JP7400378B2 - Light emitting devices, lighting devices, image display devices and nitride phosphors - Google Patents

Description

The present invention relates to a light emitting device, a lighting device using the same, an image display device, and a nitride phosphor suitably used in the light emitting device.

In recent years, with the trend toward energy conservation, demand for lighting or backlights using LEDs has been increasing. The LED used here is a white light-emitting LED in which a phosphor is placed on an LED chip that emits light in blue or near ultraviolet wavelengths. Many of these types of white-emitting LEDs use a YAG (yttrium aluminum garnet) phosphor on a blue LED chip that emits yellow light using blue light from the blue LED chip as excitation light. .

However, when YAG phosphors are used under high output power, they suffer from the problem of high temperature quenching, which is a decrease in brightness as the temperature of the phosphor increases, and the need for better color reproduction range or color rendition. (Usually, the range including violet from about 350 to 420 nm is called near ultraviolet light, which is a term used to refer to blue excitation.) When excitation is performed, there is a problem in that the brightness is significantly reduced.

In order to solve the above problem, nitride phosphors that emit yellow light have been investigated, and as a promising candidate, for example, La ₃ Si ₆ N ₁₁ phosphor (hereinafter referred to as lanthanum) described in Patent Documents 1 and 2 has been considered. This type of phosphor, including cases in which phosphors are replaced with other metals, is collectively referred to as LSN phosphors), etc., have been developed.

Furthermore, characteristics as described in Patent Documents 2 and 3 have been reported for light emitting devices using this LSN phosphor. Specifically, Patent Document 2 describes that by setting the object color of the phosphor within a specific range, a phosphor with high luminous efficiency can be obtained. Patent Document 3 discloses that by using BrF ₂ and/or SrF ₂ as a fluxing agent, it is possible to obtain a phosphor that has high brightness and can emit light with excitation light over a wide wavelength range. Patent Documents 2 and 3 disclose that light-emitting devices using these LSN phosphors have excellent light-emitting characteristics such as brightness and chromaticity.

International Publication No. 2008/132954 International Publication No. 2010/114061 Japanese Patent Application Publication No. 2016-028126

In recent years, what is required of light-emitting devices using LEDs is both an improvement in luminous efficiency that can convert LED light into white light with higher efficiency, and a reduction in the cost of the light-emitting device. Patent Documents 2 and 3 do not take into account the amount of phosphor necessary to express an arbitrary luminescent color, so the activator concentration and particle size cannot be adjusted with the phosphors described in Patent Documents 2 and 3. However, it was not possible to achieve both high efficiency of the light emitting device and reduction in the amount of phosphor used, and it was difficult to manufacture an excellent light emitting device at low cost.

An object of the present invention is to provide a device with high luminous efficiency while reducing the amount of phosphor used in a light emitting device.

As a result of intensive studies aimed at solving the above problems, the present inventors designed the activator concentration and particle size of the phosphor to be used within appropriate ranges, and a light emitting device using the same solved the above problems. We have discovered that this is possible and have arrived at the present invention.
That is, the gist of the present invention resides in the following [1] to [9].

[1] A light-emitting device comprising a first light-emitting body and a second light-emitting body that emits visible light by irradiation with light from the first light-emitting body,
The first light emitter is a semiconductor light emitting element that emits ultraviolet light or visible light,
The second light emitter includes a phosphor represented by the following general formula (1),
A light emitting device characterized in that the average particle size of the phosphor is 2 μm or more and 40 μm or less.
M1wM2xM3y:M4z...(1)
M1 represents one or more elements selected from the group consisting of Y, La, Gd, Ca, Sr, Ba and Lu, and the proportion of La to all elements constituting M1 is 90 mol% or more,
M2 represents one or more elements selected from the group consisting of Ge, Si, Hf, Zr, Al, B, Ga and Ti,
M3 requires N and represents one or more elements selected from the group consisting of N, O, F and Cl,
M4 represents one or more activating elements selected from the group consisting of Eu, Ce, Pr, Cr, Nd, Sm, Tb, Dy, Ho, Er, Tm, Yb and Mn,
w satisfies 2.0≦w≦4.0,
x satisfies 5.0≦x≦7.0,
y satisfies 10.0≦y≦12.0.
z satisfies 0.060≦z/(w+z)≦0.300.
[2] The light emitting device according to [1], wherein the phosphor has an average particle size of 20 μm or less.
[3] The light emitting device according to [1] or [2], wherein in the general formula (1), the proportion of Si to all elements constituting M2 is 50 mol% or more.
[4] A lighting device comprising the light emitting device according to any one of [1] to [3].
[5] An image display device comprising the light emitting device according to any one of [1] to [3].

[6] A nitride phosphor, which is a phosphor represented by the following general formula (2), and has an average particle size of 2 μm or more and 40 μm or less.
M5wM6xM7y:M8z...(2)
M5 represents one or more elements selected from the group consisting of Y, La, Gd, Ca, Sr, Ba and Lu, and the proportion of La to all elements constituting M5 is 90 mol% or more,
M6 represents one or more elements selected from the group consisting of Ge, Si, Hf, Zr, Al, Ga and Ti,
M7 requires N and represents one or more elements selected from the group consisting of N, O, F and Cl,
M8 represents one or more activating elements selected from the group consisting of Eu, Ce, Pr, Cr, Nd, Sm, Tb, Dy, Ho, Er, Tm, Yb and Mn,
w satisfies 2.0≦w≦4.0,
x satisfies 5.0≦x≦7.0,
y satisfies 10.0≦y≦12.0.
z satisfies 0.060≦z/(w+z)≦0.300.
[7] The nitride phosphor according to [6], wherein in the general formula (2), the proportion of Y to all elements constituting M5 is less than 8 mol%.
[8] The nitride phosphor according to [6] or [7], wherein in the general formula (2), the ratio of Si to all elements constituting M6 is 50 mol% or more.
[9] The nitride phosphor according to any one of [6] to [8], wherein the phosphor has an average particle size of 2 μm or more and 20 μm or less.

According to the present invention, a light emitting device that can achieve both luminous efficiency and cost, and a nitride phosphor for realizing the device are provided.

3 is a SEM image of the nitride phosphor of Production Example 1. 3 is a SEM image of the nitride phosphor of Production Example 3. 12 is a SEM image of the nitride phosphor of Production Example 4. 2 is a graph showing the relationship between the amount of phosphor used and the conversion efficiency of the light emitting devices of Examples 1 to 4 and Comparative Examples 1 and 2.

Embodiments of the present invention will be described in detail below. Note that the present invention is not limited to the content described below, and can be implemented with arbitrary changes within the scope of the gist thereof.

In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as lower and upper limits.
In the compositional formula of the phosphor in this specification, each compositional formula is separated by a comma (,). Furthermore, when a plurality of elements are listed separated by a comma (,), this indicates that one or more of the listed elements may be contained in any combination and composition.

<Light-emitting device of the present invention>
The light-emitting device of the present invention includes a first light-emitting body and a second light-emitting body that emits visible light by irradiation with light from the first light-emitting body, and the first light-emitting body emits ultraviolet light or A semiconductor light-emitting device that emits visible light, wherein the second light-emitting body includes a phosphor represented by the following general formula (1), and the phosphor has an average particle size of 2 μm or more and 40 μm or less. do.
M1wM2xM3y:M4z...(1)
M1 represents one or more elements selected from the group consisting of Y, La, Gd, Ca, Sr, Ba and Lu, and the proportion of La to all elements constituting M1 is 90 mol% or more,
M2 represents one or more elements selected from the group consisting of Ge, Si, Hf, Zr, Al, B, Ga and Ti,
M3 requires N and represents one or more elements selected from the group consisting of N, O, F and Cl,
M4 represents one or more activating elements selected from the group consisting of Eu, Ce, Pr, Cr, Nd, Sm, Tb, Dy, Ho, Er, Tm, Yb and Mn,
w satisfies 2.0≦w≦4.0,
x satisfies 5.0≦x≦7.0,
y satisfies 10.0≦y≦12.0.
z satisfies 0.060≦z/(w+z)≦0.300.

