β-type sialon phosphor powder and light-emitting device

Abstract

To obtain a β-type sialon phosphor having good emission intensity.SOLUTION: Provided is β-type sialon phosphor powder. In a fluorescence spectrum emitted when irradiating the phosphor powder with blue light having a wavelength of 455 nm, when a peak wavelength is denoted by λp [nm], a half band width of the peak is denoted by W [nm], absorption coefficients of the phosphor powder for light of wavelengths of 600 nm and 455 nm are denoted by A600 and A455, respectively, λp is 542 nm or less and a value of X, defined by X=(W×A600) / (A455-A600), is 10 nm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to β - sialon phosphor powder and a light - emitting device.

Background Art

[0002] As a phosphor capable of converting blue light emitted from a blue LED (Light Emitting Diode) into light of other colors, β - sialon phosphor is known. The chemical composition of β - sialon containing Eu as an activating metal is usually represented by the general formula: Si 6-z Al z O z N 8-z :Eu (z>0). For the purpose of application to lighting and display devices, various improvements have been made to β - sialon phosphor.

[0003] Patent Document 1 describes a method for producing a phosphor represented by the general formula of the composition Si 6-z Al z O z N 8-z :Re (Re is an activator containing at least one selected from the group consisting of Mn, Ce, and Eu, and 0 < z < 4.2). This production method includes a step of firing a composition represented by the above general formula at a temperature of 1500°C or higher and 2200°C or lower while applying isotropic pressure under a nitrogen atmosphere of 100 MPa or higher, and a step of annealing the fired fired body by heating it to 1400°C or higher and 2000°C or lower in an atmosphere containing hydrogen.

[0004] Patent Document 2 discloses Eu 6-z Al z O z N 8-z in β - sialon represented by 2+This manufacturing method includes a mixing step of mixing raw materials for the β-sialon, a firing step of firing the raw materials after the mixing step to form the β-sialon, a HIP treatment step of performing a hot isostatic pressing (HIP) treatment on the β-sialon after the firing step, an annealing treatment step of annealing the β-sialon after the HIP treatment step, and an acid treatment step of treating the β-sialon after the annealing treatment step with an acid.

[0005] Patent Document 3 describes a β-sialon phosphor represented by the following formula 1, in which D10, D50, and D90 (each in μm) based on volume frequency measured by a laser diffraction / scattering method are 10 μm or less, and the values ​​of D10, D50, and D90 satisfy the relationship of the following formula 2. Formula 1:Si 12-a Al a O b N 16-b :EU x (In the formula, 0 <a≦3;0<b≦3;0<x≦0.1) Formula 2: (D90-D10) / D50<1.6 (D10, D50, and D90 (each in μm) are measured by placing 0.5 g of the phosphor to be measured into 100 ml of ion-exchanged aqueous solution mixed with 0.05 wt% sodium hexametaphosphate, dispersing the solution for 3 minutes using an ultrasonic homogenizer with an oscillation frequency of 19.5 ± 1 kHz and an amplitude of 32 ± 2 μm, with the tip placed in the center of the solution.) [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2015-232150 A [Patent Document 2] JP 2011-105532 A [Patent Document 3] International Publication No. 2020 / 054350 Summary of the Invention [Problem to be solved by the invention]

[0007] As lighting and display devices using blue LEDs become more widespread and more powerful, further improvements are being demanded for β-SiAlON phosphors, such as improved emission intensity, etc. In particular, there is a demand for improved emission intensity in β-SiAlON phosphors that emit fluorescence with a relatively short wavelength.

[0008] The present inventors have now carried out various investigations with the aim of obtaining a β-SiAlON phosphor with good luminous intensity. [Means for solving the problem]

[0009] As a result of their investigations, the inventors have completed the invention provided below.

[0010] The present invention is as follows.

[0011] A β-type SiAlON phosphor powder, The phosphor powder is irradiated with blue light having a wavelength of 455 nm, and the peak wavelength in the fluorescence spectrum is λ p [nm], and the half-width of the peak is W [nm]. The absorptance of the phosphor powder at 600 nm is A 600 The absorption rate of light with a wavelength of 455 nm is A 455 When λ p is 542 nm or less, A β-type Sialon phosphor powder, in which the value of x defined by the following formula (1) is 10 nm or less. X = (W × A 600 ) / (A 455 -A 600 ) ···(1)

[0012] The present invention also provides the following.

[0013] A light emitting device including a light emitting source and a wavelength conversion member, The wavelength conversion member includes a phosphor powder, The phosphor powder is a light emitting device containing the β-sialon phosphor powder. Effect of the Invention

[0014] The β-sialon phosphor powder of the present invention has good emission intensity. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic example of the structure of a light-emitting device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, similar components are given similar symbols and descriptions thereof will be omitted as appropriate. In order to avoid complexity, when there are multiple identical components in the same drawing, only one of them may be labeled with a reference symbol, and not all of them. The drawings are for illustrative purposes only. The shapes and dimensional ratios of the components in the drawings do not necessarily correspond to the actual products.

