Fluorescent material and light-emitting device

Abstract

To provide a fluorescent member and a light-emitting device that have good light-emitting properties.SOLUTION: A fluorescent member consists of a single crystal whose crystal structure is a garnet structure and whose general formula is represented by BaxY3-x-yAl5-xSixO12:Cey, where x satisfies 0.01≤x≤0.2 and y satisfies 0.02≤y≤0.1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a fluorescent component and a light-emitting device. [Background technology]

[0002] Conventionally, white light sources combining YAG phosphors and blue LEDs have been widely known, and research on YAG phosphors is progressing. For example, Non-Patent Literature 1 describes BaY2Al4SiO2, in which Ba and Si are solid-solved in a YAG phosphor. 12 :Ce has been disclosed. [Prior art documents] [Patent Documents]

[0003] [Non-Patent Document 1] Haipeng Ji et al., "New Y2BaAl4SiO12:Ce3+ yellow microcrystal-glass powder phosphor with high thermal emission stability", Journal of Materials Chemistry C, 2016, 4, pp.9872-9878 [Overview of the project] [Problems that the invention aims to solve]

[0004] Incidentally, increasing the brightness of the light source causes thermal quenching due to heat concentration resulting from wavelength conversion (Stokes loss) in the YAG phosphor, leading to a decrease in the luminescence efficiency of the YAG phosphor. For this reason, phosphors with good luminescence characteristics are in high demand.

[0005] The present invention has been made in view of these circumstances, and one of its exemplary objectives is to provide a fluorescent material and a light-emitting device with good luminescence characteristics. [Means for solving the problem]

[0006] In order to solve the above problems, a fluorescent member according to an aspect of the present invention has a garnet crystal structure and a general formula of Ba x Y 3-x-y Al 5-x Si x O 12 :Ce y (where x satisfies 0.01 ≤ x ≤ 0.2 and y satisfies 0.02 ≤ y ≤ 0.1). It is composed of a single crystal represented by

[0007] According to this aspect, a fluorescent member with good light emission characteristics can be realized.

[0008] In the above general formula, x and y may be values included in the range surrounded by the straight line represented by y = 0.3155x + 0.0574, the straight line represented by y = 0.1052x + 0.0191, the straight line represented by x = 0.01, the straight line represented by x = 0.20, and the straight line represented by y = 0.10.

[0009] The fluorescent member may have a plate-like shape. This makes it easier to mount on a light source, etc.

[0010] The thickness t of the fluorescent member may be in the range of 0.02 mm < t < 0.6 mm. This makes it possible to further improve the light emission characteristics of the fluorescent member.

[0011] The fluorescent member may be excited by blue light with a peak wavelength in the range of 430 nm to 480 nm and emit yellow light with a dominant wavelength in the range of 567 nm to 571 nm. Thus, for example, white light can be realized in combination with a blue light source.

[0012] Another aspect of the present invention is a light-emitting device that emits white light. The light-emitting device includes a light source that emits blue light with a peak wavelength in the range of 430 nm to 480 nm, and the fluorescent member joined to the light source. According to this aspect, a light-emitting device with good light emission characteristics can be realized.

[0013] In addition, any combination of the above components, or those obtained by converting the expression of the present invention among manufacturing methods, devices such as lamps and lighting, light emitting modules, light sources, etc., are also effective as aspects of the present invention.

Advantages of the Invention

[0014] According to the present invention, a fluorescent member and a light emitting device having good light emitting characteristics can be provided.

Brief Description of the Drawings

[0015] [Figure 1] It is a diagram for explaining the amounts of Ba and Ce in the fluorescent member according to an embodiment of the present invention. [Figure 2] It is a schematic diagram of the light emitting device according to the same embodiment. [Figure 3] FIG. 3(a) is a diagram showing an example of diffraction spots of a single crystal, and FIG. 3(b) is a diagram showing an example of diffraction spots of a polycrystal. [Figure 4] It is a diagram showing the amounts of Ba and Ce in the fluorescent members according to the examples and comparative examples. [Figure 5] It is a diagram showing the relationship between the plate thickness of the fluorescent member and the effective luminous flux ratio of the light emitting device according to the example.