Each component will be explained in detail below.

(First light emitter)
The first light emitter used in the light emitting device of the present invention is a semiconductor light emitting element that emits ultraviolet light or visible light, and emits light that excites a second light emitter, which will be described later. The emission wavelength of the first light emitter is not particularly limited as long as it overlaps with the absorption wavelength of the second light emitter described later, and a light emitter with a wide emission wavelength range from ultraviolet light to visible light may be used. I can do it. Further, as the first light emitter that is suitably used, for example, one having an emission peak in a wavelength range of 300 nm or more and 420 nm or less, one having an emission peak wavelength in a wavelength range of 420 nm or more and 450 nm or less, and 420 nm or more and 500 nm or less Examples include those having an emission peak in the wavelength range of .

As the first light emitter, a light emitter having an emission wavelength from the near ultraviolet region to the blue region is usually used, and the specific numerical values are usually 300 nm or more, preferably 330 nm or more, and usually 500 nm or less, Preferably, a luminescent material having an emission wavelength of 480 nm or less is used.
In the light-emitting device of the present invention, a first light-emitting body having an emission wavelength in the violet to near-ultraviolet region of 430 nm or less can also be used in combination with a second light-emitting body to be described later.

As this first light emitter, a semiconductor light emitting element is generally used, specifically a light emitting diode (LED) or a semiconductor laser diode (semiconductor laser diode; hereinafter sometimes abbreviated as "LD"). ) etc. can be used. Regarding specific examples and preferred embodiments of the first light emitter, the matters described in the section "[4-1. First light emitter]" of Patent Document 2 (International Publication No. 2010/114061) can be applied.

(Second light emitter)
The second light-emitting body used in the light-emitting device of the present invention is a light-emitting body that emits visible light upon irradiation with light from the first light-emitting body, and at least the first phosphor is expressed by the following general formula (1). It contains a phosphor represented by (a nitride phosphor of the present invention to be described later), and also contains a second phosphor as appropriate depending on its use. Further, for example, the second light emitting body is configured by dispersing the first fluorescent substance or the first fluorescent substance and the second fluorescent substance in the sealing material.

(Nitride phosphor)
In the light emitting device of the present invention, the second luminescent material is at least one type of phosphor represented by the following general formula (1) and has an average particle size of 2 μm or more and 40 μm or less, as the first phosphor. (hereinafter sometimes referred to as "nitride phosphor of the present invention"). In addition to the nitride phosphor of the present invention, a phosphor that emits fluorescence of the same color (hereinafter sometimes referred to as "same color combination phosphor") may be used at the same time. Since the nitride phosphor of the present invention is usually a yellow phosphor, other types of yellow to orange phosphors (same color combination phosphors) can be used together with the phosphor of the present invention as the first phosphor. . Regarding specific examples and preferred embodiments of the same-color combined phosphor, the matters described in the section "[4-2. Second light emitter]" of Patent Document 2 (International Publication No. 2010/114061) can be applied. .

The nitride phosphor of the present invention includes a crystal phase having a chemical composition represented by the following general formula (1). Among these, it is more preferable that the crystal phase is tetragonal or rectangular.
M1wM2xM3y:M4z...(1)

M1 in the general formula (1) is at least one element selected from the group consisting of Y, La, Gd, Ca, Sr, Ba, and Lu, preferably Y is essential, and if necessary, La, and Gd. M1 contains lanthanum (La) from the viewpoints of excitation wavelength, emission wavelength, luminous efficiency, and cost as a base material of the LED phosphor. The proportion of La to all the elements constituting M1 is usually 90 mol% or more, preferably 95 mol% or more, since the brightness is higher from the viewpoint of luminous efficiency and visibility. Furthermore, when Y is added to adjust the luminescent color, the proportion of Y to all elements constituting M1 is preferably less than 10 mol%, more preferably less than 8 mol%, for the same reason.

M2 in the general formula (1) is one or more elements selected from the group consisting of Ge, Si, Hf, Zr, Al, B, Ga, and Ti, and preferably contains silicon (Si). The ratio of Si to all elements constituting M2 is preferably 50 mol% or more, more preferably 70 mol% or more.

M3 in general formula (1) requires N, and is one or more elements selected from the group consisting of N, O, F, and Cl, and the proportion of N to all elements constituting M3 is 50 mol% or more. It is preferably present, and more preferably 80 mol% or more.

M4 in general formula (1) is an activating element (activator) and is selected from the group consisting of Eu, Ce, Pr, Cr, Nd, Sm, Tb, Dy, Ho, Er, Tm, Yb, and Mn. Indicates at least one element. Among these, it is preferable that M4 contains Eu and/or Ce, and it is more preferable that the ratio of Ce to all the elements constituting M4 is 80 mol% or more.

The concentration of the activator in the phosphor of the present invention is usually 0.060 or more, preferably 0.065 or more, more preferably is preferably 0.070 or more from the viewpoint of absorption rate of excitation light. On the other hand, if the activator concentration is too high, the influence of concentration quenching becomes large, and furthermore, a different phase or crystal distortion indicating a chemical composition other than the nitride phosphor of the present invention occurs, so z/(w+z) is usually 0.300 or less. and is preferably 0.250 or less, more preferably 0.200 or less. It is preferable that z/(w+z) is within the above range because the light emission characteristics are good.

One of the characteristics of the nitride phosphor of the present invention is that it has a higher activator concentration than conventional phosphors such as YAG phosphors. It is generally known that when the activator concentration of a phosphor is too high, the internal quantum efficiency decreases due to concentration quenching, resulting in a decrease in efficiency. On the other hand, in the phosphor used in the present invention, the site occupied by M1 in general formula (1) has two types: a high symmetry site (2a site) and a low symmetry site (4c site), and each While the activator ions are substituted with The activator concentration can be set high while maintaining efficiency, and the excitation light absorption rate can be kept high.

A nitride phosphor using Ce as an activator emits green to yellow light with excellent visibility when La is used alone as the M1 element. At this time, the emission wavelength can be changed by using an element other than La with a different ionic radius as the M1 element. As an element to be combined with La, Y or Gd is preferable because it has a close ionic radius and the same charge as La, and therefore has little effect on the luminance of the resulting phosphor and can change the luminescent color.

Other methods for adjusting the emission color include replacing the M1 element with other rare earth elements, alkaline earth elements such as calcium (Ca) or strontium (Sr), and replacing the M2 element with other rare earth elements such as Si and Al. Examples include substituting an element with a similar charge such as a group 13-14 element of the periodic table, and substituting N as the M3 element with O or a halogen element. In any case, various elements can be used within a range that does not significantly change the crystal structure.

In general formula (1), w satisfies 2.0≦w≦4.0, x satisfies 5.0≦x≦7.0, and y satisfies 10.0≦y≦12.0.
The element molar ratios of w, x, and y in general formula (1) are set from the following viewpoints.
The molar ratio (w:x:y) of the elements in general formula (1) has a stoichiometric composition of 3:6:11. In reality, excess or deficiency occurs due to oxygen deficiencies, charge compensation, and the like. The allowable range for excess and deficiency is usually a little more than 10%, and although it is permissible to have excess or deficiency below 10%, it is known that different phases may be generated. Preferably it is about 10%. Within this range, it can be used as a phosphor. If it deviates from this range, different phases will occur, which is not preferable.

That is, w in general formula (1) usually has a value satisfying 2.0≦w≦4.0, and its lower limit is preferably 2.5, more preferably 2.7, and its upper limit is preferably is 3.5, more preferably 3.3.
Further, x in general formula (1) usually has a value satisfying 5.0≦x≦7.0, and its lower limit is preferably 5.4, more preferably 5.7, and its upper limit is preferably is 6.6, more preferably 6.3.
In general formula (1), y usually has a value satisfying 10≦y≦12, and its lower limit is preferably 10.5, and its upper limit is preferably 11.5.

