Eu-activated β-type sialon phosphor particles, β-type sialon phosphor powder and light-emitting device

Abstract

Provided are Eu activated β-type SiAlON fluorescent particles that have a crystal grain boundary. When these particles are subjected to a rectilinear line analysis of the elemental composition of both sides of a crystal grain boundary and of the crystal grain boundary, in a direction perpendicular to the crystal grain boundary at a depth of 200 nm from a part at which a crystal grain boundary of the surface of a particle exists in a cross-section including the crystal grain boundary, the value of NEu / N'Eu is not more than 3.00, where, on a line segment subjected to line analysis, (i) NEu is the Eu amount at a point P which is on the crystal grain boundary and at which the Eu amount exhibits a peak, and (ii) N'Eu is the Eu amount at a point Q separated from the point P by 50 nm.

Description

[Technical Field]

[0001] The present invention relates to Eu-activated β-sialon phosphor particles, β-sialon phosphor powder, and a light-emitting device. [Background technology]

[0002] 2. Description of the Related Art Light emitting devices are known that combine a light emitting element that emits primary light with a phosphor that absorbs the primary light and emits secondary light. In recent years, with the trend toward higher output light-emitting devices, there has been an increasing demand for phosphors with higher heat resistance and durability, and β-sialon phosphors, which have a stable crystal structure, have attracted attention.

[0003] Eu in the crystal structure of β-sialon 2+ It is known that a phosphor containing the above (Eu-activated β-type sialon phosphor) is excited by, for example, blue light and emits green light. Eu-activated β-SiAlON is being investigated as a green-emitting component for light-emitting devices such as white LEDs (Light Emitting Diodes). Eu-activated β-SiAlON tends to have a very sharp emission spectrum among phosphors containing Eu. Therefore, various researches on β-SiAlON have been conducted.

[0004] As an example, Patent Document 1 describes a method for producing a β-sialon phosphor, which includes a first heat-treatment step of heat-treating a mixture containing an aluminum compound, a first europium compound, and silicon nitride to obtain a first heat-treated product, and a second heat-treatment step of heat-treating the first heat-treated product and a second europium compound in a rare gas atmosphere to obtain a second heat-treated product. As another example, Patent Document 2 describes a method for producing a β-sialon phosphor, which includes a firing step in which a raw material mixture of the β-sialon phosphor is fired in a nitrogen atmosphere at a temperature of 1820°C to 2200°C to obtain a fired product, and an annealing step in which the fired product is annealed in a reducing atmosphere at a temperature of 1100°C or higher. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-002278 [Patent Document 2] International Publication No. 2010 / 143590 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an Eu-activated β-sialon phosphor having good internal quantum efficiency. [Means for solving the problem]

[0007] The present inventors have completed the invention provided below and solved the above problems.

[0008] The present invention is as follows.

[0009] 1. Eu-activated β-sialon phosphor particles having grain boundaries, In a cross section including the grain boundary, a line analysis was performed on the elemental composition of the grain boundary and both sides of the grain boundary in a direction perpendicular to the grain boundary at a depth of 200 nm from the portion where the grain boundary exists on the surface of the particle. On the analyzed line segment, (i) the amount of Eu at point P on the grain boundary where the amount of Eu is at its peak is calculated by N Eu (ii) The amount of Eu at point Q 50 nm away from point P is N' Eu When N Eu / N' Eu The β-sialon phosphor particles have a value of 3.00 or less. 2. β-SiAlON phosphor particles according to 1. The amount of oxygen at point P is N О Let the amount of oxygen at point Q be N' О Then, (N Eu / N O ) / (NEu ' / N O β-SiAlON phosphor particles, wherein the value of (a) is 2.00 or less. 3. β-sialon phosphor particles according to 1. or 2., The amount of oxygen at point P is N О When N Eu / N O The β-sialon phosphor particles have a value of 0.70 or less. 4. β-sialon phosphor particles according to any one of 1. to 3., The amount of oxygen at point P is N О year, When the elemental composition of the grain boundary and both sides of the grain boundary is analyzed linearly in a direction perpendicular to the grain boundary at a depth of 200 nm from the portion of the surface of the particle where the grain boundary exists, the point P on the analyzed line segment where the amount of Al on the grain boundary shows a peak (Al) The amount of Al in N Al When N Al / N O The β-sialon phosphor particles have a value of 1.00 or less. 5. Eu-activated β-sialon phosphor particles having grain boundaries, In a cross section including the grain boundary, a line analysis was performed on the grain boundary and the elemental compositions on both sides of the grain boundary in a direction perpendicular to the grain boundary at a depth of 200 nm from the portion where the grain boundary exists on the surface of the particle. On the analyzed line segment, (i) a point P on the grain boundary where the amount of O peaks (O) The amount of Eu in N Eu(O) (ii) Point P (O) Point Q 50 nm away from (O) The amount of Eu in N' Eu(O) When N Eu(O) / N' Eu(O) The β-sialon phosphor particles have a value of 2.50 or less. 6. β-SiAlON phosphor particles according to 5. point P(O) The amount of oxygen in N О(O) Let point Q (O) The amount of oxygen in N' О (O) Then, (N Eu(O) / N O(O) ) / (N' Eu(O) / N' O(O) ) is 1.20 or less. 7. β-sialon phosphor particles according to 5. or 6., point P (O) The amount of oxygen in N О(O) When N Eu(O) / N O(O) The β-sialon phosphor particles have a value of 0.70 or less. 8. β-sialon phosphor particles according to any one of 5. to 7., point P (O) The amount of oxygen in N О(O) Let P be the point (O) The amount of aluminum in N Al(O) When N Al(O) / N O(O) The β-sialon phosphor particles have a value of 1.00 or less. 9. β-sialon phosphor powder containing the β-sialon phosphor particles according to any one of 1. to 8. 10. A light emitting device including a light emitting source and a wavelength conversion member, the wavelength conversion member contains phosphor powder, 9. A light-emitting device, wherein the phosphor powder comprises the β-sialon phosphor powder according to 9. 11. 10. The light-emitting device according to claim 10, The light emitting device, wherein the light source includes an LED chip that emits light having a wavelength of 300 nm or more and 500 nm or less. [Effects of the Invention]

[0010] According to the present invention, a Eu-activated β-sialon phosphor with good internal quantum efficiency is provided. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating an example of the structure of a light-emitting device. [Figure 2] FIG. 2 is a diagram for explaining measurement positions of line analysis in the first embodiment. [Figure 3] FIG. 10 is a diagram for explaining measurement positions of line analysis in Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0013] In this specification, the Eu-activated β-sialon phosphor particles may be simply referred to as β-sialon phosphor particles.

[0014] As used herein, the term "grain boundary" refers to a discontinuous boundary surface that exists between one crystal and another. At a grain boundary, two or more crystals (crystal grains) come into contact with each other with different orientations.

[0015] In this specification, the "surface of a particle" of a β-sialon phosphor particle refers to at least one of the following: (i) The boundary between the β-sialon phosphor particles and the atmosphere in the atmosphere (ii) In the atmosphere, the boundary between the layer containing at least one of amorphous Si, Al, O, N, Eu, etc. present on the surface of the β-type sialon phosphor particle and the atmosphere. (iii) In the atmosphere, the boundary between the atmosphere and a layer containing at least one of Si, Al, O, N, Eu, etc., which exists as a crystalline phase on the surface of a β-sialon phosphor particle. The "particle surface" can also be described as the boundary between areas where at least one of Si, Al, O, N, Eu, etc. is detected and areas where it is not detected in element distribution analysis using energy dispersive X-ray spectroscopy (EDS).

