JPH0823011B2 - Yttrium vanadate phosphor and method for producing the same - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a trivalent europium-activated yttrium vanadate phosphor that emits red light when stimulated by ultraviolet rays or a cathode ray.

2. Description of the Related Art Yttrium vanadate phosphor, which emits red light when stimulated by ultraviolet rays, is used in high pressure mercury lamps. This phosphor is excited by ultraviolet rays, and emits a deep red line spectrum having a dominant wavelength of 619 nm. This phosphor, which emits a deep red color, exhibits extremely excellent temperature characteristics when stimulated by 365 nm ultraviolet light. That is, the higher the temperature, the higher the emission brightness. Luminance at 300 ℃ is 100
It is several times higher than the emission brightness at ° C. Taking advantage of this characteristic, the yttrium vanadate phosphor is widely used as a phosphor for improving the color rendering of a high pressure mercury lamp. This is because the phosphor of the high pressure mercury lamp is excited at a high temperature. However, when this phosphor is used in a low-pressure mercury lamp for a fluorescent lamp, it emits deep red light, but has a drawback that the luminous flux is low. In order to increase the emission brightness of the yttrium vanadate phosphor, a technique of firing using a halogen compound as a flux has been developed (Japanese Patent Publication No. 45-2295). This firing method is based on halogen compounds such as NaCl and BaCl.
₂ etc., halogen compounds of metal elements belonging to Group 1A, Group 2 and Group 3 in the periodic table are used. This yttrium vanadate phosphor is mixed with an extremely large amount of a halogen compound as a flux at the time of firing. The emission brightness of this phosphor is highest when the mixing ratio of the flux is set to an extremely large value of 0.6 mol with respect to the phosphor. The flux is added to improve the reaction of the phosphor raw material during firing, and is not added to the composition of the fired phosphor. Therefore, when the addition amount of the flux is large, not only the raw material cost of the phosphor increases, but also the firing cost increases. This is because a large amount of another powder that does not become a phosphor is mixed and fired, so that the amount of phosphor that can be filled in the container is reduced and a large amount of powder that does not become a phosphor is fired. In addition, in order to improve the deterioration characteristics of the yttrium vanadate phosphor, a technique of incorporating boric acid and phosphoric acid into the phosphor composition has been developed (Japanese Utility Model Publication No. 60-49083). The yttrium vanadate phosphor disclosed in this publication is yttrium partially substituted with europium,
The molar ratio of boric acid, phosphoric acid, and vanadic acid is adjusted to a specific ratio. The yttrium vanadate phosphor having a phosphor composition adjusted to a specific ratio has been used in a low-pressure mercury vapor discharge lamp to improve deterioration characteristics. Furthermore, yttrium vanadate phosphors to which phosphorus or arsenic is added in addition to boric acid have been developed (Japanese Patent Publication No. 45-37297). This phosphor was developed for a color television picture tube or a high-pressure mercury vapor discharge lamp. This publication discloses that the emission luminance of the yttrium vanadate phosphor can be adjusted to a high level by adjusting the contents of vanadium, arsenic and phosphorus. The present inventor somehow applied these conventional techniques, and conducted research to develop an yttrium vanadate phosphor having excellent emission brightness and luminous flux maintenance factor, and which can be manufactured at low cost. As a result, I found a very unique phenomenon. That is, the yttrium vanadate phosphor composition contains a Group 1A element in the periodic table in addition to phosphorus and / or boron, and further contains phosphorus and / or boron and a Group 1A element in the periodic table. By specifying the mixing ratio within a certain range, we succeeded in producing an yttrium vanadate phosphor with excellent characteristics.

[Object of the Invention]

Therefore, an important object of the present invention is to provide an yttrium vanadate phosphor which has a high emission brightness when used in a low-pressure mercury lamp and can improve the luminous flux maintenance factor.

