TW201802229A - Fluorescent substance and light-emitting device - Google Patents

Abstract

Provided is an Li-[alpha]-Sialon fluorescent substance which decreases little in luminance with the lapse of time and has excellent long-term stability. The Li-[alpha]-Sialon fluorescent substance contains stable OH groups bonded to the surface thereof in a proportion by number of 10 or greater per nm2 and contains a luminescence-enhancing element. The luminescence-enhancing element is preferably Eu. It is preferable that the Li content be 1.8-3.0 mass% and the Eu content be 0.1-1.5 mass%.

Description

Fluorescent body and light emitting device

The present invention relates to a Li-α Sialon phosphor, a light-emitting element including the phosphor and a light-emitting light source, and a light-emitting device including the light-emitting element.

A part of light emitted by a blue light emitting diode (blue LED), a laser diode (LD) of a light emitting light source, and light having a relatively high energy and short wavelength that absorbs the light emitting light source is converted into excitation light into The light emitted by phosphors of other colors with long wavelengths is synthesized, and the characteristics of light-emitting elements that emit secondary mixed light, especially white light-emitting diodes (white LEDs) have been improved. The white LED generally has a structure in which, for example, a blue LED that becomes a light emitting light source is sealed with a sealing material such as a resin containing a phosphor, but the phosphor is usually a yellow phosphor, a red phosphor, and a green phosphor. The combination of light bodies is used by being microdispersed in a sealed resin.

Examples of the red phosphor used for the white LED include an α-sialon phosphor. In addition, as a modification thereof, it is known to crystallize a phosphor precursor that is unstable in its entirety by solid-solving an activating element (referred to as a light emitting activating element) that emits light as an α-sialon phosphor, That is, because a part of the voids in the α-Sialon phosphor crystal further contains Ca ²⁺ , the stabilization of the parent crystal is for example a general formula: Ca _x Eu _y Si _{12- (m + n)} Al _{(m + n ) Ca-α} dragon phosphor O _n N _16-n indicated (refer to Patent Document 1).

Further in recent years, a review of the phosphor brightness α dragon to further enhance the shorter wavelength fluorescence spectra, the results of the proposed structure as Li- using Li ⁺ donor A phosphor precursor crystals stabilized with metal ions Alpha Cylon phosphor (see Patent Documents 2 to 4).

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2002-363554

[Patent Document 2] International Publication No. 2007/004493

[Patent Document 3] Japanese Patent Laid-Open No. 2010-202738

[Patent Document 4] International Publication No. 2010/018873

Compared with Ca-α Cylon phosphor, the aforementioned Li-α Cylon phosphor can achieve improved brightness and shorter wavelength. However, if a light-emitting element using Li-α Cylon phosphor is used for a long time, Then, the brightness of the light-emitting element gradually decreases with the lapse of time, and other problems that cannot be seen in light-emitting elements using Ca-α Cylon phosphors arise, and this problem is required to be solved. An object of the present invention is to provide a Li-α Sailong phosphor, which has a small decrease in brightness over time and excellent long-term stability; a light-emitting element using the aforementioned Li-α Sailong phosphor; and A light-emitting device including the light-emitting element is provided.

The present inventors investigated and reviewed the properties of water molecules and OH groups bonded to the surface that exist near the surface of the Li-α Cylon phosphor (in this case, the vicinity of the surface and the surface are collectively referred to as the surface). The existence of a ratio affects the change of the brightness of a light-emitting element using the aforementioned Li-α Sailong phosphor over time. As a result, it is found that it is difficult to obtain a Li-α The more the proportion of OH groups (referred to as stable OH groups) existing on the surface of the phosphor that the dragon phosphor is detached from is stabilized, the less the brightness decreases with the passage of time, and the present invention has been completed .

That is, the present invention is

(1) A Li-α Sailong phosphor, which is on the surface of the phosphor, has a stable OH group bonded to it at a ratio of 10 / nm ² or more, and contains a light-emitting activating element.

(2) The light-emitting activating element contained in the aforementioned Li-α Sailong phosphor is preferably Eu.

(3) The Li-containing ratio of the Li-α-sialon phosphor is preferably 1.8% by mass or more and 3.0% by mass or less.

(4) The Eu-containing ratio of the Li-α Sailong phosphor is preferably 0.1% by mass or more and 1.5% by mass or less.