Since the nitride phosphor of the present invention satisfies the law of conservation of charge, it is substituted with other elements at the same time, and as a result, some Si or N sites may be substituted with oxygen, etc., and such phosphors also It can be suitably used.
Further, the overall composition of the phosphor may include a small amount of impurities such as oxygen by partially oxidizing or halogenating the phosphor as long as the effects of the present invention can be obtained.
The ratio (molar percentage) of oxygen/(oxygen + nitrogen) in the phosphor represented by general formula (1) is arbitrary as long as the nitride phosphor of the present invention represented by general formula (1) can be obtained. However, it is usually 5% or less, preferably 1% or less, more preferably 0.5% or less, even more preferably 0.3% or less, particularly preferably 0.2% or less.

(Particle size of nitride phosphor)
The lower limit of the average particle size of the nitride phosphor of the present invention is usually 2 μm or more, preferably 3 μm or more, and more preferably 4 μm or more. If the average particle size is less than this lower limit, the absorption rate of excitation light will be significantly reduced, and the luminous efficiency of the light emitting device will be significantly reduced. Further, the upper limit of the average particle diameter is usually 40 μm or less, preferably 30 μm or less, more preferably 26 μm or less, and even more preferably 20 μm or less. By adjusting the average particle size to be below this upper limit, the excitation light absorption rate of the phosphor will not change much, but the specific surface area of the phosphor will be increased, allowing any color to be expressed within the light-emitting device. This is preferable because it is possible to suppress the amount of phosphor required for use, and as a result, it is possible to reduce the cost of the device.
As mentioned above, the nitride phosphor of the present invention has a higher activator concentration than conventional phosphors, so even if it is a small particle phosphor that has a high probability of excitation light scattering, As a result, due to its high efficiency and large surface area, it becomes a phosphor that requires less amount of phosphor to adjust the chromaticity.

If the average particle size of the nitride phosphor of the present invention is within the above particle size range, by adjusting the phosphor particle size, the luminous efficiency of the light emitting device and the amount of phosphor used can be adjusted depending on the application. Is possible. In other words, it is preferable to design a light-emitting device with a larger phosphor particle size if you want to emphasize luminous efficiency, and a smaller phosphor particle size if you want to reduce the amount of phosphor used and prioritize cost. .

Here, the above-mentioned average particle diameter is a volume-based average particle diameter, and indicates the volume median diameter (d50). Known methods for measuring particle size include the laser diffraction/scattering method, the electrical detection band method (Coulter method), and the centrifugal sedimentation method. Further, if the particle size distribution is not extremely wide, the particle size can also be confirmed by directly observing the particle size using a scanning electron microscope (SEM).

The method for manufacturing the nitride phosphor of the present invention is not particularly limited, but the specific details are the same as those described in the section (Method for manufacturing the nitride phosphor of the present invention) described later.

(Second phosphor)
The second light emitting body used in the light emitting device of the present invention may contain a fluorescent substance (i.e., a second fluorescent substance) in addition to the above-mentioned first fluorescent substance, depending on its use. This second phosphor has a different emission wavelength from the first phosphor. Usually, these second phosphors are used to adjust the color tone of the light emitted by the second luminescent material, so the second phosphor emits a different color of fluorescence than the first phosphor. Phosphors are often used. Regarding specific examples and preferred embodiments of the second phosphor, the matters described in the section "[4-2. Second light emitter]" of Patent Document 2 (International Publication No. 2010/114061) apply. can. In particular, when combined with the nitride phosphor of the present invention, a (S) CASN phosphor represented by the general formula (Sr, Ca)AlSiN ₃ :Eu ²⁺ or a (S) CASN phosphor represented by the general formula (La, Y) ₃ Si ₆ N ₁₁ : Combining as a red component a phosphor produced by replacing some of the cations of the nitride phosphor of the present invention with other cations and emitting long wavelength light, such as the LYSN phosphor represented by Ce ³⁺ , can produce white light. This is preferable because it can achieve both color rendering properties and color reproduction range, luminous efficiency, and long-term reliability.

(Application to light emitting device)
The second light emitting body described above is incorporated into a light emitting device using the following method.
When the above-mentioned phosphor as the second light emitter is used in a light-emitting device or the like, it is preferably used in the form of a dispersion in a liquid medium, that is, in the form of a phosphor-containing composition.

The liquid medium that can be used in the phosphor-containing composition is one that exhibits liquid properties under the desired usage conditions, can suitably disperse the nitride phosphor of the present invention, and does not cause undesirable reactions. For example, any one can be selected depending on the purpose.

Examples of the liquid medium include silicone resin, epoxy resin, polyvinyl resin, polyethylene resin, polypropylene resin, polyester resin, and the like. One type of these liquid media may be used alone, or two or more types may be used in combination in any combination and ratio. Note that the above liquid medium can also contain an organic solvent.
Specific aspects such as the amount of liquid medium to be used may be adjusted as appropriate depending on the application, and are described in the section "[3. Phosphor-containing composition]" of Patent Document 2 (International Publication No. 2010/114061). The following matters are applicable.

Furthermore, since the purpose is to disperse the phosphor of the present invention in a substance that transmits light, it may be dispersed in glass, other transparent ceramics, or inorganic compounds other than a liquid medium.

In addition to using this phosphor-containing composition, the phosphor itself may be sintered into pellets and then incorporated into a light-emitting device.

(Characteristics of light emitting device)
The characteristics of the light emitting device of the present invention will be explained.

In the light emitting device using the nitride phosphor of the present invention, there is no problem in selecting the excitation light source and combination of phosphors so as to emit light of any color depending on the application, but the color temperature of the light emission is preferably When the temperature is 3000 K or more, more preferably 4000 K or more, the nitride phosphor represented by the general formula (1) is contained in a sufficient proportion, and the light emitting device is likely to be more cost-effective.

The ratio of the emission spectrum of the LED chip to the emission spectrum irradiated from the light-emitting device, measured with an integrating sphere, is calculated by the equation shown below: the emission peak intensity of the chip (primary light) and the emission peak of the phosphor. It is expressed below as excitation light transmittance, which is a ratio of intensity.
Excitation light transmittance (%) = Ip<chip>/Ip<phos>
Ip<chip>: Emission peak intensity in the emission spectrum of the chip Ip<phos>: Emission peak intensity in the emission spectrum from the phosphor *If there are multiple phosphors, the emission in the spectrum where the emission spectra of each phosphor are superimposed Use peak intensity.
The preferred range of excitation light transmittance is 40% or more, more preferably 50% or more, 60% or more from the viewpoint of improving luminous efficiency, and the preferred range of excitation light transmittance from the viewpoint of improving color rendering properties. The transmittance is 200% or less, further 170% or less, particularly 130% or less.

(Applications of light emitting device)
The use of the light emitting device of the present invention is not particularly limited, and it can be used in various fields where ordinary light emitting devices are used. However, the light emitting device of the present invention has a wide color reproduction range and high color rendering properties. Therefore, it is particularly suitable for use as a light source for lighting devices and image display devices.

(Lighting device)
A lighting device of the present invention includes the above-described light emitting device. When applying the light emitting device using the nitride phosphor of the present invention to a lighting device, the light emitting device as described above may be appropriately incorporated into a known lighting device.

(Image display device)
The image display device of the present invention includes the light emitting device of the present invention. When using the light emitting device of the present invention as a light source of an image display device, there is no restriction on the specific configuration of the image display device, but it is preferable to use it together with a color filter. For example, when the image display device is a color image display device using a color liquid crystal display element, the light emitting device is used as a backlight, an optical shutter using a liquid crystal, and a color filter having red, green, and blue pixels. By combining these, an image display device can be formed.

<Nitride phosphor of the present invention>
Another aspect of the present invention is a nitride phosphor represented by the following general formula (2), characterized in that the average particle size of the phosphor is 2 μm or more and 40 μm or less.
M5wM6xM7y:M8z...(2)
M5, M7, and M8 in general formula (2) have the same meanings as M1, M3, and M4 in general formula (1), respectively, and M5, M7, M8, and w, x, y, and z are as defined above. These are the same as M1, M3, M4, and w, x, y, and z described regarding the phosphor represented by the general formula (1) as the (nitride phosphor) used in the light emitting device of the present invention.

