阅读说明：本技术 氮化物荧光体和发光装置 (Nitride phosphor and light-emitting device ) 是由 高村麻里奈 野见山智宏 武田雄介 于 2020-03-24 设计创作，主要内容包括：本公开的一个方式提供一种荧光体,由通式：MAlSiN-(3)(M＝Ca,Sr)表示,上述M的一部分被Eu取代,且主结晶相与CaAlSiN-(3)结晶相具有相同的结构,上述荧光体的发光峰波长为640nm以上,上述发光峰波长的半值宽度为80nm以下。(One embodiment of the present disclosure provides a phosphor represented by the general formula: MALSiN 3 (M ═ Ca, Sr), wherein M is partially substituted with Eu, and the main crystal phase is CaAlSiN 3 The crystal phase has the same structure, and the emission peak wavelength of the phosphor is 640nm or more and the half width of the emission peak wavelength is 80nm or less.)

1. A nitride phosphor represented by the general formula: MALSiN₃Wherein M is Ca, Sr, a part of the M is substituted by Eu, and the main crystal phase is CaAlSiN₃The crystalline phases have the same structure and are,

the nitride phosphor has an emission peak wavelength of 640nm or more and a half-value width of the emission peak wavelength of 80nm or less.

2. The nitride phosphor according to claim 1, further comprising halogen as a constituent element.

3. The nitride phosphor according to claim 2, wherein the halogen content is 200 μ g/g or more.

4. A light-emitting device comprising the nitride phosphor according to any one of claims 1 to 3 and a light-emitting element.

Technical Field

The present disclosure relates to a nitride phosphor and a light emitting device.

Background

White light emitting diodes (white LEDs) are widely used for illumination purposes. The white LED is a light emitting device including a light emitting element such as a blue light emitting diode and a phosphor, and emitting white light by mixing blue light emitted from the light emitting element and fluorescence emitted from the phosphor. The commonly used white LEDs have insufficient red light. Therefore, various red phosphors have been studied in order to reproduce white color close to natural light and improve color rendering properties.

As red phosphors, nitride phosphors such as CASN phosphors and SCASN phosphors are known (for example, patent document 1). These nitride phosphors are generally synthesized by heating a raw material powder containing europium oxide or europium nitride, and calcium nitride, silicon nitride, and aluminum nitride.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2005/052087

Disclosure of Invention

In view of obtaining a light-emitting device having excellent color rendering properties, a red phosphor having an emission peak wavelength in a long wavelength region and exhibiting sufficient emission intensity has been demanded. In order to obtain such a red phosphor, a method of increasing the content of europium as an emission center is considered. However, according to the studies of the present inventors, if the amount of europium oxide or europium nitride contained in the raw material powder is increased, the emission peak wavelength of the obtained nitride phosphor shifts to a longer wavelength, but the emission intensity tends to decrease. There is still room for improvement in terms of obtaining a red phosphor having an emission peak wavelength in a long wavelength region and sufficient emission intensity.

In addition, a phosphor used in a light-emitting device may be exposed to a high temperature by radiant heat accompanying light emission from a light-emitting element or the like. In general, a phosphor tends to decrease its emission intensity at high temperature. It is useful if there is a red phosphor which is excellent in emission intensity and can suppress a decrease in emission intensity even at high temperatures.

The purpose of the present disclosure is to provide a nitride phosphor that has excellent emission intensity and can suppress a decrease in emission intensity even at high temperatures. It is also an object of the present disclosure to provide a light-emitting device in which a decrease in luminance can be suppressed even at high temperatures.

One aspect of the present disclosure provides a nitride phosphor represented by the general formula: MALSiN₃(M ═ Ca, Sr), wherein M is partially substituted with Eu, and the main crystal phase is CaAlSiN₃The crystal phase has the same structure, the emission peak wavelength of the nitride phosphor is 640nm or more, and the half width of the emission peak wavelength is 80nm or less.

The nitride phosphor has an emission peak wavelength in a red region, and has a small half-value width of the emission peak wavelength, and therefore has excellent emission intensity. The phosphor can suppress a decrease in emission intensity even at high temperatures. The reason why the above-mentioned nitride phosphor can suppress the decrease in the emission intensity even at high temperatures is not yet established, but the present inventors speculate that the generation of defects in the crystal lattice of the nitride phosphor is suppressed, and the energy loss due to internal defects is alleviated in the above-mentioned peak wavelength region.

The nitride phosphor may further contain halogen as a constituent element. When the nitride phosphor contains a halogen, the phosphor can have an emission peak wavelength in a longer wavelength region, and is more useful as a red phosphor.

The halogen content of the nitride phosphor may be 200 μ g/g or more. When the halogen content is in the above range, the emission intensity can be further improved, and a phosphor in which the decrease in emission intensity at high temperatures is further suppressed can be obtained.