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. Note that the configurations described below are examples and do not limit the scope of the present invention in any way.

[0017] [Fluorescent Member] The fluorescent member according to the present embodiment is a member composed of a single crystal phosphor. Specifically, the crystal structure is a garnet structure, and the general formula is Ba x Y 3-x-y Al 5-x Si x O 12 :Ce yThe fluorescent material is composed of a single crystal represented by (where x satisfies 0.01 ≤ x ≤ 0.2, and y satisfies 0.02 ≤ y ≤ 0.1). Here, the garnet structure is a crystal structure in which the crystal system is cubic and the space group is Ia3d.

[0018] The fluorescent member according to this embodiment can be excited by blue light and emit yellow light. For example, the fluorescent member may be excited by blue light with a peak wavelength in the range of 430 to 480 nm and emit yellow light with a dominant wavelength in the range of 567 to 572 nm. The yellow emission is due to the doped Ce in the fluorescent member. 3+ This can be achieved using ions, etc. This allows for the easy fabrication of a light-emitting device that emits white light by combining a fluorescent component with, for example, a blue LED.

[0019] Figure 1 is a diagram illustrating the amounts of Ba and Ce in the fluorescent material according to this embodiment. In Figure 1, the amount of B (x) in the general formula described above is plotted on the horizontal axis, and the amount of Ce (y) is plotted on the vertical axis. By conducting experiments as shown in the examples described later, the inventors have found that a fluorescent material exhibiting good luminescence characteristics can be obtained in the range where x satisfies 0.01 ≤ x ≤ 0.2 and y satisfies 0.02 ≤ y ≤ 0.1.

[0020] More specifically, the inventors have found that a fluorescent material exhibiting better luminescence characteristics can be obtained when the amount of Ba (x) and the amount of Ce (y) fall within the region S shown by the hatching in Figure 1. That is, a fluorescent material exhibiting better luminescence characteristics can be obtained when (x, y) falls within the range enclosed by the lines L1 represented by y = 0.3155x + 0.0574, L1' represented by y = 0.1052x + 0.0191, L2 represented by x = 0.01, L3 represented by x = 0.20, and L4 represented by y = 0.10.

[0021] The fluorescent material according to this embodiment is composed of a single crystal, achieving better luminescence characteristics. This is presumed to be because, compared to the case where the fluorescent material according to this embodiment is composed of a polycrystalline material, the thermal conductivity is improved, making it easier for the heat generated during luminescence to diffuse, and thus suppressing the temperature rise in the fluorescent material.

[0022] Polycrystalline materials are solids composed of fine single-crystal particles, and grain boundaries or spaces (voids) exist between adjacent particles that make up the polycrystalline material. These grain boundaries and voids act as resistance to thermal conduction. On the other hand, single crystals are solids in which the constituent elements are arranged regularly, and the crystal axis direction is the same throughout the material. Therefore, single crystals do not have (or have few) grain boundaries and voids between particles, unlike polycrystalline materials. Thus, in the fluorescent material according to this embodiment, which is composed of single crystals, there are (or few) grain boundaries and voids that act as resistance to thermal conduction, improving thermal conductivity and, as a result, enabling the realization of good luminescence characteristics.

[0023] [Manufacturing method] An example of a method for manufacturing a fluorescent material according to one embodiment of the present invention will be described. In the method for manufacturing a fluorescent material according to this embodiment, a single crystal of phosphor is prepared using various methods, and the single crystal of phosphor is processed to produce a fluorescent material.

[0024] The phosphor material has elements included in the general formula described above, and may be, for example, Y2O3, CeO2, α-Al2O3, BaCO3, and SiO2. The shape of the material is not particularly limited, but in this embodiment, an example in powder form will be described.

[0025] These powder raw materials are mixed to obtain a desired composition ratio, and a flux such as BaF2 is added as needed to obtain the mixture. The resulting mixture can be heated in a predetermined atmosphere (e.g., a reducing atmosphere of hydrogen and nitrogen) to synthesize the phosphor powder.

