface in the container, and passed through a sieve having an opening of 45 μm. By these operations, 1.1 kg of synthetic powder was obtained. X-ray diffractometer (MXP3, MXP3) powder X-ray diffractometry was performed. As a result, the synthesized powder was α-sialon single phase.

The whole amount was mixed for 1 hour using a V-type mixer, and then the particles obtained by rolling and granulation were crushed again through a sieve having an opening of 45 μm, and lots of powders were formed.

The obtained lot of phosphor powder was spread on a table with a clean surface to obtain a rectangular powder deposit having a thickness of 10 mm and a width: depth length ratio of approximately 5: 2. Subsequently, a line was put in the deposit so that it could be equally divided into 5 in the width direction and equally divided into 2 in the depth direction, and was equally divided into 10.

Further, by using an increment scoop (a scoop of number 0.25D in FIG. 1 of JIS M 8100-1992), 2 g of powder samples were collected from 10 divided sections, and fluorescence was obtained for Ca, Eu, Si and Al. X-ray analyzer (ZSX100e manufactured by Rigaku Corporation), and O and N were subjected to component analysis using an oxygen-nitrogen analyzer (TC-436 manufactured by LECO). These measured values, average value (m), standard deviation (σ) and coefficient of variation (CV) were determined, and the results are shown in Table 1. Further, chromaticity coordinate values (x, y) were obtained from the emission spectral distribution by 455 nm excitation light measured using a spectrofluorometer (F-4500, manufactured by Hitachi High-Technology), and the results are shown in Table 1.

(Comparative Example 1) Omission of the sieve through the stainless steel sieve after mixing with the rocking mixer was omitted. Except that, a raw material powder for α-sialon synthesis was prepared in exactly the same manner as in Example 1. Heat treatment was performed under the same conditions. The obtained product was entirely sintered, and a large amount of a strong sintered portion was generated in the vicinity of the upper surface in the container as compared with Example 1. This portion was excluded and pulverized with a stamp mill, and passed through a sieve having an opening of 45 μm. By these operations, 0.8 kg of synthetic powder was obtained. As a result of powder X-ray diffraction measurement, the synthesized powder was an α-type sialon single phase. Thereafter, powder lotting, sampling, component analysis and chromaticity measurement were performed in the same manner as in Example 1, and the results are shown in Table 2.

(Comparative Example 2) Each raw material blended at the same ratio as in Example 1 was subjected to wet ball mill mixing with a silicon nitride pot and balls in an ethanol solvent for 3 hours, followed by filtration and drying, and an opening of 150 μm. A raw material powder for synthesizing α sialon was prepared by passing through a stainless steel sieve, and further subjected to heat treatment under the same conditions as in Example 1. The obtained product was entirely sintered, and a large amount of a strong sintered portion was generated in the vicinity of the upper surface in the container as compared with Example 1. This portion was excluded and pulverized with a stamp mill, and passed through a sieve having an opening of 45 μm. By these operations, 0.6 kg of synthetic powder was obtained. As a result of powder X-ray diffraction measurement, the synthesized powder was an α-type sialon single phase. Thereafter, powder lotting, sampling, component analysis and chromaticity measurement were performed in the same manner as in Example 1, and the results are shown in Table 3.

(Example 2) α-type silicon nitride powder (NP-600 grade, oxygen content 1.3% by mass) manufactured by Denki Kagaku Kogyo Co., Ltd. 95.5% by mass, aluminum nitride powder (F grade, oxygen content 0 by Tokuyama) 0.9% by mass) 3.5% by mass, 0.2% by mass of aluminum oxide powder (TM-DAR grade) manufactured by Daimei Chemical Co., Ltd., 0.8% by mass of europium oxide powder (RU grade) manufactured by Shin-Etsu Chemical Co., Ltd. It mix | blended so that it might become 1.3 kg. In this case, the Eu content is 0.09 at%.

This was mixed by a dry mixer for 60 minutes using a rocking mixer (RM-10, manufactured by Aichi Electric), and further passed through a stainless steel sieve having an opening of 150 μm to obtain a raw material powder for β-sialon synthesis.

This was filled into two square boron nitride containers with lids of 19.5 cm wide × 19.5 cm deep × 6.2 cm high inside dimensions, and a pressurized nitrogen atmosphere of 0.9 MPa in a carbon heater electric furnace. A heat treatment was performed at 1950 ° C. for 4 hours. The obtained product was crushed with an alumina mortar except for a strong sintered portion produced in a small amount near the upper surface in the container, and passed through a sieve having an opening of 45 μm. By these operations, 1.2 kg of synthetic powder was obtained. X-ray diffractometer (MXP3, MXP3) powder X-ray diffractometry was performed, and as a result, the synthetic powder was β-sialon single phase.

