JP6256868B2 - Method for producing red silicon oxynitride phosphor - Google Patents

Description

The present invention relates to the production how red silicon oxynitride phosphor using silicon oxide as a raw material.

Silicon oxynitride phosphors have attracted attention as LED phosphors. Among these, the red silicon oxynitride phosphor is indispensable for maintaining the high color rendering properties of the white LED. Conventionally, in the production of a phosphor containing oxygen as a constituent element together with silicon and nitrogen, and a phosphor containing silicon and nitrogen as a constituent element, generally silicon nitride (Si ₃ N ₄ ) or silicon dioxide ( SiO ₂ ) has been used. However, since the reactivity of these raw material powders is low, in order to promote the solid-phase reaction between the raw material mixed powders at the time of firing, compression molding is performed at a high temperature, that is, the contact area between the raw material powders is increased and heated Therefore, a very hard sintered body is produced. Therefore, the sintered body obtained in this way needs to be pulverized to a fine powder state suitable for the intended use of the phosphor. However, when a phosphor made of a hard sintered body is pulverized over a long period of time and with a large amount of energy using an ordinary mechanical pulverization method such as a jaw crusher or a ball mill, many defects are present in the crystal matrix of the phosphor. Has occurred, resulting in the disadvantage of significantly reducing the emission intensity of the phosphor.

For this reason, a method of firing in a powder state without compression molding at the time of heating has been attempted, but when conventional raw materials such as silicon nitride (Si ₃ N ₄ ) or silicon dioxide (SiO ₂ ) are used, at a low temperature, Since the target phosphor is not generated without promoting the solid-phase reaction between the raw material nitride powders, it is necessary to synthesize the phosphor at a high temperature of 1,800 ° C. or higher. However, when firing at a high temperature, there arises a disadvantage that a decomposition reaction accompanied by desorption of nitrogen from the nitride raw material occurs. Therefore, it is necessary to perform firing in a nitrogen gas atmosphere of 5 atm or more for the purpose of suppressing it. In addition, not only high firing energy is required, but also a very expensive high-temperature high-pressure firing furnace is required, which increases the manufacturing cost of the phosphor.
Note that in order to obtain a uniform phosphor from a low-reactivity starting material, it is necessary to repeat firing and pulverization many times, resulting in a large production load and a high risk of contamination with impurities. Impurity contamination is directly linked to a decrease in fluorescence characteristics, and must be reduced as much as possible.

On the other hand, (CaAlSiN ₃ ) _1-y (Si ₂ N ₂ O) _y phosphor activated by Eu known as a phosphor for white LEDs has high luminance due to its emission of orange or red light. It is known that a white light-emitting device having a luminous efficiency and rich in reddish components can be obtained (Patent Document 1: JP 2012-153737 A). The red phosphor is characterized in that the emission wavelength and emission peak width can be adjusted by changing the value of y. Since the visibility is increased by reducing the wavelength of the emission peak, the luminous flux is remarkably increased and the color reproduction range can be arbitrarily changed, and a light emitting device having a high degree of freedom can be obtained. However, as described above, the firing conditions require a high reaction temperature of 1,800 to 2,000 ° C. and a high pressure atmosphere of 5 atm or more.
In addition, the following literature is mentioned with the literature mentioned above as a prior art relevant to this invention.

JP 2012-153737 A JP 2007-231245 A

  The present invention has been made in view of the above circumstances, and provides a method for efficiently producing a silicon oxynitride phosphor at a low temperature using a more reactive starting material. Thus, an object of the present invention is to provide a phosphor having good fluorescence characteristics.

As a result of intensive investigations to achieve the above object, the present inventors have found that when producing a silicon oxynitride phosphor, SiO _x (wherein x satisfies 0.8 <x <1.2). If silicon oxide represented by) is used as a starting material and a compound of a metal element necessary as a phosphor is baked and reacted together with this silicon oxide, this silicon oxide is highly reactive at low temperatures. As compared with the case of firing using (Si ₃ N ₄ ) or silicon dioxide (SiO ₂ ), it has been found that synthesis can be performed at normal pressure and low temperature, and the production load is reduced. As a result, it has been found that a phosphor having good fluorescence characteristics can be obtained, and the present invention has been made.