[0026] A single crystal of the phosphor is prepared using the synthesized phosphor powder. For example, the single crystal of the phosphor may be prepared using the FZ (Floating Zone) method. In this case, the phosphor powder is mixed and pulverized in a wet ball mill, and then the phosphor powder is heated and dried to form a predetermined shape to produce a sintering material. This sintering material is heated in an FZ furnace at a predetermined heating temperature to grow a single crystal, thereby producing an ingot of the phosphor single crystal. By processing the single crystal ingot obtained in this way using various known processing methods, a fluorescent component of the desired shape can be obtained.

[0027] Although this document describes a method for obtaining phosphor single crystals using the FZ method, this is not the only method available. Other methods, such as the Bridgman method or the CZ (Czochralski) method, may also be used. For example, a phosphor single crystal produced by the FZ method can be used as a seed crystal to produce a fluorescent component using the Bridgman method or the CZ method.

[0028] [Light-emitting device] An example of a light-emitting device using the fluorescent material described above will be explained with reference to Figure 2. Figure 2 is a schematic side view of the light-emitting device 10 according to this embodiment. As shown in Figure 2, the light-emitting device 10 according to this embodiment comprises a substrate 12, a light source 14 provided on the substrate 12, and a fluorescent material 16 provided on the light source 14.

[0029] The light source 14 emits various types of light and may include, for example, an LED (Light Emitting Diode). The light source 14 can emit, for example, blue light with a peak wavelength in the range of 430 nm to 480 nm. The light source 14 emits light from its upper surface toward the fluorescent member 16, and the emitted light is incident on the fluorescent member 16.

[0030] The fluorescent member 16 converts the wavelength of the light emitted from the light source 14 and emits the converted light. Specifically, the fluorescent member 16 can convert the wavelength of at least a part of the incident light and emit yellow light or the like. The blue light emitted from the light source 14 and the yellow light emitted from the fluorescent member 16 may form, for example, white light. The formed white light is emitted above the fluorescent member 16.

[0031] The shape of the fluorescent member 16 is not particularly limited, but may be a plate shape as shown in FIG. 2. In this case, the thickness t of the fluorescent member 16 is preferably in the range of 0.02 mm < t < 0.6 mm, and more preferably in the range of 0.05 mm < t < 0.6 mm. By making the thickness of the fluorescent member 16 greater than 0.2 mm, the mechanical strength of the fluorescent member 16 can be increased, and for example, the yield during mounting can be improved. Also, by making the thickness of the fluorescent member 16 greater than 0.2 mm, the light emitted from the light source 14 can be sufficiently converted, making it easier to realize the desired light (for example, white light). Further, by making the thickness of the fluorescent member 16 less than 0.6 mm, the amount of light leaking from the side surface of the fluorescent member 16 can be reduced, making it easier to improve the effective luminous flux of the light emitting device 10.

[0032] The shape of the fluorescent member 16 when viewed from above may be any shape, but may be, for example, rectangular. For example, the shape of the fluorescent member 16 when viewed from above may be square, and its dimensions may be, for example, 1 mm to 3 mm square.

[0033] Also, the fluorescent member 16 may be joined to the light source 14 by any method. For example, the fluorescent member 16 may be joined to the light source 14 by room temperature joining or the like.

[0034] [Examples] Hereinafter, the present invention will be described more specifically using examples and comparative examples. However, the descriptions of the raw materials of the fluorescent member, the manufacturing method, the chemical composition of the fluorescent member, etc. below do not limit the embodiments of the fluorescent member of the present invention in any way.

[0035] (Measurement) In each example and comparative example, the dominant wavelength of light emitted by a sample excited with 460 nm light was measured using a spectrophotometer (FP-8500, manufactured by JASCO Corporation). The target range for the dominant wavelength was 567.6 nm to 570.4 nm.

[0036] Furthermore, in Examples 1-8 and Comparative Example 1, the crystallinity of the prepared samples was determined using X-ray diffraction (XRD). Specifically, the diffraction spots of the samples were observed using an X-ray diffractometer (single-crystal XRD, manufactured by Rigaku Corporation), and the crystallinity of the samples was determined based on the observed diffraction spots.