[Means for solving conventional problems]

The yttrium vanadate phosphor of the present invention has the following constitution. In this phosphor, part of yttrium is replaced with trivalent europium so that the emission color becomes red. The phosphor composition contains yttrium and vanadium. Further, the phosphor composition contains a small amount of a Group 1A element in the periodic table in addition to phosphorus and / or boron.
The content of phosphorus and / or boron is adjusted to the range of 0.1 to 0.9 mol per 1 mol of yttrium, and the Group 1A element in the periodic table is adjusted to 0.1 mol or less per 1 mol of yttrium. There is. Furthermore, the method for producing the yttrium vanadate phosphor of the present invention is a step of mixing a yttrium raw material, a europium raw material, a raw material of a Group 1A element in the periodic table, a vanadium raw material, a phosphor raw material composed of phosphorus and / or boron. In, the mixing ratio of the sum of yttrium, europium, and the raw materials of the Group 1A elements in the periodic table is adjusted to be equal to or almost equal to the stoichiometric ratio. In other words, the mixing amount of the yttrium raw material is adjusted to be smaller by the mixing ratio of the Group 1A elements in the periodic table. This is because a group 1A element in the periodic table mixed with the phosphor raw material efficiently replaces part of yttrium. In the conventional method for producing a yttrium vanadate phosphor, it has been said that it is preferable to mix the yttrium raw material with a stoichiometric ratio that is substantially equal to or more than the stoichiometric ratio and then fire it. However, when the yttrium raw material is equal to or more than the stoichiometric ratio, even if the Group 1A element in the periodic table is mixed with the phosphor raw material and fired, it is not efficiently replaced with yttrium. is there. The method for producing the yttrium vanadate phosphor of the present invention is, in order to efficiently replace a part of yttrium with a Group 1A element in the periodic table, a sum of yttrium, europium, and raw materials of the Group 1A element in the periodic table. The mixing ratio of is adjusted to be equal to or almost equal to the stoichiometric ratio. The degree to which the mixing ratio of yttrium raw materials is reduced is 1A in the periodic table.
It is adjusted by the mixing amount of the group element raw materials. Therefore, the more the raw material of the Group 1A element in the periodic table, the smaller the amount of the yttrium raw material mixed.

[Operation effect]

The yttrium vanadate phosphor according to the present invention contains a Group 1A element in the periodic table in addition to phosphorus and / or boron. FIG. 1 shows the relative luminous flux value of the yttrium vanadate phosphor of the present invention with respect to the content of the Group 1A element in the periodic table. However, the yttrium vanadate phosphor shown in FIG. 1 contains 0.350 mol of phosphorus to 1 mol of yttrium. As is clear from this figure, the phosphor of the present invention contains only 0.1 mol or less of the Group 1A element in the periodic table,
It exhibits excellent emission brightness. For example, the yttrium vanadate phosphor containing sodium, potassium, or lithium exhibits the maximum emission luminance in the content range of 0.02 to 0.05 mol. The yttrium vanadate phosphor containing sodium has an emission luminance as high as 10% as compared with the phosphor having the same composition except that it contains a Group 1A element in the periodic table. In addition, the luminous brightness is improved by 8% with lithium and 5% with potassium. Furthermore, FIG. 2 shows the luminous flux maintenance factor of a low-pressure mercury lamp using the yttrium vanadate phosphor of the present invention. In this figure, a curve A shows the characteristics of a low-pressure mercury lamp (straight tube 40ss) using the yttrium vanadate phosphor manufactured in Example 1. Curve B is a low-pressure mercury lamp using the yttrium vanadate phosphor manufactured by removing phosphoric acid and sodium carbonate from the phosphor raw material manufactured in Example 1 and increasing the amount of yttrium mixed by the number of moles corresponding to sodium. It shows the luminous flux maintenance factor of (straight tube 40ss). As is clear from this figure, the yttrium vanadate phosphor of the present invention exhibits an excellent luminous flux maintenance factor. Furthermore, the yttrium vanadate phosphor of the present invention has the characteristics that the body color can be improved and the particle shape is close to a spherical shape. The method for producing the yttrium vanadate phosphor of the present invention, in the step of mixing the phosphor raw materials, yttrium, europium, and the mixing ratio of the sum of the raw materials of the Group 1A elements in the periodic table are equal to the stoichiometric ratio. , Or adjusted almost equally. In other words, the mixing ratio of the yttrium raw material is adjusted to be smaller by the mixing ratio of the Group 1A elements in the periodic table. Group 1A elements in the periodic table mixed in this state, almost all of the materials mixed in the raw material replace yttrium,
Achieves excellent emission brightness characteristics with the addition of an extremely small amount. For example, when producing a yttrium vanadate phosphor containing a Group 1A element in the periodic table of 0.1 mol or less,
Adjusting the mixing ratio of the yttrium raw material to an amount corresponding to 0.1 mol or less, which is the mixing ratio of the Group 1A elements in the periodic table, to reduce yttrium, europium, and 1A in the periodic table.
The mixing ratio of the raw materials of the group elements is adjusted to be equal to or almost equal to the stoichiometric ratio.