Accordingly, the present invention provides a manufacturing how the following red silicon oxynitride phosphor.
[1]
A mixture of a raw material mixture containing at least Eu , Ca and Al , and optionally containing Si, and silicon oxide represented by SiO _x (where x satisfies 0.8 <x <1.2). The following formula ( Eu _a Ca _1-a AlSi N ₃ ) _1-c ( Si _{(3b + 2) / 4} N _b O) _c
(In the formula , a is 0 <a ≦ 0.1, b and c are numbers satisfying 0 ≦ b, 0 <c <0.375, 0.002 ≦ (3b + 2) c / 4 ≦ 0.9. .)
The manufacturing method of the red silicon oxynitride fluorescent substance represented by these.
[2]
The silicon oxide represented by SiO _x (wherein _x satisfies 0.8 <x <1.2) is 1 to 27 mol% in the raw material containing a tetravalent metal element [1] A method for producing a phosphor.
[3]
The method for producing a phosphor according to [1] or [2], wherein firing is performed at a temperature of 1,400 ° C. or more and less than 1,800 ° C. in an atmosphere of a gas containing nitrogen.
[4]
Baking is performed under a normal pressure, The manufacturing method of the fluorescent substance in any one of [1]-[3] characterized by the above-mentioned.
[ 5 ]
It consists of Eu ₂ O ₃ , Ca ₃ N ₂ , AlN, Si ₃ N ₄ and SiO _x (where x satisfies 0.8 <x <1.2), and SiO _x is a tetravalent metal element. The method for producing a phosphor according to any one of [1] to [ 4 ], wherein a starting material is a starting material containing 1 to 27 mol% of the starting material.
[ 6 ]
Depending on the content of silicon oxide represented by SiO _x (where x satisfies 0.8 <x <1.2), the emission peak wavelength excited by light having a wavelength of 450 nm of the obtained phosphor is changed. It controls in the range of 570-650 nm, The manufacturing method of the fluorescent substance in any one of [1]-[ 5 ] characterized by the above-mentioned .

ADVANTAGE OF THE INVENTION According to this invention, the fluorescent substance which has a favorable fluorescence characteristic as a fluorescent substance of a silicon oxynitride can be efficiently manufactured at low temperature and a normal pressure.
Conventionally, it has been impossible to synthesize a red phosphor having high crystallinity in a low temperature region around 1,600 ° C. However, in this production method, high crystallinity is achieved by making the raw material highly reactive. It became possible to obtain a red phosphor.

As a prior art, a method for producing an oxynitride phosphor or an oxide phosphor using Si ₂ N ₂ O has been disclosed (Patent Document 2: Japanese Patent Application Laid-Open No. 2007-231245). The prior art is a technique for synthesizing an oxynitride phosphor having a high oxygen-nitrogen ratio (O / N ratio) at a lower temperature, such as Eu-activated CaSi ₂ O ₂ N ₂ or Ba ₃ Si ₆ O ₁₂ N _2. This is a very promising technique for synthesizing oxynitride phosphors.
As a difference between the prior art and the present production method, an oxide phosphor having a low acid-nitrogen ratio can be synthesized at a low temperature. For that purpose, it is necessary to use SiO _x instead of Si ₂ N ₂ O as a raw material to be used. This is because SiO _x is more reactive than Si ₂ N ₂ O. In addition, since Si ₂ N ₂ O can be synthesized by reacting SiO _x with nitrogen, the use of SiO _x makes it easy to incorporate nitrogen into the compound.

It is an XRD pattern of the phosphor of Example 1 and Comparative Example 1. It is the excitation spectrum and emission spectrum of the fluorescent substance of Example 1 and Comparative Example 1. 3 is an XRD pattern of the phosphor of Example 2. FIG. It is the excitation spectrum and emission spectrum of the phosphor of Example 2. 3 is an XRD pattern of the phosphor of Example 3. FIG. It is the excitation spectrum and emission spectrum of the fluorescent substance of Example 3. It is an XRD pattern of the phosphor of Example 4 and Comparative Example 4. It is the excitation spectrum and emission spectrum of the fluorescent substance of Example 4 and Comparative Example 4.