The whole amount was mixed for 1 hour using a V-type mixer, and then the particles obtained by rolling and granulation were crushed again through a sieve having an opening of 45 μm, and lots of powders were formed.

About the obtained fluorescent substance powder, it sampled similarly to Example 1, and measured a component analysis and chromaticity. These results are shown in Table 4.

(Comparative Example 3) The raw material powder for β-sialon synthesis was prepared in the same manner as in Example 2 except that the sieving through the stainless steel sieve after mixing with the rocking mixer was omitted. Heat treatment was performed under the same conditions. The obtained product was entirely sintered, and a large amount of a strong sintered portion was generated in the vicinity of the upper surface in the container as compared with Example 2. This portion was excluded and pulverized with a stamp mill, and passed through a sieve having an opening of 45 μm. By these operations, 0.9 kg of synthetic powder was obtained. As a result of powder X-ray diffraction measurement, the synthetic powder was a β-type sialon single phase. Thereafter, powder lotting, sampling, component analysis and chromaticity measurement were performed in the same manner as in Example 2, and the results are shown in Table 5.

(Comparative Example 4) Each raw material blended in the same proportion as in Example 2 was mixed with a silicon nitride pot and a ball in a wet ball mill for 3 hours in an ethanol solvent, then filtered and dried, and further with an opening of 150 μm. A raw material powder for β-sialon synthesis was prepared by passing through a stainless steel sieve and further subjected to heat treatment under the same conditions as in Example 2. The obtained product was entirely sintered, and a large amount of a strong sintered portion was generated in the vicinity of the upper surface in the container as compared with Example 1. This portion was excluded and pulverized with a stamp mill, and passed through a sieve having an opening of 45 μm. By these operations, 1.0 kg of synthetic powder was obtained. As a result of powder X-ray diffraction measurement, the synthetic powder was a β-type sialon single phase. Thereafter, powder lotting, sampling, component analysis and chromaticity measurement were performed in the same manner as in Example 2, and the results are shown in Table 6.

The method for producing a phosphor of the present invention is very useful industrially because phosphor powder made of sialon which is easily affected by composition fluctuations can be provided easily and at low cost.

The phosphor comprising the α-sialon of the present invention stably exhibits emission characteristics having a peak in the region of 550 to 600 nm by excitation light of 440 to 480 nm due to its specific crystal structure and composition. It is suitable as a luminaire using light as a light source, particularly as a phosphor for a white LED using a blue LED as a light emitting light source, and is very useful industrially.

The phosphor comprising β-sialon according to the present invention exhibits emission characteristics having a peak in the region of 500 to 550 nm by excitation light of 350 to 500 nm due to its specific crystal structure and composition. It is suitable as a luminaire that uses light as a light source, particularly as a phosphor for a white LED that uses an ultraviolet LED or a blue LED as a light source, and is very useful in industry.

Since the lighting fixture of the present invention uses a powdered phosphor composed of α-sialon or β-sialon, which has a stable color tone of luminescent color, excellent heat resistance, and little temperature change of luminescent properties, It is a lighting device that can accurately project the color of an object and has high brightness over a long period of time, and is industrially useful.

Claims (7)

Phosphor made of sialon powder obtained by heating raw material powder obtained by mixing silicon nitride powder, aluminum nitride powder, Eu-containing compound, aluminum oxide powder or Ca-containing compound in nitrogen atmosphere or non-oxidizing atmosphere The raw material powder is mixed by a dry method without using a movable mixing medium, then passed through a sieve having an opening of 250 μm or less, and crushed to a size of 45 μm or less. A method for producing a phosphor, characterized by classifying and further mixing to classify to a size of 45 μm or less. A phosphor obtained by the method for producing a phosphor according to claim 1, wherein the sialon powder has a general formula: (Ca, Eu) _{m / 2} (Si) _{12− (m + n)} (Al) _{m + n} (O) _n ( N) Phosphor made of α-sialon represented by _16-n , wherein variation coefficient of Si, Al, O, N is 1% or less, 3% or less, 20% or less, 1% or less, respectively . The phosphor according to claim 2, wherein the coefficient of variation of Ca and Eu is 5% or less and 20% or less, respectively. The phosphor obtained by the method for producing a phosphor according to claim 1, wherein the sialon powder is a base material of β-sialon represented by the general formula: Si _6-Z Al _Z O _Z N _8-Z , and the emission center A phosphor having a variation coefficient of Si, Al, O, and N of 1% or less, 15% or less, 20% or less, and 1% or less, respectively. 5. The phosphor according to claim 4, wherein the Eu coefficient of variation is 20% or less. A lighting fixture comprising a light emitting source and a phosphor, wherein the phosphor according to any one of claims 2 to 5 is used. 7. The lighting apparatus according to claim 6, wherein ultraviolet light or visible light is used as the light emission source.