One aspect of the present disclosure provides a light-emitting device having the above-described nitride phosphor and a light-emitting element.

The light-emitting device has the nitride phosphor, and the reduction in emission intensity at high temperature is suppressed, so that the reduction in luminance associated with the long-term use of the light-emitting device can be suppressed.

According to the present disclosure, a phosphor having excellent emission intensity and being suppressed in decrease in emission intensity even at high temperatures can be provided. In addition, according to the present disclosure, a light-emitting device in which a decrease in luminance can be suppressed even at high temperatures can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of a light-emitting device.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings according to the circumstances. However, the following embodiments are examples for explaining the present disclosure, and the present disclosure is not intended to be limited to the following. Unless otherwise specified, the positional relationship such as up, down, left, right, and the like is based on the positional relationship shown in the drawings. The dimensional ratios of the elements are not limited to the ratios illustrated in the drawings.

Unless otherwise specified, 1 kind of the material exemplified in this specification may be used alone or 2 or more kinds may be used in combination. When there are a plurality of substances corresponding to each component in the composition, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless otherwise specified.

One embodiment of the nitride phosphor is represented by the general formula: MALSiN₃(M ═ Ca, Sr), wherein M is partially substituted with Eu, and the main crystal phase is CaAlSiN₃Nitride phosphor having the same structure as the crystal phase. The nitride phosphor may contain a different phase within a range not departing from the gist of the present disclosure. In the above nitride phosphor, the proportion of the main crystal phase relative to the total amount of the nitride phosphor may be usually 80 mass% or more, 90 mass% or more, 95 mass% or more, or 98 mass% or more.

The nitride phosphor is made of a material having a chemical structure similar to CaAlSiN₃A nitride phosphor having the same crystal structure and containing Eu and Sr as constituent elements has an emission peak wavelength of 640nm or more and a half-value width of the emission peak wavelength of 80nm or less. Having a chemical composition with CaAlSiN₃The nitride phosphor having the same crystal structure and having Eu and Sr as constituent elements is also referred to as a SCASN phosphor. The nitride phosphor is excellent in luminous intensity and can sufficiently suppress a decrease in luminous intensity even at a high temperature (e.g., 200 ℃), and therefore is usefulRed phosphors are useful for illumination applications. When the nitride phosphor is used for illumination, it can be used in combination with another phosphor as a phosphor composition (also referred to as a phosphor package).

The emission peak wavelength of the nitride phosphor may be, for example, 642nm or more, or 644nm or more. When the lower limit of the emission peak wavelength is within the above range, deeper red light can be emitted, and when the phosphor is used as a red phosphor for a white LED, higher color rendering properties can be exhibited. Further, by setting the lower limit value of the emission peak wavelength within the above range, the color reproduction range of the light-emitting device using the nitride phosphor can be further expanded. The emission peak wavelength of the nitride phosphor may be, for example, 655nm or less, or 650nm or less. When the upper limit value of the emission peak wavelength is within the above range, the increase in the half-value width can be suppressed, and the emission intensity can be further improved. The emission peak wavelength of the nitride phosphor can be adjusted by, for example, increasing the content of an element (e.g., Eu or the like) that becomes an emission center in the nitride phosphor.

The half-value width of the emission peak wavelength of the nitride phosphor may be, for example, 78nm or less or 76nm or less. When the upper limit value of the half-value width of the emission peak wavelength is within the above range, the emission intensity of the nitride phosphor and the suppression of the decrease in the emission intensity at high temperatures can be achieved at the same time at a higher level. The half-value width of the emission peak wavelength of the nitride phosphor is usually 50nm or more, and may be 60nm or more, or 65nm or more. When the lower limit of the half-value width of the emission peak wavelength is within the above range, a nitride phosphor having excellent emission intensity can be obtained. The half-value width of the emission peak wavelength of the nitride phosphor can be adjusted by, for example, the ratio of the Sr content to the Eu content.

In the present specification, the emission peak wavelength of the phosphor is a value determined by fluorescence spectrometry with respect to an excitation wavelength of 455 nm. The above fluorescence spectrum measurement of the emission peak wavelength of the phosphor was performed at 25 ℃. In the present specification, the "Full Width at Half Maximum" refers to a Full Width at Half Maximum (FWHM) and can be determined from a fluorescence spectrum obtained by measurement of a fluorescence spectrum at an excitation wavelength of 455 nm.

The nitride phosphor is excellent in light emission intensity at 25 ℃ and sufficiently excellent in light emission intensity even at high temperature (e.g., 200 ℃). The maintenance ratio of the emission intensity at 200 ℃ to the emission intensity at 25 ℃ of the nitride phosphor may be, for example, 70% or more, 72% or more, or 74% or more. When the maintenance ratio of the emission intensity of the nitride phosphor is within the above range, the nitride phosphor can be used for applications involving an increase in ambient temperature during use, and is useful as a red phosphor for illumination. The maintenance ratio of the emission intensity of the nitride phosphor can be improved by, for example, adjusting the ratio of the Sr content to the Eu content in the nitride phosphor.

