JP2005068365A - Phosphor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphor which is chemically stable, has a long life and is free from Cd. <P>SOLUTION: The phosphor is represented by general formula: (Y<SB>1-x</SB>Tb<SB>x</SB>)Ca<SB>4</SB>O(BO<SB>3</SB>)<SB>3</SB>(wherein 0<x<1). The manufacturing method of the phosphor comprises a step for weighing Y<SB>2</SB>O<SB>3</SB>, Tb<SB>4</SB>O<SB>7</SB>, CaCO<SB>3</SB>and B<SB>2</SB>O<SB>3</SB>as the starting materials, a step for mixing the starting materials to form a mixed material, and a step for filling a heat resistant container with the mixed material and firing the mixed material in the atmosphere to obtain the fired matter. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a phosphor and a method for producing the same.

Phosphors that absorb excitation energy and emit fluorescence are used as light sources for display devices such as a fluorescent display device (VFD) and a display device using a field emission cathode as an electron source (field emission display, FED). It's being used. Conventionally, ZnS: Zn (Zn-activated ZnS) for blue light emission, ZnS: Cu, Al (ZnS activated by Cu, Al), (Zn, Cd) S: Ag (Ag-attached) for green light emission (Zn, Cd) S) activated, (Zn, Cd) S: Ag, Cl ((Zn, Cd) S activated by Ag, Cl), Y ₂ O ₂ S: Eu (Eu) Activated Y ₂ O ₂ S) and the like have been used. These sulfide phosphors have problems such as the sulfur component decomposed and separated from the base material due to the collision of electrons and deposited on the cathode surface, causing deterioration of characteristics (decrease in luminance), and materials containing Cd may cause environmental problems. (Patent Document 1)

JP 2001-81459 A

As phosphors used in fluorescent lamps, blue-emitting barium magnesium aluminate phosphors (BaMgAl ₁₀ O ₁₇ : Eu) and strontium chloroapatite phosphors (Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu) Also known are green-emitting lanthanum phosphate phosphors (LaPO ₄ : Ce, Tb), cerium magnesium aluminate phosphors (CeMgAl ₁₁ O ₁₉ : Tb), red-emitting Y ₂ O ₃ : Eu, and the like. These phosphors have problems such that the amount of light decreases and the color changes when the temperature increases (Patent Document 2).

Japanese Patent Laid-Open No. 10-77470

  There is a demand for phosphors that have high brightness, are chemically stable, and do not cause environmental problems.

JP 2001-181622 A JP 2000-34479 A Japanese Patent Publication No.7-110945

  An object of the present invention is to provide a phosphor that is chemically stable, has a long lifetime, and does not contain Cd.

According to one aspect of the present invention, there is provided a phosphor represented by the general formula (Y _1-x Tb _x ) Ca ₄ O (BO ₃ ) ₃ (0 <x <1).

According to another aspect of the present invention, a step of weighing starting materials Y ₂ O ₃ , Tb ₄ O ₇ , CaCO ₃ , B ₂ O ₃ , a step of mixing the starting materials to form a mixed material, And a step of filling the mixed material in a heat-resistant container and firing in an air atmosphere to obtain a fired product.

  It has no hygroscopicity, is chemically stable and has a long life.

  It is difficult to cause concentration quenching and is easy to manufacture.

Rare earth calcium oxyborate (ReCa ₄ O (BO ₃ ) ₃ ; Re is a rare earth element) is not a hygroscopic material, is a highly stable material, and is less damaged by the laser. Applications are being made.

  FIG. 1 shows the crystal structure of rare earth calcium oxyborate.

The present inventors substituted and synthesized rare earth sites of rare earth calcium oxyborate to obtain a novel phosphor. The new phosphor is composed of YCa ₄ O (BO ₃ ) ₃ and TbCa ₄ O (BO ₃ ) ₃ , and has the general formula (Y _1-x Tb _x ) Ca ₄ O (BO ₃ ) ₃ (where 0 <x It is a phosphor represented by <1).

Hereinafter, a method for producing this phosphor will be described. The phosphor raw materials of Y ₂ O ₃ , Tb ₄ O ₇ , CaCO ₃ , and B ₂ O ₃ were weighed and sufficiently mixed with a dry mixer. This primary mixture was tightly filled into a heat-resistant container made of alumina, and calcined and fired at 1000 ° C. for 10 hours in an air atmosphere type electric furnace. This calcined fired product was pulverized and sufficiently mixed again with a dry mixer. This secondary mixture was tightly filled into an alumina heat-resistant container and subjected to main firing in an air atmosphere type electric furnace at 1200 ° C. for 12 hours.

This fired product can also be used as a target for forming a thin film. To obtain a powdery phosphor, grinding the secondary fired product was obtained by performing a sieving _{(Y 1-x Tb x)} Ca 4 O (BO 3) 3 powder phosphor composition.

Using this phosphor as a source, a sample thin film was prepared. Using a laser MBE apparatus equipped with a KrF excimer laser, the ultimate vacuum furnace in the chamber is 3 × 10 ⁻⁹ torr, the oxygen partial pressure is 1 × 10 ⁻⁶ torr during film formation, and the substrate temperature is 350 ° C. to 700 ° C. A phosphor was deposited by laser MBE on a glass substrate (transparent substrate).