[0017] <β-type Sialon phosphor powder> The β-sialon phosphor powder of this embodiment has the following characteristics. In the fluorescence spectrum emitted when the β-SiAlON phosphor powder of this embodiment is irradiated with blue light having a wavelength of 455 nm, the peak wavelength is λ p [nm] and the half-width of the peak is W [nm]. The absorptance of the β-SiAlON phosphor powder of this embodiment for light with a wavelength of 600 nm is A 600 The absorption rate of light with a wavelength of 455 nm is A 455 Let us assume that. λ p is below 542 nm. The value of X defined in the following formula (1) is 10 nm or less. X = (W × A600 ) / (A 455 -A 600 ) ···(1)

[0018] Just to be clear, the light absorption rate A 600 and A 455 is a dimensionless number, so if the unit of the half-width W is nm, the unit of X will be nm.

[0019] Light energy is inversely proportional to wavelength. Therefore, generally, when the peak wavelength of the fluorescence spectrum is short, the emission intensity tends to be small. However, the β-SiAlON phosphor powder of this embodiment has a good emission intensity, even though the peak wavelength of the fluorescence spectrum is relatively short (542 nm or less). This is believed to be because the β-SiAlON phosphor powder of this embodiment satisfies the requirement that the value of X defined in formula (1) be 10 nm or less.

[0020] Although the details are unclear, the reason why the emission intensity can be increased by designing a β-SiAlON phosphor powder so that the value of X is 10 nm or less can be explained as follows. The half-width W in formula (1) is thought to be related to the amount of impurities and / or defects contained in the phosphor. When the phosphor contains a large amount of impurities and / or defects, W tends to be large. In other words, from the viewpoint of improving the light emission characteristics, it is preferable that W is small. In addition, based on the inventors' past findings, the absorptance A of light with a wavelength of 600 nm is 600 It is assumed that A is related to the amount of defects and impurities in the phosphor. 600 It is considered that a smaller value is preferable. Furthermore, based on the inventors' past findings, the absorptance A of light with a wavelength of 455 nm 455 It is assumed that this is due to the absorption of β-SiAlON itself. Although the light with a wavelength of 455 nm is not the excitation light itself, from the viewpoint of improving the luminescence characteristics, A 455 It is considered that a larger value is preferable.

[0021] In formula (1), W and A are considered to be "preferably small" from the viewpoint of improving the luminous properties. 600 In terms of improving the luminescence properties, the larger the better. 455 is in the denominator. Also, A in the denominator 455 A is a value that is considered to be smaller. 600 is subtracted by In other words, the value of X being 10 nm or less means that W and A are preferably small from the viewpoint of improving the light emission characteristics. 600 is small, and from the viewpoint of improving the luminescence properties, it is preferable that it is large. 455 Therefore, it is considered that a β-SiAlON phosphor powder having an X value of 10 nm or less has high emission intensity.

[0022] The present inventors have investigated the performance improvement of β-SiAlON phosphor powder from every viewpoint. Through the investigation, they have concluded that the peak wavelength and the half width of the peak when blue light is irradiated onto the phosphor powder, and the absorption rate when light of a specific wavelength is irradiated onto the phosphor powder, may be related to the emission intensity of the β-SiAlON phosphor powder. Based on this idea, the inventors further investigated and found that the value of X defined in the formula (1) seems to correlate with the emission intensity. By newly designing a β-SiAlON phosphor powder in which X is 10 nm or less, the emission intensity of the β-SiAlON phosphor powder could be increased.

[0023] λ p The wavelength may be 542 nm or less, but is preferably 520 nm or more and 542 nm or less, and more preferably 525 nm or more and 541 nm or less. W is, for example, 55 nm or less, preferably 40 nm to 55 nm, more preferably 43 nm to 52 nm, and further preferably 44 nm to 51 nm. The smaller W is, the better, but the lower limit of W is practically about 40 nm. A 600is, for example, 0.01 or more and 0.20 or less, preferably 0.01 or more and 0.10 or less, more preferably 0.03 or more and 0.10 or less. A 455 is, for example, 0.25 or more and 0.90 or less, preferably 0.30 or more and 0.85 or less, more preferably 0.40 or more and 0.80 or less, still more preferably 0.50 or more and 0.80 or less. For these measurement methods, refer to the examples.

[0024] The β-sialon phosphor powder of this embodiment can be obtained through appropriate manufacturing methods and conditions. For example, it is preferable to perform an annealing step of annealing the fired product in a mixed gas atmosphere of hydrogen gas and nitrogen gas as described later to obtain an annealed fired product. Thereby, the value of X is likely to be 10 nm or less. Also, it is preferable to appropriately adjust the molar number of Al element with respect to the molar number of Si element in the raw material. Thereby, λ p is likely to be 542 nm or less. Details of the manufacturing methods and conditions will be described later.