(5) The oxygen-containing ratio of the Li-α Sailong phosphor is preferably 0.4% by mass or more and 1.3% by mass or less.

(6) A light-emitting element comprising the Li-α Sailong phosphor according to any one of (1) to (5) above, and a light-emitting light source that irradiates the phosphor with excitation light.

(7) The light-emitting source of the light-emitting element is preferably a light-emitting diode or a laser diode.

(8) A light-emitting device including the light-emitting element according to (6) or (7) above.

With the implementation of the present invention, a light-emitting element including a Li-α Cylon phosphor with a small decrease in luminance over time and improved long-term stability can be obtained, and a light-emitting device using the light-emitting element can be provided.

[Form of Implementing Invention]

One of the embodiments of the present invention is a Li-α Sailong phosphor, which has a stable OH group bonded to the surface of the phosphor at an existing ratio of 10 / nm ² or more, and contains a light-emitting activating element. In addition, the Li-α Sailong fluorescent system of the present invention generally has the following formula: Li _x A _y Si _{12- (m + n)} Al _{m + n} O _n N _16-n (x + y ≦ 2, m = x + 2y). In the foregoing general formula, Li represents lithium, and element A is a light-emitting activating element, and represents, for example, one or two or more elements selected from Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Er, Tm, and Yb. , Si means silicon, Al means aluminum, O means oxygen, and N means nitrogen. Part of the Si-N bond of the aforementioned α-silicon crystal of the Li-α Sailong fluorescent system is replaced by Al-N bond and Al-O bond. In order to maintain electrical neutrality, Li and element A further penetrate into solid solution. For a part of voids in the crystal, the values of m and n in the general formula correspond to the substitution ratios of Al-N bonds and Al-O bonds, respectively. In the case of a Li-α Cylon phosphor, the range of the m value that can maintain the overall structure is 0.5 or more and 2 or less, and the range of the n value is 0 or more and 0.5 or less.

Including the Li-α Sailong phosphor of the present invention, the surface of an object usually exists in the form of water molecules or OH groups, or is bonded with water having different physical and chemical binding forces. In the present invention, the moisture that is adsorbed or bonded to the surface of the Li-α Cylon phosphor is defined as follows. That is, when the Li-α Sailong phosphor is heated at atmospheric pressure, the water that is detached from the phosphor at a heating temperature of less than 200 ° C is referred to as "physical adsorbed water", and the heating temperature is less than 400 ° C. The water after desorption of "physical adsorption water" is set to "unstable OH group", and the water that does not detach if the phosphor is not heated above 400 ° C is set to "stable OH group". The aforementioned stable OH group is the OH group measured from the surface of the phosphor for the first time when the temperature of the phosphor sample is set to 400 ° C. or more by moisture analysis based on the Carr Fisher method. The Li-α-sialon phosphor of the present invention is only required to satisfy the regulations regarding the existence ratio of the stable OH group.

In addition, in the present invention, “the stable OH group is bonded in an existing ratio of 10 / nm ² or more” means the aforementioned stable OH group, and the calculated value obtained by, for example, the water analysis by the Carr Fisher method is There are 10 or more units per 1 nm ² . When the existence ratio of the stable OH group is less than 10 pieces / nm ² , the adhesion between the phosphor and the sealing material in the light-emitting element becomes insufficient, and the brightness tends to decrease with the passage of time. In order to solve the problems of the present invention, the presence ratio of stable OH groups is at least 10 / nm ² or more, preferably 25 / nm ² or more, more preferably 30 / nm ² or more, and even more preferably 35 / nm ² or more. ² or more.

The Li-α Sailong phosphor of the present invention can be manufactured through the following steps: a raw material mixing step of mixing various phosphor raw materials to make a mixed raw material; firing the mixed raw material to mainly obtain Li-α Sailong A step of firing the phosphor; a step of disintegrating or pulverizing the calcined body obtained in the step of firing as required; an step of acid treatment of immersing in an acid solution to remove impurities, etc. as required; A classification step to make the size uniform as needed; and a heat treatment to further reheat the Li-α Cylon phosphor under atmospheric pressure and below the temperature of the firing step to adjust the existence ratio of OH groups. step. Moreover, the presence ratio of the stable OH group of the Li-α Sailong phosphor of the present invention can be increased by a heat treatment step.

