JP2008285678A - Sialon fluorescent material and white luminescent diode using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sialon fluorescent material and a white luminescent diode using it. <P>SOLUTION: The sialon fluorescent material is an oxynitride containing Si, Al, O and N, and containing one or more lantanide metals selected from the group consisting of Ce, Pr, Nd, Pm, Sm, Eu, Tb, Ho, Er and Tm as activators, with the composition formula of äM<SB>1(x1)</SB>, M<SB>2(x2)</SB>, M<SB>3(x3)</SB>, Ce<SB>(x4)</SB>}(Si, Al)<SB>12</SB>(O, N)<SB>16</SB>wherein M<SB>1</SB>represents Li, M<SB>2</SB>represents one or more metals selected from the group consisting of Ca, Mg and a bivalent lantanide metal, M<SB>3</SB>represents one or more selected from the group consisting of Y and a trivalent lantanide metal (excluding Ce), wherein x1, x2 and x3 each represent 0-2, x4 represents more than 0.2 to less than 1.2, emitting blue light with an exciting source, and a white luminescent diode using the fluorescent material containing the sialon fluorescent material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a sialon phosphor and its use .

  The phosphor is used for a fluorescent display tube (VFD), a field emission display (FED), a plasma display panel (PDP), a cathode ray tube (CRT), a white light emitting diode (LED), and the like. In any of these applications, in order to make the phosphor emit light, it is necessary to supply the phosphor with energy for exciting the phosphor, and the phosphor is not limited to vacuum ultraviolet rays, ultraviolet rays, electron beams, blue light, etc. When excited by a high energy excitation source, it emits visible light. Therefore, as a result of the phosphor being exposed to the excitation source as described above, there is a problem in that the luminance of the phosphor decreases, and the conventional silicate phosphor, phosphate phosphor, aluminate phosphor, A sialon phosphor has been proposed as a phosphor having a lower luminance reduction than a phosphor such as a sulfide phosphor.

As a method for producing this sialon phosphor, for example, silicon nitride (Si ₃ N ₄ ), aluminum nitride (A1N), and europium oxide (Eu ₂ O ₃ ) are mixed so as to have a predetermined molar ratio, and 1 atmosphere ( Conventionally, a method of firing and holding in nitrogen at 0.1 MPa for 1 hour at a temperature of 1700 ° C. has been performed (for example, see Patent Document 1). However, a production method for obtaining a sialon phosphor exhibiting higher luminance has been demanded.

JP 2002-363554 A

An object of the present invention is to provide a sialon phosphor exhibiting higher luminance than a conventional sialon phosphor and a white light emitting diode using the phosphor.

  Under such circumstances, the present inventors have conducted extensive research on a method for producing a sialon phosphor, and as a result, identified a metal compound mixture that can constitute the sialon phosphor by firing in a nitrogen gas at a specific pressure. As a result, it was found that a sialon phosphor having specific properties with higher brightness than conventional ones can be produced by firing in this temperature range, and the present invention has been completed.

That is, the solving means of the present invention has the configurations described in (1) to (6) below.
(1) A lanthanide metal selected from the group consisting of Ce, Pr, Nd, Pm, Sm, Eu, Tb, Ho, Er, and Tm as an activator with an oxynitride containing Si, Al, O, and N A sialon phosphor containing one or more kinds,
Composition formula;
{M1 _(x1) , M2 _(x2) , M3 _(x3) , Ce _(x4) } (Si, Al) ₁₂ (O, N) ₁₆
[In the formula, M ₁ is Li, M ₂ is one or more selected from the group consisting of Ca, Mg and divalent lanthanide metals, and M ₃ is Y and trivalent lanthanide metal (Ce And x1 is 0 or more and 2 or less, x2 is 0 or more and 2 or less, x3 is 0 or more and 2 or less, and x4 is larger than 0.2. 2 or less], and emits blue light from an excitation source .
_{(2) x1 = 0, M} 2 is equal to or Ca, _{M 3} is Y, SiAlON phosphor of _(1).
(3) The sialon phosphor according to (1) or (2), wherein the excitation source is ultraviolet light.
(4) The sialon phosphor according to any one of (1) to (3), wherein the blue light has a peak at around 480 nm.
(5) The sialon phosphor according to any one of (1) to (4), wherein the sialon is α sialon .
(6) A white light-emitting diode using a phosphor, wherein the phosphor includes the sialon phosphor according to any one of (1) to (5).