[0016] In this specification, unless otherwise specified, the expression "X to Y" in the description of a numerical range means at least X and at most Y. For example, "1 to 5% by mass" means "at least 1% by mass and at most 5% by mass."

[0017] <First embodiment: β-type sialon phosphor particles> The β-sialon phosphor particles of the first embodiment have crystal grain boundaries. In the cross section including the grain boundary, a line analysis is performed in a straight line in the direction perpendicular to the grain boundary at a depth of 200 nm from the part of the grain boundary on the surface of the particle where the grain boundary exists, to determine the elemental composition at the grain boundary and on both sides of it. At this time, on the analyzed line segment, (i) the amount of Eu at point P on the grain boundary where the amount of Eu is at its peak is measured by N Eu (ii) The amount of Eu at point Q 50 nm away from point P is N' Eu When N Eu / N' Eu The value of is less than or equal to 3.00.

[0018] N Eu / N' Eu A value of 3.00 or less means that the amount of Eu at point P, which is the grain boundary at a relatively shallow depth of 200 nm, is three times or less the amount of Eu at point Q, which is sufficiently distant (50 nm) from point P.

[0019] Based on the findings of the present inventors and the results of past research, it is believed that in conventional β-type sialon phosphors, the Eu element that was not completely dissolved inside the crystal was unevenly distributed at the grain boundaries. Eu / N' Eu It is believed that the value of was a large value exceeding 3.00 (Note: Comparative Example shown later). Eu normally functions as a luminescence center by dissolving in a solid solution inside the crystal. However, if Eu is unevenly distributed at the grain boundaries, unintended light absorption (light absorption that does not contribute to fluorescence) occurs at and near the grain boundaries, which raises concerns about a deterioration in internal quantum efficiency. The β-sialon phosphor particles of the first embodiment have a relatively small amount of Eu at the grain boundary at a relatively shallow depth of 200 nm, which is thought to reduce unintended light absorption at and near the grain boundary, and as a result, the internal quantum efficiency of the β-sialon phosphor particles of the first embodiment is thought to be good.

[0020] Incidentally, point Q can exist on two sides of point P, and when at least one of these two points is set as point Q, Eu / N' Eu If the value of is 3.00 or less, then it is sufficient. Considering the above estimation mechanism, of the two points Q that can exist on both sides of point P, at least one of them is N. Eu / N' Eu It is estimated that if the value of is 3.00 or less, the effect of improving the internal quantum efficiency can be obtained.

[0021] The β-sialon phosphor particles of the first embodiment can be manufactured by using appropriate materials and employing appropriate manufacturing methods and conditions. Preferably, the amount of Eu at the grain boundaries can be reduced by adding a small amount of titanium oxide (Ti2O3) to the β-sialon phosphor and annealing it. The manufacturing method will be described in detail later.

[0022] N Eu / N' Eu The value of is sufficient as long as it is 3.00 or less, but is preferably 0.01 or more and 3.00 or less, more preferably 0.10 or more and 3.00 or less, even more preferably 0.50 or more and 3.00 or less, and particularly preferably 1.00 or more and 3.00 or less.

[0023] Here, we will explain the procedure for line analysis, i.e., continuous elemental analysis of a line segment of a certain length on the cross section of a phosphor particle including the grain boundary. For more detailed procedures, please refer to the examples below. (1) A sample is prepared by embedding β-sialon phosphor particles in a resin material such as epoxy resin. (2) Set the sample prepared in (1) above on a cross-section polisher, and expose the cross-section of the embedded β-sialon phosphor particles. (3) Observe the cross-section exposed in (2) above with an electron microscope, and identify the portion where there is a grain boundary suitable for analysis (a grain boundary that is at least 200 nm long from the particle surface and is substantially linear). Thin slice this portion and its periphery with a focused ion beam (FIB) processing apparatus to prepare a thin slice sample. (4) In the thin slice sample (cross-section including the grain boundary), perform a linear line analysis of the elemental composition of the grain boundary and both sides thereof in a direction perpendicular to the grain boundary at a depth of 200 nm from the portion where the grain boundary exists on the surface of the particles. For the line analysis, an apparatus combined with a scanning transmission electron microscope (STEM) and a device capable of energy dispersive X-ray analysis (EDS) can be used. (5) Based on the results of the line analysis, determine the amount of each element (unit: atom%) at each point such as point P. Then, from the determined amounts of each element, calculate the "ratio" of the amounts of elements such as N Eu / N' Eu and so on.

[0024] Continue the description of the β-sialon phosphor particles of the first embodiment.

[0025] · Composition of β-sialon phosphor β-sialon phosphor is usually a phosphor composed of β-sialon in which Eu 6-z Al z O z N 8-z :Eu 2+ a (0 < Z ≤ 4.2, 0.001 < a < 1.0) is dissolved. 2+ It is a phosphor composed of β-sialon in which Eu is dissolved.

[0026] General formula Si 6-z Al z O z N 8-z :Eu 2+ aIn the above, the Z value and the europium content are not particularly limited. The Z value is, for example, more than 0 and not more than 4.2. In order to further improve the emission intensity of the β-sialon phosphor, a is 0.001 or more and 1.0 or less. The europium content is preferably 0.1 mass % or more and 2.0 mass % or less.

[0027] ·(N Eu / N O ) / (N Eu ' / N O ') value The amount of Eu typically contained in β-sialon phosphors is small compared to the other major elements (Si, Al, O, and N). Therefore, by looking at the amount of Eu relative to the amount of O (oxygen), it becomes clearer that the amount of Eu at the grain boundaries is relatively small.

[0028] Specifically, the amount of oxygen at point P is N О Let the amount of oxygen at point Q be N' О Then, (N Eu / N O ) / (N' Eu / N' O ) is preferably 2.00 or less, more preferably 0.01 or more and 2.00 or less, even more preferably 0.020 or more and 2.00 or less, and even more preferably 0.03 or more and 1.80 or less.

[0029] N Eu / N O Value of N Eu / N' Eu is 3.00 or less, that is, the "ratio" of the Eu amounts at points P and Q is not very large, and in addition, the amount of Eu on the grain boundaries is not very large compared with other elements. This is thought to further suppress unintended light absorption at and near the grain boundaries, leading to a further improvement in internal quantum efficiency.

[0030] Specifically, N Eu / N OThat is, the ratio of the Eu amount / O amount on the grain boundary (depth 200 nm) is preferably 0.70 or less, more preferably 0.001 or more and 0.70 or less, even more preferably 0.005 or more and 0.50 or less, and particularly preferably 0.005 or more and 0.40 or less.

[0031] N Al / N O Value of The amount of Al on the grain boundaries is not so large compared to other elements, and this is also expected to lead to a further improvement in internal quantum efficiency. Although the details are unclear, previous findings suggest that charged defects called aluminum oxygen hole centers may exist near grain boundaries, which are considered to be in a glassy state. The low Al content near the grain boundaries reduces the number of these charged defects, which is thought to further improve the internal quantum efficiency.