[0037] Figure 3(a) shows an example of diffraction spots in a single crystal, and Figure 3(b) shows an example of diffraction spots in a polycrystalline material. As shown in Figure 3(a), in a single crystal, diffracted atoms corresponding to the crystal orientation and interplanar spacing form diffraction spots, exhibiting a geometric pattern. On the other hand, as shown in Figure 3(b), in a polycrystalline material, numerous diffraction spots obtained from multiple crystals exhibit concentric rings (Debye-Scherrer rings). In Examples 1 to 8 and Comparative Example 1, the crystallinity of the sample was determined according to the observed diffraction spots.

[0038] (Example 1) The compositional formula of the fluorescent material in Example 1 is Ba 0.05 Y 2.89 Al 4.95 Si 0.05 :Ce 0.06 It is represented as follows. The fluorescent material according to Example 1 was manufactured as follows. First, powder raw materials of Y2O3 (99.99%, manufactured by Kojun Chemical Laboratory Co., Ltd.), CeO2 (99.99%, manufactured by Kojun Chemical Laboratory Co., Ltd.), α-Al2O3 (99.99%, manufactured by Kojun Chemical Laboratory Co., Ltd.), BaCO3 (99.9%, manufactured by Kanto Chemical Co., Ltd.), and SiO2 (99.9%, manufactured by Tokuyama Corporation) were prepared. In Example 1, these powder raw materials were weighed to have molar ratios of Ba(x)=0.05, Y=2.89, Al=4.95, Si=0.05, and Ce(y)=0.06. The elemental charging ratios for Examples 1 to 8 and Comparative Example 1 are shown in Table 1.

[0039] [Table 1]

[0040] BaF2 (99%, manufactured by Kojun Chemical Laboratory Co., Ltd.) was weighed as flux at a concentration of 5 wt% of the total weight of the powder raw materials. This was combined with the powder raw materials and uniformly mixed in a mortar to obtain a mixture. The mixture was then placed in an alumina vessel (SSA-S B1, manufactured by Nikkatoh Co., Ltd.) and heated at 1550°C for 4 hours in a reducing atmosphere (H2:N2 = 5:95 (vol ratio)) to synthesize the phosphor powder. The synthesized phosphor powder was cooled to room temperature, and then the cooled phosphor powder was pulverized in a mortar. The luminescence characteristics of the pulverized phosphor powder, excited by light with a wavelength of 460 nm, were measured using a spectrophotometer (FP-8500, manufactured by JASCO Corporation). As a result, the dominant wavelength λd of the phosphor according to Example 1 was 569.0 nm, which fell within the target range.

[0041] 25g of phosphor powder was weighed and placed in a 500ml poly pot along with 250g of φ1mm alumina balls and 200ml of pure water. This poly pot was then rotated at 60rpm for 24 hours. Next, the phosphor powder was transferred to an aluminum tray coated with Teflon® and heated to dry the material. The dried material was then passed through a nylon mesh with a mesh size of 50μm. 5g of the dried material was weighed and molded into a shape with dimensions of φ5 × L50mm to obtain a molded body. This molded body was sintered in air at 1500°C for 12 hours to obtain a rod-shaped sintering raw material (also called a "sintering raw material rod").

[0042] Subsequently, in an FZ furnace, the sintering raw material rod was heated to 1700°C using concentrated heat from a halogen lamp, and crystal growth was carried out at a growth rate of 1.0 mm / hr in an Ar-hydrogen atmosphere (Ar:H2 = 96:4 (vol ratio)) to obtain an ingot.

[0043] A sample of the fluorescent component was cut from the obtained ingot, and the emission characteristics of the sample excited with light of a wavelength of 460 nm were measured using a spectrophotometer. As a result, the dominant wavelength λd of the sample according to Example 1 was 569.0 nm, which fell within the center of the target range. Furthermore, when the crystallinity of the sample was determined using an X-ray diffractometer, it was found to be a single crystal.

[0044] The results of the dominant wavelength measurement and crystallinity determination for the sample in Example 1 are shown in Table 1, along with the results for Examples 2-7 and Comparative Example 1. In Table 1, ○ indicates that the dominant wavelength λd satisfies 567.4 nm ≤ λd ≤ 570.6 nm, and × indicates that it does not. Regarding crystallinity, ○ indicates that the sample is a single crystal, and × indicates that it is not a single crystal.