Hereinafter, the present invention will be described in detail.
The present invention is represented by the following formula (L _a M ^I _1-a M ^II M ^III N ₃ ) _1-c (M ^III _{(3b + 2) / 4} N _b O) _c
The red silicon oxynitride phosphor, which contains at least L, M ^I and M ^II , and if necessary, a raw material mixture containing M ^IV , It is manufactured by firing a mixture of silicon oxide represented by SiO _x .

  However, L is one or more elements selected from the group consisting of rare earth elements and Mn. Specifically, Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er , One or more elements selected from the group consisting of Tm, Yb, etc., among others, one type selected from the group consisting of Mn, Ce, Sm, Eu, Tb, Dy, Er, Yb or Two or more elements are preferable, Eu is more preferably included, and Eu is still more preferable.

M ^I is at least one selected from alkaline earth metals, and specifically includes one or more elements selected from the group consisting of Be, Mg, Ca, Sr, Ba, and Ra. However, among these, one or more elements selected from the group consisting of Mg, Ca, Sr, and Ba are preferable, and Ca is more preferable.

M ^II is one or more elements selected from the group consisting of trivalent metal elements, and among them, selected from the group consisting of B, Al, Ga, In, Sc, Y, La, Gd, and Lu. It is preferable that it is 1 type, or 2 or more types of elements, and it is still more preferable that it is Al.

M ^III is one or more elements selected from the group consisting of tetravalent metal elements containing silicon atoms, and among them, Si alone or a group consisting of Si and Ge, Sn, Ti, Zr, Hf It is preferably two or more elements selected from the group consisting of Si, and more preferably Si.

M ^IV is one or more elements selected from the group consisting of tetravalent metal elements, and among them, one or two elements selected from the group consisting of Si, Ge, Sn, Ti, Zr, and Hf. The above elements are preferable, and Si is more preferable.

  Further, a is a value satisfying 0 <a ≦ 0.1. From the viewpoint of the emission intensity of the phosphor, 0.001 ≦ a ≦ 0.1 is preferable, and 0.003 ≦ a ≦ 0.05 is more preferable. When a exceeds 0.1, concentration quenching occurs, and when it falls below 0.001, light emission may be insufficient.

b is 0 ≦ b, and preferably 0 ≦ b ≦ 5.
c is 0 <c <0.375, preferably 0.1 ≦ c ≦ 0.333, and more preferably 0.2 ≦ c ≦ 0.3. In the production method of the present invention, may be used a raw material containing M ^IV, when using a raw material containing M ^IV, c is preferably 0.1 or more 0.333 or less, 0.1 or 0 Is less than .333, more preferably 0.2 or more and 0.3 or less. If the value of c is too small, the reactivity may decrease and unreacted substances may remain. If the value of c is too large, the amount of oxygen may increase and Ca-SiAlON, which is an impurity, may be generated as a main component.

  B and c are numbers satisfying 0.002 ≦ (3b + 2) c / 4 ≦ 0.9. If the value of (3b + 2) c / 4 is less than 0.002 or exceeds 0.9, the structure may be unstable and the target product may not be generated. Even if it is obtained, high luminance may not be obtained. is there.

The phosphor of the present invention is a silicon oxynitride phosphor, and is manufactured by firing a raw material containing silicon oxide represented by SiO _x as a starting material. x is a number satisfying 0.8 <x <1.2, and preferably 0.9 <x <1.1. When x is 0.8 or less, the characteristic as metallic silicon (Si) becomes strong and the reactivity may be lowered. When x is 1.2 or more, the characteristic as silicon dioxide becomes strong and the reactivity is lowered. There is a risk.

In the production method of the present invention, as described above, firing is performed by mixing a raw material mixture containing at least L, M ^I and M ^II , and optionally containing M ^IV, and silicon oxide represented by SiO _x. It is characterized by. That is, in the present invention, a raw material starting from the above-described silicon oxide, a metal compound that provides a luminescent ion that is essential as a phosphor, and a compound that includes a metal contained in the phosphor's mother crystal is fired. Manufacturing phosphors. Here, examples of the metal compound that gives luminescent ions include a raw material containing L, that is, a rare earth element or a compound of Mn, and the compound containing a metal contained in the host crystal of the phosphor includes a raw material containing M ^I , That is, examples include compounds of alkaline earth metals (Group 2 elements of the periodic table), raw materials containing M ^II, that is, compounds of trivalent metal elements, and raw materials containing M ^IV, that is, compounds of tetravalent metal elements. . Silicon oxide represented by SiO _x is also a compound containing a metal contained in the mother crystal of the phosphor. By using these compounds, the phosphor contains a metal corresponding to its composition.