[0025] Continue the description of the β-sialon phosphor powder of this embodiment.

[0026] (Elemental composition, etc.) The composition of the β-sialon phosphor is usually represented by the general formula: Si 6-z Al z O z N 8-z :Eu (z > 0). z may be greater than 0, but usually z is 4.2 or less. The content of europium is preferably 0.1% by mass or more and 2.0% by mass or less.

[0027] Mainly from the viewpoint of making λ p 542 nm or less, the value of z is preferably relatively small. Specifically, 0 < z ≤ 0.2 is preferable, 0.01 ≤ z ≤ 0.2 is more preferable, 0.01 ≤ z ≤ 0.15 is still more preferable, and 0.02 ≤ z ≤ 0.12 is particularly preferable.

[0028] From the same viewpoint, it is preferable that the value of z / (6-z), i.e., the number of moles of Al element relative to the number of moles of Si element, is relatively small. Specifically, the value of z / (6-z) is preferably 0.001 or more and 0.05 or less, more preferably 0.002 or more and 0.048 or less, and further preferably 0.002 or more and 0.045 or less.

[0029] Incidentally, by appropriately adjusting the value of z or z / (6-z), the half-width W also tends to become smaller.

[0030] (Median diameter) The median diameter D of the β-type SiAlON phosphor powder of this embodiment 50 From the viewpoint of good light emission characteristics and ease of application to various uses, the thickness is, for example, 5 μm or more and 30 μm or less, preferably 8 μm or more and 25 μm or less, and more preferably 10 μm or more and 20 μm or less. For the method of measuring the median diameter, see the Examples given later.

[0031] (Diffuse reflectance) The diffuse reflectance of the β-sialon phosphor powder of this embodiment for light with a wavelength of 800 nm is preferably 96.0% or more and 99.9% or less, more preferably 96.0% or more and 99.0% or less, even more preferably 96.5% or more and 98.5% or less, and particularly preferably 96.5% or more and 98.0% or less. The value of the diffuse reflectance can reflect the surface properties of the phosphor powder. Although the details are unknown, there are cases where the light emission characteristics are further improved by having an appropriate diffuse reflectance for light with a wavelength of 800 nm. For the method of measuring the diffuse reflectance, see the Examples given later.

[0032] Incidentally, normally, the median diameter of a phosphor powder and the magnitude of the diffuse reflectance of the phosphor powder are inversely proportional to each other. In other words, the larger the median diameter, the smaller the diffuse reflectance tends to be. However, in this embodiment, for example, by adopting the manufacturing method described below, it is possible to obtain a β-SiAlON phosphor powder having a relatively large diffuse reflectance even if the median diameter is relatively large.

[0033] <Method of manufacturing β-type Sialon phosphor powder> The β-sialon phosphor powder of this embodiment can be obtained through an appropriate manufacturing method and conditions. The β-sialon phosphor powder of this embodiment preferably has a raw material mixing step of mixing at least a silicon compound, an aluminum compound, and a europium compound to obtain a raw material mixed powder; A sintering process in which the raw material powder mixture is heated at 1800°C to 2100°C to obtain a sintered product; an annealing step of annealing the fired product under a mixed gas atmosphere of hydrogen gas and nitrogen gas to obtain an annealed fired product; It can be produced by a series of steps including the steps of:

[0034] Although the details are unclear, in this embodiment, it is speculated that, in particular, by annealing the fired product under a mixed gas atmosphere of hydrogen gas and nitrogen gas, the decomposition reaction of the β-SiAlON phosphor is suppressed, thereby reducing defects that adversely affect the luminescence characteristics, and thus a β-SiAlON phosphor powder having an X value of 10 nm or less is obtained. As a result, it is speculated that the luminescence intensity is increased compared to a β-SiAlON phosphor powder having an X value of more than 10 nm that is not subjected to such an annealing process.

[0035] Each step will now be described in detail.

[0036] (Raw material mixing process) In the raw material mixing step, at least a silicon compound, an aluminum compound, and a europium compound are mixed to obtain a raw material mixed powder. For mixing, various mixers (for example, a V-type mixer), a mortar, etc. can be used.

[0037] The europium compound as the raw material is not particularly limited. For example, an oxide containing europium, a hydroxide containing europium, a nitride containing europium, an oxynitride containing europium, a halide containing europium, etc. can be mentioned. These can be used alone or in combination of two or more. Among these, it is preferable to use europium oxide, europium nitride, and europium fluoride alone, and it is more preferable to use europium oxide alone. The europium compound is a material for forming the luminescence center in the β-type sialon.