In the firing step of the Li-α Sailong fluorescent system of the present invention, if the Li content is relatively small, the crystal grain growth in the step of firing the phosphor crystals becomes very slow. It tends to be difficult to obtain large particles with high light emission brightness. In addition, if the Li-containing ratio is excessive, a different phase (referred to as an impurity or the like) of LiSi ₂ N ₃ or the like tends to be generated during firing. Therefore, the mass ratio of Li based on the Li-α Cylon phosphor containing various impurities and the like immediately after the firing step is preferably 1.8% by mass or more and 3.0% by mass or less. The phosphor material is blended to adjust. Specifically, it can be adjusted by increasing or decreasing the blending ratio of lithium nitride and lithium oxide as the Li-containing raw material.

In addition, the Li-α Sailong phosphor of the present invention can be used for the purpose of fine-tuning the fluorescent characteristics while maintaining electrical neutrality, while including elements including Mg, Ca, Y, and lanthanum (excluding La, Ce, and Eu). ) One or more substituted elements are selected to replace a part of Li in the aforementioned general formula. Therefore, in one embodiment of the Li-α-sialon phosphor of the present invention, one or more of these substitution elements are used to replace a part of Li.

General formula of the Li-α Sailong phosphor of the present invention: Li _x A _y Si _{12- (m + n)} Al _{m + n} O _n N _16-n (x + y ≦ 2, m = x + 2y) The element A in is an element (referred to as a light-emitting activating element) responsible for light emission of the aforementioned phosphor. As the element A, one or two or more elements selected from Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Er, Tm, and Yb can be selected. Among them, Eu can be preferably used.

If element A, which is a light-emitting activating element, is relatively small, the contribution to light emission tends to be small and the fluorescence intensity tends to be low. Conversely, if it is increased above a certain concentration, it is considered that the energy transfer between elements A Due to the phenomenon of extinction caused by the concentration, the luminous brightness tends to be small. Therefore, for example, when Eu is selected as the element A, it is preferably 0.1% by mass or more and 1.5% by mass or less. The Eu-containing ratio can be adjusted by blending the raw materials of the phosphor. Specifically, it can be adjusted by increasing or decreasing the blending ratio of erbium oxide and erbium nitride of a Eu-containing raw material.

The oxygen-containing ratio in the Li-α Sailong phosphor of the present invention is related to its brightness, and is preferably 0.4% by mass or more and 1.3% by mass or less. If the content of oxygen in the phosphor raw material is less than 0.4% by mass and is too small, crystal grains grow less during the firing step, and therefore it becomes difficult to obtain a phosphor with high brightness. If the oxygen ratio exceeds 1.3% by mass, the fluorescence spectrum is broadened, and therefore it is likely that sufficient brightness cannot be obtained.

The Li-α Sailong phosphor of the present invention is based on its parent crystal The α-Sialon is a base, and the foregoing α-Sialon further includes phosphors such as Li and Eu. However, as long as it has little effect on the fluorescence characteristics, it can include secondary silicon nitride, Crystal phases such as aluminum nitride, lithium silicon nitride, and their solid solutions. The higher the purity of the Li-α Sailong phosphor, the better, it is preferably 95% by mass or more, more preferably 97% by mass or more, and still more preferably 98% by mass or more. The upper limit value does not need to be specifically set, but can be substantially set to, for example, 99% by mass or less. In addition, the purity of the Li-α Sailong phosphor can be determined by using an X-ray diffraction device (for example, Ultima IV manufactured by Rigaku Co., Ltd.) using powder X-ray diffraction (also called XRD) using CuKα rays. The ratio of the crystalline phase was determined.

The compound that is a raw material of the Li-α-sialon phosphor of the present invention is a compound containing a Si source, an Al source, an Eu source, and a Li source. Specific examples include silicon nitride powder, aluminum nitride powder, hafnium oxide powder, and lithium nitride powder. Each raw material is preferably prepared in a powder state in advance.

In the raw material mixing step, first, raw materials of phosphors other than lithium nitride powder such as silicon nitride powder, aluminum nitride powder, hafnium oxide powder, etc. are mixed at a desired ratio. In consideration of industrial productivity, mixing is preferably performed by wet mixing. As a solvent used in the wet mixing, for example, ethanol can be used. After wet mixing, the solvent is removed, dried, and pulverized to obtain a pre-mixed powder. This premixed powder and lithium nitride powder are further mixed in a desired ratio to obtain a raw material mixed powder. In order to avoid hydrolysis, the premixed powder and the lithium nitride powder are preferably mixed in an inert gas environment such as nitrogen.