[0032] Specifically, when a linear analysis of the elemental composition of the grain boundary and both sides of it was performed in a direction perpendicular to the grain boundary at a depth of 200 nm from the grain boundary on the surface of the particle, Point P on the analyzed line segment where the amount of Al on the grain boundary is at its peak (Al) The amount of Al in N Al When N Al / N O The value of this formula, that is, the ratio of the Al content to the O content near the grain boundary at a depth of 200 nm, is preferably 1.0 or less, more preferably 0.01 or more and 1.00 or less, even more preferably 0.01 or more and 0.70 or less, and particularly preferably 0.05 or more and 0.50 or less. Also, the amount of aluminum at point Q is N' Al Then, (N Al / N O ) / (N' Al / N' O The value of N' is preferably 0.47 or less, more preferably 0.01 or more and 0.47 or less. О is defined above). Also, N Al / N' AlThe value of is preferably 1.10 or less, more preferably 0.10 or more and 1.10 or less, even more preferably 0.50 or more and 1.10 or less, and particularly preferably 0.75 or more and 1.10 or less.

[0033] Supplementary information on the amount of each element N Eu Just to be safe, we will list the numerical ranges for these and other items.

[0034] N Eu The value of is usually 0.00 atom % or more and 1.50 atom % or less, preferably 0.05 atom % or more and 1.00 atom % or less, more preferably 0.10 atom % or more and 0.50 atom % or less, and even more preferably 0.10 atom % or more and 0.30 atom % or less. N' Eu The value is usually 0.01 atom % or more and 1.00 atom % or less, preferably 0.01 atom % or more and 0.80 atom % or less, more preferably 0.02 atom % or more and 0.50 atom % or less, and further preferably 0.03 atom % or more and 0.25 atom % or less.

[0035] N О The value of is usually 0.10 atom % or more and 20.00 atom % or less, preferably 0.30 atom % or more and 20.00 atom % or less, and more preferably 0.50 atom % or more and 15.00 atom % or less. N' О The value of is usually 0.01 atom % or more and 10.00 atom % or less, preferably 0.05 atom % or more and 10.00 atom % or less, and more preferably 0.10 atom % or more and 10.00 atom % or less.

[0036] N Al The value of is usually 0.00 atom % or more and 10.00 atom % or less, preferably 0.00 atom % or more and 3.50 atom % or less. N' AlThe value of is usually 0.50 atom % or more and 10.00 atom % or less, preferably 0.50 atom % or more and 5.00 atom % or less, and more preferably 1.00 atom % or more and 5.00 atom % or less.

[0037] Amount of N element at point P N is usually 5.00 atom % or more and 40.00 atom % or less, preferably 10.00 atom % or more and 35.00 atom % or less, and more preferably 10.00 atom % or more and 30.00 atom % or less. Amount N' of element N at point Q N is usually 5.00 atom % or more and 40.00 atom % or less, preferably 10.00 atom % or more and 35.00 atom % or less, more preferably 10.00 atom % or more and 30.00 atom % or less, and even more preferably 10.00 atom % or more and 25.00 atom % or less.

[0038] Amount of Si element at point P Si is usually 50.00 atom % or more and 85.00 atom % or less, preferably 60.00 atom % or more and 80.00 atom % or less. Amount of Si element N' at point Q Si is usually 50.00 atom % or more and 85.00 atom % or less, preferably 60.00 atom % or more and 80.00 atom % or less, more preferably 70.00 atom % or more and 80.00 atom % or less, and particularly preferably 75.00 atom % or more and 80.00 atom % or less.

[0039] Incidentally, as will be described later, Ti is preferably used in the manufacturing process of the β-sialon phosphor particles of Embodiment 1. Ideally, Ti is used only in the manufacturing process and does not remain in the final β-sialon phosphor particles, but in reality, a small amount of Ti may remain. Amount of Ti element at point P N Ti is preferably 0.50 atom % or less, more preferably 0.20 atom % or less. Ti is ideally zero (amount below the detection limit). Amount of Ti element N' at point Q Ti is preferably 0.50 atom % or less, more preferably 0.20 atom % or less, and further preferably 0.10 atom % or less. Ti is ideally zero (amount below the detection limit).

[0040] β-type sialon phosphor powder The β-sialon phosphor powder of the first embodiment contains the β-sialon phosphor particles of the first embodiment. The 50% cumulative diameter (D50) in the volume-based cumulative particle size distribution of the β-sialon phosphor powder can be adjusted depending on the application of the phosphor, etc. D50 is, for example, 0.1 μm or more and 50 μm or less, preferably 3 μm or more and 40 μm or less, and more preferably 6 μm or more and 30 μm or less. D50 can be controlled by adjusting conditions such as heating temperature and heating time during phosphor production, performing appropriate pulverization, classification, etc.

[0041] D50 is defined as the particle size at which the cumulative value from the smallest particle size reaches 50% of the total in the volume-based particle size distribution curve measured by laser diffraction / scattering. The particle size distribution curve for phosphors can be obtained in accordance with the particle size distribution measurement method using laser diffraction / scattering described in JIS R 1629:1997 "Method for measuring particle size distribution of fine ceramic raw materials using laser diffraction / scattering." A particle size distribution measurement device can be used for the measurement. Specifically, 0.1 g of the phosphor to be measured is first placed in 100 mL of ion-exchanged water, a small amount of sodium hexametaphosphate is added, and a dispersion is obtained by dispersing the phosphor for 3 minutes using an ultrasonic homogenizer. This dispersion is used as the measurement sample, and the particle size distribution is measured using a particle size distribution analyzer. D50 is then determined from the obtained particle size distribution. The particle size distribution measuring device may be, for example, "Microtrac MT3300EX II" (product name) manufactured by Microtrac Bell Co., Ltd. The ultrasonic homogenizer may be, for example, "Ultrasonic Homogenizer US-150E" (product name, tip size: φ20, amplitude: 100%, oscillation frequency: 19.5 kHz, amplitude: approximately 31 μm) manufactured by Nippon Seiki Seisakusho Co., Ltd.

[0042] <Second embodiment: β-type sialon phosphor particles> The β-sialon phosphor particles of the second embodiment have crystal grain boundaries. In a cross section including the grain boundary, a line analysis was performed on the grain boundary and the elemental composition on both sides of the grain boundary in a direction perpendicular to the grain boundary at a depth of 200 nm from the part where the grain boundary exists on the surface of the particle. On the analyzed line segment, (i) the point P on the grain boundary where the O content peaks (O) The amount of Eu in N Eu(O) (ii) Point P (O) Point Q 50 nm away from (O) The amount of Eu in N' Eu(O) When N Eu(O) / N' Eu(O) The value of is 2.50 or less.

[0043] In the first embodiment, (i) the Eu amount (N Eu ) and (ii) the amount of Eu at point Q 50 nm away from point P (N' Eu ) is within a certain range. In other words, in the first embodiment, the "point P where the Eu amount peaks" is set as the "reference position" in the grain boundary observed with a finite width. On the other hand, in the second embodiment, (i) the point P on the grain boundary where the O amount peaks (O) " Eu content (N Eu(O) ) and (ii) point P (O) Point Q 50 nm away from (O) Eu content (N' Eu(O)) in a certain range. In other words, in the second embodiment, the β-sialon phosphor particles were specified. (O) " was set as the "reference position" for the grain boundary observed with a finite width. That is, although the positions at which the amounts of elements such as Eu are measured are slightly different, the first embodiment and the second embodiment are similar.

[0044] The reason for providing different "reference positions" in the first and second embodiments is based on the findings of the present inventors. Specifically, measurements by the present inventors have shown that the point at which the Eu content peaks and the point at which the O content peaks do not necessarily coincide with each other at grain boundaries, and each point can be considered as the "center of the grain boundary" in grain boundaries observed with a finite width.