[0045] (Example 2) The compositional formula of the fluorescent material according to Example 2 is Ba 0.01 Y 2.97 Al 4.99 Si 0.01 :Ce 0.02 This is expressed as follows. In Example 2, the sintering material was obtained in the same manner as in Example 1, except that the powder raw materials were weighed to have the molar ratios of Ba(x)=0.01, Y=2.97, Al=4.99, Si=0.01, and Ce(y)=0.02.

[0046] Subsequently, the sintering material was placed in a crucible, and the single crystal prepared in Example 1 was used as a seed crystal. A single crystal was grown using the Bridgman method to obtain an ingot. The growth conditions were a heating temperature of 1700°C and a growth rate of 1.0 mm / hr. A sample of the fluorescent component was cut from the obtained ingot, and the dominant wavelength and crystallinity of the sample were determined. As a result, the sample according to Example 2 had a dominant wavelength of 567.6 nm, which was the lower limit of the target range, and its crystallinity was that of a single crystal.

[0047] (Example 3) The compositional formula of the fluorescent material according to Example 3 is Ba 0.01 Y 2.93 Al 4.99 Si 0.01 :Ce0.06 This is expressed as follows. In Example 3, the sintering material was obtained in the same manner as in Example 1, except that the powder raw materials were weighed to have molar ratios of Ba(x)=0.01, Y=2.93, Al=4.99, Si=0.01, and Ce(y)=0.06.

[0048] In Example 3, an ingot was obtained using the CZ method as follows. First, the single crystal sample prepared in Example 1 was attached to the tip of a rotating shaft as a seed crystal, and the sintering material was placed in a crucible and melted at 1700°C in the crucible. The seed crystal was then brought into contact with the melted material, and while rotating the shaft at 1 rpm, the seed crystal was pulled up at 1.0 mm / hr to obtain an ingot. A sample of the fluorescent component was cut from the ingot, and the dominant wavelength and crystallinity of the sample were determined. As a result, in the sample according to Example 3, the dominant wavelength was 570.4 nm, which was the upper limit of the target range, and the crystallinity was single crystal.

[0049] (Examples 4-8) The compositional formula of the fluorescent material in Examples 4 to 8 is Ba x Y 3-x-y Al 5-x Si x O 12 :Ce y In these examples, x=0.10, y=0.03 (Example 4), x=0.10, y=0.09 (Example 5), x=0.20, y=0.04 (Example 6), x=0.20, y=0.08 (Example 7), and x=0.20, y=0.10 (Example 8). In Examples 4 to 8, fluorescent material samples were prepared under the same conditions as in Example 3, except that the respective powder raw materials were weighed to achieve the desired molar ratio, similar to those in Example 3. When the dominant wavelength and crystallinity of the prepared samples were determined, the dominant wavelengths in all samples from Examples 4 to 8 were within the target range, and the crystallinity was single crystal.

[0050] (Comparative Example 1) The composition ratio of the fluorescent material in Comparative Example 1 is Ba x Y 3-x-y Al 5-x Si x O 12 :Ce yIn this case, x=0.20 and y=0.12. In Comparative Example 1, a sample of the fluorescent material was prepared under the same conditions as in Example 3, except that the same powder raw materials as in Example 3 were weighed to achieve the desired composition ratio, and the dominant wavelength and crystallinity of the sample were determined.

[0051] The dominant wavelength of the sample in Comparative Example 1 was 570.4 nm, which was the upper limit of the target range. Furthermore, the sample in Comparative Example 1 was a translucent crystal containing a different phase derived from Ce, and was not a single crystal. It is presumed that the cause of the different phase was that the amount of Ce contained in the powder raw material mixture was excessive, making it impossible to dope all of the Ce into the crystal lattice.

[0052] Figure 4 shows the charging ratios of Ba and Ce in the samples for Examples 1-8 and Comparative Example 1. In Figure 4, the horizontal axis shows the charging ratio of Ba, and the vertical axis shows the charging ratio of Ce, both of which represent molar ratios.