The nitride phosphor may contain halogen as a constituent element. When the nitride phosphor contains a halogen, the phosphor has an emission peak wavelength in a longer wavelength region, and is more useful as a red phosphor. The halogen content in the nitride phosphor may be, for example, 200. mu.g/g or more, 300. mu.g/g or more, or 500. mu.g/g or more, based on the total amount of the nitride phosphor. When the lower limit of the halogen content in the nitride phosphor is within the above range, the reduction in the emission intensity of the nitride phosphor can be suppressed. The present inventors speculate that this effect is due to the fact that the crystal structure of the nitride phosphor is maintained in a state in which high quantum efficiency can be exhibited. The halogen content in the nitride phosphor may be, for example, 2000. mu.g/g or less, 1500. mu.g/g or less, or 1000. mu.g/g or less. Examples of the halogen include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). The nitride phosphor preferably contains fluorine.

The nitride phosphor can be produced, for example, by the following production method. Is represented by the general formula: MALSiN₃(M ═ Ca, Sr), wherein M is partially substituted with Eu, and the main crystal phase is CaAlSiN₃One embodiment of a method for producing a nitride phosphor having a crystal phase with the same structure includes: the method includes a first step of heating a raw material powder containing a nitride and a europium halide to obtain a first phosphor, and a second step of heating the first phosphor at a temperature lower than that in the first step to obtain a second phosphor (nitride phosphor).In the method for producing the nitride phosphor, a europium halide is used as a raw material powder. The above method for producing a nitride phosphor can suppress the occurrence of defects in the crystal lattice of the obtained phosphor, as compared with a conventional method for producing a nitride phosphor in which europium is mixed in the form of an oxide or nitride, and therefore, the Eu content in the obtained nitride phosphor can be increased more easily.

The first step is to heat a raw material powder containing a halide of nitride and europium to form a nitride-doped europium-doped aluminum nitride film having a structure similar to that of CaAlSiN₃And a step of forming a first phosphor having the same crystal structure. The heating temperature in the first step may be, for example, 1650 ℃ or 1700 ℃ or higher. When the lower limit of the heating temperature is within the above range, the reaction for forming the first phosphor can be more sufficiently performed, and the amount of unreacted materials can be further reduced. The heating temperature in the first step may be, for example, 2000 ℃. By setting the upper limit of the heating temperature within the above range, the heating temperature can be suppressed to be equal to CaAlSiN₃Generation of defects due to partial decomposition of the main crystal phase of the same crystal structure. The heating temperature can be adjusted within the above range, and may be 1700 to 2000 ℃.

The first step may be performed in an inert gas atmosphere, for example. The inert gas may contain, for example, nitrogen, argon, etc., preferably may contain nitrogen, more preferably nitrogen. The first step may be performed in an atmosphere with a pressure adjusted. The pressure (gauge pressure) in the first step may be, for example, less than 1MPaG, or may be 0.9MPaG or less. When the upper limit value of the pressure is within the above range, the productivity can be further improved. The pressure (gauge pressure) in the first step may be, for example, 0.1MPaG (atmospheric pressure) or more, 0.5MPaG or more, 0.7MPaG or more, or 0.8MPaG or more. When the lower limit of the pressure is within the above range, thermal decomposition of the first phosphor formed during the heat treatment of the raw material powder can be more sufficiently suppressed.

The heating time of the raw material powder in the first step may be, for example, 2 to 24 hours or 5 to 15 hours. By adjusting the heating time, the amount of unreacted materials in the raw material powder can be further reduced, and crystal growth can be controlled.

The nitride used in the first step may contain a nitride of an element constituting the above nitride phosphor. The nitride includes, for example, strontium nitride (Sr)₃N₂) Calcium nitride (Ca)₃N₂) Europium nitride (EuN), aluminum nitride (AlN) and silicon nitride (Si)₃N₄) And the like.

Examples of the halide of europium used in the first step include europium fluoride, europium chloride, europium bromide, and europium iodide. By using the europium halide, the formation of defects in the crystal lattice caused by the incorporation of oxygen atoms from the raw material powder into the crystal structure can be suppressed as compared with the case of using the europium oxide, and the light emission characteristics and temperature characteristics of the obtained nitride phosphor can be improved. The valence number of europium in the europium halide may be 2 or 3. Examples of europium fluoride include EuF₂And EuF₃. As europium chloride, EuCl can be mentioned₂And EuCl₃. As europium bromide, EuBr can be mentioned₂Or EuBr₃. As europium iodide, EuI can be mentioned₂Or EuI₃. The europium halide preferably comprises europium fluoride, more preferably europium fluoride. The europium fluoride is preferably EuF₃. By using a fluoride having superior handling properties, industrial productivity can be improved as compared with the case of using another halide. In addition, when fluoride is used as the halide of europium, the reaction by heating of the raw material powder proceeds well, and the formation of a heterogeneous phase tends to be further suppressed.