M6 in general formula (2) is at least one element selected from the group consisting of Ge, Si, Hf, Zr, Al, Ga, and Ti, and preferably contains silicon (Si). The ratio of Si to all elements constituting M6 is preferably 50 mol% or more, more preferably 70 mol% or more.
Further, the average particle diameter and other characteristics of the phosphor are also the same as those described in the above section (Nitride phosphor).

<Method for manufacturing phosphor>
Hereinafter, the method for manufacturing a nitride phosphor of the present invention will be explained step by step. In addition, although the manufacturing method of the nitride phosphor represented by the general formula (1) will be explained below, the nitride phosphor represented by the general formula (2) will also be explained according to the general formula in the following explanation. They can be produced in the same manner by replacing (1) with general formula (2) and replacing M1, M2, M3, and M4 with M5, M6, M7, and M8, respectively.

(material)
The raw materials used in the present invention include, for example, M1, M2, M3, which are constituent elements of the matrix of the phosphor, other elements added to adjust the emission wavelength, etc., and M4, which is an activator element. Examples include metals, alloys, or compounds containing.

Compounds used as raw materials include, for example, halides such as nitrides, oxides, hydroxides, carbonates, nitrates, sulfates, oxalates, carboxylates, and fluorides of the respective elements constituting the phosphor. etc. The specific type of metal compound may be selected as appropriate from among these metal compounds, taking into account the reactivity to the target object or the low amount of NOx, SOx, etc. generated during firing. From the viewpoint that the substance phosphor is a nitrogen-containing phosphor, it is preferable to use a nitride and/or an oxynitride. Among them, it is preferable to use nitrides because they also serve as a nitrogen source.

Specific examples of nitrides and oxynitrides include nitrides of elements constituting phosphors such as LaN, Si ₃ N ₄ or CeN, and nitrides of elements constituting phosphors such as La ₃ Si ₆ N ₁₁ or LaSi ₃ N ₅ . Composite nitrides of elements such as
Further, the above nitride may contain a trace amount of oxygen. The ratio (molar ratio) of oxygen/(oxygen + nitrogen) in the nitride is arbitrary as long as the phosphor of the present invention can be obtained, but if oxygen derived from adsorbed moisture is not included, it is usually 5% or less, preferably 1%. % or less, more preferably 0.5% or less. If the proportion of oxygen in the nitride is too high, the brightness may decrease. However, in consideration of the reactivity between the raw materials, it is also possible to use some of the oxide raw materials, which have a lower reaction temperature than normal nitrides.

When using oxides, especially when a large amount is used, in order to prevent more oxygen from being mixed into the phosphor than necessary, remove oxygen by heating in an atmosphere containing ammonia or hydrogen at the beginning of firing. It is preferable to take measures to remove it. As for these raw materials, various materials described in the aforementioned Patent Document 1 (International Publication No. 2008/132954) and Patent Document 2 (International Publication No. 2010/114061) can be used. In particular, the method using an alloy is detailed in Patent Document 2. Of course, it is also possible to use an alloy and add a flux used as a growth aid.

(Growth aid: addition of flux)
Flux is also described in detail in Patent Document 1 (International Publication No. 2008/132954) and Patent Document 2 (International Publication No. 2010/114061), and those described therein can be used.

That is, examples include, but are not limited to, ammonium halides such as NH ₄ Cl and NH ₄ F.HF; alkali metal carbonates such as Na ₂ CO ₃ and Li ₂ CO ₃ ; LiCl, NaCl, KCl, and CsCl. , LiF, NaF, KF, CsF and other alkali metal halides; CaCl ₂ , BaCl ₂ , SrCl 2 , CaF ₂ , BaF ₂ , SrF ₂ , MgCl _{2 ,} MgF ₂ and other alkali metal halides; BaO, etc. Alkaline earth metal oxides; boron oxides such as B ₂ O ₃ , H ₃ BO ₃ , Na ₂ B ₄ O ₇ , boric acid and borate compounds of alkali metals or alkaline earth metals; Li ₃ PO ₄ , Phosphate compounds such as NH ₄ H ₂ PO ₄ ; Aluminum halides such as AlF ₃ ; Group 15 element compounds of the periodic table such as Bi ₂ O ₃ ; Li ₃ N, Ca ₃ N ₂ , Sr ₃ N ₂ , Ba Examples include nitrides of alkali metals such as ₃ N ₂ and BN, alkaline earth metals, and Group 13 elements of the periodic table.

Furthermore, as a flux, for example, halides of rare earth elements such as LaF ₃ , LaCl ₃ , GdF ₃ , GdCl ₃ , LuF ₃ , LuCl ₃ , YF ₃ , YCl ₃ , ScF ₃ , ScCl ₃ , La ₂ O ₃ , Gd Oxides of rare earth elements such as ₂ O ₃ , Lu ₂ O ₃ , Y ₂ O ₃ and Sc ₂ O ₃ can also be mentioned.

The above-mentioned flux is preferably a halide, and specifically, for example, an alkali metal halide, an alkaline earth metal halide, or a rare earth element halide is preferable. Furthermore, among the halides, fluorides and chlorides are preferred.

Here, among the above-mentioned fluxes, it is preferable to use an anhydride as to those having deliquescent properties. Further, regarding the flux used in combination, two or more types may be used in combination in any combination and ratio. Particularly preferable fluxes used in combination include MgF ₂ , CeF ₃ , LaF ₃ , YF ₃ and GdF ₃ .

In addition, in cases where there is no specific description in Patent Document 1 (International Publication No. 2008/132954) and Patent Document 2 (International Publication No. 2010/114061), a flux containing rubidium or cesium halide, etc. This is preferable because it is large in size and difficult to incorporate into the phosphor. Further, a halide activator is also preferable since it can serve as a raw material and a flux. The amount of these fluxes used is preferably 0.1% by mass or more and 20% by mass or less based on the charged phosphor. The selection of raw materials and flux is important in that it greatly influences the quality of the phosphor after the firing process.

(Mixing of raw materials)
When using an alloy for phosphor production, if the composition of the metal elements contained matches the composition of the metal elements included in the crystal phase represented by the general formula (1), it is suitable for phosphor production. The alloy may be fired alone, or a flux may be mixed as required.

On the other hand, if the phosphor manufacturing alloy is not used or the compositions do not match, an alloy for phosphor manufacturing, an elemental metal, a metal compound, etc. having a different composition may be mixed with the phosphor manufacturing alloy. The composition of the metal elements contained in the raw material is adjusted to match the composition of the metal elements contained in the crystal phase represented by the general formula (1), and firing is performed.

The composition of the raw material may be changed within a range of about 0.5 to 2 times the theoretical composition. For example, in the case of the nitride phosphor of the present invention, the theoretical composition ratio of element M1 and element M2 in the general formula (1) is 1:2. Since there is a compound with a similar molar ratio of 1:3, it is also preferable to make the molar ratio of the M1 element high in order to prevent this occurrence. This change in composition ratio is particularly preferred when the proportions of oxygen and halogen in the raw materials are high.

A known method may be used for mixing the phosphor raw materials. Particularly preferable methods include adding the raw materials together with a solvent into a pot and mixing them while crushing them with a ball, dry mixing and passing through a mesh, and using a mixer such as a mixer for powder mixing. When dispersed and mixed in a solvent, the solvent is of course removed and, if necessary, dried to loosen aggregates. These operations are preferably performed in a nitrogen atmosphere.

Further, when the nitride phosphor of the present invention is manufactured by firing multiple times, it is preferable to mix the flux before the step with the highest firing temperature and to mix well by passing it through a sieve or the like.