[0045] As in the first embodiment, N Eu(O) / N' Eu(O) The fact that the value of is 2.5 or less indicates that the amount of Eu in the grain boundary portion at a relatively shallow depth of 200 nm is relatively small. In other words, the β-sialon phosphor particles of the second embodiment are also less likely to have unintended light absorption at or near the grain boundaries, resulting in good internal quantum efficiency.

[0046] N Eu(O) / N' Eu(O) The value of is sufficient as long as it is 2.50 or less, but is preferably 0 or more and 3.00 or less, more preferably 0 or more and 2.00 or less, and even more preferably 0 or more and 1.50 or less.

[0047] The following is a continued description of the β-sialon phosphor particles of the second embodiment. As mentioned above, the first embodiment and the second embodiment are similar, and therefore, the matters described in the first embodiment can be applied to the second embodiment as appropriate.

[0048] The chemical composition of the β-sialon phosphor particles of the second embodiment is the same as that of the first embodiment, and is represented by the general formula Si6-z Al z O z N 8-z :Eu 2+ a (0 < Z ≤ 4.2, 0.001 < a < 1.0) can be expressed as such.

[0049] In the second embodiment as well, by looking at the amount of Eu based on the amount of O (oxygen), it can be more clearly expressed that the amount of Eu at the grain boundaries is relatively small. Specifically, for the amount of oxygen at point P (O) being N О(O) and the amount of oxygen at point Q (O) being N' О (O) when, (N Eu(O) / N O(O) ) / (N' Eu(O) / N' O(O) ) value is preferably 1.20 or less, more preferably 0 or more and 1.20 or less, still more preferably 0 or more and 1.00 or less, particularly preferably 0 or more and 0.50 or less, and especially preferably 0 or more and 0.30 or less.

[0050] In the second embodiment as well, since the amount of Eu on the grain boundaries itself is not much more than that of other elements, unintended light absorption at the grain boundaries and in their vicinity is further suppressed, leading to a further improvement in the internal quantum efficiency. Specifically, when the amount of oxygen at point P (O) is N О(O) , the value of N Eu(O) / N O(O) is preferably 0.70 or less, more preferably 0 or more and 0.70 or less, still more preferably 0 or more and 0.50 or less, particularly preferably 0 or more and 0.30 or less, and especially preferably 0 or more and 0.10 or less.

[0051] In the second embodiment as well, since the amount of Al on the grain boundaries is not much more than that of other elements, a further improvement in the internal quantum efficiency can be expected. Specifically, for the amount of oxygen at point P (O) being N О(O) and the amount of aluminum at point P (O) being NAl(O) When N Al(O) / N O(O) The value of is preferably 1.00 or less, more preferably 0 or more and 1.00 or less, and even more preferably 0.01 or more and 1.00 or less. Also, point Q (O) The amount of aluminum in N' Al(O) Then, (N Al(O) / N O(O) ) / (N' Al(O) / N' O(O) The value of is preferably 0.45 or less, preferably 0 or more and 0.45 or less, more preferably 0 or more and 0.30 or less, and particularly preferably 0.005 or more and 0.25 or less. Also, N Al(O) / N' Al(O) The value of is preferably 1.10 or less, more preferably 0.1 or more and 1.10 or less, even more preferably 0.50 or more and 1.10 or less, and particularly preferably 0.75 or more and 1.10 or less.

[0052] N Eu(O) The value of is usually 1.50 atom % or less, preferably 0 atom % or more and 1.00 atom % or less, more preferably 0 atom % or more and 0.50 atom % or less, and further preferably 0 atom % or more and 0.30 atom % or less. N' Eu(O) The value of N' Eu can be similar to:

[0053] N О(O) The value of is usually 1.00 atom % or more and 50.0 atom % or less, preferably 1.00 atom % or more and 45.0 atom % or less, and more preferably 1.00 atom % or more and 40.0 atom % or less. N' О (O) The value of N' О can be similar to:

[0054] N Al(O) The value of is usually 0.10 atom % or more and 10.00 atom % or less, preferably 0.10 atom % or more and 5.00 atom % or less, and more preferably 0.10 atom % or more and 3.00 atom % or less. N' Al(O) The value of N' Al can be similar to:

[0055] point P (O) The amount of N in N(O) is usually 5.00 atom % or more and 40.00 atom % or less, preferably 5.00 atom % or more and 30.00 atom % or less, and more preferably 5.00 atom % or more and 25.00 atom % or less.

[0056] The β-sialon phosphor powder of the second embodiment includes the β-sialon phosphor particles of the second embodiment. The 50% cumulative diameter (D50) in the volume-based cumulative particle size distribution of the β-sialon phosphor powder of the second embodiment can be similar to that of the β-sialon phosphor powder of the first embodiment.

[0057] <Method of manufacturing β-type Sialon phosphor particles> The β-sialon phosphor particles of the first embodiment and the β-sialon phosphor particles of the second embodiment can be manufactured by using appropriate materials and employing appropriate manufacturing methods and manufacturing conditions.

[0058] A preferred manufacturing method is to add a small amount of titanium oxide (Ti2O3) to the β-sialon phosphor and then anneal it, which reduces the amount of Eu at the grain boundaries.

[0059] Although the details of this mechanism are unclear, based on the inventors' past findings, it is believed that such annealing treatment generates compounds containing Eu and Ti at and near the grain boundaries of the phosphor particles, which are then removed by the acid treatment described below, thereby controlling the amount of Eu at and near the grain boundaries. Furthermore, since (i) compounds containing Eu and Ti are produced, and (ii) compounds containing Al and Ti are also produced, it is believed that the amount of Al at and near the grain boundaries is also controlled.

[0060] An example of the manufacturing method is: a firing step of obtaining a fired body containing β-sialon from a raw material composition containing a silicon source, an aluminum source, and a europium source, with at least one of them being present as a nitride, by one or more heat treatments; an annealing step of obtaining an annealed body from a mixture containing the fired body and titanium oxide (Ti2O3) by one or more annealing treatments under an atmosphere containing at least one kind selected from the group consisting of a rare gas, a reducing gas, and an inert gas; The method can include: This example will be described below.

[0061] The raw material composition contains a compound having elements that are constituent elements of β-sialon, including europium, and can contain at least a silicon source, an aluminum source, and a europium source. In the raw material composition, at least one of the silicon source, aluminum source, and europium source is a nitride. The nitride contains nitrogen, which is a constituent element of β-sialon, and is therefore also a nitrogen source. The silicon source refers to a compound or element containing silicon as a constituent element, the aluminum source refers to a compound or element containing aluminum as a constituent element, and the europium source refers to a compound or element containing europium as a constituent element. In this specification, a compound containing silicon as a constituent element is also referred to as a silicon compound, a compound containing aluminum as a constituent element is also referred to as an aluminum compound, and a compound containing europium as a constituent element is also referred to as a europium compound. The silicon compound, aluminum compound, and europium compound may each be any of a nitride, oxide, oxynitride, and hydroxide. The raw material composition may further contain β-sialon or europium-containing β-sialon. Here, the β-sialon or europium-containing β-sialon is a material that serves as an aggregate or core.