The present invention is described in detail below.
In the method for producing a sialon phosphor of the present invention, a mixture of metal compounds, which can be fired to form a sialon containing a specific metal element M, has a pressure range of 0.2 MPa to 100 MPa. In nitrogen, firing is performed in a temperature range of 2000 ° C. to 2400 ° C.

  The specific metal element is at least one selected from the group consisting of Li, Ca, Mg, Y, and a lanthanide metal, and other metal elements do not form a high-brightness sialon phosphor.

  The firing atmosphere consists essentially of nitrogen. In particular, nitrogen is substantially free of oxygen (oxygen content is 0.1% by volume or less). A rare gas such as argon or helium may be contained in an amount of about 1% by volume. However, when nitrogen contains a large amount of a rare gas, the nitrogen partial pressure changes, making it difficult to synthesize the desired sialon phosphor. It is not preferable. Nitrogen used for firing preferably has a purity of 99.9% by volume or more.

  In the method for producing a sialon phosphor of the present invention, the pressure of nitrogen, which is a firing atmosphere, ranges from 0.2 MPa to 100 MPa, preferably from 2 MPa to 70 MPa, and more preferably from 10 MPa to 50 MPa. preferable. If the pressure is too small, a sialon phosphor exhibiting high luminance cannot be obtained, and if it is too high, it is disadvantageous for industrial production.

In the method for producing a sialon phosphor of the present invention, the firing temperature is in the temperature range of 2000 ° C. or higher and 2400 ° C. or lower, preferably 2100 ° C. or higher and 2300 ° C. or lower. When the firing temperature is less than 2000 ° C. or exceeds 2400 ° C., a sialon phosphor exhibiting high luminance cannot be obtained.

Here, the sialon phosphor produced by the production method of the present invention is made of Ce, Pr, Nd, Pm, Sm, Eu, Tb , Ho , Er, Tm as an activator made of oxynitride containing Si. A compound containing at least one lanthanide metal selected from the group, and α-sialon is preferred because of its high luminance,
{M1 _(x1) , M2 _(x2) , M3 _(x3) } (Si, Al) ₁₂ (O, N) ₁₆ (1)
The oxynitride represented by these is preferable. However, _{M 1} in the formula is Li, _{M 2} is at least one element selected from the group consisting of Ca, Mg, 2 divalent lanthanide metal, _{M 3} is selected from the group consisting of Y, 3-valent lanthanide metals 1 or more, x1 is 0 or more and 2 or less, x2 is 0 or more and 2 or less, and x3 is greater than 0 and less than 2.

Moreover, since it is preferable that Ce is contained in the lanthanide metal of M ₃ , the composition formula;
An oxynitride represented by {M1 _(x1) , M2 _(x2) , M3 _(x3) , Ce _(x4) } (Si, Al) ₁₂ (O, N) ₁₆ (2) is preferable. However, _{M 1} in the formula is Li, _{M 2} is at least one element selected from the group consisting of Ca, Mg, 2 divalent lanthanide metal, _{M 3} from Y, 3-valent lanthanide metals (except for Ce) X1 is 0 or more and 2 or less, x2 is 0 or more and 2 or less, x3 is 0 or more and 2 or less, and x4 is greater than 0.2 and less than 1.2. is there.