The above raw material powder may contain other compounds in addition to the nitride and the halide of europium. The other compound may include, for example, an oxide, a hydride, a carbonate, and the like of the elements constituting the nitride phosphor.

The method for producing a nitride phosphor may include a step of adjusting the Sr content in the raw material powder before the first step, or may include a step of adjusting the Eu content relative to the Sr content in the raw material powder.

The second step is a step of heating the first phosphor obtained in the above manner at a temperature lower than that in the first step to obtain a second phosphor (nitride phosphor). The second step can reduce crystal defects and the like in the first phosphor, and the emission peak wavelength and the half-value width of the peak wavelength can be adjusted by passing through the second step.

The heating temperature in the second step may be, for example, 1100 ℃ or higher, or 1200 ℃ or higher. When the lower limit of the heating temperature is within the above range, crystal defects and the like in the first phosphor can be more sufficiently reduced. The heating temperature in the second step may be 1650 ℃ or lower, or 1450 ℃ or lower, for example. When the upper limit of the heating temperature is within the above range, CaAlSiN in the first phosphor can be sufficiently suppressed₃Partial decomposition of the main crystalline phase with the same crystal structure. The heating temperature can be adjusted within the above range, and may be, for example, 1100 to 1650 ℃.

The second step may be performed, for example, in the same inert gas atmosphere as in the first step, or may be performed in an inert gas atmosphere different from that in the first step. The inert gas may be the gas exemplified in the first step, and preferably includes argon gas, and more preferably argon gas. The second step may be performed in the same pressure atmosphere as the first step, or may be performed in a different pressure atmosphere from the first step. The pressure (gauge pressure) in the second step may be, for example, 0.65MPaG or less, 0.1MPaG or less, or 0.01MPaG or less. When the upper limit value of the pressure is within the above range, crystal defects in the first phosphor can be more sufficiently reduced, and the emission intensity of the nitride phosphor can be further improved. The pressure (gauge pressure) in the second step is not particularly limited, and may be 0.001MPaG or more, or 0.002MPaG or more in view of industrial productivity.

The heating time of the first phosphor in the second step may be, for example, 4 to 24 hours or 8 to 15 hours. By adjusting the heating time, the crystal defects of the first phosphor can be further reduced and the emission intensity of the nitride phosphor can be improved.

The container used in the method for producing a nitride phosphor is preferably a container made of a material which is stable in a high-temperature and high-temperature inert atmosphere and which is less likely to react with the raw material powder, the first phosphor, the second phosphor (nitride phosphor), and the like. Such a container is preferably a metal container made of, for example, molybdenum, tantalum, and tungsten or an alloy containing these metals, and more preferably a container with a lid.

The method for producing a nitride phosphor may include other steps in addition to the first step, the second step, and the step of adjusting the composition in the raw material powder. Examples of the other step include a step of subjecting the second phosphor (nitride phosphor) obtained in the second step to an acid treatment. The content of impurities in the phosphor can be reduced by the acid treatment of the nitride phosphor. Examples of the acid include hydrochloric acid, formic acid, acetic acid, sulfuric acid, and nitric acid. After the acid treatment, the nitride phosphor may be washed with water to remove the acid, and dried.

The nitride phosphor obtained by the above-described production method is obtained in the form of fine particles. The median particle diameter (d50) of the nitride phosphor may be, for example, 1 to 50 μm. When the median diameter is within the above range, the excitation light can be received, the decrease in emission intensity can be sufficiently suppressed, and the chromaticity shift of the fluorescence emitted from the nitride phosphor can be suppressed. In the present specification, the "median particle diameter (d 50)" means a particle diameter measured in accordance with JIS R1622: 1997, the value calculated from the volume average diameter measured by laser diffraction scattering method.

The nitride phosphor obtained by the above-described production method has, for example, the following composition. In the nitride phosphor, the Eu content is 4.5 to 7.0 mass%, the Sr content is 30 to 42 mass%, and the Ca content may be 0.8 to 3.0 mass%. When the Eu content, Sr content, and Ca content in the nitride phosphor are in the above ranges, the emission intensity of the nitride phosphor and the suppression of the decrease in the emission intensity at high temperatures can be achieved at a higher level.

The Eu content in the nitride phosphor may be, for example, 5.0 to 7.0 mass%, and may be 5.0 to 6.0 mass%. The Sr content in the nitride phosphor may be 34.0 to 41.0 mass%, or 36.0 to 40.0 mass%, for example. The content of Ca in the nitride phosphor may be, for example, 0.8 to 2.9% by mass, 0.8 to 2.8% by mass, 0.8 to 1.0% by mass, or 0.8 to 0.9% by mass. By setting the Eu content, Sr content, and Ca content within the above ranges, a nitride phosphor with further reduced crystal defects can be produced.