[0062] Examples of silicon compounds include silicon nitride (Si3N4) and silicon oxide (SiO2). It is preferable to use silicon nitride with a high α fraction. The α fraction of silicon nitride may be, for example, 80 mass% or more, 90 mass% or more, or 95 mass% or more. When the α fraction of silicon nitride is within the above range, primary particle growth can be promoted. It is preferable to use silicon nitride with a low oxygen content. The oxygen content of silicon nitride may be, for example, 3.0 mass% or less, or 1.3 mass% or less. When the oxygen content of silicon nitride is within the above range, the occurrence of defects in the β-sialon crystal can be suppressed.

[0063] Examples of aluminum compounds include aluminum nitride (AlN), aluminum oxide (Al2O3), and aluminum hydroxide (Al(OH)3).

[0064] Examples of europium compounds include europium oxide (europium oxide), europium nitride (europium nitride), and europium halides. Examples of europium halides include europium fluoride, europium chloride, europium bromide, and europium iodide. The europium compound preferably contains europium oxide. The valence of europium in the europium compound may be divalent or trivalent, and is preferably divalent.

[0065] The raw material mixture can be prepared by weighing and mixing each compound. A dry mixing method or a wet mixing method can be used for mixing. The dry mixing method may be, for example, a method in which each component is mixed using a V-type mixer or the like. The wet mixing method may be, for example, a method in which a solvent or dispersion medium such as water is added to prepare a solution or slurry, the components are mixed, and then the solvent or dispersion medium is removed.

[0066] The heating temperature in the firing step is, for example, 1800 to 2500°C, 1800 to 2400°C, 1850 to 2100°C, 1900 to 2100°C, 1900 to 2050°C, or 1920 to 2050°C. By setting the heating temperature in the firing step to 1800°C or higher, the particle growth of β-sialon can be promoted and the amount of europium dissolved in the solid solution can be made more sufficient.By setting the heating temperature in the firing step to 2500°C or lower, the decomposition of the β-sialon crystals can be sufficiently suppressed.

[0067] The heating time in the firing step is preferably long from the viewpoint of promoting the growth of primary particles of β-sialon, but if the heating time is too long, crystal defects may increase. Therefore, the heating time is, for example, 1 to 30 hours, 3 to 25 hours, or 5 to 20 hours.

[0068] The raw material mixture in the firing step is heated, for example, in a nitrogen atmosphere. Heating under conditions of high nitrogen partial pressure can suppress decomposition of silicon nitride at high temperatures. Furthermore, treatment at high temperatures can promote particle growth. The raw material mixture in the firing step is heated, for example, under pressure. The pressure may be, for example, 0.010 to 200 MPaG, 0.020 to 200 MPaG, 0.1 to 200 MPaG, 0.1 to 100 MPaG, 0.1 to 50 MPaG, 0.1 to 15 MPaG, or 0.1 to 5 MPaG.

[0069] The number of times of heat treatment in the firing step may be one, two or more, two to five, or two to four. By performing heat treatment multiple times, more light can be emitted. strength Therefore, a β-sialon phosphor having excellent luminance can be obtained.

[0070] In the firing step, one or more heat treatments are performed. When multiple heat treatments are performed, they are sequentially referred to as a first heat treatment, a second heat treatment, etc., and the steps of performing each heat treatment may be sequentially referred to as a first firing step, a second firing step, etc. For example, when the above-mentioned manufacturing method performs two heat treatments in the firing step, the firing step may also be referred to as including a first heat treatment of a raw material composition containing a nitride to obtain a first heat-treated body, and a second heat treatment of the first heat-treated body to obtain a second heat-treated body. In this case, the second heat-treated body corresponds to a fired body containing β-sialon. Before performing the multiple heat treatments, the silicon source, aluminum source, and europium source may be further mixed and heat-treated.

[0071] When the firing step includes two or more heating treatments, the heating temperature, heating time, heating atmosphere, and heating pressure in the first firing step can be the same as the heating temperature, heating time, heating atmosphere, and heating pressure in the above-mentioned heating step. The heating temperature, heating time, heating atmosphere, and heating pressure in the second firing step and thereafter can be the same as or different from those in the first firing step. However, in the second firing step, onwards Even if the heating temperature, heating time, heating atmosphere, and heating pressure in the second baking step are different from those in the first baking step, they are within the range of conditions shown for the heating step above.

[0072] The fired body obtained in the firing step has β-sialon crystals, and is a solid solution in which an element serving as a luminescence center is dissolved in a part of the crystals, and can itself emit fluorescence. Since the fired body obtained in the firing step may be in the form of a mass, the particle size may be adjusted by crushing or the like prior to the annealing step.

[0073] Next, an annealing step is performed. The annealing step in this manufacturing method refers to a step of annealing a mixture containing the fired body obtained in the firing step and titanium oxide (Ti2O3). In the annealing step, an annealed body is obtained from the mixture by one or more heat treatments.

[0074] The amount of titanium oxide (Ti2O3) added can be, for example, 0.01 to 4 mass %, 0.05 to 3 mass %, or 0.1 to 3 mass % relative to the total amount of the mixture. By making the blending amount 0.01% by mass or more, excess Eu and Al in the grain boundaries can be sufficiently removed, and the internal quantum efficiency of the resulting β-sialon phosphor can be further improved. By setting the blending amount to 4 mass % or less, titanium oxide and various products can be easily removed by acid treatment, and deterioration of the luminescence properties of the β-sialon phosphor can be suppressed.

[0075] The annealing step is performed in an atmosphere containing at least one gas selected from the group consisting of a rare gas, a reducing gas, and an inert gas. By performing the annealing in an atmosphere containing a rare gas, a reducing gas, or an inert gas, the proportion of divalent europium in the europium in the solid solution can be increased.

[0076] The rare gas may contain, for example, argon, helium, etc., or may contain argon or may consist of argon. The reducing gas may contain, for example, ammonia, hydrocarbon, carbon monoxide, hydrogen, etc., or may contain hydrogen or may consist of hydrogen. The inert gas may contain, for example, nitrogen, etc., or may consist of nitrogen. The atmosphere for the annealing step may be a mixed gas of two or more of the rare gas, the reducing gas, and an inert gas. When the mixed gas is used as the atmosphere for the annealing step, the content of the reducing gas may be, for example, 1 to 50 vol% or 4 to 20 vol% based on the total volume of the mixed gas. The content of the inert gas may be, for example, 1 to 50 vol% or 4 to 20 vol% based on the total volume of the mixed gas.

[0077] The pressure during the annealing treatment may be the same as that during the firing step, but is preferably lower than the pressure conditions during the firing step, and more preferably atmospheric pressure.

[0078] The annealing temperature must be set lower than the heating temperature in the sintering step. The upper limit of the annealing temperature is, for example, 1700°C or lower, preferably 1680°C or lower. By setting the upper limit of the annealing temperature within the above range, further particle growth in the sintered body can be prevented from occurring, resulting in aggregation between solid solutions and the formation of secondary particles, thereby preventing particle coarsening. The lower limit of the annealing temperature is, for example, 1000°C or higher, 1100°C or higher, 1200°C or higher, 1300°C or higher, or 1400°C or higher. Setting the lower limit of the annealing temperature within the above range can reduce the crystal defect density of the β-sialon contained in the annealed body and further improve the internal quantum efficiency. The annealing temperature can be adjusted within the above range, for example, 1000 to 1700°C or 1100 to 1680°C.

[0079] The heating time in the annealing treatment may be, for example, 1 to 30 hours, 2 to 25 hours, or 3 to 20 hours, from the viewpoint of further reducing crystal defects in the phosphor contained in the annealed body.