(Firing process)
The raw material mixture thus obtained is usually filled into a container such as a crucible or a tray, and placed in a heating furnace where the atmosphere can be controlled. At this time, examples of the material of the container include boron nitride, silicon nitride, carbon, aluminum nitride, molybdenum, and tungsten. Among these, molybdenum and boron nitride are preferable because they have excellent corrosion resistance and produce good phosphors. Note that the above materials may be used alone or in combination of two or more in any combination and ratio. When firing multiple times and at relatively low temperatures, the crucible has a high degree of freedom, and can be made of ceramic materials such as boron nitride, alumina, zirconia, metal materials such as molybdenum or tungsten, or boron nitride crucibles. A composite material coated with a paste such as molybdenum on the inside can be used.

By firing the raw material mixture in this firing step, the nitride phosphor of the present invention can be obtained.

The most preferable firing temperature is the temperature at which the matrix of the phosphor begins to form and nuclei for subsequent crystal growth occur. This temperature varies slightly depending on the raw material and pressure, but is preferably 1100°C or more and 2000°C or less. A more preferable lower limit of the firing temperature is 1250°C or higher, most preferably 1350°C or higher. At the lower limit of the firing temperature, growth nuclei should be generated and the nuclei should not grow more than necessary, so even if the temperature is low, it is sufficient to take a corresponding amount of time. On the other hand, the upper limit of the firing temperature is 2000°C or less, more preferably 1800°C or less, and most preferably 1700°C or less, because if it is too high, it becomes difficult to properly control the firing time. When firing in an environment where the gas pressure in the furnace is higher than atmospheric pressure, the appropriate temperature shifts to a higher temperature side.

Further, the firing time is preferably 2 hours or more and 50 hours or less from the viewpoint of productivity and control of crystal growth.

The firing atmosphere is preferably a nitrogen atmosphere or an ammonia atmosphere, and more preferably an atmosphere containing nitrogen mixed with 10% by volume or less of hydrogen. If the amount of hydrogen is large, there is a danger of explosion. Therefore, the most preferable content is 4% by volume or less.

In addition, when performing multiple firings, flux etc. may be added to the obtained primary fired product as necessary, and then redispersion, for example, redispersion in a mortar or mesh pass, may be performed by heating. It is preferable to prevent agglomeration and improve the uniformity of the raw material. This operation is preferably carried out in a nitrogen atmosphere or an inert atmosphere. The oxygen concentration in the atmosphere at this time is preferably controlled to 1% by volume or less, particularly 100 ppm or less. Although it can be carried out within the same range as the above-mentioned firing conditions, in order to grow the crystal efficiently, it is preferable to use the conditions described in Patent Document 2 (International Publication No. 2010/114061).

The firing device used here is arbitrary as long as the effects of the present invention can be obtained, but a device that can control the atmosphere inside the device is preferable, and a device that can also control the pressure is preferable. For example, a hot isostatic presser (HIP), a vacuum pressurized atmosphere heat treatment furnace, etc. are preferable.

Furthermore, before starting heating, it is preferable to circulate a nitrogen-containing gas through the firing apparatus to sufficiently replace the inside of the system with the nitrogen-containing gas. If necessary, nitrogen-containing gas may be passed through the system after the system is evacuated.

(Washing process)
After firing, a cleaning step can be performed in which the surface of the phosphor is washed with water such as deionized water, an organic solvent such as ethanol, or an alkaline aqueous solution such as aqueous ammonia.

For the purpose of removing the used flux, removing impurity phases attached to the surface of the phosphor, and improving the luminescent properties, for example, hydrochloric acid, nitric acid, sulfuric acid, aqua regia, hydrofluoric acid and sulfuric acid. It is also possible to use an acidic aqueous solution containing an inorganic acid such as a mixture with acetic acid, an organic acid such as acetic acid, and the like.

These methods are described in detail in Patent Document 1 (International Publication No. 2008/132954) and Patent Document 2 (International Publication No. 2010/114061), and may be performed according to the descriptions thereof.

(Other post-processing steps)
In manufacturing the nitride phosphor of the present invention, in addition to the steps described above, other steps may be performed as necessary. For example, after the above-mentioned washing step, a particle size adjustment step (pulverization step, classification step), surface treatment step, drying step, etc. may be performed as necessary. Further, in addition to the basic steps of these phosphor manufacturing methods, a low temperature heating step, a steam heat treatment step, etc., which will be described later, may be performed.

(Crushing process)
For the pulverization step, for example, a pulverizer such as a hammer mill, roll mill, ball mill, jet mill, ribbon blender, V-type blender, or Henschel mixer, or pulverization using a mortar and pestle can be used. At this time, in order to suppress the destruction of the generated phosphor crystals and proceed with the intended treatment such as crushing secondary particles, it is necessary to use a container made of alumina, silicon nitride, ZrO ₂ or glass, etc. It is preferable to insert a ball made of a material such as or urethane with an iron core and perform ball milling for about 10 minutes to 24 hours. In this case, a dispersant such as an organic acid or an alkali phosphate such as hexametaphosphoric acid may be used in an amount of 0.05% by mass to 2% by mass.

(Classification process)
The classification step can be carried out, for example, by dry or wet sieving, or by using various classifiers such as various air classifiers or vibrating sieves. Among these, when dry classification using a nylon mesh is used, a phosphor with excellent dispersibility and an average particle size (d50) of about 10 μm can be obtained. Further, when dry classification using a nylon mesh and elutriation treatment are used in combination, a phosphor with good dispersibility and an average particle size (d50) of about 20 μm can be obtained.

In the water sieving or elutriation treatment, phosphor particles are usually dispersed in an aqueous medium at a concentration of preferably about 0.1% by mass to 10% by mass. Further, in order to suppress deterioration of the phosphor, it is preferable that the pH of the aqueous medium is usually 4 or more, preferably 5 or more, and usually 9 or less, preferably 8 or less.

In addition, when obtaining phosphor particles with the average particle size (d50) as described above, water sieving and water elutriation treatment are carried out in two steps, for example, to obtain particles of 50 μm or less, and then to obtain particles of 30 μm or less. It is preferable to perform sieving treatment from the viewpoint of balance between work efficiency and yield. Moreover, as a lower limit of the particle size, it is preferable to carry out a process of sieving out particles having a particle size of usually 1 μm or more, preferably 2 μm or more.

(drying process)
In the drying step, the phosphor that has undergone the cleaning step is dried at about 100° C. to 200° C. If necessary, a dispersion treatment (for example, dry sieving) may be performed to prevent dry agglomeration.

(Low temperature heating process)
The phosphor obtained in the cleaning step is heated again at a temperature lower than the firing temperature in an atmosphere with an oxygen content of 10,000 ppm or less or a water content of 10.0 volume% or less, thereby increasing the brightness. , a highly reliable phosphor can be obtained.

This low-temperature heating step can be carried out by filling a container such as a crucible or a tray with the phosphor, placing the container in a heating furnace whose atmosphere can be controlled, and heating the container.

At this time, the material of the container is, for example, in addition to quartz, a ceramic material such as boron nitride, alumina, zirconia, or silicon carbide, a metal material such as molybdenum or tungsten, or a paste such as molybdenum on the inside of the boron nitride crucible. Coated composite materials can be used. Note that the above-mentioned materials may be used alone or in any combination of two or more.

The heating furnace is arbitrary as long as the effects of the present invention can be obtained, but a device that can control the atmosphere inside the device, such as the one used in the above-mentioned firing step, is preferable, and a device that can also control the pressure is preferable. For example, a hot isostatic presser (HIP), a vacuum pressurized atmosphere heat treatment furnace, etc. are preferable.

The heating temperature in the low temperature heating step is preferably 500°C or higher, more preferably 650°C or higher, even more preferably 750°C or higher, and preferably 1300°C or lower, more preferably 1100°C or lower. be.

In addition, the relationship between the heating temperature and the firing top temperature in the main firing of the phosphor in the above-mentioned firing process is also important, and the heating temperature is -1000 to -400°C with respect to the firing top temperature, and with respect to the synthesis temperature. Another feature is that it is carried out at sufficiently low temperatures. If the heating temperature is higher than the above lower limit, the desired reaction will easily occur and high brightness will be easily achieved, while if the temperature is lower than the above upper limit, the structure of the phosphor itself will decompose or the lattice will not be assembled. This is preferable since it is possible to suppress a decrease in brightness due to the change in brightness.