The above nitride phosphor may be represented by the general formula: MALSiN₃(M ═ Ca, Sr, Eu), and a main crystal phase and CaAlSiN₃The crystalline phases have the same structure. The content of Eu as an emission center element in the above nitride phosphor (SCASN phosphor) is adjusted in accordance with the Ca content and Sr content that can occupy the same site on the crystal lattice. For example, when the Eu content is increased, the total amount of the Ca content and the Sr content is relatively decreased. In the conventional method for producing a nitride phosphor, if the amount of a compound having a luminescence center (e.g., a europium compound) added to a raw material powder is increased, the luminescence center does not enter the phosphor or a main crystal phase, and the luminescence center enters Sr₂Si₅N₈Such heterogeneous phase causes side reactions, and it is difficult to increase the content of an element (e.g., Eu) serving as a luminescence center in the phosphor.

In addition, in the conventional method for producing a nitride phosphor, when a compound containing oxygen is used as a source for supplying each element, defects are generated in the crystal lattice due to substitution of any element in the crystal lattice by an oxygen atom or the like by oxygen from the compound. According to the studies of the inventors, when an oxide is used as a compound for supplying an element which becomes a center of light emission, particularly, the generation of a large amount of such lattice defects tends to be found. As a result, the emission peak wavelength of the obtained nitride phosphor does not become long of a desired level, or the half-value width of the emission peak wavelength becomes wide, and thus the emission intensity does not exhibit a desired level. The method for producing a nitride phosphor according to the present disclosure is based on the finding that a nitride phosphor having an emission peak wavelength of 640nm or more and a half-value width of the emission peak wavelength of 80nm or less can be produced by reducing the amount of oxide in raw material powder in the production of a nitride phosphor, and particularly by adjusting the amount of oxide using a halide as a compound for supplying an emission center element. Further, the nitride phosphor reduces defects in crystal lattices and is excellent in temperature characteristics.

The above-mentioned nitride phosphor may be used alone, or may be used in combination with another phosphor, or may be used as a phosphor composition. One embodiment of the phosphor composition includes the above-described nitride phosphor and another phosphor. The other phosphor may include, for example, a red phosphor, a yellow-green phosphor, a green phosphor, and the like. The other phosphor can be selected according to the use of the phosphor composition, and for example, can be selected and combined according to the luminance, color tone, color rendering property, and the like required for the light-emitting device. Examples of the red phosphor include a red phosphor containing CaSiAlN₃A nitride phosphor (CASN phosphor) of (2), an SCASN phosphor having an emission peak wavelength of less than 640nm, and the like. Examples of the green to yellow phosphors (phosphors having a fluorescence wavelength in a green to yellow wavelength band) include a LuAG phosphor, a YAG phosphor, and the like, examples of the yellow phosphor include a Ca — α -SiAlON phosphor, and the like, and examples of the green phosphor include a β -SiAlON phosphor, and the like.

The nitride phosphor can be used for a light emitting device such as a white LED, for example. One embodiment of a light-emitting device has a nitride phosphor and a light-emitting element. Fig. 1 is a schematic cross-sectional view showing an example of a light-emitting device. The light-emitting device shown in fig. 1 is an example classified as a surface-mount type optical semiconductor device. The light-emitting device 100 includes a substrate 10, a metal layer 20 provided on a surface of the substrate 10, a light-emitting element 40 electrically connected to the metal layer 20, a reflection portion 30 provided on a surface of the substrate 10 so as to surround the light-emitting element 40, and a transparent sealing resin 60 filled in a recess formed by the substrate 10 and the reflection portion 30 to seal the light-emitting element 40. The nitride phosphor 52 and the other phosphors 54 are dispersed in the transparent sealing resin 60.

The metal layer 20 is formed on a part of the surface of the substrate 10, and the metal layer 20 serves as an electrode that is electrically connected to the light-emitting element 40 disposed on the surface of the substrate 10. The light emitting element 40 is die-bonded to the metal layer 20 on either the anode side or the cathode side, and is electrically connected to the metal layer 20 through a die bonding material 42. The light-emitting element 40 is electrically connected to the metal layer 20 on either the anode side or the cathode side via bonding wires 44.

The reflection section 30 is filled with a transparent sealing resin 60 for sealing the light emitting element 40, and reflects light (excitation light) emitted from the light emitting element 40 and fluorescence emitted from the nitride phosphor 52 and the other phosphor 54 upon receiving the light to the surface side of the light emitting device 100. The nitride phosphor 52 and the other phosphors 54 are exposed to a high temperature condition due to the excitation light from the light emitting element 40 as described above, and the fluorescence. The light emitting device 100 uses the nitride phosphor described above as the nitride phosphor 52. By using the above nitride phosphor, a decrease in emission intensity can be suppressed even when the temperature rises with use. In addition, even if the temperature becomes high with long-term use of the light-emitting device 100, a decrease in luminance can be suppressed. That is, the light-emitting device 100 can suppress a decrease in luminance even when used in a high-temperature environment.

