JP2017048338A - Phosphor and light emitting device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphor more excellent in light emitting characteristics, particularly in luminous efficiency than the conventional one and to provide a light emitting device using the phosphor.SOLUTION: The phosphor includes a crystal phase represented by a composition of the following formula (1): MEuLuMO(in which Mis one or more kinds of metal elements selected from the group consisting of Mg, Ca, Sr, and Ba; Mis a metal element of Group III or Group XIII; 3.5≤a+b+c≤4.5; 0<b≤0.5; 0<c≤0.5; 13≤d≤17; and 24≤e≤30.)SELECTED DRAWING: None

Description

  The present invention relates to a phosphor and a light emitting device using the same, and more particularly, to a phosphor exhibiting blue-green light emission and a light emitting device using the same.

  Conventionally, a white light emitting diode (white LED) is widely used as a two-color mixed type that obtains white light by mixing blue and yellow by combining a semiconductor light emitting element that emits blue light and a yellow phosphor. ing. However, the white light emitted from this two-color mixed type white LED has a problem that the color rendering is poor. Therefore, as another configuration, a combination of a semiconductor light emitting element that emits blue light and two types of phosphors, green and red, is used to excite each phosphor with light from the semiconductor light emitting element. In combination with three-color mixed type white LED that obtains white light by mixing green and red, a semiconductor light emitting element that emits ultraviolet light with a wavelength of 350 to 430 nm, and three kinds of phosphors of blue, green, and red, Development of a three-color mixed-type white LED that obtains white light in a mixed color of blue, green, and red by exciting each phosphor with light from a semiconductor light emitting element is underway. In addition, in recent years, the color rendering properties have been further improved compared to the three-color mixed type. In addition to the three types of phosphors of blue, green and red, phosphors emitting light at wavelengths between blue and green, from green White LEDs that combine phosphors that emit light at wavelengths between red and the like have also been developed.

Conventionally, green phosphors having various compositions have been developed as blue-green phosphors used in white LEDs. For example, Patent Document 1 discloses Sr _4-az A _a Eu _z D ₁₄ O ₂₅ composition (wherein A is at least one alkaline earth metal other than strontium, and D is a group 13 metal, group 3 One element selected from the group consisting of metals and rare earth metals other than europium, with 0 <a <4, 0.001 <z <M0.3, and 4-az> 0) A phosphor is described, which can be used to provide a visible light source based on UV or UV-blue light emitting diodes, and can be blended with other phosphors to provide a light source that emits white light It also describes what you can do.

JP-A-2005-330483

  However, the blue-green phosphor of Patent Document 1 has a problem that the light emission characteristics are not sufficient when applied to LED applications, and the light emission efficiency is particularly low.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a phosphor excellent in light emission characteristics, particularly light emission efficiency, and a light emitting device using the same.

  In order to achieve the above object, the present inventors have conducted extensive research. As a result, the luminous efficiency of the blue-green phosphor activated by europium is greatly increased by containing a specific amount of lutetium (Lu). As a result, the present invention has been found.

That is, the present invention ^relates to a phosphor containing a crystal phase represented by the composition of _{^{M 1 a Eu b Lu c M}} 2 d O e.

  The present invention also relates to a light-emitting device comprising the phosphor and a light source that emits light by irradiating the phosphor with excitation light.

  ADVANTAGE OF THE INVENTION According to this invention, the fluorescent substance excellent in the light emission characteristic, especially the light emission efficiency than before, and a light-emitting device using the same can be provided.

1. Phosphor of the phosphor present invention ^includes a crystal phase represented by the composition of _{^{M 1 a Eu b Lu c M}} 2 d O e. That is, the phosphor of the present invention is a phosphor activated by europium (Eu), and is a blue-green phosphor having a peak between 480 and 520 nm when excited with light having a wavelength of 380 to 410 nm. .

In the phosphor of the present invention, M ¹ is one or more metal elements selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba), and strontium (Sr) It is preferable that The molar ratio of M1 in the phosphor, that is, the value of a is in the range of 2.5 ≦ a ≦ 4.5, preferably in the range of 2.7 ≦ a ≦ 4.3, and 2.9 ≦ a. A range of ≦ 4.1 is more preferable.