[0053] In the fluorescent material samples of Examples 1 to 8, the dominant wavelength was within the target range (567.5 nm to 570.5 nm), and the crystallinity was single crystal. Therefore, the general formula Ba x Y 3-x-y Al 5-x Si x O 12 :Ce y In this case, when x satisfies 0.01 ≤ x ≤ 0.2 and y satisfies 0.02 ≤ y ≤ 0.1, it can be said that a fluorescent material with a dominant wavelength within the target range and crystallinity being single crystal has been obtained. More specifically, in the general formula, it was found that when (x,y) is within the range enclosed by the five lines L1 (y=0.3155x+0.0574), L1' (y=0.1052x+0.0191), L2 (x=0.01), L3 (x=0.20), and L4 (y=0.10), a fluorescent material with a dominant wavelength within the target range and crystallinity being single crystal has been obtained.

[0054] The results for Examples 9-1 to 8, 10-1 to 6, and Comparative Example 2 are shown below. In Examples 9-1 to 8, 10-1 to 6, and Comparative Example 2, a plate-shaped fluorescent material was mounted on a blue LED light source to create the light-emitting device shown in Figure 2. In the following, when Examples 9-1 to 8 are not distinguished from each other, they will be collectively referred to simply as "Example 9," and when Examples 10-1 to 6 are not distinguished from each other, they will be collectively referred to simply as "Example 10."

[0055] In Examples 9, 10, and Comparative Example 2, the thermal conductivity of the fabricated fluorescent material was measured using a thermal conductivity meter and a steady-state method. Furthermore, in Examples 9, 10, and Comparative Example 2, the dominant wavelength of light emitted by the fluorescent material excited with 460 nm light was measured, in the same manner as in Examples 1-8 and Comparative Example 1 described above.

[0056] Furthermore, in Examples 9 and 10 and Comparative Example 2, the luminous flux (effective luminous flux) of the fabricated light-emitting devices was measured using a multi-channel spectrometer (MCPD-1000, manufactured by Otsuka Electronics Co., Ltd.). Specifically, the probe of the multi-channel spectrometer was placed 5 cm directly above the light-emitting device, and a current of 500 mA was applied to the blue LED for 10 minutes. After the temperature of the fluorescent material stabilized, the effective luminous flux emitted from the light-emitting device, as received by the probe of the multi-channel spectrometer, was measured. In addition, the effective luminous flux ratio was calculated by dividing the measured effective luminous flux of the light-emitting device by the effective luminous flux of the light-emitting device in Comparative Example 2.

[0057] (Comparative Example 2) In Comparative Example 2, the phosphor powder prepared in the same manner as in Example 1 was kneaded with a silicone resin at a concentration of 3 vol% to obtain a fluorescent resin mixed with the phosphor powder. This fluorescent resin was molded into a resin sheet (fluorescent component) with a thickness of 0.2 mm and a square diameter of 1 mm. When the thermal conductivity of this resin sheet was measured, the thermal conductivity of the resin sheet of Comparative Example 2 was found to be 0.3 W / m·K. Furthermore, when the dominant wavelength was measured using a spectrophotometer, the dominant wavelength of the resin sheet of Comparative Example 2 was found to be 569.0 nm, which was the central value of the target. This resin sheet was mounted on a 1 mm square blue LED to create a light-emitting device, and the effective luminous flux of the light-emitting device was measured.

[0058] In conjunction with Examples 9 and 10, Table 2 summarizes the results for Comparative Example 2, including the dominant wavelength, thermal conductivity, and effective luminous flux ratio of the fluorescent material and the light-emitting device. In Table 2, ○ indicates an effective luminous flux ratio of 1.0 or higher, and × indicates an effective luminous flux ratio of less than 1.0. Note that since the effective luminous flux of Comparative Example 2 is used as the standard for the effective luminous flux ratio, the effective luminous flux ratio is not shown in Table 2.