By firing the aforementioned raw material mixed powder, for example, a Li-α-sialon phosphor activated by Eu can be obtained. As a crucible for firing, It is preferably made of a material that is physically and chemically stable in a high-temperature gas environment, and is preferably made of a high-melting-point metal such as boron nitride, carbon, molybdenum, or tantalum. The firing gas environment is not particularly limited, and it is usually carried out in an inert gas environment or a reducing gas environment. Only one kind of inert gas or reducing gas may be used, or two or more kinds of gases may be used in combination at any combination ratio. Examples of the inert gas or the reducing gas include hydrogen, nitrogen, argon, and ammonia, and nitrogen is preferably used. The pressure of the firing gas environment is selected based on the firing temperature. The higher the ambient gas pressure, the higher the decomposition temperature of the phosphor. In consideration of industrial productivity, it is preferably performed under a pressure of about 0.02 to 1.0 MPa. If the firing temperature is lower than 1650 ° C, the crystal defects and unreacted residual amount of the parent crystal will increase. If it exceeds 1900 ° C, the parent crystal will be decomposed, which is not preferable. Therefore, the firing temperature is preferably 1650 to 1900 ° C. If the firing time is short, the crystal defects and unreacted residual amount of the parent crystal will increase, and if the firing time becomes longer, it is not good to consider industrial productivity. Therefore, it is preferably set to 2 to 24 hours. The Li-α Sailong phosphor obtained in the firing step can be disintegrated and classified into a desired particle size according to the needs of subsequent operations.

Generally, the Li-α Sailong phosphor obtained immediately after the firing step may not have a sufficiently high crystal ratio, and it is difficult to exhibit the desired fluorescent characteristics under such conditions. The mixed solution of hydrofluoric acid and nitric acid is subjected to acid treatment to increase the crystallization ratio of Li-α Sailong phosphor.

The Li-α Sailong phosphor of the present invention is usually used in a micro-dispersed sealing resin of a light-emitting element, so it is used in the form of fine particles. If the particle size of the Li-α Sailong phosphor of the present invention is too small, Fluorescent The intensity tends to be low. If it is too large, the chromaticity of the luminous color of the LED sealed with a resin or the like containing a phosphor may be changed, or the luminous color may be uneven. Therefore, the Li-α The average primary particle diameter of the dragon fluorescent body represented by the volume-based median diameter (D50) based on the laser diffraction-scattering method is preferably 7 μm or more and 35 μm or less. Therefore, in order to obtain a phosphor that does not cause color unevenness at high brightness, it is preferable to further classify the Li-α Sailong phosphor of the present invention that has been appropriately defragmented after acid treatment. Step to remove fine powder. The classification step can be either wet or dry. For example, it is preferable to disperse the acid-treated Li-α Sailong phosphor in a mixed solvent of ion-exchanged water and sodium hexametaphosphate as a dispersant. Or, in a mixed alkaline solvent of ion-exchanged water and ammonia water, elutriation classification using a difference in sedimentation speed after standing caused by a difference in particle size, or dry classification using a screen.