  As these compounds, conventionally known compounds used in the production of phosphors such as oxides, nitrides, carbonates, hydroxides, oxalates, nitrates, chlorides, acetates, and organic acid salts are used. Can do.

Specifically, as a raw material containing L (rare earth element or Mn compound), a metal L (particularly europium) nitride, oxide, carbonate, chloride, nitrate is preferable. For example, europium nitride (EuN), Europium oxide (EuO, Eu ₂ O ₃ ), europium carbonate (EuCO ₃ , Eu ₂ (CO ₃ ) ₃ ), europium chloride (EuCl ₂ , EuCl ₃ ), europium nitrate (Eu (NO ₃ ) ₂ , Eu (NO _{3) 3} ) and the like, and Eu ₂ O ₃ is preferable.

The raw material containing M ^I (alkaline earth metal compound) is preferably a metal M ^I (especially calcium) nitride, hydroxide, oxide or carbonate, particularly preferably calcium nitride (Ca _3). N ₂ ), calcium oxide (CaO), calcium carbonate (CaCO ₃ ), and more preferably Ca ₃ N ₂ .

As a raw material containing M ^II (a compound of a trivalent metal element), a nitride, oxide, carbonate, chloride, or nitrate of metal M ^II (particularly aluminum) is preferable. For example, aluminum nitride (AlN), oxidation Aluminum (Al ₂ O ₃ ), aluminum carbonate (Al ₂ (CO ₃ ) ₃ ), aluminum chloride (AlCl ₃ ), aluminum nitrate (Al (NO ₃ ) ₃ ) and the like can be mentioned, and AlN is more preferable. These raw materials may be used alone or in combination.

As the raw material (compound of tetravalent metal element) containing M ^IV , a nitride or oxide of metal M ^III (especially silicon) is preferable. For example, silicon nitride (Si ₃ N ₄ ), silicon dioxide (SiO ₂ ) Etc., and Si ₃ N ₄ is preferable. However, SiO _x is not included in the raw material containing M ^IV .

The raw material containing L, M ^I , M ^II and M ^IV and the silicon oxide represented by SiO _x have an element ratio of L, M ^I , M ^II and M ^III supplied from each raw material represented by the following formula (L _a M ^I _1-a M ^II M ^III N ₃ ) _1-c (M ^III _{(3b + 2) / 4} N _b O) _c
In the red silicon oxynitride phosphor represented by the formula, they are mixed within a range satisfying the relationship of a, b, and c.
Specifically, a, b, and c in the above formula are 0.0 <a ≦ 0.1, 0 <b, 0 <c <0.375, 0.001 ≦ a ≦ 0.1, 0 <b ≦ 11.3 and 0.1 ≦ c ≦ 0.333 are preferable, and more preferably, a = 0.02, b = 2, and c = 0.25.

In the production method of the present invention, the peak of the emission wavelength excited by light having a wavelength of 450 nm of the obtained phosphor is preferably in the range of 570 to 650 nm, more preferably 580 to 620 nm, depending on the blending amount of SiO _x. Can be controlled. By increasing the amount of SiO _{x, the} phosphor can be shifted to the lower wavelength side, and a phosphor with higher visibility can be obtained. However, if the addition amount is too large, a CaSiAlON phase may be generated as an impurity. When the addition amount is small, the effect of SiO _x is lowered, and thus there is a possibility that unreacted raw materials remain. Therefore, the amount of SiO _x added is preferably 1 to 27 mol%, more preferably 10 to 25 mol%, and still more preferably 18 to 22 mol% in the raw material containing a tetravalent metal element.

