JP2018150433A - Orange phosphor and light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an orange phosphor having a small color shift when used in a light emitting device. Another object of the present invention is to provide a light emitting device using the orange phosphor. General formula: (M) x (Eu) y (Si, Al) 12 (O, N) 16 (where M is from Li, Mg, Ca, Y and lanthanoid elements (excluding La and Ce). It is an α-type sialone phosphor represented by at least one element containing at least Ca selected from the group, and is characterized in that the median diameter d50 measured by the laser diffraction / scattering method is 0.2 μm or more and 5 μm or less. It is an orange phosphor. In addition, the general formula: (M) x (Eu) y (Si, Al) 12 (O, N) 16 (where M is a group consisting of Li, Mg, Ca, Y and lanthanoid elements (excluding La and Ce). An α-type sialone phosphor represented by at least one element containing at least Ca selected from the above, which is an orange phosphor characterized by having a maximum particle diameter dmax of 30 μm or less measured by a laser diffraction / scattering method. is there. [Selection diagram] None

Description

The present invention relates to an α-type sialon phosphor that is excited by ultraviolet or blue light and emits orange light, and a light-emitting device using the same.

  Among the nitride and oxynitride phosphors, α-sialon phosphors are known to have excellent temperature characteristics as well as fluorescence emission efficiency. In particular, α-sialon phosphors activated by europium are excited in a wide wavelength range from ultraviolet to blue and emit yellow to orange, so they are used for yellow phosphors instead of YAG: Ce or light bulb color LEDs with low color temperature. Application as a phosphor has been studied (Patent Documents 1 and 2, Non-Patent Document 1).

  In the α-type sialon, the Si—N bond of the α-type silicon nitride crystal is partially replaced by an Al—N bond and an Al—O bond, and in order to maintain electrical neutrality, a specific element (Ca And lanthanoid elements excluding Li, Mg, Y, or La and Ce). Fluorescence characteristics are manifested by using a part of the intruding solid solution element as an emission center. As a method for obtaining α-sialon, a mixed powder composed of silicon nitride, aluminum nitride, and an oxide of an intruding solid solution element including a luminescent center (including a compound that becomes an oxide by heat treatment) is heat-treated in a nitrogen atmosphere. The method of doing is mentioned. In such a synthesis method, since an oxide raw material is used, an α-sialon in which a certain amount of oxygen is dissolved is inevitably formed. In particular, the emission color of the α-sialon phosphor in which calcium (Ca) having excellent fluorescence characteristics and europium (Eu) as the emission center are dissolved is orange (fluorescence peak wavelength is around 580 nm).

  On the other hand, α-sialon having a low oxygen content synthesized using calcium nitride as a calcium raw material can dissolve calcium at a higher concentration than the conventional α-sialon. In particular, when the Ca solid solution concentration is high, a phosphor having a fluorescence peak wavelength on the higher wavelength side (590 nm or more) than the conventional composition using an oxide raw material is obtained (Patent Documents 3 and 4).

In the phosphor particles used in the LED obtained in the past, if the particle size is too small, the crystallinity is low, and therefore the luminance is lowered. Therefore, the fluorescent particles having an average particle size of several tens of μm with excellent light emission characteristics. Although body particles have been used, there has been a problem that color unevenness and color shift occur.

Japanese Patent No. 3668770 JP 2003-124527 A JP-A-2005-307012 JP 2006-28295 A

Ken Sakuma et al. “Warm-white light-emitting diode with yellow orange ore SiAlON ceramic phosphor”, OPTICS LETTERS, 29 (17), 2001-2003 (2004)

It is an object of the present invention to provide a light emitting device with a small color shift that includes an orange phosphor.

As a result of intensive studies to solve the above problems, the present inventors have found that the general formula: (M) _x (Eu) _y (Si, Al) ₁₂ (O, N) ₁₆ (where M is Li, Mg, Ca) An orange phosphor represented by α-sialon represented by Y, and lanthanoid elements (excluding La and Ce) and one or more elements containing at least Ca selected from the group consisting of Thus, it has been found that a light emitting device with a small color shift can be obtained by adjusting the median diameter d50 or the maximum particle diameter dmax.