  In the phosphor of the present invention, europium (Eu) is an activator and has a property of emitting light as a light emitting atom in the phosphor. The molar ratio of europium in the phosphor, that is, the value of b is in the range of 0 <b ≦ 0.5, preferably in the range of 0.01 ≦ b ≦ 0.2, and 0.05 ≦ b ≦ A range of 0.1 is more preferable. If the value of b exceeds 0.5, the luminescent atoms become high in concentration and cancel each other close to each other, so that the emission intensity tends to be weak.

Furthermore, in the phosphor of the present invention, M ² is a group 3 or group 13 metal element, and is preferably aluminum (Al). The molar ratio of M2 in the phosphor, that is, the value of d is in the range of 13 ≦ d ≦ 17, preferably 13.5 ≦ d ≦ 16.5, and more preferably d = 14. preferable.

  In the phosphor of the present invention, the molar ratio of oxygen (O) in the phosphor is within the range of 24 ≦ e ≦ 30, preferably within the range of 24.5 ≦ e ≦ 26.5, e = More preferably, it is 25.

  The phosphor of the present invention is further characterized by containing lutetium (Lu). The molar ratio of lutetium in the phosphor is in the range of 0 <c ≦ 0.5, preferably in the range of 0.005 ≦ c ≦ 0.015, and in the range of 0.007 ≦ c ≦ 0.012. Is more preferable. When the value of c is in the range of 0 <c ≦ 0.5, the light emission efficiency can be greatly improved.

  Further, in the phosphor of the present invention, the molar ratio of M1 in the phosphor, that is, the value of a, the sum of the molar ratio of europium, that is, the value of b, and the molar ratio of lutetium, that is, the value of c. The value a + b + c is in the range of 3.5 ≦ a + b + c ≦ 4.5, preferably 3.7 ≦ a + b + c ≦ 4.3, preferably 3.9 ≦ a + b + c ≦ 4.1, and a + b + c = 4 It is more preferable.

  Further, the ratio of lutetium (Lu) to europium (Eu) in the phosphor, that is, c / b is preferably 0.07 ≦ c / b ≦ 0.18, and 0.09 ≦ c / b ≦ 0. .18 is preferred. If it is smaller than 0.07, the luminous efficiency is not sufficiently improved, and if it is larger than 0.18, the amount of Lu becomes excessive and light energy is converted into heat, so that the luminous efficiency is lowered.

2. Method for Producing Phosphor The phosphor of the present invention includes, for example, an M ¹ -containing compound (where M ¹ is one or more metal elements selected from the group consisting of Mg, Ca, Sr, and Ba), an Eu-containing compound, Lu Containing compound, M ² -containing compound (wherein M ² is a Group 3 or 13 metal element) and O-containing compound to obtain a raw material mixture (mixing step), and containing the raw material mixture with an inert gas It can manufacture by the manufacturing method provided with the process (baking process) baked in an atmosphere or reducing gas atmosphere, and a grinding | pulverization and a classification process as needed.

(1) Mixing step Each of the raw material-containing compounds of the M ¹ -containing compound, Eu-containing compound, Lu-containing compound, and M ² -containing compound is a nitride, an oxynitride, an oxide, or a precursor substance that becomes an oxide by thermal decomposition. However, it is necessary to select a compound in which one or more of them contains oxygen (O).

Specific examples of the magnesium (Mg) -containing compound in the M ¹ -containing compound are not particularly limited, but are selected from the group consisting of magnesium nitride (Mg ₃ N ₂ ), magnesium carbonate (MgCO ₃ ), and magnesium oxide (MgO), for example. One or more kinds of powders can be preferably used.

Specific examples of the calcium (Ca) -containing compound in the M ¹ -containing compound are not particularly limited, but are selected from the group consisting of calcium nitride (Ca ₃ N ₂ ), calcium carbonate (CaCO ₃ ), and calcium oxide (CaO), for example. One or more kinds of powders can be preferably used.