The heating time in the low-temperature heating step is preferably 2 hours or more, more preferably 4 hours or more, even more preferably 6 hours or more, in order to heat the entire phosphor to a uniform temperature. From the viewpoint of performance, it is preferably 80 hours or less, more preferably 50 hours or less.

(Steam heat treatment process)
The nitride phosphor of the present invention may be subjected to steam heat treatment. By performing the low-temperature heating step after this steam heat treatment step, the brightness of the phosphor can be further improved.

When providing a steam heat treatment step, the steam heat treatment temperature is usually 50°C or higher, preferably 80°C or higher, more preferably 100°C or higher, and usually 300°C or lower, preferably 200°C or lower, More preferably, the temperature is 170°C or lower. If the steam heat treatment temperature is too low, the effect of adsorbed water on the surface of the phosphor tends to be difficult to obtain, and if it is too high, the surface of the phosphor particles may become rough.

The humidity (relative humidity) in the steam heat treatment step is usually 50% or more, preferably 80% or more, and particularly preferably 100%. If the humidity is too low, it tends to be difficult to obtain the effect of adsorbed water on the surface of the phosphor. Note that a liquid phase may coexist with a gas phase having a humidity of 100%, as long as the effect of forming an adsorbed water layer can be obtained.

The pressure in the steam heat treatment step is usually normal pressure or higher, preferably 0.12 MPa or higher, more preferably 0.3 MPa or higher, and usually 10 MPa or lower, preferably 1 MPa or lower, more preferably 0.1 MPa or higher. It is preferably 6 MPa or less. If the pressure is too low, it tends to be difficult to obtain the effect of the steam heat treatment process, and if the pressure is too high, the processing equipment becomes large-scale, and there may be problems with work safety.

The time for which the phosphor is held in the presence of the vapor varies depending on the temperature, humidity, and pressure mentioned above, but generally, the higher the temperature, the higher the humidity, and the higher the pressure, the shorter the holding time is. It's over. The specific time range is usually 0.5 hours or more, preferably 1 hour or more, more preferably 1.5 hours or more, and usually 200 hours or less, preferably 100 hours or less, The heating time is more preferably 70 hours or less, and even more preferably 50 hours or less.

A specific method for performing the steam heat treatment step while satisfying the above conditions is to place the phosphor in an autoclave under high humidity and high pressure. Here, in addition to or instead of using an autoclave, a device such as a pressure cooker that can be heated to the same high temperature and high humidity conditions as an autoclave may be used.
As a pressure cooker, for example, TPC-412M (manufactured by ESPEC Co., Ltd.) can be used, and according to this, the temperature is set at 105°C to 162.2°C and the humidity is set at 75% to 100% (however, the temperature condition pressure can be controlled to 0.020 MPa to 0.392 MPa (0.2 kg/cm ² to 4.0 kg/cm ² ).

By holding the phosphor in an autoclave and performing a steam heat treatment process, it is possible to form a special layer of water in an environment of high temperature, high pressure, and high humidity. can be present on the surface of the phosphor. Specifically, the phosphor is preferably placed in an environment where the pressure is normal pressure (0.1 MPa) or higher and where steam is present for 0.5 hours or more.

(Surface treatment process)
When manufacturing a light emitting device using the nitride phosphor of the present invention, in order to further improve weather resistance such as moisture resistance, or to improve dispersibility in resin in the phosphor-containing part of the light emitting device, If necessary, surface treatment such as partially covering the surface of the phosphor with a different substance may be performed.

Hereinafter, the present invention will be explained in more detail by showing Examples and Comparative Examples. However, the present invention is not limited to the following Examples, and may be arbitrarily modified without departing from the gist of the present invention. It can be implemented.
The particle diameters of the phosphors produced in the following production examples and comparative production examples were measured by the following method.

[Particle size]
The average particle size of the phosphor is the average particle size on a volume basis.The phosphor is dispersed in water and the volume distribution and number distribution are evaluated using a laser scattering diffraction method. The average particle size of the phosphor was determined as the particle size d50 (μm) corresponding to a cumulative distribution of 50%. A particle size meter MT3000 (manufactured by Microtrac Bell Co., Ltd.) or CILAS-1064 (manufactured by Cirrus Co., Ltd.) was used as a particle size distribution measuring device.
In addition, the morphology of some samples was observed using a scanning electron microscope (manufactured by Hitachi High Technologies) at a magnification of 1000 times.

<Comparative manufacturing example 1>
(Preparation of raw materials to filling process)
A glove in a nitrogen atmosphere with an oxygen concentration of 1% by volume or less using LaSi, Si ₃ N ₄ and CeF ₃ so that La:Si:Ce=3.1:6.0:0.2 (molar ratio) Weighed in the box. Thereafter, the weighed raw materials were thoroughly mixed, and the mixed powder was filled into a molybdenum crucible.

(Firing process)
A molybdenum crucible filled with raw material mixed powder was placed in an electric furnace. After the inside of the furnace was evacuated, the temperature was raised to 120° C., and hydrogen-containing nitrogen gas (nitrogen:hydrogen=96:4 (volume ratio)) was introduced until atmospheric pressure was reached. Thereafter, the temperature inside the furnace was raised to 1550°C, held at 1550°C for 8 hours, and then lowered to obtain a fired powder.

(Particle size adjustment process)
After passing the fired phosphor through a sieve, it was pulverized in a ball mill with the average particle size adjusted to 22 μm.

(Washing process)
The pulverized phosphor was washed with 1N hydrochloric acid, dehydrated, dried in a hot air dryer at 120° C., and passed through a sieve with an opening of 63 μm.

(Low temperature heating process)
The phosphor powder obtained in the above cleaning step was filled into a boron nitride (BN) crucible, and the crucible was placed in an electric furnace. After the inside of the furnace was evacuated, nitrogen gas was introduced until the pressure reached atmospheric pressure. Thereafter, the temperature inside the furnace was raised to 900° C., maintained for 12 hours, and then lowered to obtain the desired phosphor powder.
The obtained phosphor was used as the phosphor of Comparative Production Example 1.

<Comparative production example 2>
A phosphor of Comparative Production Example 2 was obtained in the same manner as Comparative Production Example 1 except that the average particle diameter was adjusted to 5 μm in the particle size adjustment step of Comparative Production Example 1.

<Comparative production example 3>
Using LaSi, Si ₃ N ₄ , CeF ₃ and CeO ₂ , La:Si:Ce=3.1:6.0:0.1 (molar ratio), CeF ₃ :CeO ₂ =8:5 (molar ratio) ), the temperature in the firing process was 1575°C, and the average particle size was adjusted to 16 μm in the particle size adjustment process. phosphor was obtained.

<Comparative production example 4>
Same as Comparative Production Example 3 except that they were weighed so that La:Si:Ce = 3.1:6.0:0.03 (mole ratio) and CeF ₃ :CeO ₂ = 2:1 (mole ratio) A phosphor of Comparative Production Example 4 was obtained.

<Manufacture example 1>
(Preparation of raw materials to filling process)
Using LaSi, Si ₃ N ₄ , CeF ₃ and CeO ₂ , La:Si:Ce=3.1:6.0:0.3 (molar ratio), CeF ₃ :CeO ₂ =2:1 (molar ratio ) in a glove box in a nitrogen atmosphere with an oxygen concentration of 1% by volume or less. Thereafter, the weighed raw materials were thoroughly mixed, and the mixed powder was filled into a molybdenum crucible.

(Firing process)
A molybdenum crucible filled with raw material mixed powder was placed in an electric furnace. After the inside of the furnace was evacuated, the temperature was raised to 120° C., and hydrogen-containing nitrogen gas (nitrogen:hydrogen=96:4 (volume ratio)) was introduced until atmospheric pressure was reached. Thereafter, the temperature inside the furnace was raised to 1575°C, held at 1575°C for 6 hours, and then lowered to obtain a fired powder.