The light emitting element 40 may also emit light capable of exciting the nitride phosphor 52 and the other phosphors 54. The light emitting element 40 may be, for example, a near ultraviolet light emitting diode (near ultraviolet LED), an ultraviolet light emitting diode (ultraviolet LED), a blue light emitting diode (blue LED), or the like.

The phosphor included in the light emitting device 100 may include another phosphor 54 in addition to the nitride phosphor 52, or may be only the nitride phosphor 52. The other phosphor 54 may include, for example, a red phosphor, a yellow phosphor, a green phosphor, a blue phosphor, and the like.

In the above examples, the light-emitting device has been described as an example of an optical semiconductor device classified as a surface-mount type, but the invention is not limited thereto. The light-emitting device may be, for example, a lighting device, a signal device, an image display apparatus, a light-emitting panel, a backlight of a liquid crystal display, a liquid crystal panel, or the like.

While several embodiments have been described above, the present disclosure is not limited to the above embodiments at all.

Examples

The present disclosure is described in more detail with reference to examples and comparative examples, but the present disclosure is not limited to the following examples.

(example 1)

< preparation of nitride phosphor >

63.4g of alpha-silicon nitride (Si) were weighed out and premixed in a vessel₃N₄SN-E10 grade manufactured by Udo Kyoho K.K.), 55.6g of aluminum nitride (AlN, E grade manufactured by Tokuyama K.K.) and 16.7g of europium fluoride (EuF)₃Fuji film and Wako pure chemical industries, Ltd.). Next, in a glove box kept in a nitrogen atmosphere in which the moisture content is adjusted to 1 ppm by mass or less and the oxygen concentration is adjusted to 50ppm or less, 5.4g of calcium nitride (Ca) is further measured in the container₃N₂Materion Co., Ltd.) and 109.1g of strontium nitride (Sr)₃N₂Purity 2N, manufactured by high purity chemical research corporation), and dry-mixed to obtain a raw material powder (mixed powder).

In a glove box, a tungsten container with a lid was filled with 250g of the above raw material powder. After the vessel with the lid was taken out from the glove box and placed in an electric furnace equipped with a carbon heater, vacuum evacuation was sufficiently performed until the pressure in the electric furnace became 0.1PaG or less. The temperature was raised in a state where the vacuum evacuation was continued until the temperature in the electric furnace became 600 ℃. After the temperature reached 600 ℃, nitrogen gas was introduced into the electric furnace, and the pressure in the electric furnace was adjusted to 0.9 MPaG. Then, the temperature was raised in a nitrogen atmosphere until the temperature in the electric furnace became 1950 ℃ and reached 1950 ℃, and then the heat treatment was performed for 8 hours (corresponding to the first step). Then, the heating was terminated, and the mixture was cooled to room temperature. After cooling to room temperature, the red mass was recovered from the vessel. The collected cake was disintegrated with a mortar, and finally passed through a sieve having a mesh size of 75 μm to obtain a powder (calcined powder).

The obtained calcined powder was filled in a tungsten container, quickly transferred to an electric furnace equipped with a carbon heater, and sufficiently vacuum-exhausted until the pressure in the furnace became 0.1PaG or less. Heating was started with the vacuum evacuation continued, and argon gas was introduced into the furnace at the time when the temperature reached 600 ℃ to adjust the furnace gas pressure to 0.2 MPaG. The temperature was increased to 1300 ℃ after the start of the argon gas introduction. After the temperature reached 1300 ℃, heat treatment (annealing treatment, corresponding to the second step) was performed for 8 hours. Then, the heating was terminated, and it was cooled to room temperature. After cooling to room temperature, the annealed powder was recovered from the container. The collected powder was passed through a 75 μm mesh sieve to adjust the particle size, thereby obtaining a red phosphor.

After the heat treatment, the heating in the electric furnace was stopped and the temperature was cooled to room temperature. The sample was collected in a mortar, and disintegrated into a block form in the container with a lid. After the disintegration, the resultant was passed through a sieve having a 75 μm mesh opening to obtain a red phosphor (nitride phosphor, median particle diameter (d 50): 25 μm) of example 1.

(example 2)

63.1g of alpha-silicon nitride (Si) were weighed out and premixed in a vessel₃N₄SN-E10 grade manufactured by Utsu Kaisha, Ltd.), 55.2g of aluminum nitride (AlN, E grade manufactured by Tokuyama Kaisha), and 16.9g of europium fluoride (EuF)₃Fuji film and Wako pure chemical industries, Ltd.). Then, in a glove box kept in a nitrogen atmosphere in which the moisture content is adjusted to 1 mass ppm or less and the oxygen concentration is adjusted to 50ppm or less, 6.0g of calcium nitride (Ca) is further measured in the container₃N₂Materion Co., Ltd.) and 108.6g of strontium nitride (Sr)₃N₂Purity 2N, manufactured by high purity chemical research corporation), and dry-mixed to obtain a raw material powder. The subsequent steps were carried out in the same manner as in example 1 to obtain a red phosphor (nitride phosphor, median particle diameter (d 50): 25 μm) of example 2.

