JPH11158464A - Manganese-activated germanate phosphor and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a manganese-activated germanate phosphor having a large primary particle diameter and high luminance and being free from agglomerations of fine particles. SOLUTION: A manganese-activated germnanate phosphor having a large primary particle diameter and being free from agglomerates of fine particles can be obtained by using magnesium oxide as a starting material and firing the material while regularly or irregularly agitating a container 1 in which the material is placed or while agitating the material by means of an external agitation means. Further, a manganese-activated germanate phosphor having a large primary particle diameter even when the amount of the manganese activator is large can be obtained by firing only the matrix of a phosphor, mixing the fired matrix with a manganese compound, and re-firing the mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a deep red phosphor used in a fluorescent lamp and a method of manufacturing the same.

[0002]

2. Description of the Related Art A red phosphor used for a fluorescent lamp is disclosed in, for example, the 1989 National Meeting of the Illuminating Engineering Institute, 337 pages of proceedings. According to this, in order to improve the color rendering properties for red, it is considered that deep red, in which the red light-emitting component is on the longer wavelength side, is preferable, and a manganese-activated germanic acid phosphor is introduced.

The composition of a manganese-activated germanic acid phosphor is as follows:
For example, a phosphor handbook (edited by Phosphors Society of Japan, 198
(December 7), page 231. According to this, the composition formula of this phosphor is represented by 3.5MgO.0.5MgF ₂ .GeO ₂ : Mn ⁴⁺ , and the activation amount of manganese is 1 atomic% with respect to germanium.

[0004] In addition, firing is performed by mixing magnesium oxide, magnesium fluoride, germanium oxide and manganese carbonate, firing in air at 1000 ° C for several hours, then pulverizing the mixture, and firing in air at 1200 ° C for more than 10 hours. It has been done.

[0005] However, magnesium carbonate, which is advantageous in terms of cost, has been used as the raw material for the phosphor instead of magnesium oxide.

[0006]

However, the manganese-activated germanic acid phosphor fired by such a method is 1 μm.
It is an aggregate of small particles of about m. Therefore, the crystallinity is low and the brightness is low as compared with those having large primary particles and little aggregation.

Further, in order to eliminate a difference in color at the end of a tube when a plurality of phosphors are applied to a glass tube, as in a three-wavelength band fluorescent lamp, it is necessary to adjust the specific gravity by changing the particle size of each phosphor. is there. For this reason, it is necessary to pulverize the aggregate in accordance with the specific gravity of the other phosphor to be mixed, and the brightness is further reduced due to the crushing of the crystal due to excessive pulverization.

In addition, since the manganese compound acts as a flux, the particle size of the phosphor changes greatly depending on the amount of manganese activation, and the phosphor becomes smaller as the amount of manganese activation increases. For example, when the manganese activation amount is 0.1 atomic% based on germanium atoms, the particle size of the primary particles is 5 μm.
m, whereas 1
In the case of about atomic%, the particle diameter of the primary particles becomes as small as about 1 μm.

[0009] Further, most fluorescent lamp phosphors generally have a particle size of about 3 μm to 5 μm, and each of them contains almost no aggregate of fine particles. Is less dispersible in the slurry than other phosphors.

The present invention has been made in order to overcome the problems of the conventional phosphor, and the primary particles are large and have high brightness, the particle size is almost the same as other phosphors, and the aggregation of fine particles is small. An object of the present invention is to provide a phosphor containing no aggregate and a manufacturing method.

[0011]

In order to achieve the above object, a manganese-activated germanic acid phosphor of the present invention comprises a magnesium compound which becomes magnesium oxide by heating, magnesium fluoride, germanium oxide, and a manganese compound. A manganese-activated germanic acid phosphor characterized by having a particle size of 2 μm or more and containing no aggregate of fine particles. The sum of the magnesium compound and the magnesium atoms contained in the magnesium fluoride is 400 at% with respect to germanium, and the magnesium fluoride is at least 50 at% and at most 100 at% with respect to germanium.

Further, in order to increase the reactivity of the raw material and produce large primary particles, the firing is performed while the phosphor and the container are moved regularly or irregularly.