(Particle size adjustment process)
After passing the fired phosphor through a sieve, it was pulverized in a ball mill with the average particle size adjusted to 15 μm.

(Washing process)
The pulverized phosphor was washed with 1N hydrochloric acid, dehydrated, dried in a hot air dryer at 120° C., and passed through a sieve with an opening of 63 μm.

(Low temperature heating process)
The phosphor powder obtained in the above cleaning step was filled into a boron nitride (BN) crucible, and the crucible was placed in an electric furnace. After the inside of the furnace was evacuated, nitrogen gas was introduced until the pressure reached atmospheric pressure. Thereafter, the temperature inside the furnace was raised to 900° C., maintained for 18 hours, and then lowered to obtain the desired phosphor powder.
The obtained phosphor was used as the phosphor of Production Example 1.

<Manufacture example 2>
A phosphor of Production Example 2 was obtained in the same manner as Production Example 1 except that the average particle diameter was adjusted to 10 μm in the particle size adjustment step of Production Example 1.

<Manufacture example 3>
The phosphor of Production Example 3 was produced in the same manner as Production Example 1 except that the average particle diameter was adjusted to 5 μm in the particle size adjustment step of Production Example 1.

<Manufacture example 4>
A phosphor of Production Example 4 was obtained in the same manner as Production Example 1 except that the average particle diameter was adjusted to 25 μm in the particle size adjustment step of Production Example 1.

<Manufacture example 5>
Production example except that the raw material mixing ratio in Production example 4 was La:Si:Ce = 3.1:6.0:0.4 (mole ratio) and CeF ₃ :CeO ₂ = 3:1 (mole ratio) The phosphor of Production Example 5 was obtained in the same manner as in Production Example 4.

<Manufacture example 6>
The raw material mixing ratio in Production Example 4 was La:Si:Ce = 3.1:6.0:0.5 (mole ratio) and CeF ₃ :CeO ₂ = 4:1 (mole ratio), and in the particle size adjustment step. A phosphor of Production Example 6 was obtained in the same manner as Production Example 4 except that the average particle size was adjusted to 23 μm.

<Manufacture example 7>
The phosphor of Production Example 7 was produced in the same manner as Production Example 5 except that the firing process of Production Example 5 was as follows, and the average particle diameter was adjusted to 10 μm in the particle size adjustment step. Ta.

(Firing process)
A molybdenum crucible filled with raw material mixed powder was placed in an electric furnace. After the inside of the furnace was evacuated, the temperature was raised to 120° C., and hydrogen-containing nitrogen gas (nitrogen:hydrogen=96:4 (volume ratio)) was introduced until atmospheric pressure was reached. Thereafter, the temperature inside the furnace was raised to 1300°C, held at 1300°C for 6 hours, and then lowered to obtain a primary fired powder. After taking out this primary fired powder from the firing container, it was passed through a sieve with an opening of 100 μm, filled into a molybdenum crucible again, placed in an electric furnace, and then evacuated and hydrogen-containing nitrogen gas introduced again. The temperature inside the furnace was raised to 1575°C, held at 1575°C for 6 hours, and then lowered to obtain a fired powder.

<Manufacture example 8>
Production example except that the raw material mixing ratio of Production example 7 was La:Si:Ce = 3.1:6.0:0.5 (mole ratio) and CeF ₃ :CeO ₂ = 4:1 (mole ratio) The phosphor of Production Example 8 was obtained in the same manner as in Example 7.

<Manufacture example 9>
The phosphor of Production Example 9 was produced in the same manner as Production Example 8 except that the average particle diameter was adjusted to 16 μm in the particle size adjustment step of Production Example 8.

<Manufacture example 10>
Production example except that the raw material mixing ratio of Production example 4 was La:Si:Ce=3.1:6.0:0.8 (molar ratio) and CeF ₃ :CeO ₂ =1:1 (molar ratio) The phosphor of Production Example 10 was obtained in the same manner as in Production Example 10.

<Comparative manufacturing example 5>
In the raw material preparation step of Production Example 4, using LaSi, Si ₃ N ₄ , CeF ₃ and Y ₂ O ₃ , La:Si:Ce:Y=3.0:6.0:0.3:0.4 The phosphor of Comparative Production Example 5 was obtained by manufacturing in the same manner as Production Example 4 except that the molar ratio was changed to (molar ratio).

<Comparative production example 6>
A phosphor of Comparative Production Example 6 was obtained in the same manner as Comparative Production Example 5 except that the average particle diameter was adjusted to 19 μm in the particle size adjustment step of Comparative Production Example 5.

<Comparative production example 7>
A phosphor of Comparative Production Example 7 was obtained in the same manner as Comparative Production Example 5 except that the average particle diameter was adjusted to 6 μm in the particle size adjustment step of Comparative Production Example 5.

<Comparative production example 8>
The raw material mixing ratio of Comparative Production Example 5 is La:Si:Ce:Y=2.8:6.0:0.6:0.7 (molar ratio), and the average particle size is 16 μm in the particle size adjustment process. A phosphor of Comparative Production Example 8 was obtained by manufacturing in the same manner as Comparative Production Example 5 except for making the following adjustments.

<Comparative production example 9>
A phosphor of Comparative Production Example 9 was obtained in the same manner as Comparative Production Example 8 except that the average particle diameter was adjusted to 6 μm in the particle size adjustment step of Comparative Production Example 8.

<Comparative production example 10>
In _{the raw} material preparation _step of Comparative Production Example ₉ , _La :Si:Ce:Y=2.8 _{: 6} . 0:0.3:1.1 (mole ratio), Y ₂ O ₃ :YF ₃ = 4:3 (mole ratio), except that the average particle size was adjusted to 21 μm in the particle size adjustment step. It was produced in the same manner as Comparative Production Example 9 to obtain a phosphor of Comparative Production Example 10.

<Comparative production example 11>
_{In the raw material} preparation step of Comparative Production Example ₁₀ , La:Si:Ce:Y= _2.8 : ₆ . A phosphor of Comparative Production Example 11 was obtained by manufacturing in the same manner as Comparative Production Example 10 except that the molar ratio was 0:1.0:1.0 (molar ratio).

<Comparative production example 12>
A phosphor of Comparative Production Example 12 was obtained in the same manner as Comparative Production Example 11 except that the average particle diameter was adjusted to 19 μm in the particle size adjustment step of Comparative Production Example 11.

<Comparative production example 13>
A phosphor of Comparative Production Example 13 was obtained in the same manner as Comparative Production Example 11 except that the average particle diameter was adjusted to 6 μm in the particle size adjustment step of Comparative Production Example 11.

<Comparative production example 14>
_{In the raw material} preparation step of Comparative Production Example ₁₁ , La:Si:Ce:Y= _2.6 : ₆ . A phosphor of Comparative Production Example 14 was obtained by manufacturing in the same manner as Comparative Production Example 11 except that the molar ratio was 0:0.7:1.3 (molar ratio).

<Comparative production example 15>
_{In the raw material} preparation step of Comparative Production Example ₁₁ , La:Si:Ce:Y= _2.6 : ₆ . A phosphor of Comparative Production Example 15 was obtained by producing in the same manner as Comparative Production Example 11 except that the molar ratio was 0:1.1:1.3 (molar ratio).

The average particle diameter d50 of the phosphors of the obtained Production Examples 1 to 10 and Comparative Production Examples 1 to 15, the composition analysis results by ICP-AES, the z / (w + z) value calculated from the composition analysis results, and M1 Table 1 shows the La ratio (mol%) (described as "La ratio" in Table 1). Further, SEM images of the nitride phosphors of Production Examples 1, 3, and 4 are shown in FIGS. 1, 2, and 3, respectively. From FIGS. 1 to 3, it can be seen that most of the nitride phosphors are particles having a diameter close to the average particle diameter of each nitride phosphor.