[0080] In the annealing step, one or more annealing treatments are performed. When multiple annealing treatments are performed, they are sequentially referred to as a first annealing treatment, a second annealing treatment, etc., and the steps of performing each annealing treatment may be sequentially referred to as a first annealing treatment, a second annealing treatment, etc. For example, when the above-mentioned manufacturing method performs two annealing treatments in the annealing step, the annealing step is also said to include a step of performing a first annealing treatment on the fired body to obtain a first annealed body, and a second annealing treatment on the first annealed body to obtain a second annealed body. In this case, the second annealed body corresponds to the above-mentioned annealed body.

[0081] When the annealing step includes two or more annealing steps, the temperature, heating time, and pressure during heating of the first annealing step can be the same as those of the annealing step described above. The temperature, heating time, and pressure during heating of the second annealing step and subsequent annealing steps can be the same as or different from those of the first annealing step. However, even if the temperature, heating time, and pressure during heating of the second annealing step and subsequent annealing steps are different from those of the first annealing step, they are still within the range of conditions described above for the annealing step.

[0082] The number of annealing treatments in the annealing step may be one, but may also be, for example, two or more, such as 2 to 5 or 2 to 4. By performing annealing treatments multiple times, the crystal defect density of the β-sialon contained in the annealed body can be reduced, and a europium-containing β-sialon phosphor with better internal quantum efficiency can be obtained.

[0083] When annealing is performed multiple times in the annealing step, titanium oxide (Ti2O3) may be added all at once in the first annealing step, or may be added in portions over multiple annealing steps. However, it is preferable to add it all at once in the first annealing step. Incidentally, when these compounds are added in portions, the description of the amount of titanium oxide (Ti2O3) added should be interpreted as the total amount of titanium oxide (Ti2O3) added over multiple annealing steps. Compounds of the constituent elements of the β-sialon phosphor may be co-doped with titanium oxide (Ti2O3) in the annealing step.

[0084] The method for producing a β-sialon phosphor may include other steps in addition to the firing step and the annealing step. Examples of the other steps include a step of treating the annealed body obtained in the annealing step with at least one of an acid and an alkali, and a classification step of adjusting the particle size of the annealed body or the annealed body that has been subjected to an acid treatment or the like. The step of treating the annealed body with an acid is called the acid treatment step, and the step of treating the annealed body with an alkali is called the alkali treatment step.

[0085] The acid treatment step or alkali treatment step is expected to further reduce the crystal defect density in the phosphor contained in the annealed body, remove silicon present on the surface of the solid solution formed by thermal decomposition of β-sialon, and remove AlN polytypoid, a pseudopolymorph of aluminum nitride (AlN) formed as a by-product during preparation of the first fired body. Examples of acids include hydrofluoric acid and nitric acid. The acid can be a mixed acid of hydrofluoric acid and nitric acid. Examples of alkalis include sodium hydroxide.

[0086] The classification step may be performed by, for example, either a wet classification method or a dry classification method. Examples of wet classification include elutriation classification, in which the annealed body is added to a mixed solvent containing ion-exchanged water and a dispersant (e.g., sodium hexametaphosphate) or a mixed solvent containing ion-exchanged water and aqueous ammonia, stirred, and then allowed to stand to remove particles with a small particle size.

[0087] <Light-emitting device> The light emitting device of this embodiment is a light emitting device including a light source and a wavelength conversion member. The wavelength conversion member includes a phosphor. The phosphor includes the β-sialon phosphor powder of the first embodiment and / or the β-sialon phosphor powder of the second embodiment.

[0088] FIG. 1 is a cross-sectional view showing a schematic example of the structure of a light emitting device 10. As shown in FIG. 1 is formed of an LED chip as a light source 12, a first lead frame 13 on which the light source 12 is mounted, a second lead frame 14, a wavelength conversion member 15 that covers the light source 12, a bonding wire 16 that electrically connects the light source 12 and the second lead frame 14, and a synthetic resin cap 19 that covers these. The wavelength conversion member 15 has a phosphor 18 and a sealing resin 17 in which the phosphor 18 is dispersed.

[0089] 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 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.

[0090] Various types of LED chips can be used as the light source 12. Particularly preferred is an LED chip that emits light with a wavelength of 300 nm or more and 500 nm or less, which is from near ultraviolet to blue light.

[0091] The phosphor 18 used in the wavelength conversion member 15 of the light emitting device 10 includes the β-sialon phosphor powder of the first embodiment and / or the β-sialon phosphor powder of the second embodiment. Furthermore, from the viewpoint of controlling the light wavelength of the light emitting device 10, the phosphor 18 may further include, in addition to the β-sialon phosphor powder of the first embodiment and / or the β-sialon phosphor powder of the second embodiment, a phosphor such as an α-sialon phosphor, a KSF-based phosphor, CaAlSiN3, or a mixture of YAG. 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 singly or in combination of two or more. Among these, a KSF-based phosphor containing manganese as a solid solution is preferable as the phosphor to be used in combination with the β-sialon phosphor powder of the first embodiment and / or the β-sialon phosphor powder of the second embodiment. By using a combination of a β-sialon phosphor that exhibits green and a KSF-based phosphor that exhibits red, the phosphor can be suitably used as an LED for backlighting suitable for, for example, a high color rendering television. By combining the light emitting source 12 and the wavelength converting member 15, it is possible to emit light with high luminous intensity. Just to be clear, KSF phosphors containing manganese in solid solution have the general formula: A2M (1-n) F6:Mn 4+ n In this general formula, the element A is one or more alkali metal elements containing K, the element M is Si alone, Ge alone, or a combination of Si with one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf, and 0 <n≦0.1である。

[0092] In the case of the light emitting device 10 using a β-sialon phosphor, the device exhibits green light emission characteristics with a peak wavelength in the range of 520 nm to 560 nm when near-ultraviolet light or visible light containing a wavelength of 300 nm to 500 nm is irradiated as the excitation source for the light source 12. Therefore, by using a near-ultraviolet LED chip or a blue LED chip and the β-sialon phosphor of this embodiment as the light source 12 and further combining it with a single or mixture of a red-, blue-, yellow-, or orange-emitting phosphor having a wavelength of 600 nm to 700 nm, it is possible to produce white light.

[0093] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0094] The embodiments of the present invention will be described in detail based on Examples and Comparative Examples. However, it should be noted that the present invention is not limited to the Examples.

[0095] <Production of β-type Sialon phosphor particles> [Example 1] The following steps (1) to (4) were carried out.

[0096] (1) Raw material mixing process The raw materials were weighed into a container so that the silicon nitride (Si3N4) was 95.7% by mass, aluminum nitride (AlN) was 2.6% by mass, aluminum oxide (Al2O3) was 1.0% by mass, and europium oxide (Eu2O3) was 0.7% by mass, and mixed using a V-type mixer (manufactured by Tsutsui Scientific Machinery Co., Ltd.) to obtain a mixture. The obtained mixture was passed through a sieve with 250 μm openings to remove aggregates, thereby obtaining a raw material composition. The aggregates that did not pass through the sieve were crushed and the particle size was adjusted so that they would pass through the sieve.