A conventionally known method can be applied as a firing method for manufacturing the phosphor. Specifically, for example, a silicon oxide powder represented by SiO _x and a powder of a metal compound (a raw material containing L, M ^I , M ^II , and M ^IV ) are mixed and pulverized as necessary to obtain carbon. After being placed in a tray made of aluminum, made of boron nitride, alumina, etc., it is placed in a reaction furnace, and atmospheric gas is circulated in the reaction furnace and heated at a predetermined temperature for a predetermined time.

The firing condition is a nitrogen gas-containing atmosphere, the temperature range is 1,400 ° C. or more and less than 1,800 ° C., and considering that the nitriding reaction proceeds more efficiently, 1,600 ° C. or more and 1,800 ° C. Less than is preferable. When the firing temperature is less than 1,400 ° C., the reaction does not end, and Ca-α-SiAlON that is not the target product may be produced. Further, at a firing temperature of 1,800 ° C. or higher, the raw material nitride may be decomposed.
Although it does not specifically limit about baking time, The baking for 0.5 to 6 hours, especially 2 to 4 hours is preferable. If it is less than 0.5 hours, unreacted raw materials may remain. If firing for more than 6 hours does not change the characteristics of the phosphor obtained, the manufacturing cost increases.

The firing atmosphere is not particularly limited as long as it is in a non-oxidizing atmosphere containing nitrogen gas (N ₂ gas). In addition to the nitrogen gas alone atmosphere, the pressure is controlled for the purpose of controlling reactivity, for example. And an atmosphere in which a non-oxidizing gas such as Ar, H ₂ , and He is mixed with the nitrogen gas for the purpose of adjusting the nitrogen partial pressure. In view of cost, firing in a nitrogen atmosphere is preferable. It is also possible to promote the reduction effect by switching from a nitrogen atmosphere to a nitrogen-hydrogen atmosphere during firing.
In the present invention, it can be produced under normal pressure.

  The product thus obtained is pulverized as necessary to form a powder. Moreover, the process of baking the obtained powder by the same method again can be repeated as many times as necessary. The production method is not particularly limited, and the reaction can be performed by a continuous method or a batch method. In addition, annealing firing in which a material fired in a nitrogen atmosphere is fired in a nitrogen-hydrogen atmosphere in order to enhance the reducing property is also possible.

In particular, in the present invention, a raw material composed of AlN, Si ₃ N ₄ , Eu ₂ O ₃ , Ca ₃ N ₂ , and SiO _x is used, and SiO _x is 1 to 27 mol% in a raw material containing a tetravalent metal element. It is preferable to use a certain mixture as a starting material and to produce the mixture by the above-described method. The following formula (Eu _a Ca _1-a AlSiN ₃ ) _1-c (Si _{(3b + 2) / 4} N _b O) _c
(Wherein a, b and c are the same as above)
The wavelength of the phosphor that is excited by light having a wavelength of 450 nm and emits light is 650 nm or less.

Ca-α-SiAlON is also a very promising yellow phosphor for LEDs, and is not an object of the present invention, but can be synthesized by this production method. The Ca-alpha-SiAlON may be prepared by synthesizing in excess addition of SiO _x or more solid solution amount of SiO _x.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In the following example, XRD (X-ray diffraction) measurement of the phosphor and identification of the sample after firing were performed using a powder X-ray diffractometer (MX-Labo, manufactured by Mac Science Co., Ltd.). A spectrofluorophotometer (JASCO Corporation, FP-6500) was used for the measurement of the spectrum.

[Example 1, Comparative Example 1]
The influence of the addition condition of Si ₃ N ₄ and SiO _x on the phosphor characteristics was evaluated.
Specifically, (Eu _0.02 Ca _0.98 AlSiN ₃ ) _1-c (Si ₂ N ₂ O) _c is a raw material at a stoichiometric ratio such that the c value is 0.143, 0.250, 0.333. What weighed was made into Example 1-1-Example 1-3, respectively. In addition, the one obtained by adding only Si ₃ N ₄ (c = 0.000) and baking without adding SiO _x at all is referred to as Comparative Example 1-1, and the above c values are 0.375 and 0.500. The raw materials weighed at such a stoichiometric ratio were referred to as Comparative Examples 1-2 and 1-3, respectively. Detailed values such as c value, raw material ratio, SiO _x molar ratio are shown in Table 1.