[0059] [Table 2]

[0060] (Example 9) In Example 9, the ingot from Example 1 was moderately cut and mirror-polished to obtain single crystal plates with thicknesses of 0.02 mm, 0.05 mm, 0.10 mm, 0.20 mm, 0.30 mm, 0.40 mm, 0.50 mm, or 0.60 mm. Each single crystal plate was cut into 1 mm squares to be used as a fluorescent material. When the thermal conductivity and dominant wavelength of the fabricated fluorescent materials were measured, the thermal conductivity for all fluorescent materials was 13 W / m·K, and the dominant wavelength was 569.0 nm, which fell within the center of the target range.

[0061] Next, a light-emitting device was fabricated by bonding the fabricated fluorescent material to a blue LED at room temperature. When the luminescence performance of the fabricated light-emitting device was measured using a multi-channel spectrometer, the effective luminous flux ratio was greater than 1.0 when the thickness of the fluorescent material (hereinafter also referred to as "plate thickness") was in the range of 0.05 mm to 0.50 mm (Examples 9-2 to 9-7). It is presumed that the good effective luminous flux ratio was achieved because the thermal conductivity was improved by constructing the fluorescent material as a single crystal, thereby suppressing the deterioration of luminescence characteristics due to heat generation. On the other hand, when the plate thickness was 0.02 mm (Example 9-1) or 0.60 mm (Example 9-8), the effective luminous flux ratio was less than 1.0.

[0062] (Example 10) In Example 10, the ingot from Example 2 was moderately cut and mirror-polished to obtain single crystal plates with thicknesses of 0.05 mm, 0.10 mm, 0.20 mm, 0.40 mm, 0.50 mm, or 0.60 mm. Each single crystal plate was cut into 1 mm squares to be used as a fluorescent material. When the thermal conductivity and dominant wavelength of the fabricated fluorescent materials were measured, the thermal conductivity for all fluorescent materials was 13 W / m·K, and the dominant wavelength was 567.6 nm, which was the lower limit of the target range.

[0063] Next, a light-emitting device was fabricated by bonding the fabricated fluorescent material to a blue LED at room temperature. When the luminescence performance of the fabricated light-emitting device was measured using a multi-channel spectrometer, the effective luminous flux ratio was greater than 1.0 when the plate thickness was in the range of 0.10 mm to 0.50 mm (Examples 10-2 to 10-5). It is presumed that the good effective luminous flux ratio was achieved because the thermal conductivity was improved by constructing the fluorescent material from a single crystal, suppressing the deterioration of luminescence characteristics due to heat generation. Furthermore, when the plate thickness was 0.05 mm (Example 10-1) or 0.60 mm (Example 10-6), the effective luminous flux ratio was less than 1.0.

[0064] FIG. 5 is a diagram showing the relationship between the plate thickness of the fluorescent member according to Examples 9 and 10 and the effective luminous flux ratio of the light-emitting device. In FIG. 5, the round plots show the relationship between the plate thickness of the fluorescent member according to Example 9 and the effective luminous flux ratio of the light-emitting device, and the plots of white squares show the relationship between the plate thickness of the fluorescent member according to Example 10 and the effective luminous flux ratio of the light-emitting device.

[0065] In Example 9 where the Ce amount is 0.06 mol in the charging ratio of the fluorescent member, the relationship between the plate thickness and the effective luminous flux ratio of the light-emitting device became a mountain-shaped graph as shown in FIG. 5. In Example 9, when the plate thickness was 0.02 mm, the effective luminous flux ratio was 0.98, which was smaller than 1.0. However, as the plate thickness became larger than 0.02 mm, the effective luminous flux ratio increased, and when the plate thickness was 0.20 mm, the effective luminous flux ratio peaked at 1.4. When the plate thickness was further increased, the effective luminous flux ratio decreased, and when the plate thickness was 0.60 mm, the effective luminous flux ratio became 0.98 and was smaller than 1.0 again. From the above, when the Ce amount in the charging ratio is 0.06 mol, the effective luminous flux ratio becomes larger than 1.0 when the plate thickness t satisfies 0.02 mm < t < 0.60 mm.