Further, in order that the particle size hardly changes even if the manganese activation amount changes, the manganese is activated after firing the phosphor matrix.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

According to the method for synthesizing a manganese-activated germanic acid phosphor of the present invention, a magnesium compound which becomes magnesium oxide by heating, magnesium fluoride, germanium oxide and a manganese compound are mixed and fired in air. The mixing ratio of the raw materials, the composition of the phosphor after firing formula _{AMgO · BMgF 2 · GeO 2:} xMn 4+ However, the composition represented by 0.001 ≦ x ≦ 0.1,2 ≦ A + B ≦ 5 To be. In particular, the general formula (4-y) MgO · yMgF 2 · GeO 2: xM
n ⁴⁺ However, a composition represented by 0.5 ≦ y ≦ 1.0 is preferable because a phosphor with particularly high luminance is obtained and by-products are hardly formed.

In the first embodiment, when magnesium oxide is used as the magnesium compound instead of basic magnesium carbonate having a small content, a phosphor having a large particle size and containing no aggregate of fine particles can be obtained. Can be.

In order to make the whole react uniformly, 80
0 to 1100 ° C, preferably 900 to 1000 ° C for 10
After pre-firing for at least one minute, preferably at least one hour,
It is desirable to perform the main firing at 00 to 1400 ° C, preferably 1100 to 1300 ° C, for one hour or more.

In the second embodiment, the raw materials are mixed in the same manner as in the first embodiment, placed in a furnace tube, and fired while rotating the furnace tube around the longitudinal axis of the tube. And a phosphor containing no aggregates of fine particles can be obtained.

As the magnesium compound, a raw material other than magnesium oxide such as basic magnesium carbonate may be used.

The firing temperature is 800 to 1100.
C., preferably at 900 to 1000 ° C. for at least 10 minutes, preferably at least 1 hour, and
It is desirable to perform main firing at 0 ° C., preferably 1100 to 1300 ° C., for one hour or more.

In the pre-firing and main firing, the furnace tube is set at 5 rpm or more and 200 rpm or less, preferably 10 rpm or less.
It is desirable to rotate at a speed of not less than m and not more than 100 rpm. Further, the furnace tube must be made of a material having extremely low reactivity with the phosphor material, and is preferably made of alumina.

Further, a solid having extremely low reactivity with the phosphor raw material may be put in the furnace tube. As a solid,
Beads are preferred, and the material is preferably alumina or zirconia.

Also, a stirring spring made of a material having extremely low reactivity with the phosphor raw material may be inserted into the furnace tube, and the raw material may be agitated by rotating the stirring spring. The material of the stirring spring is preferably alumina.

In the third embodiment, the raw materials excluding the manganese compound are mixed and fired in the same manner as in the first embodiment, and then the manganese compound is mixed and fired.
A phosphor having a large particle size and containing no aggregate of fine particles can be obtained.

The firing conditions are as follows: after mixing the raw materials excluding the manganese compound, the temperature is set to 800 to 1100 ° C.
After preliminarily firing at 00 to 1000 ° C for 10 minutes or more, preferably for 1 hour or more, it is desirable to perform main firing at 1000 to 1400 ° C, preferably 1100 to 1300 ° C for one hour or more. The firing conditions after mixing the manganese compound are 600 to 1000 ° C, preferably 800 to 1000 ° C.
It is desirable to bake at a temperature of at least 2 hours.

[0026]

The present invention will be described below in detail with reference to examples.

(Example 1) A composition formula of 3.5MgO.0.5MgF ₂ .GeO ₂ : 0.5 using magnesium oxide as a magnesium compound.
Manganese-activated germanic acid phosphor represented by 003Mn ⁴⁺ (hereinafter referred to as MF
G phosphor) 3.5 g of magnesium oxide and 0.3 g of magnesium fluoride.
5 mol, 1.0 mol of germanium oxide and 0.003 mol of manganese carbonate were weighed, an appropriate amount of acetone was added thereto, and the mixture was wet-mixed in a mortar. Then, the mixture was placed in an alumina crucible with a lid and heated at a rate of 400 ° C./hour in an air atmosphere. And perform preliminary firing at 1000 ° C. for 2 hours. After further crushing using a mortar, put in an alumina crucible with a lid,
The temperature is raised at a rate of 400 ° C./hour in an air atmosphere,
The main baking is performed at 200 ° C. for 2 hours. Further, the fired product is ground using a mortar.

FIG. 1 shows an electron micrograph of the MFG phosphor thus obtained. FIG. 2 shows an electron micrograph of a conventional MFG phosphor obtained by a similar method using magnesium carbonate as a magnesium compound. It is considered that when magnesium carbonate was used, the particle size was reduced due to the gas generated during firing.

FIGS. 1 and 2 show that the use of magnesium oxide resulted in an MFG phosphor having a large primary particle and containing no aggregate of fine particles.

Further, the brightness was improved by 7% as compared with the conventional MFG phosphor shown in FIG. 2 because the primary particles became large.