Furthermore, in x1 = 0, since _{M 2} is Ca and _{M 3} is Y, 1 or more is preferably selected from the group consisting of lanthanide metals, the composition formula;
A sialon phosphor made of an oxynitride represented by {M _{2 (x 2)} , M _{3 (x 3)} , Ce _{(x 4)} } (Si, Al) ₁₂ (O, N) ₁₆ (3) is more preferable. However, _{M 2} in the formula is C a, _{M 3} is at least one element selected from the group consisting of trivalent lanthanide metal other than Y, and Ce, x2 is 0 to 2, x3 0 It is 2 or less and x4 is greater than 0.2 and less than 1.2.

In the method for producing a sialon phosphor of the present invention, Si, Al, Li, Ca, a metal compound that can be used to produce a mixture of metal compounds that can constitute sialon by firing. Among the compounds of Mg, Y, and lanthanide metals, compounds that generate oxides by decomposition reaction or oxidation reaction by firing, oxynitrides, and nitrides can be given. Examples of compounds that generate oxides by decomposition reaction or oxidation reaction by firing include carbonates, oxalates, nitrates, hydroxides, hydrous hydroxides, and oxyhydroxides.

  Most preferred as the Si compound and Al compound are silicon nitride and aluminum nitride, respectively, both of which are preferably powders having an average particle size of 1 μm or less. Silicon nitride can be used in the same manner regardless of whether it is α-type or β-type. In addition, 1 to 10% by weight of α-type or β-type sialon can be mixed in the mixture of metal compounds. In particular, when α-sialon powder is mixed with 1 to 10% by weight of raw material powder, the production ratio of α-sialon after firing is increased, and the emission intensity as a phosphor is also improved. This is because α-sialon powder grows around the added α-sialon powder as a nucleus. When the addition amount is 1% by weight or less, the effect of addition is small. Even if it is added in an amount of 10% by weight or more, the production rate of α-sialon does not improve any more, so 10% or less is desirable from an industrial point of view.

  For the mixing of these compounds, for example, a generally industrially used apparatus such as a ball mill, a vibration mill, a V-type mixer or a stirrer can be used. Next, the obtained mixture is fired under the above conditions. The furnace used for firing is a metal resistance heating method or a graphite resistance heating method because the firing temperature is high and the firing atmosphere is nitrogen, and an electric furnace using carbon as the material of the high temperature part of the furnace is suitable. .

  The sialon phosphor obtained by firing can be pulverized by an industrially used pulverizer such as a ball mill or a jet mill. It can also be washed and classified. Moreover, in order to further improve the brightness | luminance of the fluorescent substance obtained, rebaking can also be performed.

  The sialon phosphor obtained by the production method of the present invention exhibits higher luminance than the conventional sialon phosphor, and since the luminance of the phosphor is less decreased when exposed to an excitation source, VFD, FED, PDP, CRT, It is a sialon phosphor suitable for white LEDs and the like.

  Next, the present invention will be described in more detail with reference to the following examples, which are disclosed as an aid for easy understanding of the present invention, and the present invention is limited to these examples. It is not a thing.