[0066] The reason why the effective luminous flux ratio is smaller than 1.0 when the plate thickness is 0.02 mm is considered to be that there is a lot of excitation light that passes through the fluorescent member without being wavelength-converted by the fluorescent member, and the yellow light emitted by the fluorescent member is weak. Also, at this plate thickness, it is推测 that the mechanical strength of the fluorescent member becomes weak and the yield during mounting decreases. On the other hand, when the plate thickness is 0.60 mm, the area ratio of the side surface of the fluorescent member to the upper surface of the fluorescent member becomes larger compared to other plate thicknesses (0.02 mm to 0.50 mm). The reason why the effective luminous flux ratio is smaller than 1.0 when the plate thickness is 0.60 mm is considered to be that the yellow light converted from blue light inside the fluorescent member propagates inside the fluorescent member, and the amount of light leaking from the side surface of the fluorescent member increases.

[0067] In Example 10, where the Ce content of the fluorescent material is 0.03 mol (half the Ce content of Example 9), the effective luminous flux ratio is 0.95 when the plate thickness is 0.05 mm, which is less than 1.0. However, when the plate thickness is increased beyond 0.05 mm, the effective luminous flux ratio increases, peaking at 1.3 when the plate thickness is 0.40 mm. When the plate thickness is further increased, the effective luminous flux ratio decreases, becoming 0.95 when the plate thickness is 0.60 mm, which is less than 1.0. Therefore, in a light-emitting device using a fluorescent material with a Ce content of 0.03 mol, the plate thickness t range in which the effective luminous flux ratio is greater than 1.0 is 0.02 mm. <t<0.60mmであった。

[0068] In the light-emitting device according to Example 9-2, which has a plate thickness of 0.05 mm, the effective luminous flux ratio is greater than 1.0, whereas in the light-emitting device according to Example 10-1, which also has a plate thickness of 0.05 mm, the effective luminous flux ratio is less than 1.0. This is thought to be because more excitation light passes through the fluorescent material without being converted to yellow light in Example 9, resulting in a weaker intensity of yellow light emitted by the fluorescent material compared to Example 9. Furthermore, the effective luminous flux ratio of the light-emitting device according to Example 10-6, which has a plate thickness of 0.60 mm, is 0.95, which is less than 1.0. This is thought to be because the plate thickness is greater, making it easier for light to leak from the sides of the fluorescent material.

[0069] The above describes each example and each comparative example. According to the above example, the crystal structure is a garnet structure and the general formula is Ba x Y 3-x-y Al 5-x Si x O 12 :Ce y By using a fluorescent material composed of a single crystal represented by (where x satisfies 0.01 ≤ x ≤ 0.2 and y satisfies 0.02 ≤ y ≤ 0.1), a light-emitting device with a good effective luminous flux was fabricated. In particular, the effective luminous flux of the light-emitting device according to Example 9-4 was 1.4 times that of the light-emitting device using a phosphor sheet according to Comparative Example 1.

[0070] [supplement] The present invention has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of these components and processing processes, and that such modifications also fall within the scope of the present invention. [Explanation of symbols]

[0071] 10 Light-emitting device, 12 Substrate, 14 Light source, 16 Fluorescent component.

Claims

1. The crystal structure is garnet, and the general formula is Ba ｘ Y ３－ｘ－ｙ Al ５－ｘ Si ｘ O １２ : Ce ｙ A fluorescent component composed of a single crystal represented by (where x satisfies 0.01 ≤ x ≤ 0.2, and y satisfies 0.02 ≤ y ≤ 0.1), In the above general formula, x and y are values ​​that fall within the range enclosed by the lines represented by y = 0.3155x + 0.0574, y = 0.1052x + 0.0191, x = 0.01, x = 0.20, and y = 0.

10. Fluorescent material.

2. The fluorescent member has a plate-like shape. The fluorescent member according to claim 1.

3. The thickness t of the fluorescent element is in the range of 0.02 mm < t < 0.6 mm. The fluorescent member according to claim 2.

4. It is excited by blue light with a peak wavelength in the range of 430 nm to 480 nm and emits yellow light with a dominant wavelength in the range of 567 nm to 571 nm. The fluorescent member according to any one of claims 1 to 3.

5. A light-emitting device that emits white light, A light source that emits blue light with a peak wavelength in the range of 430 nm to 480 nm, The light source is joined to the fluorescent member according to any one of claims 1 to 4, Light-emitting device.

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