[0038] The silicon compound as the raw material typically includes silicon nitride, and the aluminum compound as the raw material typically includes aluminum nitride. Silicon nitride and aluminum nitride are materials for forming the skeleton of β-sialon.

[0039] The mixed raw material powder may further contain aluminum oxide and / or silicon oxide, which are materials for forming the skeleton of the β-sialon. The raw material mixed powder may further contain β-sialon, which is a material that serves as an aggregate or a core.

[0040] Each component contained in the raw material powder mixture is preferably in the form of a powder. In addition, when the prepared raw material mixed powder contains agglomerates, it is preferable to remove the agglomerates by sieving or the like.

[0041] The mixing ratio of each raw material may be appropriately adjusted based on the composition of the target β-sialon phosphor. In this embodiment, by appropriately adjusting the molar ratio of each element in the raw material mixed powder, the emission intensity of the finally obtained β-SiAlON phosphor powder can be further increased. Specifically, the number of moles of Si element in the raw material powder mixture is M Si The number of moles of Al element in the raw mixed powder is M Al Then, M Al / MSi The value of is preferably 0.001 or more and 0.05 or less, more preferably 0.002 or more and 0.048 or less, and further preferably 0.002 or more and 0.045 or less. M Al / M Si By making the value of M equal to or less than 0.05, for example, the peak wavelength of the fluorescence spectrum when the finally obtained β-SiAlON phosphor powder is irradiated with blue light tends to be shorter. This is preferable in that it meets the needs for shorter wavelengths in the market. Al / M Si By keeping the value of x=0.05 or less, the spectrum of the fluorescence emitted when blue light is irradiated onto the finally obtained β-SiAlON phosphor tends to be sharper (i.e., fluorescence closer to monochromatic light is obtained).

[0042] By the way, M Al / M Si In the composition of the finally obtained β-SiAlON phosphor, the value of 6-z Al z O z N 8-z : In Eu(z>0), this corresponds to the value of z / (6-z) (when the firing reaction proceeds ideally and all of the raw material is converted into a β-SiAlON phosphor).

[0043] (Firing process) In the firing step, the raw material mixed powder obtained in the raw material mixing step is heated at 1800° C. or more and 2100° C. or less, preferably 1850° C. or more and 2050° C. or less, to obtain a fired product. The raw material mixed powder is usually filled into a container made of a material (such as boron nitride) that does not react with the raw material mixed powder during sintering, and then heated.

[0044] The firing step is usually carried out in an atmosphere of an inert gas such as nitrogen gas, although a rare gas such as argon may also be used as the inert gas. The firing step is preferably carried out in an inert gas atmosphere with an absolute pressure of 0.01 MPa to 10 MPa, more preferably in an inert gas atmosphere with an absolute pressure of 0.05 MPa to 5 MPa, and even more preferably in an inert gas atmosphere with an absolute pressure of 0.08 MPa to 1 MPa. The firing reaction is facilitated by the absolute pressure being moderately high in the firing step. In addition, it is believed that the occurrence of unintended defects in the phosphor is suppressed by the absolute pressure being not too high in the firing step.

[0045] The firing step preferably includes a first firing step and a second firing step. A crushing step is preferably carried out between the first firing step and the second firing step. Such a firing method is preferable from the viewpoint of suppressing excessive agglomeration during firing and promoting a uniform firing reaction.

[0046] The crushing step between the first and second firing steps can be carried out, for example, using a supersonic jet mill. The fired product that is not sufficiently small even after crushing can be removed, for example, by sieving. When using a sieve, the sieve opening is typically 100 μm or less, more preferably 50 μm or less.

[0047] The time for the calcination step (when the first calcination step and the second calcination step are performed, the total time for these steps) is preferably from 2 hours to 60 hours, more preferably from 10 hours to 40 hours. When the first and second firing steps are carried out, the times for the first and second firing steps are each preferably 1 hour or more and 30 hours or less, more preferably 5 hours or more and 20 hours or less.

[0048] The fired product obtained in the firing step is preferably subjected to a crushing treatment before the annealing step. The crushing treatment increases the surface area of ​​the fired product, increasing the contact area with the mixed gas, and it is believed that the performance improvement by the annealing step can be further improved. This crushing treatment can also be performed using, for example, a supersonic jet mill, as in the crushing step between the first and second firing steps.

[0049] (Annealing process) In the annealing step, the fired product obtained in the firing step is annealed in a mixed gas atmosphere of hydrogen gas and nitrogen gas to obtain an annealed fired product.

[0050] As long as a β-SiAlON phosphor having good luminous intensity can be obtained, the ratio of hydrogen gas to nitrogen gas in the mixed gas is not particularly limited. The ratio of hydrogen gas to nitrogen gas in the mixed gas is, for example, hydrogen gas:nitrogen gas=30:70 to 70:30, preferably hydrogen gas:nitrogen gas=40:60 to 60:40, by volume.