After undergoing the acid treatment step and the classification step, the effective crystalline ratio of the Li-α Sailong phosphor can generally be increased. Therefore, a phosphor with high luminous efficiency can be obtained. Under such conditions, the light emitting element and the light emitting device can be obtained. When used for a long period of time, the brightness of the light-emitting element decreases with time. Therefore, according to the present invention, the following new knowledge was discovered: the proportion of the presence of water molecules or OH groups on or on the surface of the Li-α Sailong phosphor is dependent on the brightness of the light-emitting element containing the phosphor. The change over time affects the effect; or the proportion of the OH groups (stable OH groups) stably bonded among the OH groups bonded to the surface of the aforementioned Li-α Sailong phosphor can be adjusted, so that it is difficult to cause the brightness The invention of the Li-α Sailong phosphor that decreases over time. In addition, in order to obtain a Li-α-Sialon phosphor which can provide a light-emitting element with a small decrease in luminance over time and excellent long-term stability, it is difficult to emit light from the Li-α-Sialon phosphor even in a high-temperature environment. It is sufficient that the ratio of the presence of the stable OH groups to be detached is 10 or more per nm ² . In order to adjust the existence ratio of the stable OH group, specifically, it is preferable to heat-treat the Li-α Sailong phosphor. The gas environment in the case of performing a heat treatment is not particularly limited, but preferably a gas environment of the atmosphere, nitrogen, and hydrogen, and an atmospheric environment is particularly preferred. In addition, in order to leave only stable OH groups that have been detached for the first time above 400 ° C on the surface, the heat treatment temperature in the case of heat treatment is at least, preferably 1,000 ° C or lower, more preferably 700 ° C or lower, and even more preferably Below 500 ° C. The lower limit of the heat treatment temperature is preferably 100 ° C or higher, more preferably 200 ° C or higher, and even more preferably 400 ° C or higher. When the heat treatment temperature is 1000 ° C. or higher, the characteristics of the Li-α Cylon phosphor itself are deteriorated, and thus the brightness is decreased. On the other hand, if it is 100 ° C or higher, the existence ratio of the stable OH group can be adjusted by adjusting the holding time. The time for heating the Li-α Sailong phosphor depends on the heating temperature, preferably 3 hours or more, and considering mass production efficiency, it is preferably less than 20 hours. However, in the present invention, if the existence ratio of the stable OH groups that are stably bonded to the surface of the Li-α Cylon phosphor is 10 or more per nm ² , there is no particular limitation on the heating temperature and the holding time. limited.

A second embodiment of the present invention is a light-emitting element including the Li-α Sailong phosphor of the first embodiment of the present invention and a light source. The light-emitting light source is preferably an LED or an LD that emits monochromatic light having a peak wavelength of 240 nm to 480 nm. The reason is that the monochromatic light with a peak wavelength of 240nm to 480nm is the peak wavelength region of the most commonly used blue LEDs. In addition, Li-α Cylon phosphors can be efficiently used from the front. Light having a wavelength in the above range is excited to emit light with high brightness.

The light-emitting element including the Li-α Cylon phosphor and the light-emitting light source of the present invention can be manufactured by, for example, operating in the following manner. First, the phosphor of the present invention is mixed with a sealing material to adjust the slurry. For example, the slurry can be adjusted by mixing at a ratio of 30 to 50 parts by mass with respect to 100 parts by mass of the sealing material. Examples of the sealing material include a thermoplastic resin, a thermosetting resin, and a photocurable resin. Specific examples include methacrylic resins such as polymethyl methacrylate; styrene resins such as polystyrene and styrene-acrylonitrile copolymers; polycarbonate resins; polyester resins; benzene Oxygen resin; Butyraldehyde resin; Polyvinyl alcohol; Cellulose resins such as ethyl cellulose, cellulose acetate, cellulose acetate butyrate; epoxy resin; phenol resin; silicone resin, etc. In addition, inorganic materials such as a solution obtained by hydrolyzing and polymerizing a metal alcoholate, a ceramic precursor polymer, or a solution containing a metal alcoholate by a sol-gel method, or a combination of inorganic materials that cure these can be used. The material is, for example, an inorganic material having a siloxane bond. Moreover, if it is a sealing part (for example, an external cap, a dome-shaped sealing part, etc.) which can be externally attached without making direct contact with an LED chip, a fused glass can also be used. Further, one type of sealing material may be used, or two or more types may be used in any combination and ratio.

Among the sealing materials, for reasons of dispersibility and moldability, it is preferable to use a resin having thermosetting properties and fluidity at normal temperature. As the resin having thermosetting property and fluidity at ordinary temperature, for example, a silicone resin can be used. For example, Toray-Dow Corning Co., Ltd.'s product name: JCR6175, OE6631, OE6635, OE6636 , OE6650 and so on.

Next, 3 to 4 μL of the above slurry is injected into a top view type package in which a blue LED chip having a light emission peak wavelength at 460 nm is mounted. The paste-injected top-view package is heated at a temperature in the range of 140 to 160 ° C for 2 to 2.5 hours to harden the paste. By operating in this manner, a light-emitting element capable of absorbing light in a wavelength range of 420 to 480 nm and emitting light in a wavelength exceeding 480 nm to 800 nm can be manufactured.