  At this time, the film obtained at a substrate temperature of 700 ° C. or lower was in an amorphous state, but high-luminance fluorescence characteristics were obtained. When the substrate temperature was higher than 700 ° C., a polycrystalline film was obtained, but fluorescence characteristics were obtained in the same manner. The amorphous phase phosphor emitted higher brightness fluorescence. When forming a phosphor thin film, it is more desirable to form an amorphous phase film. When sapphire was used as the transparent substrate, an amorphous phase was formed at less than 700 ° C., and a polycrystalline film was formed at 700 ° C. or more.

FIG. 2A is a perspective view schematically showing a sample. A phosphor thin film 2 having a (Y _1-x Tb _x ) Ca ₄ O (BO ₃ ) ₃ composition is formed on a quartz substrate 1 which is a transparent substrate.

In FIG. 2B, the sample thin film was irradiated with a HeCd laser having a wavelength of 325 nm as excitation light for photoluminescence measurement, and the fluorescence emitted from the (Y _1-x Tb _x ) Ca ₄ O (BO ₃ ) ₃ thin film was emitted. Spectral characteristics are shown. Green light emission showing a main peak in the vicinity of a wavelength of 540 nm was confirmed. It was confirmed that (Y _1-x Tb _x ) Ca ₄ O (BO ₃ ) ₃ (however, 0 <x <1) can be used as the green phosphor.

YCa ₄ O (BO ₃ ) ₃ does not emit light. TbCa ₄ O (BO ₃ ) ₃ emits light at a low concentration. However, if the concentration is increased, concentration quenching occurs and high-luminance light emission cannot be obtained. By substituting a part of Tb with Y, high-intensity light emission was obtained in a wide composition range without causing concentration quenching. If YCa ₄ O (BO ₃ ) ₃ that does not emit light is considered as a base material, it can be considered that it is activated by TbCa ₄ O (BO ₃ ) ₃ and emits fluorescence. It would be possible to add other activators.

  In addition to use as a normal green phosphor, it can be used as a green phosphor when white light is generated by combining an ultraviolet light emitting LED and phosphors of red, green, blue, and each color. Similarly, it can be used as a green phosphor for a three-wavelength fluorescent tube, a green phosphor for a cold fluorescent tube (CFL), or the like.

_{Incidentally,} prepared the _{(Y 1-x Tb x)} Ca 4 O (BO 3) 3 in order to form a _{phosphor, YCa 4 O (BO 3)} 3 and TbCa ₄ O _{(BO 3)} 3 of the sintered body And it can also be laminated | stacked alternately by the film thickness control of 1 atomic layer level.

  Laser ablation can also be performed using the phosphor target described in the above preparation method. Laser ablation tends to transfer the target composition itself onto the film. In addition, a known method such as printing the powdery phosphor as a paste can be used. The above-mentioned powdery phosphor is polycrystalline.

  It would be possible to obtain a phosphor in an amorphous phase by depositing a phosphor film by MBE, sputtering, electron beam evaporation or the like on a support such as a substrate held at a low temperature of 700 ° C. or less.

  As mentioned above, although this invention was demonstrated along the Example, this invention is not limited to these. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

  It can be used for various fluorescent light emitting devices.

It is a perspective view which shows the crystal structure of rare earth calcium oxyborate. A perspective view illustrating the fabricated _{(Y 1-x Tb x)} Ca 4 O (BO 3) 3 samples of phosphor thin film is a graph showing the spectrum of the fluorescence from the sample by ultraviolet excitation.

Explanation of symbols

1 Quartz substrate 2 Phosphor thin film

Claims (6)

Formula _{(Y 1-x Tb x)} Ca 4 O (BO 3) 3 phosphor represented by (0 <x <1). A substrate,
A phosphor thin film formed on the substrate and represented by the general formula (Y _1-x Tb _x ) Ca ₄ O (BO ₃ ) ₃ (0 <x <1), which is an amorphous phase;
Fluorescent light emitting device having Weighing starting materials Y ₂ O ₃ , Tb ₄ O ₇ , CaCO ₃ , B ₂ O ₃ ;
Mixing the starting materials to form a mixed material;
Filling the mixed material into a heat-resistant container, firing in an air atmosphere, and obtaining a fired product;
The manufacturing method of the fluorescent substance containing this. further,
Crushing the fired product;
Mixing the pulverized fired product to form a secondary mixed material;
Filling the secondary mixed material into a heat-resistant container and firing in an air atmosphere to obtain a secondary fired product;
The manufacturing method of the fluorescent substance of Claim 3 containing this. further,
Crushing the secondary fired product,
Sieving the pulverized secondary fired product,
The manufacturing method of the fluorescent substance of Claim 4 containing this. Preparing a substrate;
Formula _{(Y 1-x Tb x)} Ca 4 O (BO 3) 3 (0 <x <1) as the source of the phosphor represented by amorphous phosphor thin film at a substrate temperature of 700 ° C. or less on the substrate Depositing in phase;
The manufacturing method of the fluorescent light-emitting device containing this.

Images