[0051] Preferably, the annealing step is performed in a mixed gas atmosphere consisting essentially of hydrogen gas and nitrogen gas. Specifically, it is preferable that the atmosphere in the annealing step contains essentially only hydrogen gas and nitrogen gas, and the ratio of other gases present is 1 volume % or less. Ideally, it is preferable that the atmosphere in the annealing step contains only hydrogen gas and nitrogen gas, and does not contain other gases. However, this does not exclude the atmosphere in the annealing step from inevitably containing other gases than hydrogen gas or nitrogen gas.

[0052] The annealing temperature in the annealing step is not particularly limited as long as a β-SiAlON phosphor having good luminescence intensity can be obtained. The annealing temperature is preferably 1350°C or higher and 1750°C or lower, more preferably 1400°C or higher and 1700°C or lower, and even more preferably 1420°C or higher and 1680°C or lower. By setting the annealing temperature appropriately, a β-SiAlON phosphor having a higher luminescence intensity can be obtained, and unintended decomposition of the β-SiAlON phosphor can be suppressed.

[0053] The annealing step is preferably carried out in an atmosphere with a pressure controlled to be relatively low. Specifically, the annealing step is preferably carried out in an atmosphere with an absolute pressure of 0.001 MPa or more and 1 MPa or less, more preferably 0.005 MPa or more and 0.8 MPa or less, and even more preferably 0.01 MPa or more and 0.5 MPa or less. Although the details are unclear, by carrying out the annealing step in an atmosphere with a pressure controlled to be relatively low, there is a tendency to obtain a β-SiAlON phosphor with a higher emission intensity.

[0054] The time for the annealing step is preferably 1 hour or more, and more preferably 4 hours or more, from the viewpoint of obtaining a sufficient effect of the annealing. Moreover, the time for the annealing step is preferably 25 hours or less, and more preferably 20 hours or less, from the viewpoints of reducing energy costs and suppressing unintended decomposition of the fired product.

[0055] (Acid treatment process) The method for producing a β-sialon phosphor powder of this embodiment preferably includes an acid treatment step in which the annealed fired product in the annealing step is brought into contact with an acid. By carrying out the acid treatment step, impurities and heterogeneous phases (phases that do not contribute to light emission or have low light emission efficiency) on the surface of the fired product can be removed or reduced, and the light emission intensity can be further increased in some cases.

[0056] In the acid treatment step, for example, an aqueous solution containing one or more acids selected from hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid can be used. From the viewpoint of increasing the efficiency of removing impurities and heterogeneous phases, two or more acids may be used in combination. In this embodiment, it is preferable to use hydrofluoric acid and nitric acid in combination.

[0057] The acid treatment step can usually be carried out by putting the fired product into an acidic aqueous solution and stirring for several minutes to several hours (for example, 10 minutes to 6 hours). After stirring is completed, it is desirable to separate the precipitated fired product by filtration and wash off any substances adhering to the β-SiAlON phosphor powder with water.

[0058] <Light emitting device> The light emitting device of the present embodiment includes a light source and a wavelength conversion member. The wavelength conversion member includes a phosphor powder, and this phosphor powder includes the above-mentioned β-sialon phosphor powder.

[0059] FIG. 1 is a cross-sectional view showing a schematic example of the structure of a light emitting device 10. As shown in FIG. The light emitting device 10 includes an LED chip as a light emitting source 12, a first lead frame 13 on which the light emitting source 12 is mounted, a second lead frame 14, a wavelength conversion member 15 that covers the light emitting source 12, a bonding wire 16 that electrically connects the light emitting source 12 and the second lead frame 14, and a synthetic resin cap 19 that covers these. The wavelength conversion member 15 includes a phosphor 18 and a sealing resin 17 in which the phosphor 18 is dispersed.

[0060] A recess 13b is formed in the upper portion 13a of the first lead frame 13 for mounting a light emitting diode chip as the light emitting source 12. The recess 13b has a generally funnel shape with a hole diameter gradually increasing from the bottom surface toward the top, and the inner surface of the recess 13b serves as a reflective surface. An electrode on the lower surface of the light emitting source 12 is die-bonded to the bottom surface of this reflective surface. The other electrode formed on the upper surface of the light emitting source 12 is connected to the surface of the second lead frame 14 via a bonding wire 16.

[0061] As the light emitting source 12, various types of LED chips can be used, and in particular, LED chips that emit light with a wavelength of 300 nm or more and 500 nm or less as near ultraviolet to blue light are preferable.