In addition to Ca ₃ N ₂ (Pacific Cement Co., Ltd.), Eu ₂ O ₃ (Shin-Etsu Chemical Co., Ltd.) and AlN (Tokuyama Co., Ltd.), SiO _x (x = 1.02) (Shin-Etsu Chemical Co., Ltd.) )) Or Si ₃ N ₄ (Ube Industries, Ltd.). Each raw material other than the above-mentioned Ca ₃ N _{2 was} weighed according to the stoichiometric ratio and mixed in an agate mortar. After mixing, Ca ₃ N ₂ was dry mixed in a glow box. After mixing all the raw materials, the mixture was placed on a carbon boat, placed in a furnace and baked. In the firing operation, first, the firing atmosphere was evacuated by a vacuum pump, and nitrogen having a purity of 99.99% by volume was introduced to normal pressure. After completion of the nitrogen substitution, the temperature was raised from room temperature to 1,600 ° C. at a rate of 200 ° C. per hour and held at the target temperature for 2 hours.
After firing, the obtained fired body was roughly pulverized, and then manually pulverized using an agate mortar to obtain a phosphor, and the phosphor was measured.

The obtained phosphor was analyzed by XRD (X-ray diffraction). The results are shown in FIG. As a result of identification by XRD, the crystal structure of CaAlSiN ₃ was detected. However, in Comparative Example 1-1, since the half width of the X-ray peak is wide, the crystallinity is low and unreacted AlN remains. In Comparative Examples 1-2 and 1-3, impurities were present.
FIG. 2 is a diagram showing excitation emission spectra of (Eu _0.02 Ca _0.98 AlSiN ₃ ) _1-c (Si ₂ N ₂ O) _c produced in Example 1 and Comparative Example 1. In FIG. 2, the curve group drawn on the left side shows an excitation spectrum under each test condition, and the curve group drawn on the right side shows an emission spectrum when excited at 450 nm. FIG. 2 shows that this phosphor has absorption in the vicinity of 450 nm, which is the emission region of the blue LED, and emits red light having a peak in the vicinity of a wavelength of 610 nm, which is the target (Eu _0.02 Ca _0.98 AlSiN ₃ ). _It can be determined that _1-c (Si ₂ N ₂ O) _c emits light. The light emission intensity was improved under all the conditions where SiO _x was added. When c = 0.250 (Example 1-2), the light emission intensity in Comparative Example 1-1 was about 2.6 times. . Further, the peak wavelength is shifted by changing the addition amount of SiO _x .

[Example 2]
The influence of the firing temperature on the phosphor characteristics was evaluated.
Specifically, in Example 1-2, the firing temperature was changed to 1,400 ° C., 1,500 ° C., 1,600 ° C. did. The addition amount of Si ₃ N ₄ and SiO _x was set to c = 0.250, which showed good results in Example 1. Detailed values such as the c value, the ratio of each raw material, and the firing temperature are shown in Tables 1 and 2.

In addition to Ca ₃ N ₂ (Pacific Cement Co., Ltd.), Eu ₂ O ₃ (Shin-Etsu Chemical Co., Ltd.) and AlN (Tokuyama Co., Ltd.), SiO _x (x = 1.02) (Shin-Etsu Chemical Co., Ltd.) )) And Si ₃ N ₄ (Ube Industries, Ltd.). Each raw material other than the above-mentioned Ca ₃ N _{2 was} weighed according to the stoichiometric ratio and mixed in an agate mortar. After mixing, Ca ₃ N ₂ was dry mixed in a glow box. After mixing all the raw materials, the mixture was placed on a carbon boat, placed in a furnace and baked. In the firing operation, first, the firing atmosphere was evacuated by a vacuum pump, and nitrogen having a purity of 99.99% by volume was introduced to normal pressure. After completion of the nitrogen substitution, the temperature was raised from room temperature to 1,400 ° C., 1,500 ° C., or 1,600 ° C. at a rate of 200 ° C. per hour and held at the target temperature for 2 hours.
After firing, the obtained fired body was roughly pulverized, and then manually pulverized using an agate mortar to obtain a phosphor, and the phosphor was measured.

