JP6946159B2 - Green phosphor, light emitting element and light emitting device - Google Patents

Description

The present invention relates to a green phosphor, a light emitting element having the green phosphor and a light emitting light source, and a light emitting device having the light emitting element.

A white LED, which is one of the light emitting elements, is a device that emits pseudo white light by combining a semiconductor light emitting element which is a light emitting light source and a phosphor, and typical examples thereof are a blue LED and a YAG yellow of the light emitting semiconductor element. White LEDs in combination with a phosphor are known. However, although the white LED of this type is in the white region as its chromaticity coordinate value, it has a low color rendering property for lighting equipment applications because it lacks a green light emitting component and a red light emitting component, and an image display device. There is a problem that the color reproducibility is poor when applied to the backlight of. Therefore, in order to make up for the deficient light emitting component, a white LED of a method in which a blue LED is combined with a green phosphor and a red phosphor has been proposed.

As a nitride phosphor that emits green light, elements such as Mn and Mg, Mn and Eu and Mg, and Mn and Si are dissolved in an AlON crystal having a cubic spinel-type crystal structure called γ-AlON. Γ-AlON based phosphors are known (Patent Documents 1 and 2). Since the half-value width of the emission spectrum of the γ-AlON-based phosphor is relatively narrow and the emission peak wavelength is closer to the short wavelength of the green phosphor, it is possible to obtain a light emitting element or a light emitting device having high efficiency and wide color reproducibility. Can be done. A light emitting device that combines this γ-AlON-based phosphor with a red phosphor and a light source has also been proposed (Patent Documents 3 and 4).

International Publication No. 2007/099862 Japanese Unexamined Patent Publication No. 2009-096854 Japanese Unexamined Patent Publication No. 2009-218422 JP-A-2010-09132

However, sufficient studies have not yet been made on the γ-AlON-based phosphor, and it has not been possible to obtain sufficient emission brightness for use as a light emitting element or a light emitting device. Therefore, in order to provide a light emitting element or a light emitting device having a high light emitting brightness, a γ-AlON-based phosphor having an increased light emitting brightness is expected in the industry.

An object of the present invention is to provide a green phosphor having high emission brightness. Another object of the present invention is to provide a light emitting element having the green phosphor of the present invention and a light emitting device having the light emitting element.

As a result of diligent studies to solve the above problems, the present inventors have determined the content ratio of Mg and N in the chemical composition of the green phosphor containing AlON whose main crystal layer has a cubic spinel-type crystal structure. It has been found that when controlled, a green phosphor having high emission brightness can be obtained, and the present invention has been made.

That is, the embodiments of the present invention are as follows (1) to (6).

(1) At least Mn and Mg are solid-dissolved, the main crystal phase is AlON having a cubic spinel-type crystal structure, and the content ratio of Mg with respect to the total composition is 5.0 mol% to 13.0 mol%. , A green phosphor having an N content of 0.5 mol% to 6.0 mol%.

(2) At least Mn and Mg are solid-dissolved, the main crystal phase is AlON having a cubic spinel-type crystal structure, and the composition formula is Mn _a Mg _b Al _{c Od Ne} (however, a + b + c + d + e = in the formula). When 1) is set, the green phosphor is characterized by satisfying 0.110 ≦ b / (a + b + c) ≦ 0.300 and 0.005 ≦ e / (d + e) ≦ 0.105.

(3) The green phosphor according to (1) or (2) above, wherein the sum of the content ratios of Mg and N is 10.0 mol% to 14.0 mol%.

(4) The green color according to any one of (1) to (3) above, wherein the sum of the content ratios of Mn, Mg and Al is 42.5 mol% to 43.5 mol%. Fluorescent material.

(5) A light emitting device having the green phosphor and a light emitting light source according to any one of (1) to (4) above.

(6) A light emitting device having the light emitting element according to (5) above.

By implementing the present invention, it is possible to provide a green phosphor having high emission brightness. Further, by combining with a light emitting light source such as a blue LED that emits a light emitting wavelength corresponding to the excitation wavelength of the green phosphor or, if necessary, another phosphor, it is possible to provide a light emitting element having high brightness. Further, a light emitting device having the light emitting element can be provided.

Hereinafter, embodiments of the present invention will be described in detail. Unless otherwise specified, the numerical range described in this specification shall include the upper limit value and the lower limit value.