Specific examples of the strontium (Sr) -containing compound in the M ¹ -containing compound are not particularly limited, but are selected from the group consisting of strontium nitride (Sr ₃ N ₂ ), strontium carbonate (SrCO ₃ ), and strontium oxide (SrO), for example. One or more kinds of powders can be preferably used, and in particular, a powder of strontium carbonate (SrCO ₃ ) can be preferably used.

Specific examples of M ¹ containing barium in the compound (Ba) containing compound is not particularly limited, for example, barium nitride _{(Ba 3 N} 2), barium carbonate (BaCO _3), selected from the group consisting of barium oxide (BaO) One or more kinds of powders can be preferably used.

No particular limitation is imposed on the specific examples of the Eu-containing compounds, for example, europium oxide _{(III) (Eu 2 O 3} ), europium oxide (II) (EuO), the group consisting of europium nitride (EuN), metal europium (Eu) One or more kinds of powders more selected can be preferably used.

  Although it does not specifically limit as a specific example of a Lu containing compound, For example, lutetium oxide (III), lutetium carbonate (III), lutetium hydroxide (III), lutetium nitrate (III), lutetium sulfate (III), lutetium chloride (III) One or more kinds of powders selected from the group consisting of) can be preferably used.

Specific examples of the aluminum (Al) -containing compound in the M ² -containing compound are not particularly limited. For example, aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ), aluminum carbonate (Al ₂ (CO ₃ ) ₃ ) One or more kinds of powders selected from the group consisting of: aluminum oxide (Al ₂ O ₃ ), particularly γ-alumina powder, can be preferably used.

Each of these raw material-containing compounds may be used alone or in combination of two or more. Each raw material-containing compound preferably has a purity of 99% by mass or more. The said raw material containing compound adjusts the mixing ratio so that it may become a composition ratio of Formula (1). However, the M ² -containing compound may be used in excess, and can be mixed, for example, so that the Al amount is about 16 mol with respect to 4 mol of the total amount of M ¹ , Eu, and Lu.

Moreover, in baking, the halogen-containing compound used as a reaction accelerator can be added for the purpose of promoting sintering and producing | generating at lower temperature. Examples of the halogen-containing compound to be used include halides of M ¹ (magnesium fluoride (MgF ₂ ), magnesium chloride (MgCl ₂ ), magnesium bromide (MgBr ₂ ), calcium fluoride (CaF ₂ ), calcium chloride (CaCl ₂ ). , calcium bromide (CaBr _2), strontium fluoride _(SrF 2), strontium chloride (SrCl _2), strontium bromide (SrBr _2), barium fluoride _(BaF 2), barium chloride (BaCl _2), barium bromide (BaBr ₂ )), or Al halides (aluminum fluoride (AlF ₃ ), aluminum chloride (AlCl ₃ ), aluminum bromide (AlBr ₃ )), etc., and each of these powders is used alone. It may be used in combination. Preferably, strontium fluoride (SrF ₂ ) is used. Moreover, 0.01-0.5 mol is suitable as a halogen element with respect to 1 mol of baked products obtained by the baking process mentioned later for the addition amount of a halogen containing compound. The halogen-containing compound is easily volatilized in the firing step and is hardly contained in the phosphor powder.

  The mixing method of the raw material powder is not particularly limited, and a method known per se, for example, a dry mixing method, a method of removing the solvent after wet mixing in an inert solvent that does not substantially react with each component of the raw material, etc. Can be adopted. As the mixing device, a V-type mixer, a rocking mixer, a ball mill, a vibration mill, a medium stirring mill, or the like is preferably used.