[Preferred embodiment]

Hereinafter, embodiments of the present invention will be described. (Example 1) The following phosphor raw materials are weighed and prepared. The _{Y 2 O 3 429.0g Eu 2 O} 3 21.1g V 2 O 5 235.4g 75 % by weight of _{H 3 PO 4 182.9g H 3 BO} 3 0.7g Na 2 CO 3 4.2g or more ingredients, together with 3 liters of water In a 10 liter porcelain pot. Five alumina balls having a diameter of 20 mmφ are put in the pot so that the phosphor raw material is well stirred, and the mixture is stirred for 15 hours. Then, dry for 15 hours, 1250
Bake at 6 ° C for 6 hours. The fired phosphor is washed with water and dried to obtain a phosphor having an average particle size of 3.5 μm. The composition of the obtained phosphor is Y _0.95 Eu _0.03 Na _0.02 (P _0.350 V _0.647 ) O ₄ (BO ₃ ).
_0.003 , using this phosphor, low pressure mercury lamp (straight tube 40s
s) was prototyped. The initial luminous flux of the prototype low-pressure mercury vapor discharge lamp is lower than that of the conventional low-pressure mercury vapor discharge lamp that does not contain Na and uses the conventional yttrium vanadate phosphor.
The initial luminous flux is improved by 10%, and the luminous flux maintenance rate after 100 hours is also improved. (Example 2) The following phosphor raw materials are weighed and prepared. The _{Y 2 O 3 429.0g Eu 2 O} 3 21.1g V 2 O 5 235.4g 75 % by weight of _{H 3 PO 4 182.9g H 3 BO} 3 0.7g K 2 CO 3 5.5g Example 1 and phosphor in the same manner A low-pressure mercury lamp was manufactured by using this phosphor. The initial luminous flux of the prototype low-pressure mercury vapor discharge lamp was 8% higher than that of the low-pressure mercury vapor discharge lamp using the conventional yttrium vanadate phosphor containing no K. Similar to (Example _{3) Y 2 O 3 424.5g Eu} 2 O 3 21.1g V 2 O 5 235.4g 75 % by weight of _{H 3 PO 4 182.9g H 3 BO} 3 0.7g Li 2 CO 3 4.4g Example 1 Then, a phosphor was manufactured, and a low-pressure mercury lamp was prototyped using this phosphor. The initial luminous flux of the prototype low-pressure mercury vapor discharge lamp was improved by 5% as compared with the low-pressure mercury vapor discharge lamp using the conventional yttrium vanadate phosphor containing no Li.

[Brief description of drawings]

FIG. 1 shows the case where the phosphor of the present invention is used in a low pressure mercury lamp.
FIG. 2 is a graph showing a relative luminous flux value with respect to a 1A group metal element amount, and FIG. 2 is a graph showing a luminous flux maintenance factor.

Claims (2)

[Claims] 1. A yttrium vanadate phosphor having the following constitution. (A) A part of yttrium is replaced with trivalent europium. (B) The phosphor composition contains yttrium and vanadium. (C) The phosphor composition contains both phosphorus and / or boron and a Group 1A element in the periodic table. (D) In the periodic table, the content of the Group 1A element is 0.1 mol or less per 1 mol of yttrium, and the content of phosphorus and / or boron is 0.1 to 0.9 per 1 mol of yttrium.
Adjusted to the molar range. 2. A method for producing a yttrium vanadate phosphor, which comprises the following steps. (A) A step of mixing a yttrium raw material, a europium raw material, a raw material of a Group 1A element in the periodic table, a vanadium raw material, a phosphor raw material made of phosphorus and / or boron. (B) In the step of mixing the phosphor raw materials, the number of moles of yttrium and europium mixed should be 1A in the periodic table.
Yttrium and europium are mixed with the group 1A element in the periodic table in an amount equal to or almost equal to the stoichiometric ratio by reducing the mixing mole number of the raw material of the group element. (C) A step of burning the mixed phosphor raw material.