Comparative example 1

64.4g of alpha-type silicon nitride powder (Si) was weighed out and premixed in a vessel₃N₄SN-E10 grade, available from Udo Kyoho K.K.), 56.4g of aluminum nitride powder (AlN, E grade, available from Tokuyama K.K.), and 2.9g of europium oxide (Eu)₂O₃RU grade manufactured by shin-Etsu chemical Co., Ltd.). Then, a nitrogen gas is maintained so that the water content is adjusted to 1 ppm by mass or less and the oxygen concentration is adjusted to 50ppm or lessIn the glove box of atmosphere, 2.6g of calcium nitride (Ca) was further measured in the above container₃N₂Materion Co., Ltd.) and 123.7g of strontium nitride (Sr)₃N₂Purity 2N, manufactured by high purity chemical research corporation), and dry-mixed to obtain a raw material powder. The subsequent steps were carried out in the same manner as in example 1 to obtain a red phosphor (nitride phosphor, median particle diameter (d 50): 25 μm) according to comparative example 1.

Comparative example 2

66.8g of alpha-silicon nitride powder (Si) were weighed out and premixed in a vessel₃N₄SN-E10 grade manufactured by Utsui Kabushiki Kaisha), 58.6g of aluminum nitride powder (AlN, E grade manufactured by Tokuyama K.K.), and 7.6g of europium oxide (Eu) powder₂O₃RU grade manufactured by shin-Etsu chemical Co., Ltd.). Then, in a glove box kept in a nitrogen atmosphere in which the moisture content is adjusted to 1 mass ppm or less and the oxygen concentration is adjusted to 50ppm or less, 15.5g of calcium nitride (Ca) is further measured in the container₃N₂Materion Co., Ltd.) and 101.5g of strontium nitride (Sr)₃N₂Purity 2N, manufactured by high purity chemical research corporation), and dry-mixed to obtain a raw material powder. The subsequent steps were carried out in the same manner as in example 1 to obtain a red phosphor (nitride phosphor, median particle diameter (d 50): 21 μm) according to comparative example 2.

Comparative example 3

66.5g of alpha-type silicon nitride powder (Si) were weighed out and premixed in a vessel₃N₄SN-E10 grade manufactured by Utsui Kabushiki Kaisha), 58.3g of aluminum nitride powder (AlN, E grade manufactured by Tokuyama K.K.), and 5.0g of europium oxide (Eu) powder₂O₃RU grade manufactured by shin-Etsu chemical Co., Ltd.). Then, in a glove box kept in a nitrogen atmosphere in which the moisture content was adjusted to 1 mass ppm or less and the oxygen concentration was adjusted to 50ppm or less, 12.6g of calcium nitride (Ca) was further measured in the container₃N₂Materion Co., Ltd.) and 107.6g of strontium nitride (Sr)₃N₂Purity 2N, manufactured by high purity chemical research corporation), and dry-mixed to obtain a raw material powder. Subsequent process steps andthe procedure of example 1 was carried out in the same manner as in comparative example 3 to obtain a red phosphor (nitride phosphor, median particle diameter (d 50): 37 μm).

Comparative example 4

63.8g of alpha-type silicon nitride powder (Si) was weighed out and premixed in a vessel₃N₄SN-E10 grade manufactured by Utsui Kabushiki Kaisha), 55.9g of aluminum nitride powder (AlN, E grade manufactured by Tokuyama K.K.) and 14.4g of europium oxide (Eu)₂O₃RU grade manufactured by shin-Etsu chemical Co., Ltd.). Then, in a glove box kept in a nitrogen atmosphere in which the moisture content is adjusted to 1 mass ppm or less and the oxygen concentration is adjusted to 50ppm or less, 6.0g of calcium nitride (Ca) is further measured in the container₃N₂Materion Co., Ltd.) and 109.7g of strontium nitride (Sr)₃N₂Purity 2N, manufactured by high purity chemical research corporation), and dry-mixed to obtain a raw material powder. The subsequent steps were carried out in the same manner as in example 1 to obtain a red phosphor (nitride phosphor, median particle diameter (d 50): 24 μm) according to comparative example 4.