[0097] (2) Firing process 200 g of the raw material composition was placed in a cylindrical boron nitride container with a lid (a molded product made by Denka Co., Ltd., primarily composed of boron nitride (trade name: Denka Boron Nitride N-1), inner diameter: 10 cm, height: 10 cm). The container was then placed in an electric furnace equipped with a carbon heater, and heated to 2020°C under a nitrogen gas atmosphere (pressure: 0.90 MPaG). The mixture was then heated at 2020°C for 8 hours (firing step). After heating, the sample formed loosely agglomerated lumps in the container and was placed in a mortar and crushed. After crushing, the sample was passed through a sieve with 250 μm openings and subjected to strong crushing. A powdery first fired body was thus obtained.

[0098] (3) Annealing process The first fired body and titanium oxide (Ti2O3) were mixed to obtain a mixture for annealing treatment. The amount of titanium oxide was 0.1 parts by mass when the total amount of the first fired body and titanium oxide was 100 parts by mass. The annealing mixture was then filled into a cylindrical boron nitride container. This container was placed in an electric furnace equipped with a carbon heater. The temperature was raised to 1450°C in an argon gas atmosphere (pressure: 0.025 MPaG), and heating was continued at 1450°C for 3 hours (annealing step). After heating, the loosely aggregated particles in the container were crushed in a mortar and passed through a 250 μm sieve to obtain powder.

[0099] (4) Acid treatment, removal of fine particles, etc. The obtained powder was added to a mixed acid of hydrofluoric acid (concentration: 50% by mass) and nitric acid (concentration: 70% by mass) (a mixture of hydrofluoric acid and nitric acid in a volume ratio of 1:1), and subjected to acid treatment for 30 minutes while stirring at 75°C. After the acid treatment, the stirring was stopped, the powder was allowed to settle, and the supernatant and fine powder refined by the acid treatment were removed. Thereafter, more distilled water was added and the mixture was stirred again. The stirring was stopped, the powder was allowed to settle, and the supernatant and fine powder were removed. This procedure was repeated until the pH of the aqueous solution was 8 or less and the supernatant was transparent, and the resulting precipitate was filtered and dried. In this way, a β-sialon phosphor powder containing Eu-activated β-sialon phosphor particles was obtained.

[0100] [Example 2] (2) A β-sialon phosphor powder was obtained in the same manner as in Example 1, except that the final pulverization in the firing step was weak pulverization instead of strong pulverization.

[0101] [Example 3] (3) In the annealing treatment step, the β-sialon phosphor powder was obtained in the same manner as in Example 1, except that the amount of titanium oxide added was changed from 0.1 parts by mass to 0.2 parts by mass.

[0102] [Comparative Example 1] (3) A β-sialon phosphor powder was obtained in the same manner as in Example 1, except that in the annealing treatment step, titanium oxide was not used and only the first fired body was heated for annealing treatment.

[0103] Comparative Example 2 (3) In the annealing treatment step, a β-sialon phosphor powder was obtained in the same manner as in Example 1, except that the same mass of europium oxide was added instead of titanium oxide and the annealing treatment was carried out.

[0104] Comparative Example 3 (3) A β-sialon phosphor powder was obtained in the same manner as in Example 2, except that in the annealing treatment step, titanium oxide was not used and only the first fired body was heated for annealing treatment.

[0105] <Line analysis> This was done according to the following procedure. (1) A sample was prepared by embedding β-sialon phosphor powder in epoxy resin. (2) The sample prepared in (1) above was set in a cross-section polisher (SM-09010 manufactured by JEOL Ltd.) and processed under the condition of an acceleration voltage of 6 kV, thereby exposing the cross section of the embedded β-sialon phosphor particles. (3) The cross section exposed in (2) above was observed using a SEM (field emission type, accelerating voltage 5 kV) to identify the area where the grain boundary suitable for analysis was located (a grain boundary at least 200 nm long from the particle surface and nearly linear). This area and its surrounding area were thinned using a focused ion beam (FIB) processing device to prepare a thin section sample. (4) For thin-section samples (cross sections including grain boundaries), linear line analysis was performed on the grain boundaries and their respective sides in a direction perpendicular to the grain boundaries, at a depth of 200 nm from the grain boundary on the particle surface. A JEOL JEM-ARM200F (a combination of a scanning transmission electron microscope (STEM) and an energy dispersive X-ray analyzer (EDS)) was used for the line analysis. The accelerating voltage was 200 kV. (5) Based on the results of the line analysis, the amount of each element (unit: atom%) at each point, such as point P, was determined. The amount of each element (unit: atom%) was determined by analysis using NORAN System 7, a software provided with the JEM-ARM200F, manufactured by Thermo Fisher Scientific. In this analysis, the elements to be considered were Si, N, Al, O, Ti (K line), and Eu (L line). The Cliff-Limer (no absorption) model was also specified as the semi-quantitative model. Then, from the amount of each element calculated, N Eu / N' Eu The ratios of the amounts of elements such as:

[0106] For reference, the positions where line analysis (4) was performed on a flake sample obtained by slicing the β-sialon phosphor particles of Example 1 as described above in (1) to (3) are shown in Fig. 2. Similarly, the positions where line analysis (4) was performed on a flake sample obtained by slicing the β-sialon phosphor particles of Comparative Example 1 as described above in (1) to (3) are shown in Fig. 3.

[0107] The amount of each element at each point (unit: atom%) and N Eu / N' Eu The ratios of the amounts of these elements are summarized in Table 1. In addition, in a region sufficiently distant (about 50 nm) from the grain boundary, it is considered that there is no significant difference in the element composition even if the measurement point is shifted by a few nm. (O) The amount of each element measured at the position was considered to be the amount of each element at point Q.

[0108] [Table 1]

[0109] <Evaluation of internal quantum efficiency, etc.> The β-sialon phosphors obtained in each example and comparative example were evaluated for absorptance, internal quantum efficiency, external quantum efficiency, and chromaticity X when irradiated with excitation light having a wavelength of 455 nm. The absorptance was also evaluated when irradiated with excitation light having a wavelength of 600 nm. The specific evaluation methods are as follows:

[0110] [Absorptivity, Internal Quantum Efficiency and External Quantum Efficiency] The absorptance (excitation light absorptance), internal quantum efficiency, and external quantum efficiency of a phosphor when irradiated with excitation light of 455 nm wavelength were calculated using the following procedure. First, the phosphor to be measured 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 of 455 nm wavelength, which was split from a Xe lamp serving as a light source, was introduced into the integrating sphere using an optical fiber as excitation light for the phosphor. This monochromatic excitation light was irradiated onto the phosphor to be measured, and the fluorescence spectrum was measured. A spectrophotometer (manufactured by Otsuka Electronics Co., Ltd., product name: MCPD-7000) was used for the measurements.

[0111] The emission intensity of the phosphor was determined from the obtained fluorescence spectrum data. The number of reflected excitation light photons (Qref) and the number of fluorescence photons (Qem) were also calculated from the obtained fluorescence spectrum data. The number of reflected excitation light photons was calculated in the same wavelength range as the number of excitation light photons, and the number of fluorescence photons was calculated in the range of 465 to 800 nm. 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. The number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm.