Example 1;
In order to obtain a compound represented by the composition formula Ce _0.5 (Si, Al) ₁₂ (O, N) ₁₆ , the average particle size is 0.5 μm, the oxygen content is 0.93% by weight, and the α-type content is 92%. Silicon nitride powder, aluminum nitride powder, and cerium oxide were weighed to be 71.89 wt%, 14.54 wt%, 13.57 wt%, respectively, and silicon nitride powder, aluminum nitride powder, and cerium oxide Y-containing α-sialon powder in an amount of 5 parts by weight when the total amount was 100 parts by weight was mixed for 2 hours with a wet ball mill using n-hexane. N-Hexane was removed by a rotary evaporator, and the resulting mixture was molded by applying a pressure of 20 MPa using a mold to obtain a molded body having a diameter of 12 mm and a thickness of 5 mm. This compact was placed in a boron nitride crucible and set in a graphite resistance heating type electric furnace. First, the firing atmosphere is evacuated with a diffusion pump, heated from room temperature to 800 ° C. at a rate of 500 ° C. per hour, nitrogen at 500 ° C. is introduced with a purity of 99.9% by volume, and the pressure is set to 30 MPa. The temperature was raised to 2200 ° C. at 500 ° C. and held at 2200 ° C. for 2 hours. After firing, the resulting product was pulverized using an agate mortar, and the X-ray diffraction pattern of the obtained powder was examined. As a result, it was found that α sialon was produced. As a result of irradiating the powder with a lamp emitting light having a wavelength of 365 nm, it was confirmed that the powder emitted blue light.
As a result of measuring the absorption spectrum and emission spectrum of this powder using a fluorescence spectrophotometer, this powder has an excitation spectrum peak at 370 nm as shown in FIG. It was found that the phosphor had a peak in blue light of 480 nm as shown in FIG. The emission intensity by excitation with ultraviolet light at 365 nm was 42000.
Normally, Ce Ru only Ah is difficult to synthesize alpha sialon containing, according to the present method of applying alpha sialon powder in the raw material powder, alpha sialon powder added is a nuclear for crystal growth Thus, the production rate of α sialon after firing was improved.

Examples 2-8;
It carried out like Example 1 except not mixing Y content alpha type sialon powder with a raw material. In order to obtain the metal species M shown in Table 1 and the α-sialon having the content x, the raw materials were mixed according to the weight shown in Table 1 and fired under the firing conditions shown in Table 2.
The produced phase was investigated about the obtained powder. As shown in Table 2, the formation phase of each compound was α-sialon. Further, it was confirmed that the powder emitted blue light as a result of irradiation with a lamp emitting light having a wavelength of 365 nm. The powder results of excitation and emission spectra were measured using a fluorescence spectrophotometer, the powder, as shown in FIG. 2, showing a high strength emits blue light having a peak around 480 nm. In addition, Table 2 shows the light emission intensity due to ultraviolet excitation at 365 nm.

The sialon phosphor of the present invention is excited by an excitation source and emits blue light. The sialon phosphor obtained by the production method of the present invention exhibits a higher luminance than the conventional sialon phosphor, and there is little decrease in the luminance of the phosphor when exposed to an excitation source. Such a sialon phosphor is industrially extremely useful because it is suitable for VFD, FED, PDP, CRT, white LED, and the like.

Excitation spectrum of Ce-containing α-type sialon (Example 1) Fluorescence spectrum of Ce-containing α-sialon (Example 1)

Claims (6)

One or more lanthanide metals selected from the group consisting of Ce, Pr, Nd, Pm, Sm, Eu, Tb, Ho, Er, and Tm as an activator in an oxynitride containing Si, Al, O, and N A sialon phosphor containing:
Composition formula;
{M1 _(x1) , M2 _(x2) , M3 _(x3) , Ce _(x4) } (Si, Al) ₁₂ (O, N) ₁₆
[In the formula, M ₁ is Li, M ₂ is one or more selected from the group consisting of Ca, Mg and divalent lanthanide metals, and M ₃ is Y and trivalent lanthanide metal (Ce And x1 is 0 or more and 2 or less, x2 is 0 or more and 2 or less, x3 is 0 or more and 2 or less, and x4 is larger than 0.2. 2 or less], and emits blue light from an excitation source . x1 = 0, _{M 2} is equal to or Ca, _{M 3} is Y, sialon phosphor according to claim 1. The sialon phosphor according to claim 1 or 2, wherein the excitation source is an ultraviolet ray.   The sialon phosphor according to any one of claims 1 to 3, wherein the blue light has a peak around 480 nm. The sialon phosphor according to any one of claims 1 to 4, wherein the sialon is α sialon . It is a white light emitting diode using fluorescent substance, Comprising: The said fluorescent substance contains the sialon fluorescent substance as described in any one of Claims 1-5, The white light emitting diode characterized by the above-mentioned.

Images