This is a case of evaluating the long-term stability of the light-emitting element including the Li-α Sailong phosphor according to the second embodiment of the present invention during use. For example, a combination can be actually produced. The light-emitting element samples of blue light-emitting diodes and phosphors were used. The light-emitting element samples were subjected to a power-on test while being placed in a high-temperature and high-humidity environment. The beam retention ratio (%) obtained from the total beam measurement value was evaluated. Since the beam value immediately after the start of the energization test is used as a reference, it is desirable that the beam retention rate after a predetermined time is close to 100%.

A third embodiment of the present invention is a light emitting device including the aforementioned light emitting element. More specific examples of the light-emitting device referred to in the present invention include a device for displaying information such as a traffic light and a display device, a headlight for a vehicle such as a car, and a lighting device instead of an incandescent lamp or a fluorescent lamp. .

[Example]

Examples of the present invention are compared with comparative examples, and a table is used for explanation.

<Example 1>

A method for manufacturing the phosphor of Example 1 will be described. The fluorescent system is produced by a mixing step and a firing step of the raw materials.

(Raw material mixing step)

The raw materials of the phosphor in Example 1 are Si ₃ N ₄ (E10 grade manufactured by Ube Kosan Co., Ltd.), AlN (F grade manufactured by Tokuyama Corporation), Eu ₂ O ₃ (RU grade manufactured by Shin-Etsu Chemical Industry Co., Ltd.), Li ₃ N powder (99.5% by mass, -60 mesh, manufactured by Materion). First, the powder was weighed and mixed to obtain a molar ratio of Si ₃ N ₄ : AlN: Eu ₂ O ₃ = 84.5: 14.8: 0.64 to obtain a pre-mixed powder.

Under a nitrogen environment, the molar number of the premixed powder (the total molar number of Si ₃ N ₄ , AlN, and Eu ₂ O ₃ ): the molar number of Li ₃ N = 94.1: 5.9, The premixed powder and the Li ₃ N powder are mixed to obtain a raw material mixed powder.

(Baking step)

In the glove box, the foregoing raw material mixed powder was filled into a boron nitride crucible, and an electric furnace using a carbon heater was fired at 1800 ° C for 8 hours in a pressure nitrogen atmosphere with a gauge pressure of 0.8 MPa to obtain Eu activates Li-α Sailong phosphor.

(Pulverization step)

In addition, since the particles of the Eu-activated Li-α Sailong fluorescent system after firing are large and massive, they are pulverized by a dry mill using a roll mill and a jet mill, and are screened to be pressed against the perforations. Those who pass through a 45 μm sieve.

(Acid treatment step)

For the Eu-activated Li-α-sialon phosphor after the classification, 100 g of the phosphor is immersed in a mixed solution (80 ° C.) of hydrofluoric acid and nitric acid of at least 300 mL to perform acid treatment.

(Classification step)

200 g of Li-α Cylon phosphor after the acid treatment step was allowed to stand in a sufficient amount of a mixed solvent of at least 2 L or more of ion exchanged water and dispersant sodium hexametaphosphate for 10 minutes, thereby removing fine powder of 5 μm or less .

(Heat treatment step)

The magnetic crucible was filled with the Li-α Sailong phosphor after the classification step, and then heated in an electric furnace at 200 ° C. for 3 hours in an atmospheric environment to obtain the Eu-activated Li- Alpha Cylon.

<Example 2>

The Eu-activated Li-α-sialon of Example 2 was obtained by performing the same manufacturing method as that of Example 1 except that the conditions of the heat treatment step were annealing at 500 ° C. for 3 hours in the atmosphere.

<Example 3>

The Eu-activated Li-α-sialon of Example 3 was obtained by performing the same manufacturing method as that of Example 1 except that the conditions of the heat treatment step were annealing at 700 ° C. for 3 hours in the atmosphere.

<Example 4>

The Eu-activated Li-α-sialon of Example 4 was obtained by performing the same manufacturing method as that of Example 1 except that the conditions of the atmospheric heating step were annealing at 1100 ° C. for 3 hours in the atmosphere.

<Comparative example 1>

The Eu-activated Li-α-sialon of Comparative Example 1 is the same as the one prepared in Example 1. The manufacturing step was obtained by the same manufacturing method as in Example 1 except that the acid treatment step, the classification step, and the heat treatment step were omitted.