[0062] The phosphor 18 used in the wavelength conversion member 15 of the light emitting device 10 is a phosphor particle contained in the β-sialon phosphor powder of this embodiment. From the viewpoint of controlling the light wavelength of the light emitting device 10, the phosphor 18 may further contain phosphors such as an α-sialon phosphor, a KSF phosphor, CaAlSiN3, and a simple substance or a mixture of YAG, in addition to the β-sialon phosphor. Examples of elements that are dissolved in these phosphors include europium (Eu), cerium (Ce), strontium (Sr), calcium (Ca), and manganese (Mn). These phosphors may be used alone or in combination of two or more. Among these, in this embodiment, KSF phosphors in which manganese is dissolved are preferable. By using a combination of a β-SiAlON phosphor that emits green light and a KSF phosphor that emits red light, it is possible to configure a backlight LED suitable for a high color rendering TV or the like. By combining the light emitting source 12 and the wavelength conversion member 15, it is possible to emit light having a high emission intensity.

[0063] In the case of the light emitting device 10 using a β-type Sialon phosphor, by irradiating near-ultraviolet light or visible light containing a wavelength of 300 nm or more and 500 nm or less as an excitation source as the light emission source 12, it has green light emission characteristics with a peak in a wavelength range of 520 nm or more and 550 nm or less. Therefore, by using a near-ultraviolet LED chip or a blue LED chip and a β-type Sialon phosphor as the light emission source 12 and further combining it with a single substance or a mixture of a red-emitting phosphor, a blue-emitting phosphor, a yellow-emitting phosphor, or an orange-emitting phosphor having a wavelength of 600 nm or more and 700 nm or less, it is possible to obtain white light.

[0064] The light emitting device 10 tends to have good brightness since it includes a β-SiAlON phosphor with improved emission intensity.

[0065] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of the present invention are included in the present invention. EXAMPLES

[0066] The embodiments of the present invention will be described in detail based on Examples and Comparative Examples. It should be noted that the present invention is not limited to the Examples.

[0067] <Ingredients> The following raw materials were prepared and used: Si3N4: α-type silicon nitride powder (SN-E10 grade) manufactured by Ube Industries AlN: Tokuyama aluminum nitride powder (F grade) Eu2O3: Europium oxide powder (RU grade) manufactured by Shin-Etsu Chemical Co., Ltd.

[0068] <Production of β-type Sialon phosphor powder> A β-type Sialon phosphor powder was produced according to the following procedure. (1) Raw material mixing process Using a V-type mixer (Tsutsui Rikagaku Kikai S-3), the above-mentioned raw materials were mixed in the ratio (mass%) shown in the table below to obtain a mixture. The mixture was then passed through a sieve with a mesh size of 250 μm to remove aggregates. In this way, a raw material mixture powder was obtained.

[0069] (2) Firing process (2-1) First firing process 200 g of the raw material powder mixture was packed into a cylindrical boron nitride container with a lid, measuring 10 cm in inner diameter and 10 cm in height, and then heat-treated in an electric furnace equipped with a carbon heater in a nitrogen atmosphere of 0.8 MPa at 1950°C for 15 hours. (2-2) Crushing process The powder obtained in (2-1) above was pulverized using a supersonic jet pulverizer (PJM-80SP, manufactured by Nippon Pneumatic Mfg. Co., Ltd.), and the pulverized material obtained was then passed through a nylon sieve with 45 μm openings to obtain a pulverized and sintered powder. (2-3) Second firing process The crushed and sintered powder obtained in (2-2) above was again packed into a cylindrical boron nitride container with a lid and an inner diameter of 10 cm and a height of 10 cm, and then heat-treated in an electric furnace equipped with a carbon heater in a nitrogen atmosphere of 0.8 MPa at 1950°C for 15 hours. (2-4) Crushing process The powder obtained in (2-3) above was pulverized using a supersonic jet pulverizer (PJM-80SP, manufactured by Nippon Pneumatic Mfg. Co., Ltd.), and the pulverized material obtained was then passed through a nylon sieve with 45 μm openings to obtain a pulverized and sintered powder.

[0070] (3) Annealing process The crushed and sintered powder obtained in (2-4) above was annealed under the conditions described in the "Annealing conditions" section of the table below, using as the atmospheric gas the gas described in the "Atmospheric gas (annealing step)" section of the table below (Example: mixed gas of hydrogen gas and nitrogen gas, Comparative example: hydrogen gas alone, nitrogen gas alone, or argon gas). As a result, an annealed sintered product was obtained.

[0071] (4) Acid treatment process After the annealing step, the fired product was allowed to cool to room temperature and then placed in an acid solution of 25 vol% 50% hydrofluoric acid, 25 vol% 70% nitric acid, and 50 vol% water, and stirred at 75° C. for 30 minutes. After the stirring was completed, the mixture was left to stand for a while, and the fired product that had precipitated was washed with water, filtered, and dried to obtain a β-SiAlON phosphor powder.