<Examples 1 to 10, Comparative Examples 1 to 15>
(Production of semiconductor light emitting device)
A blue light emitting diode (LED) chip that emits light at an emission wavelength of 445 nm to 455 nm was used and was bonded to the terminal at the bottom of the recess of the package using a silicone resin-based transparent die bond paste. Thereafter, the transparent die-bonding paste was cured by heating at 150° C. for 2 hours, and then the blue LED and the electrodes of the package were wire-bonded using a gold wire with a diameter of 25 μm.

On the other hand, the phosphors of Production Examples 1 to 10 and Comparative Production Examples 1 to 15 were weighed together with silicone resin (KER-2500) manufactured by Shin-Etsu Chemical Co., Ltd. and Aerosil (RX200) manufactured by Nippon Aerosil Co., Ltd., respectively, and placed in a stirring and defoaming device. The mixture was mixed to obtain a phosphor-containing resin paste. This resin paste was combined with light emission from a blue LED and the amount was adjusted so that CIE y=0.352, thereby obtaining semiconductor light emitting devices of Examples 1 to 10 and Comparative Examples 1 to 15.

Also, as a reference example, YAG phosphor 1 with (Ce content)/(Ce content + Y content) = 0.01 and YAG phosphor 1 with (Ce content) / (Ce content + Y content) = 0.05. Semiconductor light emitting devices of Reference Examples 1 and 2 were obtained by combining phosphor 2 with an LED in the same manner.

A current of 350 mA is applied to the blue LED chip of the obtained semiconductor light emitting device to cause it to emit light, and the chromaticity x and y in the XYZ color system specified by JIS Z8701 and the conversion efficiency (lm/W) are determined from the obtained emission spectrum. ) was calculated.

The phosphors used in Examples 1 to 10, Comparative Examples 1 to 15, and Reference Examples 1 and 2 and their d50 values, the chromaticity x and y of the light emitting device, and the phosphor used to match the chromaticity. The usage amount and conversion efficiency are shown in Table 2. Note that the amount of phosphor used and the conversion efficiency are expressed as relative values with the amount of phosphor used and conversion efficiency of Comparative Example 1 set as 100%.

As can be seen from Table 2, compared to the light emitting device of Comparative Example 1, the light emitting devices of Examples 1 and 2 and Examples 4 to 9 of the present invention all have higher conversion efficiency, and are necessary for matching the chromaticity. It can be seen that the amount of fluorescent material is also small. In the light emitting device of Example 3, the particle size of the phosphor used is small, and although the efficiency is slightly inferior compared to Comparative Example 1, the amount of phosphor used is about 1/3. However, when compared with Comparative Example 2 in which a phosphor of the same particle size is used, the efficiency is still high and the amount of phosphor used is small. Compared to the light emitting device of Comparative Example 1, the light emitting device of Example 10 uses a slightly larger amount of phosphor due to the large chromaticity x value, but the conversion efficiency is a sufficiently high value.

Among these, the relationship between the amount of phosphor used and the conversion efficiency in Examples 1 to 4 and Comparative Examples 1 and 2 is shown in FIG. In FIG. 4, the upper left point indicates higher efficiency and less amount of phosphor used, so it can be seen from this figure that the light emitting device of the present invention achieves both brightness and cost.

The light emitting device of the present invention achieves both characteristics and cost by controlling the activator concentration of the phosphor used to be high and controlling the particle size. It is generally known that when the activator concentration of a phosphor is too high, the internal quantum efficiency decreases due to concentration quenching, resulting in a decrease in efficiency. Specifically, even when comparing Reference Examples 1 and 2 shown in Table 2, Reference Example 2, which is a light emitting device using YAG2, a YAG phosphor with a higher activator concentration, has a higher concentration than Reference Example 1. It can be seen that the conversion efficiency has decreased.

On the other hand, although the phosphor used in the light emitting device of the present invention has a higher concentration of activator in trivalent ions expressed by the z/(w+z) value than the YAG phosphor used in the reference example, The efficiency is higher than that of the light emitting device using a phosphor with a low z/(w+z) value shown in Comparative Examples 1 and 2. In other words, in the light-emitting device of the present invention, the concentration of the activator of the phosphor is adjusted within a range that is not affected by concentration quenching, and a phosphor with a small particle size is used to achieve high efficiency and a light-emitting device that uses a small amount of phosphor. It turns out that it is possible to do this.

In the light-emitting devices of Comparative Examples 5 to 15, yttrium is dissolved in solid solution in the phosphor used, and the chromaticity x value of the light-emitting device becomes large according to the amount of solid solution. This means that the emitted light color is approaching red, and the green component with high visibility decreases, resulting in a decrease in conversion efficiency. Therefore, Examples 1, 2, and 4 to 10 exhibit higher conversion efficiency than Comparative Examples 5 to 15. Furthermore, when Example 3 is compared with Comparative Examples 7, 9, and 13, which use phosphor having a similar particle size, it can be seen that the conversion efficiency is still high even with the same amount of phosphor used. From this, it can be seen that in order to exhibit higher conversion efficiency, it is better to prevent elements other than the activator element that red-shift the emission color from being solid-dissolved in the La site of the phosphor used.

Claims (9)

A light-emitting device comprising a first light-emitting body and a second light-emitting body that emits visible light upon irradiation with light from the first light-emitting body,
The first light emitter is a semiconductor light emitting element that emits ultraviolet light or visible light,
The second light emitter includes a phosphor represented by the following general formula (1),
A light emitting device characterized in that the average particle size of the phosphor is 2 μm or more and 40 μm or less.
M1wM2xM3y:M4z...(1)
M1 represents one or more elements selected from the group consisting of Y, La, Gd, Ca, Sr, Ba and Lu, and the proportion of La to all elements constituting M1 is 90 mol% or more,
M2 represents one or more elements selected from the group consisting of Ge, Si, Hf, Zr, Al, B, Ga and Ti,
M3 requires N and represents one or more elements selected from the group consisting of N, O, F and Cl,
M4 represents one or more activating elements selected from the group consisting of Eu, Ce, Pr, Cr, Nd, Sm, Tb, Dy, Ho, Er, Tm, Yb and Mn,
w satisfies 2.0≦w≦4.0,
x satisfies 5.0≦x≦7.0,
y satisfies 10.0≦y≦12.0.
z satisfies 0.060≦z/(w+z)≦0.300. The light emitting device according to claim 1, wherein the average particle size of the phosphor is 20 μm or less. The light emitting device according to claim 1 or 2, wherein in the general formula (1), the proportion of Si to all elements constituting M2 is 50 mol% or more. A lighting device comprising the light emitting device according to any one of claims 1 to 3. An image display device comprising the light emitting device according to claim 1. A nitride phosphor, which is a phosphor represented by the following general formula (2), and has an average particle size of 2 μm or more and 40 μm or less.
M5wM6xM7y:M8z...(2)
M5 represents one or more elements selected from the group consisting of Y, La, Gd, Ca, Sr, Ba and Lu, and the proportion of La to all elements constituting M5 is 90 mol% or more,
M6 represents one or more elements selected from the group consisting of Ge, Si, Hf, Zr, Al, Ga and Ti,
M7 requires N and represents one or more elements selected from the group consisting of N, O, F and Cl,
M8 represents one or more activating elements selected from the group consisting of Eu, Ce, Pr, Cr, Nd, Sm, Tb, Dy, Ho, Er, Tm, Yb and Mn,
w satisfies 2.0≦w≦4.0,
x satisfies 5.0≦x≦7.0,
y satisfies 10.0≦y≦12.0.
z satisfies 0.060≦z/(w+z)≦0.300. The nitride phosphor according to claim 6, wherein in the general formula (2), the ratio of Y to all elements constituting M5 is less than 8 mol%. The nitride phosphor according to claim 6 or 7, wherein in the general formula (2), the ratio of Si to all elements constituting M6 is 50 mol% or more. The nitride phosphor according to any one of claims 6 to 8, wherein the average particle size of the phosphor is 2 μm or more and 20 μm or less.