<Comparative example 2>

The Eu-activated Li-α-sialon of Comparative Example 2 was obtained by the same manufacturing method as in Example 1 except that the heat treatment step was omitted in the manufacturing steps of Example 1.

(Light-emitting element manufacturing steps)

The phosphors of Examples 1 to 4 and Comparative Examples 1 and 2 were mixed at a ratio of 30 parts by mass to 100 parts by mass of silicone resin (manufactured by Toray-Dow Corning Co., Ltd., trade name: JCR6175, etc.), and adjusted. Slurry. After that, 3 to 4 μL of the above slurry was injected into a top-view type package in which a blue LED wafer having a peak wavelength at 460 nm was mounted. The paste-injected top-view package was heated at 150 ° C for 2 hours, and the paste was cured to produce a light-emitting element rated at 150 mA as a sample.

The simple comparison and evaluation results of the phosphors of Examples 1 to 4 and Comparative Examples 1 and 2 (collectively referred to as examples above) and the evaluation results are shown in Table 1. Table 1 shows the temperature of the acid treatment step, the classification step, the heat treatment step, the presence ratio of stable OH groups (unit: unit / nm ² ), the peak wavelength (unit: nm), and the median diameter. (Unit: μm), the ratio of the α-Sialon crystal to the total crystalline phase (unit:%), the fluorescence intensity (unit:%), and the beam retention rate of the LED (unit:%).

(Identification of the main crystalline phase)

For each of the phosphors in Examples and the like, an X-ray diffraction device (Ultima IV manufactured by Rigaku Co., Ltd.) was used, and the crystal phase was identified by powder X-ray diffraction (XRD) using CuKα rays. In Examples 1 to 4, The X-ray diffraction pattern of the phosphor obtained in Comparative Examples 1 and 2 was confirmed to be the same diffraction pattern as that of the Li-α-sialon crystal, and it was confirmed that the main crystal phase was Li-α-sialon.

(Measurement of OH group)

The quantification of the stable OH group in the present invention was performed using the Carr Fisher method. The Carr Fisher measurement uses a moisture vaporization device VA-122 made by Mitsubishi Chemical Corporation and a moisture measurement device CA-100 made by Mitsubishi Chemical Corporation. The anolyte of the water measurement apparatus uses Aquamicron AX (manufactured by Mitsubishi Chemical Corporation) and the catholyte Aquamicron CXU (manufactured by Mitsubishi Chemical Corporation) was used. When Carr Fisher measurement was performed, the background value was fixed at 0.10 (μg / sec), and the measurement was continued until the detected moisture was lower than the background value. The measurement was performed at 550 ° C. During the heat treatment, the phosphor sample was operated so as not to be exposed to the outside air, and the water generated from the water vaporization device was introduced into the Carr Fisher device with 300 ml / min of high-purity argon to measure the water content. A sample introduced into the moisture gasification device was set to 4 g.

<Moisture converted to OH base number>

Considering that the moisture detected in the Carr Fisher measurement is that two OH groups are condensed to become one water molecule, the number of OH groups per unit area is calculated by the following formula.

Number of OH groups per unit area (number / nm ² ) = 0.0668 × Moisture content (ppm) / Specific surface area of the phosphor sample (m ² / g)

The coefficient of 0.0668 in the above formula is a coefficient for matching the left and right units.

<Specific surface area measurement>

The specific surface area is measured using AUTO manufactured by Micro Data MATIC SURFACE ANALYZER MODEL-4232-2 (Roman numerals).

(Median diameter (D50))

The following procedures were used to measure the median diameter (D50) (average primary particle diameter) of each phosphor in the examples and comparative examples. First, a 1: 1 mixture of hydrofluoric acid (concentration 46 to 48 g / 100 ml) and nitric acid (concentration 60 g / 100 ml) was diluted 4 times with distilled water to prepare a treatment solution. This treatment liquid was heated to 80 ° C, and the phosphors of Examples or Comparative Examples were added and dispersed in an amount of 20 g or less with respect to 100 ml of the treatment liquid while stirring. The phosphor was dispersed and left for 1 hour, and the insoluble powder was recovered by decantation. The recovered powder was washed with water and dried. For the insoluble powder after drying, the particle size distribution was measured using a laser diffraction scattering particle size distribution measuring device (LS 13 320 manufactured by Beckman Coulter Co., Ltd.), and the 50% volume-based cumulative particle diameter was used as the median diameter (D50 ).