[0072] <Composition analysis> The ratios of Si, Al, O, N and Eu in the phosphor powder of each of the examples and comparative examples were determined based on the following analytical methods. 6-z Al z O z N 8-zConsidering Eu (z>0), the relative molar amount was assumed to be Si+Al=6 (mol). The results of analysis for Si, Al, and Eu were based on the results of an ICP emission spectrometer (Rigaku, CIROS-120). ·O and N were calculated from the analysis results using an oxygen / nitrogen analyzer (Horiba, EMGA-920).

[0073] <Various characteristics> (Peak wavelength λ p , half-width W and absorptance A of light with a wavelength of 455 nm 450 ) The phosphor powder of each Example or Comparative Example was filled into a concave cell so that the surface was smooth, and the cell was attached to the opening of an integrating sphere. Monochromatic light having a wavelength of 455 nm, which was split from a light source (Xe lamp), was introduced into the integrating sphere using an optical fiber as excitation light for the phosphor. The monochromatic light was irradiated onto a phosphor sample, and the fluorescence spectrum of the sample was measured using a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.). The number of photons of the reflected excitation light (Qref) was calculated from the obtained spectral data. The number of photons of the reflected excitation light was calculated in the same wavelength range as the number of photons of the excitation light. In addition, using the same device, a standard reflector with a reflectance of 99% (Spectralon (registered trademark) manufactured by Labsphere) was attached to the opening of the integrating sphere to measure the spectrum of excitation light with a wavelength of 455 nm. At this time, the number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm. Absorption rate A of light with a wavelength of 455 nm 455 was calculated by the following formula: A 455 =((Qex-Qref) / Qex)

[0074] The wavelength that showed the highest intensity in the obtained fluorescence spectrum in the wavelength range from 465 nm to 800 nm was defined as the peak wavelength λ p It was decided. In addition, the half-width (full width at half maximum) W was defined as the difference between the long-wavelength side wavelength and the short-wavelength side wavelength at which the intensity is half the intensity of the peak wavelength in the spectrum appearing in the wavelength range from 465 nm to 800 nm of the obtained fluorescence spectrum.

[0075] By the way, when a standard sample of β-type SiAlON phosphor (NIMS Standard Green lot No.NSG1301, manufactured by SiAlON Co., Ltd.) was measured using the above measurement method, A 455 The value was 0.744, the peak wavelength was 543 nm, and the half-width was 53 nm. 455 The measured values ​​of the peak wavelength and half-width may vary if the manufacturer of the measuring device, the production lot number, etc. are changed. Therefore, when the manufacturer of the measuring device, the production lot number, etc. are changed, each measured value is corrected using the measured value of the standard sample as the reference value.

[0076] (Absorptance A of light with a wavelength of 600 nm 600 ) A standard reflector (Spectralon (registered trademark) manufactured by Labsphere) with a reflectance of 99% was set at the opening of the integrating sphere. Monochromatic light separated into wavelengths of 600 nm from a light emitting source (Xe lamp) was introduced into the integrating sphere via an optical fiber. The reflected light spectrum was then measured using a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.). At this time, the number of incident light photons (Qex(600)) was calculated from the spectrum in the wavelength range of 590 nm to 610 nm.

[0077] Next, the concave cell was filled with β-SiAlON phosphor powder so that the surface was smooth, and then set in the opening of the integrating sphere. After that, monochromatic light with a wavelength of 600 nm was irradiated, and the incident reflected light spectrum was measured using a spectrophotometer. The incident reflected light photon number (Qref(600)) was calculated from the obtained spectrum data. The incident reflected light photon number (Qref(600)) was calculated in the same wavelength range as the incident light photon number (Qex(600)). From the obtained two types of photon numbers, the absorptance A of light with a wavelength of 600 nm was calculated based on the following formula: 600 was calculated. A 600=((Qex(600)-Qref(600)) / Qex(600))

[0078] By the way, when a standard sample of β-type SiAlON phosphor (NIMS Standard Green lot No.NSG1301, manufactured by SiAlON Co., Ltd.) was measured using the above measurement method, A 600 was 0.076. 600 Since the values ​​may vary when the manufacturer of the measuring device, the production lot number, etc. are changed, when the manufacturer of the measuring device, the production lot number, etc. are changed, each measured value was corrected using the measured value of the standard sample as the reference value.

[0079] (Calculation of X) The A calculated as above 455 , A 600 From and W, X was calculated based on formula (1).

[0080] (Diffuse reflectance of light with a wavelength of 800 nm) Measurements were performed using an integrating sphere device (ISV-469) attached to a JASCO UV-Vis spectrophotometer (V-550). Specifically, baseline correction was performed using a standard reflector (Spectralon (registered trademark)), and a solid sample holder filled with phosphor powder was attached to a predetermined position on the device to measure diffuse reflectance in the wavelength range from 500 nm to 850 nm. The diffuse reflectance of light with a wavelength of 800 nm was then calculated.