The obtained phosphor was analyzed by XRD (X-ray diffraction). The results are shown in FIG. As a result of identification by XRD, the crystal structure of CaAlSiN ₃ was detected under the conditions of all the examples. The sample (Example 2-1) at 1,400 ° C. is mixed with Ca-α-SiAlON, and 1,400 ° C. is considered the lower limit.
FIG. 4 is a diagram showing an excitation emission spectrum of (Eu _0.02 Ca _0.98 AlSiN ₃ ) _1-c (Si ₂ N ₂ O) _c produced in Example 2. In FIG. 4, the curve group drawn on the left side shows an excitation spectrum under each test condition, and the curve group drawn on the right side shows an emission spectrum when excited at 450 nm. In any condition baked at 1,400 to 1,600 ° C., red light emission is shown, and it can be confirmed that the target product was produced. Further, the emission intensity was improved as the temperature was increased.

[Example 3]
The influence of the firing time on the phosphor characteristics was evaluated.
Specifically, in Example 1-2, the example in which the firing time was set to 12 hours was changed to Example 3-1 or 2 hours, the example 3-2 was changed to 0.5 hours, and the example 3 was set. -3. The addition amount of Si ₃ N ₄ and SiO _x was set to c = 0.250, which showed good results in Example 1. Detailed values such as the c value, the ratio of each raw material, and the firing time are shown in Tables 1 and 3.

In addition to Ca ₃ N ₂ (Pacific Cement Co., Ltd.), Eu ₂ O ₃ (Shin-Etsu Chemical Co., Ltd.) and AlN (Tokuyama Co., Ltd.), SiO _x (x = 1.02) (Shin-Etsu Chemical Co., Ltd.) )) And Si ₃ N ₄ (Ube Industries, Ltd.). Each raw material other than the above-mentioned Ca ₃ N _{2 was} weighed according to the stoichiometric ratio and mixed in an agate mortar. After mixing, Ca ₃ N ₂ was dry mixed in a glow box. After mixing all the raw materials, the mixture was placed on a carbon boat, placed in a furnace and baked. In the firing operation, first, the firing atmosphere was evacuated by a vacuum pump, and nitrogen gas having a purity of 99.99% by volume was introduced to normal pressure. After completion of the nitrogen gas replacement, the temperature was raised from room temperature to 1,600 ° C. at a rate of 200 ° C. per hour and held at the target temperature for 0.5 hour or 12 hours.
After firing, the obtained fired body was roughly pulverized, and then manually pulverized using an agate mortar to obtain a phosphor, and the phosphor was measured.

The obtained phosphor was analyzed by XRD (X-ray diffraction). The results are shown in FIG. As a result of identification by XRD, the crystal structure of CaAlSiN ₃ was detected under the conditions of all the examples. However, the sample (Example 3-3) having a firing time of 0.5 hours had an increase in unreacted AlN.
FIG. 6 is a diagram showing an excitation emission spectrum of (Eu _0.02 Ca _0.98 AlSiN ₃ ) _1-c (Si ₂ N ₂ O) _c produced in Example 3. In FIG. 6, the curve group drawn on the left side shows an excitation spectrum under each test condition, and the curve group drawn on the right side shows an emission spectrum when excited at 450 nm. All of these spectra were confirmed to emit red light. There was almost no difference in emission intensity between the phosphor baked for 12 hours (Example 3-1) and the phosphor baked for 2 hours (Example 3-2). In the case of baking for 0.5 hour (Example 3-3), a slight decrease in light emission intensity was confirmed, but it was determined that the level could be used and the target product was obtained.

[Example 4, Comparative Example 4]
The influence of the firing atmosphere on the phosphor characteristics was evaluated.
Specifically, in Example 1-2 and Comparative Example 1-3, the firing atmosphere was changed to nitrogen hydrogen gas having a purity of 99.99% by volume and a hydrogen concentration of 5% by volume, respectively. -1 and Comparative Example 4-1. In addition, the addition amount of Si ₃ N ₄ and SiO _x in Example 4-1 is a stoichiometry such that the c value of (EuCaAlSiN ₃ ) _1-c (Si ₂ N ₂ O) _c is 0.250. In the comparative example, only Si ₃ N ₄ (c = 0.000) was added without adding any SiO _x . Detailed values such as the c value, the ratio of each raw material, and the firing atmosphere are shown in Tables 1 and 4.