[0112] From the above calculation results, the absorptance of the 455 nm excitation light, internal quantum efficiency, and external quantum efficiency of the phosphor to be measured were calculated based on the following calculation formulas. Absorbance of 455 nm excitation light = ((Qex-Qref) / Qex) x 100 Internal quantum efficiency = (Qem / (Qex-Qref)) x 100 External quantum efficiency = (Qem / Qex) x 100 Incidentally, the relational expression among the external quantum efficiency, the absorption rate of the excitation light at 455 nm, and the internal quantum efficiency can be expressed as follows from the above formula. External quantum efficiency = Absorption rate of 455 nm light × Internal quantum efficiency

[0113] [Chromaticity X, Chromaticity Y] The chromaticity X and chromaticity Y were obtained by calculating the CIE chromaticity coordinate x value (chromaticity X) and y value (chromaticity Y) in the XYZ colorimetric system defined in JIS Z8781-3:2016 from the spectral data in the wavelength range of 465 to 780 nm of the fluorescence spectrum in accordance with JIS Z8724:2015.

[0114] [Absorption rate of 600 nm light] A standard reflector (Spectralon (registered trademark) manufactured by Labsphere) with a reflectance of 99% was set at the side opening of the integrating sphere. Monochromatic light spectrally separated to a wavelength of 600 nm from a light-emitting light source (Xe lamp) was introduced into this integrating sphere by an optical fiber, and the reflected light spectrum was measured by a spectrophotometer (MCPD-7000 manufactured by Otsuka Electronics Co., Ltd.). At that time, the number of incident photons Qex(600) was calculated from the spectrum in the wavelength range of 590 to 610 nm. Next, after filling a concave cell with the β-sialon phosphor so that the surface becomes smooth and setting it at the opening of the integrating sphere, monochromatic light with a wavelength of 600 nm was irradiated, and the incident and reflected light spectrum was measured by a spectrophotometer. The number of incident and reflected photons Qref(600) was calculated from the obtained spectral data. The number of incident and reflected photons Qref(600) was calculated in the same wavelength range as the number of incident photons Qex(600). The absorption rate of 600 nm light was calculated based on the following formula from the two types of photon numbers obtained. Absorption rate of 600 nm light = ((Qex(600) - Qref(600)) / Qex(600)) × 100

[0115] <Measurement of D50> The D50 of the β-sialon phosphor of each example and comparative example was measured. The specific procedures and conditions of the measurement were the same as described above.

[0116] The evaluation and measurement results are summarized in Table 2.

[0117] [Table 2]

[0118] As shown in Tables 1 and 2, N Eu / N' Eu is less than or equal to 3.00, and / or N Eu(O) / N' Eu(O) The internal quantum efficiency of Examples 1 to 3, in which the value of is 2.50 or less, is N Eu / N' Eu is greater than 3.00 and / or N Eu(O) / N' Eu(O) The internal quantum efficiency was better than that of Comparative Examples 1 to 3, in which the value was more than 2.50. In addition, from the "difference in manufacturing method" between the example and the comparative example, the annealing treatment using titanium oxide Eu / N' Eu is less than or equal to 3.00, and / or N Eu(O) / N' Eu(O) It is understood that this is a preferred method for obtaining β-sialon phosphor particles having a value of 2.50 or less.

[0119] This application claims priority based on Japanese Patent Application No. 2022-034169, filed on March 7, 2022, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0120] 10. Light-emitting device 12 Light 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 (β-type sialon phosphor particles) 19 Cap

Claims

1. Eu-activated β-sialon phosphor particles having grain boundaries, The β-sialon phosphor is a β-sialon containing Eu 2+ as a solid solution, and is represented by the general formula Si 6-z Al z O z N 8-z :Eu 2+ a (0<z≦4.2, 0.001<a<1.0), In a cross section including the grain boundary, a line analysis was performed on the elemental compositions of the grain boundary and both sides of the grain boundary in a direction perpendicular to the grain boundary at a depth of 200 nm from a portion of the surface of the particle where the grain boundary exists. On the analyzed line segment, (i) the amount of Eu at point P on the grain boundary where the amount of Eu is at its peak is calculated. Ｅｕ (ii) the amount of Eu at point Q 50 nm away from point P is N' Ｅｕ When N Ｅｕ / N' Ｅｕ The β-sialon phosphor particles have a value of 3.00 or less.

2. β-sialon phosphor particles according to claim 1, The amount of oxygen at point P is N О and the amount of oxygen at point Q is N' О When this is done, (N Ｅｕ / N Ｏ ) / (N Ｅｕ ' / N Ｏ β-sialon phosphor particles, wherein the value of (a) is 2.00 or less.

3. 3. The β-sialon phosphor particle according to claim 1 or 2, The amount of oxygen at point P is N О When N Ｅｕ / N Ｏ The β-sialon phosphor particles have a value of 0.70 or less.

4. 3. The β-sialon phosphor particle according to claim 1 or 2, The amount of oxygen at point P is N О year, When the elemental composition of the grain boundary and both sides of the grain boundary is linearly analyzed in a direction perpendicular to the grain boundary at a depth of 200 nm from the portion of the surface of the particle where the grain boundary exists, the point P on the line segment obtained by the line analysis is where the amount of Al on the grain boundary shows a peak. （Ａl） The amount of Al in Ａｌ When N Ａｌ / N Ｏ The β-sialon phosphor particles have a value of 1.00 or less.

5. Eu-activated β-sialon phosphor particles having grain boundaries, The β-sialon phosphor is a β-sialon containing Eu 2+ as a solid solution, and is represented by the general formula Si 6-z Al z O z N 8-z :Eu 2+ a (0<z≦4.2, 0.001<a<1.0), In a cross section including the grain boundary, a line analysis was performed on the elemental compositions of the grain boundary and both sides of the grain boundary in a direction perpendicular to the grain boundary at a depth of 200 nm from a portion of the surface of the particle where the grain boundary exists. On the analyzed line segment, (i) a point P on the grain boundary where the amount of O is at its peak （Ｏ） The amount of Eu in Ｅｕ（Ｏ） (ii) Point P （Ｏ） Point Q 50 nm away from （Ｏ） The amount of Eu in N' Ｅｕ（Ｏ） When N Ｅｕ（Ｏ） / N' Ｅｕ（Ｏ） The β-sialon phosphor particles have a value of 2.50 or less.

6. 6. The β-sialon phosphor particle according to claim 5, Point P （Ｏ） The amount of oxygen in N О（Ｏ） Let point Q （Ｏ） The amount of oxygen in N' О （Ｏ） When this is done, (N Ｅｕ（Ｏ） / N Ｏ（Ｏ） ) / (N' Ｅｕ（Ｏ） / N' Ｏ（Ｏ） β-sialon phosphor particles, wherein the value of (a) is 1.20 or less.

7. 7. The β-sialon phosphor particle according to claim 5 or 6, Point P （Ｏ） The amount of oxygen in N О（Ｏ） When N Ｅｕ（Ｏ） / N Ｏ（Ｏ） The β-sialon phosphor particles have a value of 0.70 or less.

8. 7. The β-sialon phosphor particle according to claim 5 or 6, Point P （Ｏ） The amount of oxygen in N О（Ｏ） Let point P （Ｏ） The amount of aluminum in N Ａｌ（Ｏ） When N Ａｌ（Ｏ） / N Ｏ（Ｏ） The β-sialon phosphor particles have a value of 1.00 or less.

9. β-sialon phosphor powder comprising the β-sialon phosphor particles according to claim 1 or 5.

10. A light emitting device including a light emitting source and a wavelength conversion member, the wavelength conversion member contains phosphor powder, A light emitting device, wherein the phosphor powder comprises the β-sialon phosphor powder according to claim 9 .

11. 11. The light emitting device according to claim 10, The light emitting device, wherein the light source includes an LED chip that emits light having a wavelength of 300 nm or more and 500 nm or less.

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