The first embodiment of the present invention is AlON in which at least Mn and Mg are solid-dissolved and the main crystal phase has a cubic spinel-type crystal structure, and the content ratio of Mg to the total composition is 5.0 mol. It is a green phosphor having a content of% to 13.0 mol% and an N content of 0.5 mol% to 6.0 mol%. Here, Mn indicates manganese as an element, Mg indicates magnesium, Al indicates aluminum, O indicates oxygen, and N indicates nitrogen as an element, and the same applies to the following description.

Another embodiment of the present invention is AlON in which at least Mn and Mg are solid-solved and the main crystal phase has a cubic spinel-type crystal structure, and the composition formula is Mn _a Mg _b Al _{c Od Ne.} (However, a + b + c + d + e = 1 in the formula, and the term “composition formula” described below indicates the composition formula.) 0.110 ≦ b / (a + b + c) ≦ 0.300 and 0.005 ≦ e /. It is a green phosphor characterized by satisfying (d + e) ≦ 0.105.

In the present specification, the above-mentioned "AlON having a cubic spinel type crystal structure" is also referred to as "γ-AlON". Further, the above-mentioned "main crystal phase" means that the green phosphor of the present invention preferably has a crystal phase consisting of only γ-AlON, but the raw material is used so that a green phosphor having a desired composition can be obtained. Even if it is blended, a trace amount of crystal phase (also referred to as "heterogeneous phase" in the present specification) is used in addition to the main crystal phase to the extent that the composition of the green phosphor does not fluctuate during firing and the effect intended by the present invention is not impaired. ) May be included, so it is an expression that includes the meaning of including such fluctuations. The γ-AlON may include, for example, an AlON crystal, a solid solution crystal of AlON, or a crystal having the same crystal structure as AlON as a parent crystal.

Whether or not the main crystal phase of the green phosphor is γ-AlON can be confirmed by powder X-ray diffraction measurement. When the main crystal phase of the produced green phosphor is different from that of γ-AlON, the emission color is not green and the emission brightness is greatly reduced, which is not preferable. The main crystal phase is preferably a single phase consisting of only γ-AlON, but may contain a different phase as long as it does not significantly affect the phosphor characteristics such as emission brightness. The presence or absence of a heterogeneous phase can be determined by, for example, the presence or absence of a peak not attributable to γ-AlON by powder X-ray diffraction. Further, a part of the present invention in which the lattice constant is changed by partially replacing the constituent elements of γ-AlON with other elements is also included.

The Mn content of the green phosphor according to the embodiment of the present invention is 0.1 mol% to 10.0 mol% based on the entire composition of the green phosphor (a = 0 in the composition formula). It is preferably .001 to 0.100), more preferably 0.5 mol% to 5.0 mol%, still more preferably 0.5 mol% to 3.0 mol%. If the proportion of Mn is smaller than 0.1 mol%, the number of ions at the center of emission is small, so that the emission brightness is lowered. Further, when the ratio of Mn element is larger than 10.0 mol%, the concentration quenching phenomenon due to the interference between ions becomes remarkable, so that the emission brightness is lowered.

The Mg content of the green phosphor according to the embodiment of the present invention is 5.0 mol% to 13.0 mol% based on the entire composition of the green phosphor (b = 0 in the composition formula). It is necessary to be .050 to 0.130), preferably 7.0 mol% to 13.0 mol%. If the proportion of Mg is less than 5.0 mol% or exceeds 13.0 mol%, the main crystal phase considered to be γ-AlON becomes unstable and the proportion of different phases increases, so that the emission brightness increases. descend.

The N content of the green phosphor according to the embodiment of the present invention is 0.5 mol% to 6.0 mol% based on the entire composition of the green phosphor (e = 0 in the composition formula). It is necessary to be .005 to 0.060), preferably 0.7 mol% to 6.0 mol%, and particularly preferably 0.7 mol% to 5.5 mol%. If the proportion of N is less than 0.5 mol% or exceeds 6.0 mol%, the emission brightness decreases.