That is, the present invention
(1) General formula: (M) _x (Eu) _y (Si, Al) ₁₂ (O, N) ₁₆ (where M is composed of Li, Mg, Ca, Y and lanthanoid elements (excluding La and Ce)) An α-sialon phosphor selected from the group consisting of at least one element containing at least Ca), having a median diameter d50 measured by a laser diffraction scattering method of 0.2 μm or more and 5 μm or less. Orange phosphor.
(2) General formula: (M) _x (Eu) _y (Si, Al) ₁₂ (O, N) ₁₆ (where M is composed of Li, Mg, Ca, Y and lanthanoid elements (excluding La and Ce)) An α-sialon phosphor selected from the group consisting of at least one element containing Ca and having a maximum particle diameter dmax of 30 μm or less measured by a laser diffraction scattering method .
(3) The orange phosphor according to (1), wherein the maximum particle diameter dmax measured by a laser diffraction scattering method is 0.2 μm or more and 30 μm or less.
(4) General formula: (M) _x (Eu) _y (Si, Al) ₁₂ (O, N) ₁₆ (where M is composed of Li, Mg, Ca, Y and lanthanoid elements (excluding La and Ce)) An at least one element containing at least Ca selected from the group) having a median diameter d50 of 0.2 μm to 1 μm and a maximum particle diameter dmax measured by a laser diffraction scattering method. An orange phosphor having a size of 0.2 μm or more and 10 μm or less.

(5) A light emitting member formed by sealing a semiconductor light emitting element with a sealing material containing the orange phosphor according to any one of (1) to (4).
(6) A light emitting device having the light emitting member according to (5).

The light-emitting device including a phosphor having an α-sialon in which Eu ²⁺ is solid-solved and having a controlled particle diameter according to the present invention can provide a light-emitting element with little color shift. Moreover, according to this invention, the light-emitting device which has a light emitting element and the instrument which accommodates a light emitting element can be provided. Examples of the light emitting device include a lighting device, a backlight device, an image display device, and a signal device.

Hereinafter, embodiments for carrying out the present invention will be described in detail.

The α-type sialon according to the embodiment of the present invention has a specific positive polarity in order to maintain a part of Si—N bonds in α-type silicon nitride by Al—N bonds and Al—O bonds, thereby maintaining electrical neutrality. A solid solution in which ions enter the lattice, and is represented by the general formula: Mz (Si, Al) ₁₂ (O, N) ₁₆ . Here, M is an element that can penetrate into the lattice, and is Li, Mg, Ca, Y, and a lanthanide element (excluding La and Ce), and particularly preferably Li and Ca. The solid solution amount z value of M is a numerical value determined by the Al—N bond substitution rate of the Si—N bond.

  In order for the α-sialon to exhibit fluorescence characteristics, it is necessary to use a part of M as a light-emitting center element that can be partly dissolved in M, and examples of the light-emitting center element include Eu and Ce. For example, by using Ca as M and substituting it with Eu, which is the emission center, α-sialon is stabilized in a wide composition range, excited by light in a wide wavelength range from ultraviolet to blue, and from yellow to orange A phosphor exhibiting visible light emission is obtained.

The emission wavelength varies depending on the solid solution composition of α-sialon, that is, the Al—N and Al—O bond substitution rates of Si—N bonds (m and n values, respectively) and the Eu solid solution concentration. By increasing the Eu solid solution concentration, which is the emission center, the emission wavelength shifts to the longer wavelength side, but the shift amount is small and accompanied by a change in the emission intensity, so it is not suitable for a control factor. Eu dissolved in the lattice of α-type sialon exists as a divalent cation, and its excitation and fluorescence are due to the 4f-5d transition, and the emission wavelength is greatly influenced by the coordination environment of Eu ²⁺ . Therefore, by controlling the solid solution composition of α-sialon, it is possible to control a broad emission wavelength while maintaining the emission intensity.

The solid solution composition of the α-type sialon is expressed as follows: x and y in the general formula: (M) _x (Eu) _y (Si, Al) ₁₂ (O, N) ₁₆ and the accompanying Si / Al ratio and O / N ratio It is represented by Since α-sialon generally synthesized is a second crystal phase different from α-sialon or an unavoidably present amorphous phase, the solid solution composition cannot be strictly defined by composition analysis or the like. The crystal phase present in the phosphor is preferably an α-type sialon single phase, but it does not matter if it contains a trace amount of crystal phases such as β-type sialon, aluminum nitride and its polytypoid as long as it does not affect the light emission characteristics. .