In addition to Ca ₃ N ₂ (Pacific Cement Co., Ltd.), Eu ₂ O ₃ (Shin-Etsu Chemical Co., Ltd.) and AlN (Tokuyama Co., Ltd.), SiO _x (x = 1.02) (Shin-Etsu Chemical Co., Ltd.) )) Or Si ₃ N ₄ (Ube Industries, Ltd.). Each raw material other than the above-mentioned Ca ₃ N _{2 was} weighed according to the stoichiometric ratio and mixed in an agate mortar. After mixing, Ca ₃ N ₂ was dry mixed in a glow box. After mixing all the raw materials, the mixture was placed on a carbon boat, placed in a furnace and baked. First, the firing atmosphere was evacuated by a vacuum pump, and nitrogen hydrogen gas having a purity of 99.99% by volume and a hydrogen concentration of 5% by volume was introduced to normal pressure. After completion of the nitrogen-hydrogen gas replacement, the temperature was raised from room temperature to 1,600 ° C. at a rate of 200 ° C. per hour and held at the target temperature for 2 hours.
After firing, the obtained fired body was roughly pulverized, and then manually pulverized using an agate mortar to obtain a phosphor, and the phosphor was measured.

The obtained phosphor was analyzed by XRD (X-ray diffraction). The results are shown in FIG. As a result of identification by XRD, the crystal structure of CaAlSiN ₃ was detected under all conditions.
FIG. 8 is a diagram showing excitation emission spectra of (Eu _0.02 Ca _0.98 AlSiN ₃ ) _1-c (Si ₂ N ₂ O) _c produced in Example 4 and Comparative Example 4. In FIG. 8, the curve group drawn on the left side shows an excitation spectrum under each test condition, and the curve group drawn on the right side shows an emission spectrum when excited at 450 nm. It was confirmed that all of these spectra emitted red light. From this result, it was confirmed that the firing atmosphere does not affect the phosphor characteristics.

  From the above description, it has been clarified that if the manufacturing method of the present invention is used, a red silicon oxynitride phosphor can be manufactured under low temperature and normal pressure conditions, and a manufacturing method can be provided at a low cost. .

Claims (6)

A mixture of a raw material mixture containing at least Eu , Ca and Al , and optionally containing Si, and silicon oxide represented by SiO _x (where x satisfies 0.8 <x <1.2). The following formula ( Eu _a Ca _1-a AlSi N ₃ ) _1-c ( Si _{(3b + 2) / 4} N _b O) _c
(In the formula , a is 0 <a ≦ 0.1, b and c are numbers satisfying 0 ≦ b, 0 <c <0.375, 0.002 ≦ (3b + 2) c / 4 ≦ 0.9. .)
The manufacturing method of the red silicon oxynitride fluorescent substance represented by these. 2. The silicon oxide represented by SiO _x (wherein _x satisfies 0.8 <x <1.2) is 1 to 27 mol% in a raw material containing a tetravalent metal element. A method for producing a phosphor.   The method for producing a phosphor according to claim 1 or 2, wherein firing is performed at a temperature of 1,400 ° C or higher and lower than 1,800 ° C in an atmosphere of a gas containing nitrogen.   The method for producing a phosphor according to any one of claims 1 to 3, wherein the firing is performed under normal pressure. It consists of Eu ₂ O ₃ , Ca ₃ N ₂ , AlN, Si ₃ N ₄ and SiO _x (where x satisfies 0.8 <x <1.2), and SiO _x is a tetravalent metal element. The method for producing a phosphor according to any one of claims 1 to 4 , wherein a starting material is a starting material containing 1 to 27 mol% of the starting material. Depending on the content of silicon oxide represented by SiO _x (where x satisfies 0.8 <x <1.2), the emission peak wavelength excited by light having a wavelength of 450 nm of the obtained phosphor is changed. The method for producing a phosphor according to any one of claims 1 to 5 , wherein the phosphor is controlled in a range of 570 to 650 nm .

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