In the green phosphor according to the embodiment of the present invention, when the composition formula of the green phosphor is Mn _a Mg _b Al _{c Od} N _e , the total amount of positively charged elements (that is, Mn, Mg, and Al). Is 11.0% to 30.0%, that is, 0.110 ≦ b / (a + b + c) ≦ 0.300, and the element has a negative charge (that is, O). When the total amount of (oxygen) and N) is used as a reference, the ratio of N is 0.5% to 10.5%, that is, 0.005 ≦ e / (d + e) ≦ 0.105. The charge balance of the phosphor as a whole is excellent, and the effect of increasing the emission brightness can be achieved. On the other hand, if both of these conditions cannot be satisfied, there may be a problem that the emission brightness of the phosphor is lowered. More preferably, 0.120 ≦ b / (a + b + c) ≦ 0.290 and 0.010 ≦ e / (d + e) ≦ 0.105 can also be set.

Further, the sum of the content ratios of Mg and N in the green phosphor according to the embodiment of the present invention is 10.0 mol% to 14.0 mol% based on the whole green phosphor. It is preferable because the balance of charge of the whole body is good, more preferably 11.0 mol% to 14.0 mol%, and further preferably 11.0 mol% to 13.5 mol%.

Further, the sum of the contents of positively charged Mn, Mg and Al contained in the green phosphor according to the embodiment of the present invention is 42.5 mol% to 43.5 mol% based on the entire green phosphor. Is preferable in order to facilitate the balance of the charge of the phosphor as a whole, more preferably 42.6 mol% to 43.4 mol%, still more preferably 42.6 mol% to 43.3 mol%. It may be in the range of.

The content ratio of O (oxygen) in the green phosphor according to the embodiment of the present invention is 50.0 mol% to 65.0 mol% based on the whole green phosphor (d = in the composition formula). It is preferably 0.5000 to 0.650), and more preferably 50.0 mol% to 60.0 mol%. If the O content is less than 50.0 mol% or exceeds 65.0 mol%, the emission brightness may decrease.

The Al content ratio of the green phosphor according to the embodiment of the present invention is 20.0 mol% to 40.0 mol% based on the whole green phosphor (c = 0.200 to 0200 to the composition formula). It is preferably 0.400), and more preferably 25.0 mol% to 40.0 mol%. If the proportion of Al is less than 20.0 mol% or exceeds 40.0 mol%, the emission brightness may decrease.

In a preferred embodiment, the half width of the emission spectrum of the phosphor when irradiated with excitation light can be narrowed. Specifically, the half width can be 45 nm or less, preferably 40 nm or less, and more preferably 38 nm or less. With such a narrow full width at half maximum, it is possible to improve the emission color as a phosphor and obtain more pure green emission.

As a method for producing the present phosphor, the same production method as that for a conventional phosphor having a γ-AlON crystal can be used. Here, as one embodiment of the present invention, as a method for obtaining a crystal in which Mn element and Mg element are solidly dissolved in γ-AlON, a raw material mixed powder capable of forming the crystal is inert in a nitrogen gas atmosphere. An example of a method of firing in a predetermined temperature range in either a gas atmosphere or an atmosphere of a mixed gas of nitrogen gas and an inert gas is exemplified, but the method is not particularly limited.

In this production method, Mn alone, an alloy containing Mn, an oxide of Mn, a carbonate, a nitride, a fluoride, a chloride, an oxynitride, or a raw material as a Mn source that can be selected from a combination thereof, and Mg alone. , Mg-containing alloys, Mg oxides, carbonates, nitrides, fluorides, chlorides, nitrides or combinations thereof, and raw materials that can be selected as Mg sources, Al alone, alloys containing Al, Al. A raw material mixed powder containing a raw material as an Al source that can be selected from the oxides, nitrides, or a combination thereof in a predetermined ratio is prepared and placed in a baking vessel.

The firing container is preferably made of a material that is mechanically stable even under a predetermined firing temperature and atmosphere and that does not easily react with the raw material mixed powder and its reaction product. For example, it is made of boron nitride, carbon, or high. Examples include containers made of melting point metals (tungsten, molybdenum, tantalum).

The firing container containing the raw material mixed powder is set in a firing furnace and fired in a nitrogen atmosphere of 1500 ° C. or higher and 2200 ° C. or lower (baking step). If the calcination temperature is lower than 1500 ° C., the amount of unreacted substances increases, and if it exceeds 2200 ° C., γ-AlON, which is the main crystal phase, is decomposed, which is not preferable.

The calcination time can be selected in consideration of a time in which a large amount of unreacted material is present, the target green phosphor particles are not insufficiently grown, or the productivity is not lowered. The preferred firing time for producing the green phosphor of the present invention is 1 hour or more and 24 hours or less.