Further, in the orange phosphor of the present invention, when the median diameter (also referred to as d50) is as large as several tens of μm, the chromaticity of the emission color tends to vary when the phosphor is mounted on the light emitting surface of the LED. Therefore, d50 is preferably 5 μm or less, and more preferably 1 μm or less. Moreover, since luminance will fall when d50 is too small, it is preferable that it is 0.2 micrometer or more. The d50 is a value calculated from the volume average diameter measured by the laser diffraction scattering method according to JIS R1622 and R1629.

Furthermore, the orange phosphor of the present invention preferably has a maximum particle size (also referred to as dmax) in a particle size distribution measured by a laser diffraction scattering method of 30 μm or less, and more preferably 10 μm or less. If dmax is larger than 30 μm, the dispersion in the sealing resin used for the LED and the mixing with other types of phosphors become non-uniform, which causes the chromaticity variation of the LED and the uneven color of the irradiated surface. There is a case.

Although the manufacturing method of LED provided with the fluorescent substance of this invention does not have a restriction | limiting in particular, For example, it can manufacture as follows. First, the phosphor is mixed in an amount of 30 to 50% by mass with respect to a resin having thermosetting properties and fluidity at room temperature to prepare a slurry. Examples of the resin having thermosetting properties and fluidity at room temperature include silicone resins (specifically, Toray Dow Corning Co., Ltd., trade name: JCR6175).

Next, 3 to 4 μL of the slurry is injected into a top view type package on which a blue LED chip having a peak wavelength at 460 nm is mounted. The top view type package into which this slurry has been injected is heated at a temperature in the range of 140 to 160 ° C. for 2 to 2.5 hours to cure the slurry. In this manner, an LED that absorbs light in the wavelength range of 420 to 480 nm and emits light having a wavelength of more than 480 nm and not more than 800 nm can be manufactured.

  First, a comparative example will be described prior to the description of the examples of the present invention.

[Comparative Example 1]
"Production of powder mixed raw materials"
"Mixing process"
62.8 g of α-type silicon nitride powder (Si ₃ N ₄ , SN-E10 grade, manufactured by Ube Industries) in a glove box maintained in a nitrogen atmosphere having a moisture content of 1 mass ppm or less and an oxygen content of 1 mass ppm or less. , Calcium nitride powder (Ca ₃ N ₂ , manufactured by Materion) 13.4 g, aluminum nitride powder (AlN, E grade, manufactured by Tokuyama) 22.7 g, europium oxide powder (Eu ₂ O ₃ , RU grade, Shin-Etsu Chemical) 1.1 g) was mixed to obtain a raw material mixed powder. 100 g of this raw material mixed powder was filled into a cylindrical boron nitride container with a lid having an internal volume of 0.4 liter (manufactured by Denka, N-1 grade).

"Baking process"
The raw material mixed powder was heat-treated at 1800 ° C. for 16 hours in an atmospheric pressure nitrogen atmosphere in an electric furnace of a carbon heater together with the container. Since calcium nitride contained in the raw material mixed powder is easily hydrolyzed in the air, the boron nitride container filled with the raw material mixed powder is taken out of the glove box and immediately installed in the electric furnace. Evacuated to prevent calcium nitride reaction. The orange lump collected from the container was lightly crushed with a mortar and passed through a sieve having an opening of 150 μm to obtain phosphor powder.

[Example 1]
The α-type sialon phosphor obtained in Comparative Example 1 was crushed in ethanol using zirconia balls having a ball diameter of φ5 for 50 hours to obtain Eu-activated Ca-α-type sialon phosphor of Example 1.

[Example 2]
The Eu-activated Ca-α of Example 2 was prepared under the same conditions as in Example 1 except that the crushing time of α-sialon using a zirconia ball having a ball diameter of φ5 in ethanol was 24 hours. Type sialon phosphor was obtained.