For each phosphor in the examples and comparative examples, a spectrofluorimeter (F-7000, manufactured by Hitachi High Technologies) was used, which was corrected with rhodamine B and a sub-standard light source. The solid sample holder was measured, and the fluorescence spectrum and peak wavelength at an excitation wavelength of 455 nm were measured.

(Fluorescence intensity)

The fluorescence intensity is calculated from the product of the fluorescence spectrum intensity and the CIE standard specific sensitivity. The unit varies depending on the measurement device and conditions. Therefore, it is optional, and comparative examples and comparative examples measured under the same conditions are compared. The fluorescence intensity of Example 1 was set to 100% as a reference. If the fluorescence intensity is 85% or more, it is a pass value.

(Evaluation of long-term stability of light-emitting elements)

Next, the light-emitting elements having the phosphor particles of the examples and comparative examples were measured for the change rate of the total beam value, and the beam retention rate was calculated to evaluate the long-term stability during use. The measurement of the change in the total light beam can be, for example, a high-temperature, high-humidity bias test, test according to the environment and durability test method (life test 1 (Roman numerals)) of the semiconductor device according to the JEITA ED-4701 / 100A semiconductor device specification. Method 102A, a light-emitting element sample is prepared by combining, for example, a blue light-emitting diode and a phosphor with a rated current of 150 mA, and the sample is placed under a condition of a temperature of 85 ° C and a relative humidity of 85RH%, and the device is allowed to emit light at a current of 150 mA For a 1,000-hour conduction test, a beam retention rate (%) after 1000 hours based on the value immediately after the start of the test was determined and evaluated. The beam retention rate after 1000 hours is preferably 95% or more. The light beam was measured using a full-beam measurement system (Half Moon: HH41-0773-1, manufactured by Otsuka Electronics), and was used to measure the fluorescent light beam emitted from a light-emitting element sample.

As can be seen from Table 1, compared with the comparative example, the existence ratio of the stable OH groups of the Li-α-sialon fluorescent system of Examples 1 to 4 is higher than 10 / nm ² or more, and the ratio of α-sialon crystals is also high. From this, it can be seen that, in order to obtain a high fluorescence intensity, even if used for a long time, the light-emitting device has a small decrease in luminous efficiency and has a small electrical defect. Since the light-emitting elements using the phosphors of Examples 1 to 4 had many stable OH groups, the adhesion to the resin was improved, and the possibility of electrical abnormalities such as short circuits was extremely small, and it is estimated to have a long life. In addition, the Li-α-Sialon phosphor of Example 4 has many stable OH groups. Therefore, similar to the Li-α-Sialon phosphors of Examples 1 to 3, the beam retention rate is high. Since the temperature of the processing step is high, the luminous efficiency of the phosphor tends to decrease slightly.

In contrast, Comparative Example 1 has few stable OH groups, and the proportion of Li-α-sialon crystals is also low. Therefore, the fluorescence intensity is low and the beam maintenance ratio is also reduced. Comparative Example 2 reproduces a Li-α-sialon phosphor that does not exceed the range of the prior art. The proportion of Li-α-sialon crystals is high, so the fluorescence intensity is high, but the number of stable OH groups is small, and the beam retention rate is judged. Low and lack long-term stability.

Claims (8)

A Li-α Sialon phosphor, which is on the surface of the phosphor, has a stable OH group bonded to it at an existing ratio of 10 / nm ² or more, and contains a light-emitting activating element. For example, the Li-α Sailong phosphor of claim 1, wherein the luminescence activating element is Eu. For example, the Li-α Sailong phosphor of claim 1 or 2 has a Li content of 1.8% by mass or more and 3.0% by mass or less. For example, the Li-α Sailong phosphor according to any one of claims 1 to 3, which contains Eu in an amount of 0.1% to 1.5% by mass. The Li-α-sialon phosphor according to any one of claims 1 to 4, wherein the oxygen content is 0.4 mass% or more and 1.3 mass% or less. A light-emitting element includes the Li-α Sailong phosphor according to any one of claims 1 to 5 and a light-emitting light source that irradiates the phosphor with excitation light. The light-emitting element according to claim 6, wherein the light-emitting light source is a light-emitting diode or a laser diode. A light-emitting device includes a light-emitting element according to claim 6 or 7.