The pressure of the firing atmosphere is selected according to the firing temperature. The higher the firing atmosphere pressure, the higher the decomposition temperature of the phosphor, but it is preferably 1 MPaG or less in consideration of industrial productivity.

The state of the fired product obtained by firing the raw material mixed powder varies from powdery, lumpy, and sintered body depending on the raw material composition and firing conditions. When used as a phosphor, the calcined product can be made into a powder of a predetermined size by combining crushing, pulverization and / or classification operations.

In the production of the green phosphor according to the embodiment of the present invention, an annealing step for the purpose of improving crystallinity and an acid treatment step for the purpose of removing impurities can be further carried out after the firing step.

Another embodiment of the present invention is a light emitting device having the green phosphor of the present invention and a light emitting light source. In particular, when an emission source that emits ultraviolet light or visible light containing a wavelength of 350 nm or more and 500 nm or less is used as an excitation source and the green phosphor of the present invention is irradiated, it emits green light having an emission peak at a wavelength of 510 nm to 550 nm. The element can be obtained. By combining the green phosphor of the present invention with another phosphor and a light emitting light source, a light emitting element that emits a different color can be obtained. For example, by combining the green phosphor of the present invention, the red phosphor, and a light emitting light source such as an ultraviolet LED or a blue LED, a light emitting element (so-called white LED) that emits white light can be obtained.

Further, a light emitting device having the light emitting element of the present invention is also an embodiment of the present invention. Examples of the light emitting device include a lighting device, a backlight device, an image display device, a signal device, and the like depending on the use, but the light emitting device of the present invention is not limited to each use.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

(Example 1)
_{Aluminum oxide powder (Al 2} O ₃ , TM-DAR grade manufactured by Daimei Chemical Co., Ltd.), aluminum nitride powder (AlN, E grade manufactured by Tokuyama Co., Ltd.), magnesium oxide powder (MgO, Wako Pure Chemical Industries, Ltd.) as raw materials for green phosphors. industry Co., Ltd.), manganese oxide powder (MnO, Kojundo Chemical Laboratory, Ltd.) was used, Ltd., a = 0.017 in the composition formula shown in Table _{1 Mn a Mg b Al c O} d N e, b = Dry mixing was performed for 10 minutes so that 0.054, c = 0.355, d = 0.517, and e = 0.057. The raw material after mixing was classified with a nylon sieve having a mesh size of 250 μm, and after confirming that no excessive particles were mixed, the raw material was prepared as a raw material mixed powder. 13 g of the classified raw material mixed powder was placed in a cylindrical boron nitride container with a lid (N-1 grade manufactured by Denka Corporation).

The firing container containing the raw material mixed powder was set in an electric furnace of a carbon heater, and the inside of the furnace was exhausted to 0.1 PaG or less. While maintaining the reduced pressure state, heating was started at a rate of 300 ° C. per hour from room temperature (20 ± 10 ° C.), nitrogen gas was introduced at 1000 ° C., and the atmospheric pressure in the furnace was set to 0.8 MPaG. Even after the introduction of nitrogen gas, the temperature was raised to 1900 ° C. by heating at a rate of 300 ° C. per hour as it was, and firing was continued at 1900 ° C. for 4 hours.

After that, it was cooled to room temperature, and the fired product was recovered from the firing container. The calcined product was a green mass, which was crushed in a mortar to obtain a green phosphor sample of Example 1.

(Comparative Example 1)
Aluminum nitride powder (F grade manufactured by Tokuyama) having an oxygen content of 0.79% as a raw material, following Example 2 which is said to have the highest emission intensity in Patent Document 2 described above for use as a reference for emission brightness. ), Specific surface area 13.6 m ² / g, 99.99% pure aluminum oxide powder (Daimei Kagaku Taimicron grade), 99.9% pure manganese carbonate powder (high-purity chemical reagent grade), and specific surface area. surface area 7m ² / g magnesium oxide (Konoshima Chemical Co., Ltd., part number HP-30A) with, a = 0.019 in the composition formula shown in Table _{1 Mn a Mg b Al c O} d N e, b = 0 The raw material mixed powder was prepared so that .027, c = 0.377, d = 0.511, and e = 0.067. Then, the firing container containing the raw material mixed powder was set in an electric furnace of a carbon heater, and the inside of the furnace was exhausted to 0.1 PaG or less.