Example 2 A furnace tube was fired while being rotated about an axis in the tube length direction. Composition formula: 3.5MgO.0.5MgF ₂ .GeO ₂ : 0.
MFG phosphor represented by 003Mn ⁴⁺ 3.5 mol of magnesium oxide and magnesium fluoride 0.
5 mol, 1.0 mol of germanium oxide and 0.003 mol of manganese carbonate were weighed, an appropriate amount of acetone was added thereto, and the mixture was wet-mixed in a mortar, then placed in an alumina furnace tube, and heated at a heating rate of 400 ° C./hour in an air atmosphere. Warm 10
Preliminary baking is performed at 00 ° C. for 2 hours. FIG. 3 shows a conceptual diagram of the electric furnace used for firing. The core tube 1 is inclined at an angle of about 40 degrees from the horizontal, and is rotated at a speed of 30 rpm around an axis in the tube length direction. Further, after pulverizing using a mortar, the mixture is put into an alumina furnace tube, and while the furnace tube 1 is rotated by the above-described method, the temperature is raised at a heating rate of 400 ° C./hour in an air atmosphere. Perform baking. In addition, 2 is a heat insulating material, and 3 is a heater wire. Further, the fired product is ground using a mortar.

FIG. 4 shows an electron micrograph of the MFG phosphor thus obtained. From FIG. 4, it can be seen that by rotating the furnace tube and baking while stirring the raw material, a result was obtained in which an MFG phosphor having a larger primary particle and containing no aggregate of fine particles was obtained.

The rotational speed of the furnace tube is most preferably 10 rpm or more and 100 rpm or less. If the rotation speed is 10 rpm or less, a sufficient stirring effect cannot be obtained. If the rotation speed is 100 rpm or more, the raw material sticks to the side surface of the furnace tube due to centrifugal force, and it is difficult to obtain a sufficient stirring effect.

The rotation direction of the furnace tube may be reversed in a fixed direction or at regular intervals. In particular, the reversal increases the stirring effect.

Further, even when magnesium carbonate or the like is used as a magnesium compound which becomes magnesium oxide upon heating, it is possible to obtain an MFG phosphor having a primary particle larger than that of the prior art by calcination by the above method.

Further, beads made of a material having low reactivity with the phosphor raw material may be put in the furnace tube.

The same effect can be obtained by inserting a stirring spring made of a material having low reactivity with the phosphor raw material into the furnace tube, rotating the stirring spring and firing the raw material while stirring the raw material. At this time, the core tube may or may not be rotated.

Similar effects can be obtained by using a magnetic stirrer or the like in addition to the stirring by the stirring spring.

As a material having low reactivity with the raw material of the phosphor, alumina ceramic is most preferable because beads and a stirring spring can be easily formed, but other materials may be used.

The above-mentioned method is not limited to the MFG phosphor, but also has an effect of improving the reactivity of a general phosphor, and a material having a melting point lower than the firing temperature is contained in the raw material of the phosphor matrix. The effect is particularly high when the reaction is through the liquid phase.

(Example 3) After mixing and firing only the base material, a manganese compound was mixed and fired. Composition formula 3.5 MgO.0.5 MgF ₂ .GeO ₂ : xM
MFG phosphor represented by n ⁴⁺ (x = 0.003, 0.01) Magnesium oxide, magnesium fluoride, and germanium oxide are mixed in the same manner as in the first embodiment, and an alumina crucible with a lid is provided. Then, the temperature is increased at a rate of 400 ° C./hour in an air atmosphere, and preliminary firing is performed at 1000 ° C. for 2 hours. Furthermore, after pulverizing using a mortar, the mixture is put into an alumina crucible with a lid, heated at a rate of 400 ° C./hour in an air atmosphere, and subjected to main firing at 1200 ° C. for 2 hours. Further, the fired product is ground using a mortar. Here, 0.01 mol of manganese carbonate is weighed and added to the fired product, an appropriate amount of acetone is added, and wet mixing is performed in a mortar. The mixture was placed in an alumina crucible with a lid and heated at a rate of 400 ° C./hour in an air atmosphere.
Refire for a time. Further, the fired product is ground using a mortar.

FIGS. 5 and 6 show electron micrographs of the MFG phosphor thus obtained. 7 and 8 show electron micrographs of a conventional MFG phosphor obtained by mixing all the raw materials at one time and firing under the same temperature conditions. By activating the manganese after firing the matrix, manganese, which is the emission center, enters the crystal while maintaining the grain size of the matrix, so that even if the manganese activation amount changes, the phosphor particles obtained can be changed. The diameter does not change much.