(2) Firing step Next, the raw material mixture is fired. The firing of the raw material mixture is preferably carried out in a reducing gas atmosphere after firing in the air. In the firing in the air, the firing temperature is generally in the range of 500 to 1000 ° C. The firing time is generally in the range of 1 to 10 hours, and preferably in the range of 2 to 5 hours. In the firing under a reducing gas atmosphere, the reducing gas atmosphere can be composed of a mixed gas of a rare gas such as nitrogen or argon and hydrogen gas or carbon monoxide gas. Since it is a reducing gas atmosphere, it is desirable not to contain oxygen, but oxygen may be contained as an impurity in an amount of less than 0.1 vol%, or even less than 0.01 vol%. The firing temperature is in the range of 1000 to 1800 ° C, more preferably 1300 to 1500 ° C. The firing time is generally in the range of 1 to 24 hours, and preferably in the range of 3 to 10 hours. The firing pressure may be normal pressure or higher, and is preferably less than 0.92 MPa. By changing the settings of the type of atmospheric gas, the oxygen concentration and nitrogen concentration in the atmospheric gas, the firing temperature, and the firing time, the oxygen amount and nitrogen amount of the target phosphor can be adjusted.

(3) Pulverization and classification step The phosphor obtained by firing does not need to be pulverized, and for example, when used as a light-emitting element of a white LED, a desired particle size can be obtained. Pulverized and optionally classified to a desired particle size range. In this case, the pulverization method may be either a wet pulverization method or a dry pulverization method. Also, as for the classification method, any operation method generally used for classification of powder, such as sieving operation, operation using fluid, etc. May be used. Moreover, the phosphor obtained by firing may be subjected to an acid cleaning treatment or a baking treatment with a mineral acid such as hydrochloric acid or nitric acid, if necessary.

3. Light-emitting device The phosphor of the present invention can be used in various light-emitting devices. The light emitting device of the present invention includes at least a phosphor represented by the above formula (1) and a light source that emits light by irradiating the phosphor with excitation light. Specific examples of the light emitting device include a white light emitting diode (white LED), a fluorescent lamp, a fluorescent display tube (VFD), a cathode ray tube (CRT), a plasma display panel (PDP), and a field emission display (FED). it can. Among these, the white LED includes a blue phosphor, a red phosphor, and the phosphor of the present invention (blue-green phosphor), and a semiconductor light emitting element that emits ultraviolet light having a wavelength of, for example, 350 to 430 nm. This is a light emitting device that excites a blue phosphor, a red phosphor, and a blue-green phosphor with light to obtain a white color by mixing blue, red, and blue-green. Further, as another configuration, a semiconductor element that emits blue light having a wavelength of 430 to 500 nm is provided, and these phosphors are excited by blue light from the light emitting element to obtain white by a mixed color of blue, red, and blue-green. It can also be applied to a light emitting device. Furthermore, a green light emitting phosphor may be used in combination with these phosphors.

Examples of blue light emitting phosphors include (Ba, Sr, Ca) ₃ MgSi ₂ O ₈ : Eu, (Ba, Sr, Ca) MgAl ₁₀ O ₁₇ : Eu, (Ba, Sr, Mg, Ca) ₁₀ (PO ₄ ) ₆ (Cl, F) ₂ : Eu and the like. Examples of the red light emitting phosphor include (Ba, Sr, Ca) ₃ MgSi ₂ O ₈ : Eu, Mn, Y ₂ O ₂ S: Eu, La ₂ O ₃ S: Eu, (Ca, Sr, Ba ) ₂ Si ₅ N ₈ : Eu, CaAlSiN ₃ : Eu, Eu ₂ W ₂ O ₉ , (Ca, Sr, Ba) ₂ Si ₅ N ₈ : Eu, Mn, CaTiO ₃ : Pr, Bi, (La, Eu) ₂ W ₃ O _{12 and the} like can be mentioned. Examples of the semiconductor light emitting device include an AlGaN semiconductor light emitting device.

  The blue fluorescent substance used in the light emitting device according to the present invention preferably emits light having a peak wavelength in the range of about 420 nm to about 500 nm, and the red fluorescent substance has a peak in the range of about 600 nm to about 620 nm. It is preferred to emit light having a wavelength, and the green-emitting phosphor preferably emits light having a peak emission in the range of about 530 nm to about 550 nm.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, these do not limit the objective of this invention. First, the measurement method used in this example is shown.