[Example 3]
The Eu-activated Ca-α type sialon fluorescence of Example 3 was prepared under the same conditions as in Example 1 except that the material of the balls used for crushing was changed to silicon nitride and the crushing time was 12 hours. Got the body.

[Example 4]
The Eu-activated Ca-α type sialon phosphor of Example 4 was prepared under the same conditions as in Example 1 except that the material of the balls used for crushing was changed to silicon nitride and the crushing time was 8 hours. Got.

[Comparative Example 2]
"Production of powder mixed raw materials"
"Mixing process"
82.0 g of α-type silicon nitride powder (Si ₃ N ₄ , SN-E10 grade, manufactured by Ube Industries) in a glove box maintained in a nitrogen atmosphere having a moisture content of 1 mass ppm or less and an oxygen content of 1 mass ppm or less. Lithium nitride powder (Materion purity 99.5%, -60 mesh) 5.1 g, Aluminum nitride powder (AlN, E grade, Tokuyama) 12.3 g, Europium oxide powder (Eu ₂ O ₃ , RU grade) 0.6 g of Shin-Etsu Chemical Co., Ltd.) was mixed to obtain a raw material mixed powder. 100 g of this raw material mixed powder was filled into a cylindrical boron nitride container with a lid having an internal volume of 0.4 liter (manufactured by Denka, N-1 grade).

"Baking process"
This raw material mixed powder was heat-treated at 1850 ° C. for 4 hours in an atmospheric pressure nitrogen atmosphere in an electric furnace of a carbon heater together with the container. Since the lithium nitride contained in the raw material mixed powder is easily hydrolyzed in the air, the boron nitride container filled with the raw material mixed powder is taken out of the glove box and immediately installed in the electric furnace. Evacuated to prevent lithium nitride reaction. The orange lump collected from the container was lightly crushed with a mortar and passed through a sieve having an opening of 150 μm to obtain phosphor powder.

[Example 5]
The α type sialon phosphor obtained in Comparative Example 2 was crushed in ethanol using zirconia balls having a ball diameter of φ5 for 50 hours to obtain Eu-activated Li-α type sialon phosphor of Example 5.

[Example 6]
The Eu-activated Li-α of Example 6 was prepared under the same conditions as in Example 5 except that the crushing time of α-sialon using zirconia balls having a ball diameter of φ5 in ethanol was changed to 24 hours. Type sialon phosphor was obtained.

[Example 7]
The Eu-activated Li-α type sialon fluorescence of Example 7 was prepared under the same conditions as in Example 5 except that the material of the balls used for crushing was changed to silicon nitride and the crushing time was 12 hours. Got the body.

[Example 8]
The Eu-activated Li-α type sialon fluorescence of Example 8 was prepared under the same conditions as in Example 5 except that the material of the balls used for crushing was changed to silicon nitride and the crushing time was 8 hours. Got the body.

(Confirmation of crystal structure)
About each obtained sample, the crystal structure was confirmed with the powder X-ray-diffraction pattern using a CuK alpha ray using the X-ray-diffraction apparatus (Rigaku Corporation Ultimate IV). As a result, the same diffraction pattern as the α-sialon crystal was observed in the powder X-ray diffraction patterns of the phosphors of Examples 1 to 8 and Comparative Examples 1 and 2 obtained.

(Measurement of particle diameter)
The particle size distributions of the phosphors obtained in Examples 1 to 8 and Comparative Examples 1 and 2 were measured in accordance with JIS R1622 and R1629 using a particle size distribution measuring device (Microtrack MT3000II manufactured by Microtrack Bell Co., Ltd.). Measured by diffraction scattering method. The results are summarized in Table 1 shown below.

"LED evaluation"
“Comparative Example 3”
An LED was fabricated using the α-type sialon phosphor obtained in Comparative Example 1. That is, the phosphor particles are added in an amount of 10% by mass with respect to a silicone resin having thermosetting properties and fluidity at normal temperature (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KER6150), and the slurry is stirred and mixed. It was adjusted. Next, 6 mg of the slurry was injected into a top view type package on which a blue LED chip having a peak at a wavelength of 450 to 460 nm was mounted, and then heated at a temperature of 150 ° C. for 2 hours to cure the slurry. In this manner, an LED having the α-sialon phosphor particles of Comparative Example 1 and absorbing light in the wavelength range of 420 to 480 nm and emitting light in the range of over 480 nm to 800 nm or less was produced. .