From FIGS. 5 and 6, it can be seen that, even if the manganese activation amount is large, the primary particle size is large, It can be seen that the result that an MFG phosphor containing no aggregate was obtained was obtained.

[0044]

As is apparent from the above description, the present invention is a phosphor having a large primary particle and containing no aggregate of fine particles.

According to the present invention, a phosphor having a large primary particle can be obtained even when the manganese activation amount is increased.

[Brief description of the drawings]

FIG. 1 is an electron micrograph instead of a drawing of a manganese-activated germanic acid phosphor using magnesium oxide of the first embodiment of the present invention.

FIG. 2 is an electron micrograph instead of a drawing of a manganese-activated germanic acid phosphor using magnesium carbonate of the first embodiment of the present invention.

FIG. 3 is a conceptual diagram of an electric furnace in which a furnace tube according to a second embodiment of the present invention is fired while rotating a core tube around an axis in a tube length direction.

FIG. 4 is an electron micrograph, instead of a drawing, of a manganese-activated germanic acid phosphor fired while rotating a core tube of a second embodiment of the present invention about an axis in the tube length direction.

FIG. 5 is an electron micrograph (x in place of a drawing) of a manganese-activated germanic acid phosphor obtained by calcining only a base material and mixing a manganese compound according to the third embodiment of the present invention and recalcining the mixture.
= 0.003)

FIG. 6 is an electron micrograph (x in place of a drawing) of a manganese-activated germanic acid phosphor obtained by calcining only the base material of the third embodiment of the present invention, mixing a manganese compound, and calcining the mixture again.
= 0.01)

FIG. 7 is an electron micrograph (x = 0.003) instead of a drawing of a manganese-activated germanic acid phosphor fired by a conventional method according to the third embodiment of the present invention.

FIG. 8 is an electron micrograph (x = 0.01) instead of a drawing of a manganese-activated germanic acid phosphor fired by a conventional method according to the third embodiment of the present invention.

[Explanation of symbols]

 1 Furnace tube 2 Insulation material 3 Heater wire

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomizo Matsuoka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (13)

[Claims] 1. A phosphor obtained by heating and calcining a magnesium compound, magnesium fluoride, germanium oxide, and a manganese compound which become magnesium oxide by heating, and have a particle size of 2 μm or more and do not contain aggregates of fine particles. A manganese-activated germanic acid phosphor characterized by the following. 2. A composition after firing, the general formula _{AMgO · BMgF 2 · GeO 2:} xMn 4+ However, A + B = 4, according to claim 1, characterized in that a 0.5 ≦ B ≦ 1.0 Phosphor. 3. The phosphor according to claim 1, wherein a magnesium oxide powder is used as the magnesium compound. 4. A method for producing a phosphor, wherein the container is fired while moving a container containing the mixed phosphor material. 5. The method for producing a phosphor according to claim 4, wherein the vessel containing the mixed phosphor material is a furnace tube, and the furnace tube is fired while being rotated about an axis in the tube length direction. 6. The furnace core tube has a rotation speed of 10 rpm or more.
The method for producing a phosphor according to claim 5, wherein the rotation speed is 0 rpm or less. 7. A method for producing a phosphor, wherein a solid having low reactivity with a phosphor raw material is mixed with the raw material, placed in a container, and fired while stirring the raw material by moving the solid. 8. The method for producing a phosphor according to claim 5, wherein beads of alumina or zirconia as a solid material having low reactivity with the phosphor material are placed in the furnace tube and fired. 9. A method for producing a phosphor, characterized in that the phosphor material in the container is fired while being stirred by a stirring means inserted into the container from the outside. 10. The container is a furnace tube, and the stirring means inserted in the container is a stirring spring made of alumina, and the stirring is performed by rotating the stirring spring to stir the phosphor material. The method for producing a phosphor according to claim 9, wherein 11. A method for producing a phosphor, wherein a magnesium compound which becomes magnesium oxide by heating, magnesium fluoride and germanium oxide are mixed and fired, and then a manganese compound is mixed and fired again. 12. The method for producing a phosphor according to claim 11, wherein a sintering temperature when the manganese compound is mixed and re-sintered is 600 ° C. or more and 1000 ° C. or less. 13. The composition of the phosphor after firing, the general formula _{AMgO · BMgF 2 · GeO 2:} xMn 4+ where, 0.001 ≦ x ≦ 0.01, A + B = 4,
13. The method for producing a phosphor according to claim 4, wherein 0.5 ≦ B ≦ 1.0.