[0081] (Median diameter D 50 ) Median diameter D 50 was measured using a particle size measuring device using the laser diffraction / scattering method, Microtrac MT3300EXII (Microtrac Bell Co., Ltd.). The measurement procedure was as follows. (1) 0.5 g of phosphor powder was added to 100 mL of an aqueous solution of ion-exchanged water mixed with 0.05% by mass of sodium hexametaphosphate, and the solution was dispersed for 3 minutes using an ultrasonic homogenizer, Ultrasonic Homogenizer US-150E (Nihon Seiki Seisakusho Co., Ltd.), with an amplitude of 100%, an oscillation frequency of 19.5±1 kHz, a tip size of 20φ, and an amplitude of 32±2 μm, by placing the tip in the center of the liquid. (2) After that, the particle size distribution was measured using the above-mentioned device. (3) From the obtained particle size distribution, the median diameter D 50 (unit: μm) was calculated.

[0082] (Emission Intensity) The peak intensity of the β-sialon phosphor powder was measured using a spectrofluorometer (Hitachi High-Technologies Corporation, F-7000) calibrated by the Rhodamine B method and a standard light source as follows.

[0083] First, the phosphor powder was packed into a dedicated solid sample holder. Next, the fluorescent spectrum was measured by irradiating the phosphor powder with excitation light split to a wavelength of 455 nm using a spectrofluorometer, and the peak intensity was calculated from the obtained fluorescent spectrum. The peak intensity varies depending on the measuring device and conditions, so the units are arbitrary. The measuring conditions are the same in each example and comparative example, and the measurements in each example and comparative example were performed consecutively. The table below shows the intensity when the peak intensity of the β-SiAlON phosphor powder in Example 1 is taken as 100%.

[0084] The various information is summarized in the table below.

[0085] [Table 1]

[0086] As shown in the table above, λ pThe emission intensity of the β-SiAlON phosphor powder having a value of 540 nm or less and a value of x of 10 nm or less is p was 540 nm or less, but was greater than the emission intensity of a β-SiAlON phosphor powder having an X value of more than 10 nm. Specifically, by comparing Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3, that is, Examples and Comparative Examples having the same element composition and the same peak wavelength but different X values ​​due to different manufacturing conditions, it can be seen that the emission intensity can be increased by designing a β-SiAlON phosphor powder so that the X value is 10 nm or less. Just to be clear, generally, the larger (longer) the peak wavelength is, the greater the emission intensity tends to be. Therefore, it should be noted that the fact that the emission intensity of Comparative Example 3 (peak wavelength: 540 nm) is greater than that of Example 1 (peak wavelength: 527 nm) and Example 2 (peak wavelength: 529 nm) does not mean that the invention has no effect. [Explanation of symbols]

[0087] 10 Light emitting device 12 Light emitting source (LED chip) 13 First lead frame 13a Upper 13b Recess 14 Second Lead Frame 15 Wavelength conversion material 16 Bonding Wire 17 Sealing resin 18 Phosphor powder 19 Cap

Claims

1. A β-type SiAlON phosphor powder, In the fluorescence spectrum emitted when the phosphor powder is irradiated with blue light having a wavelength of 455 nm, the peak wavelength is λ ｐ [nm], and the half-width of the peak is W [nm]. The absorptance of the phosphor powder at a wavelength of 600 nm is A ６００ The absorptance of light with a wavelength of 455 nm is A ４５５ When λ ｐ is 529 nm or less, The value of X defined by the following formula (1) is 10 nm or less, Median diameter D determined by laser diffraction / scattering method ５０ is 10.2 μm or more, S ６－ｚ A ｚ O ｚ N ８－ｚ β-type sialon phosphor powder represented by the composition formula: Eu (0.02≦z≦0.12). X=(W×A ６００ ) / (A ４５５ -A ６００ ) ・・・(1)

2. β-SiAlON phosphor powder according to claim 1, Median diameter D determined by laser diffraction / scattering method ５０ The β-sialon phosphor powder has a particle size of 20 μm or less.

3. 3. The β-sialon phosphor powder according to claim 1, A β-SiAlON phosphor powder having a diffuse reflectance of 96.0% or more and 99.9% or less for light with a wavelength of 800 nm.

4. A light emitting device including a light emitting source and a wavelength conversion member, The wavelength conversion member includes a phosphor powder, A light emitting device, wherein the phosphor powder comprises the β-sialon phosphor powder according to any one of claims 1 to 3.

5. 5. The light emitting device according to claim 4, The light emitting device, wherein the light emitting source includes an LED chip that emits light having a wavelength of 300 nm or more and 500 nm or less.

6. 6. The light emitting device according to claim 4, The light emitting device, wherein the phosphor powder further contains KSF phosphor powder containing manganese as a solid solution.

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