(Method for evaluating characteristics of phosphor)
Measurement was performed in the following procedure using FP-8500 manufactured by Jusco Engineering Co., Ltd.
1) A standard white plate was attached to the inner bottom of the integrating sphere. The standard white plate was irradiated with ultraviolet light having a peak wavelength of 400 nm perpendicular to the surface. The spectrum of light scattered by the integrating sphere wall was measured, and the peak area (Ll) of light having a wavelength of 380 to 410 nm was measured.
2) The aluminate phosphor sample was filled in the sample holder, and the sample holder was attached to the inner bottom of the integrating sphere. The aluminate phosphor sample in the sample holder was irradiated with ultraviolet light having a peak wavelength of 400 nm perpendicular to the surface. The spectrum of light scattered by the integrating sphere wall was measured, and the peak area (L2) of light having a wavelength of 380 to 410 nm and the peak area (E) of light having a wavelength of 410 to 700 nm were measured. And the absorptivity, internal quantum efficiency, and external quantum efficiency of the silicate fluorescent substance sample were computed from the following formula.
Absorption rate (%) = 100 × (L1-L2) / L1
Internal quantum efficiency (of aluminate phosphor sample) (%) = 100 × E / (L1-L2)
External quantum efficiency (%) of aluminate phosphor sample = 100 × E / L1

(Example 1: Sr _3.9125 Eu _0.08 Lu _0.0075 Al ₁₄ O ₂₅ )
Strontium carbonate powder (purity: 99.8% by mass), dieuropium trioxide powder (purity: 99.9% by mass), dialuminum trioxide powder (γ-alumina, purity: 99.9% by mass), strontium fluoride Powder (purity: 99.9% by mass), lutetium oxide (III) (purity: 99.9% by mass) in a molar ratio of SrCO ₃ : Eu ₂ O ₃ : Al ₂ O ₃ : SrF ₂ : Lu ₂ O ₃ Were measured to be 3.7625: 0.04: 8: 0.15: 0.00375, respectively.
Each raw material powder weighed was put into a dedicated mill together with ethanol and nylon balls, and wet mixed in a rocking mill (vibration mill) for 1 hour to obtain a slurry of a powder mixture. The obtained slurry was dried with a rotary evaporator to obtain a mixture. The obtained powder mixture was put in an alumina crucible, calcined at a temperature of 800 ° C. for 3 hours in an air atmosphere, then allowed to cool to room temperature, and then in a mixed gas atmosphere of 3 vol% hydrogen-97 vol% argon. and calcined for 6 hours at a temperature of 1400 ° C. at obtain a phosphor _{(Sr 3.91 Eu 0.08 Lu 0.01 Al} 14 O 25). The external quantum efficiency of the obtained phosphor was calculated by the phosphor property evaluation method. The results are shown in Table 1.

(Other examples and comparative examples)
A phosphor was produced in the same manner as in Example 1 except that the raw material mixing ratio was changed as shown in the table, and the external quantum efficiency of the obtained phosphor was calculated. The results are shown in Table 1.

  Since the phosphors of Examples 1 to 3 contained Lu, the external quantum efficiency was improved as compared with the phosphor of Comparative Example 1 not containing Lu. In addition, the phosphors of Comparative Examples 2 to 8 contain elements other than Lu (Gd, In, Sc, Tb, Ge, Ga, La), but the external quantum efficiency compared to the phosphor of Comparative Example 1 Did not improve.

Claims (4)

A phosphor containing a crystal phase represented by the composition of the following formula (1).
^{_{M 1 a Eu b Lu c M}} 2 d O e ··· (1)
(Here, M ¹ is one or more metal elements selected from the group consisting of Mg, Ca, Sr, and Ba, M ² is a group 3 or group 13 metal element, and 3.5 ≦ a + b + c ≦ 4. .5, 0 <b ≦ 0.5, 0 <c ≦ 0.5, 13 ≦ d ≦ 17, 24 ≦ e ≦ 30.) 2. The phosphor according to claim 1, wherein in the formula (1), a + b + c = 4, d = 14, and e = 25.   3. The phosphor according to claim 1, wherein, in the formula (1), 0.07 ≦ c / b ≦ 0.18.   A light emitting device comprising: the phosphor according to claim 1; and a light source that emits light by irradiating the phosphor with excitation light.