While maintaining the reduced pressure state, heating was started at a rate of 500 ° C. per hour, nitrogen gas was introduced at 1000 ° C., and the atmospheric pressure in the furnace was set to 1.0 MPaG. Even after the gas was introduced, the mixture was heated at a rate of 500 ° C. per hour to raise the temperature to 1900 ° C. and fired at 1900 ° C. for 4 hours. After that, the same treatment as in Example 1 was carried out to obtain a green fluorescent substance sample of Comparative Example 1.

(Examples 2 to 7, Comparative Examples 2 to 12)
A fluorescent sample was prepared in the same manner as in Example 1 except that the chemical composition was set to the ratio shown in Table 1 below. However, in Comparative Example 11, europium oxide (Eu ₂ O ₃ , manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of the raw material magnesium oxide powder, and in Comparative Example 12, calcium oxide (CaO, manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of the raw material magnesium oxide powder. High-purity reagent manufactured by Kanto Chemical Co., Inc.) was used.

All the fluorescent material samples obtained in Examples and Comparative Examples were subjected to powder X-ray diffraction using CuKα rays using an X-ray diffractometer (Ultima IV manufactured by Rigaku Co., Ltd.). The obtained X-ray diffraction pattern showed the same diffraction pattern as γ-AlON, and it was confirmed that the main crystal phase was AlON having a cubic spinel-type crystal structure.

Further, for all the green phosphor samples obtained in Examples and Comparative Examples, the phosphors were prepared using a spectrofluorometer (F-7000, manufactured by Hitachi High-Technologies Corporation) corrected by Rhodamine B and a substandard light source. The emission brightness was measured. That is, the emission spectrum at the excitation wavelength of 445 nm was measured using the solid sample holder attached to the photometer. The peak wavelength of the emission spectrum of each of the green phosphors of Examples and Comparative Examples was in the range of 520 nm to 530 nm. The intensity value at the peak wavelength of the emission spectrum is defined as the emission brightness of the phosphor (also referred to as emission peak intensity or emission intensity), the emission brightness of Comparative Example 1 is set to 100%, and this is used as a reference for other Examples and Comparative Examples. It was converted as a relative ratio and shown in Table 1. The full width at half maximum of the emission spectrum (referred to simply as "full width at half maximum" in the present specification) was also measured and is also shown in Table 1.

By controlling the composition of the green phosphor as shown in Table 1, in the examples, the emission brightness of 147% or more based on Comparative Example 1 and more than 200% in the good ones can be obtained. Recognize. Further, in the example sample, a relatively narrow peak not exceeding 40 nm was obtained even if the half-value width was wide, whereas in the comparative example, the half-value width was obtained in all the samples having the emission brightness exceeding 100%. It was found that the wavelength is 40 nm or more, and the balance between the emission brightness and the half width tends to be poor.

The present invention has been described above based on examples. It is understood by those skilled in the art that this embodiment is merely an example, and that various modifications are possible and that such modifications are also within the scope of the present invention.

Since the green phosphor of the present invention is excited by blue light and exhibits green light emission with high emission brightness, it can be suitably used as, for example, a green phosphor for a white LED using a blue LED as a light source. Further, it can be suitably used for a light emitting device such as a lighting device or an image display device having the white LED.

Claims (6)

At least Mn and Mg are solid-dissolved, and the main crystal phase is AlON having a cubic spinel-type crystal structure, and the Mg content is 5.0 mol% to 13.0 mol% and N in the total composition. A green phosphor having a content ratio of 0.5 mol% to 6.0 mol%. At least Mn and Mg are solid-dissolved, and the main crystal phase is AlON having a cubic spinel-type crystal structure, and the composition formula is Mn _a Mg _b Al _{c Od Ne} (however, a + b + c + d + e = 1 in the formula). A green phosphor characterized by satisfying 0.110 ≦ b / (a + b + c) ≦ 0.300 and 0.005 ≦ e / (d + e) ≦ 0.105. The green phosphor according to claim 1 or 2, wherein the sum of the content ratios of Mg and N is 10.0 mol% to 14.0 mol%. The green phosphor according to any one of claims 1 to 3, wherein the sum of the content ratios of Mn, Mg and Al is 42.5 mol% to 43.5 mol%. A light emitting device having the green phosphor and a light emitting light source according to any one of claims 1 to 4. A light emitting device having the light emitting element according to claim 5.