"Example 9"
An LED was produced under the same conditions as in Comparative Example 3 except that the α-sialon phosphor particles obtained in Example 1 were used.

"Example 10"
An LED was produced under the same conditions as in Comparative Example 3 except that the α-sialon phosphor particles obtained in Example 2 were used.

"Example 11"
An LED was produced under the same conditions as in Comparative Example 3 except that the α-sialon phosphor particles obtained in Example 3 were used.

"Example 12"
An LED was produced under the same conditions as in Comparative Example 3 except that the α-sialon phosphor particles obtained in Example 4 were used.

“Comparative Example 4”
An LED was produced under the same conditions as in Comparative Example 3 except that the α-sialon phosphor particles obtained in Comparative Example 2 were used.

"Example 13"
An LED was produced under the same conditions as in Comparative Example 3 except that the α-sialon phosphor particles obtained in Example 5 were used.

"Example 14"
An LED was produced under the same conditions as in Comparative Example 3 except that the α-sialon phosphor particles obtained in Example 6 were used.

"Example 15"
An LED was produced under the same conditions as in Comparative Example 3 except that the α-sialon phosphor particles obtained in Example 7 were used.

"Example 16"
An LED was produced under the same conditions as in Comparative Example 3 except that the α-sialon phosphor particles obtained in Example 8 were used.

"LED chromaticity evaluation"
About 50 of each LED was produced about LED of this invention produced in said Examples 9-16 and Comparative Examples 3-4, and chromaticity was used using LED measuring apparatus (InstrumentSystem company make, brand name: CAS140B). Evaluation was performed.
The results are summarized in Table 2 below. In addition, chromaticity evaluation shows each standard deviation of CIEx and CIEy.

From the results of Examples and Comparative Examples shown in Table 2, it can be seen that an LED including an α-sialon phosphor having a d50 of 5 μm or less has a small color shift. In particular, it can be seen that the LED including the phosphors of Example 1 and Example 5 has a small color shift.

General formula of the present invention: (M) _x (Eu) _y (Si, Al) ₁₂ (O, N) ₁₆ (where M is composed of Li, Mg, Ca, Y and lanthanoid elements (excluding La and Ce)) The α-sialon phosphor represented by (at least one element containing at least Ca selected from the group) is excited by blue light, exhibits high-luminance orange light emission, and obtains an LED having a small color shift. The phosphor can be suitably used as a white LED phosphor using light as a light source, and can be suitably used for light-emitting devices such as lighting fixtures and image display devices.

Claims (6)

General formula: (M) _x (Eu) _y (Si, Al) ₁₂ (O, N) ₁₆ (where M is selected from the group consisting of Li, Mg, Ca, Y and lanthanoid elements (excluding La and Ce)) An sialon phosphor having at least one element containing Ca, and having a median diameter d50 measured by a laser diffraction scattering method of 0.2 μm or more and 5 μm or less. . General formula: (M) _x (Eu) _y (Si, Al) ₁₂ (O, N) ₁₆ (where M is selected from the group consisting of Li, Mg, Ca, Y and lanthanoid elements (excluding La and Ce)) An orange-type phosphor having a maximum particle diameter dmax of 30 μm or less measured by a laser diffraction scattering method. 2. The orange phosphor according to claim 1, wherein the maximum particle diameter dmax measured by a laser diffraction scattering method is 0.2 μm or more and 30 μm or less. General formula: (M) _x (Eu) _y (Si, Al) ₁₂ (O, N) ₁₆ (where M is selected from the group consisting of Li, Mg, Ca, Y and lanthanoid elements (excluding La and Ce)) One or more elements including at least Ca) having a median diameter d50 of 0.2 μm to 1 μm and a maximum particle diameter dmax of 0.2 μm as measured by a laser diffraction scattering method. An orange phosphor having a thickness of 10 μm or less. The light emitting member formed by sealing a semiconductor light emitting element with the sealing material containing the orange fluorescent substance as described in any one of Claims 1-4. A light emitting device comprising the light emitting member according to claim 5.