< confirmation of Crystal Structure of Red phosphor >

The red phosphors obtained in examples 1 and 2 and comparative examples 1 to 4 were subjected to a powder X-ray analysis using an X-ray diffraction apparatus (product name: UltimaIV, manufactured by Rigaku corporation) to obtain X-ray diffraction patterns of the respective red phosphors. The crystal structure was confirmed from the obtained X-ray diffraction pattern. As a result, it was confirmed that all of the X-ray diffraction patterns of the red phosphors of examples 1 and 2 and comparative examples 1 to 4 were in agreement with CaAlSiN₃The crystals were the same diffraction pattern. The measurement uses CuK α rays (characteristic X-rays).

< analysis of composition of Red phosphor >

The red phosphors obtained in examples 1 and 2 and comparative examples 1 to 4 were analyzed for their composition. First, a sample solution was prepared by dissolving a red phosphor by a pressure acid decomposition method. Quantitative analysis of the elements was carried out using an ICP emission spectrophotometer (product name: CIROS-120, manufactured by Rigaku K.K.) with respect to the obtained sample solution. The results are shown in Table 1.

From the results of the above crystal structure and composition analysis, it was confirmed that the red phosphors obtained in examples 1 and 2 and comparative examples 1 to 4 were both SCASN phosphors.

< evaluation of fluorine content of nitride phosphor >

The SCASN phosphors obtained in examples 1 and 2 and comparative examples 1 to 4 were evaluated for fluorine content. The SCASN phosphor was burned by using an automatic sample burner (product name: AQF-2100H, manufactured by Mitsubishi Chemical Analyticech Co., Ltd.) to prepare a sample solution in which the generated gas was absorbed. The prepared sample solution was measured for fluorine content by ion chromatography. The results are shown in Table 1. In table 1, the case where the fluorine content of the nitride phosphor is not more than the detection limit is represented by "-".

The measurement conditions of the ion chromatography are as follows.

The device comprises the following steps: ion chromatograph (ICS-2100 product name manufactured by Thermo Fisher Scientific Co., Ltd.)

Column: AS17-C (product name, manufactured by Thermo Fisher Scientific Co., Ltd.)

Introduction amount: 25 μ L

Eluent: potassium hydroxide (KOH) solution

Liquid feeding speed: 1.00 mL/min

Measuring temperature: 35 deg.C

[ Table 1]

< measurement of emission Peak wavelength and half Width of nitride phosphor >

The SCASN phosphors obtained in examples 1 and 2 and comparative examples 1 to 4 were measured for emission peak wavelength and half-value width. The fluorescence spectrum was measured using a spectrofluorometer (product name: F-7000, manufactured by Hitachi High Technologies Co., Ltd.) calibrated with rhodamine B and a sub-standard light source. Measurement using a solid sample holder attached to a photometer, the following were measured with respect to the excitation wavelength: fluorescence spectrum at 455 nm. The emission peak wavelength and the half-value width of the emission peak wavelength are determined from the obtained fluorescence spectrum. The results are shown in Table 2.

< measurement of the luminous intensity of nitride phosphor and the luminous intensity maintenance ratio at 200 >

The SCASN phosphors obtained in examples 1 and 2 and comparative examples 1 to 4 were measured for their emission intensity and the maintenance ratio of the emission intensity at 200 ℃. Specifically, the measurement was performed by the following method.

The concave groove was filled with the SCASN phosphor prepared as above in such a manner that the surface of the sample became smooth. A groove filled with SCASN phosphor is arranged on the integrating sphereSide opening part ofMonochromatic light having a wavelength of 455nm split from a light emitting source (Xe lamp) was introduced into the integrating sphere through an optical fiber, and the excitation reflection spectrum and the fluorescence spectrum were measured using a spectrophotometer (manufactured by tsukamur electronic corporation, product name: QE-2100). The luminescence intensity at 25 ℃ was obtained from the obtained fluorescence spectrum.

Further, the inside of the cell filled with the SCASN phosphor was heated, and the fluorescence spectrum of the SCASN phosphor at 200 ℃ was measured in the same manner as in the above method, to obtain the emission intensity at 200 ℃. From the obtained emission intensity, the emission intensity maintenance ratio at 200 ℃ was calculated based on the following formula (1). The results are shown in Table 2. The emission intensities shown in table 2 are relative values based on the emission intensity measured at 25 ℃.

Luminescence intensity maintenance rate [% ] [ (luminescence intensity at 200 ℃)/(luminescence intensity at 25 ℃) ] × 100 … formula (1)

[ Table 2]

Industrial applicability

According to the present disclosure, a nitride phosphor having excellent emission intensity and being suppressed in the decrease in emission intensity even at high temperatures can be provided. By using the nitride phosphor capable of emitting red fluorescence as described above, a light-emitting device in which luminance reduction can be suppressed even at high temperatures can be provided.

Description of the symbols

10 … base material, 20 … metal layer, 30 … reflection part, 40 … luminous element, 42 … chip bonding material, 44 … bonding wire, 52 … nitride phosphor, 54 … other phosphor, 60 … transparent sealing resin and 100 … luminous device.