JP2005048092A - Light-emitting material emitting in three primary colors, its manufacturing method and light emitting-device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a LuVO<SB>4</SB>light-emitting material capable of causing a parent material to emit in the primary blue, red and yellow colors without changing the type of the parent material, its manufacturing method and a light-emitting device using it. <P>SOLUTION: The material consists of a LuVO<SB>4</SB>light-emitting material mixed with an activator and is produced by forming portions without the activator mixed and spots of oxide powders of the Dy and Eu activating elements dissolved in a solvent, on a substrate rod of LuVO<SB>4</SB>obtained by sintering, melting the sintered material in a solidification furnace and growing crystals by the floating method. The material serves as a light-emitting material for light-emitting devices: the portions without the activator mixed emit in the primary blue color, the portions with the Dy activating agent mixed do in the primary red color, and the portions with the Eu activating agent do in the primary yellow color. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light emitting material composed of a specific rare earth element, a specific transition element, and a specific chalcogen element (including oxygen), and a phosphor material, a laser material, a plasma display, an electroluminescence element, and a radiation detection It is applied to a container.

Conventionally, various luminescent materials are known. For example, yttrium vanadate (Patent Document 1) containing a rare earth element having high emission intensity, a Tb-containing Al oxide single crystal (Patent Document 2), and the like are known.
However, there has been no systematic development of a luminescent material that can emit light in a number of colors while using one kind of base material.

Japanese Patent Application Laid-Open No. 08-91999 JP 07-149599 A

In order to realize a high-performance light-emitting substance, the problem that the present inventors are trying to solve is to develop a light-emitting substance that can emit light in many colors while using one kind of base material. . In particular, if there is a substance that can emit light in three primary colors of blue, red, and yellow without changing the type of the host substance, it is considered that the display element has high utility value.
Rare earth elements are excellent as luminescent centers of luminescent materials, and luminescent materials composed of rare earth elements, transition elements and chalcogen elements (including oxygen) contain rare earth elements, and thus can be used as luminescent materials. However, there has been no systematic investigation or research as a luminescent material for the substance group based on LuVO ₄ .
The present invention provides a light emitting material having a substance group based on LuVO ₄ , a method for producing the light emitting material, and a light emitting element.

On the other hand, the inventors of the present invention have studied the characteristics of LuVO ₄ as a luminescent substance, and as a result, discovered that pure LuVO ₄ emits blue light and has a very high luminous efficiency. Furthermore, when Dy was added as an activator and when Eu was added, it was found that the light emitted was red and yellow, respectively, and the luminous efficiency was very high.

LuVO ₄ alone, in the case of adding Dy in LuVO _4, in the case of adding Eu to LuVO _4, respectively emitting blue, red and yellow, can be made three primary colors all in LuVO ₄ compound. Therefore, color display is possible only with LuVO ₄ compounds.

The LuVO ₄ -based compound of the present invention can be prepared with either a single crystal or a polycrystalline crystal system.
As a method for producing the light emitting material, first, the constituent elements of the light emitting material are mixed in the same molar ratio as the stoichiometric ratio of the light emitting material. Next, the mixed raw material is melted or dissolved and solidified, and then molded. Here, forming means processing into an ingot shape, a thin film shape or a powder shape. Before the mixed raw material is melted or dissolved, it may be sintered once. The sintered product may be molded as it is without melting or dissolving.

The sintering temperature is 500 ° C. to 1500 ° C., and the atmosphere is oxygen or a mixed gas of at least one gas other than oxygen and oxygen. Further, a binder (sintering aid) is added as necessary.
The atmosphere of the melting or melting process is oxygen or a mixed gas of oxygen and at least one gas other than oxygen.

In the production of the crystal of the LuVO ₄ compound of the present invention, a substance having a crystal structure equivalent or similar to that of the material is added to the melt or solution of the material in the melting or dissolution process by the Czochralski method or the floating zone method. Crystals of the material can be grown by contact.

As a method for depositing the light emitting material on the substrate, vacuum evaporation, MBE, sputtering, reactive sputtering, CVD, MOCVD, or the like can be performed.
Further, in order to control the stoichiometric ratio of the light emitting material, the element may be replenished and extracted after the end of the process.

  Further, by using the light emitting material of the present invention, a light source device can be manufactured by changing the intensity, wavelength, and polarization direction of light emission by applying a magnetic field, an electric field, or stress to the light emitting material.

  In the embodiment, as shown in FIG. 1, an infrared heating system comprising a quartz tube 1, a condensing spheroid mirror 2, a halogen lamp or xenon lamp 3, a monitoring window 4, a lens 5 and a screen 6 as a heat source. A single crystal was produced by a floating zone method using a crystal growth furnace.

Using a raw material fired body in which a plurality of different types of activator materials are provided in the raw material fired body with a concentration gradient, a three-color light emitting single crystal having different emission colors in the crystal is produced as follows. did.
Lu ₂ O ₃ and V ₂ O ₅ are mixed in a 1: 1 ratio, filled into a rubber tube, hydrostatic pressure is applied, molded into a rod shape with a diameter of 8 mm and a length of 50 mm, and then fired at 1200 ° C. ₄ Create a raw material bar. The LuVO ₄ raw material rod was not attached with an activator, and Eu ₂ O ₃ and Dy ₂ O ₃ powders dissolved in water were each applied to the brush to provide spots, and three zones were provided.
That is, about 1% of the weight of the LuVO ₄ raw material fired body was used as an activator, and Eu ₂ O ₃ was prepared as a powder that emitted red light and Dy ₂ O ₃ emitted yellow light, and dissolved in water to prepare a solution. It is applied to the porous surface in a spot shape with a brush or an insulator to produce a raw material fired body. When this raw material fired body is melted in a crystal furnace and crystal growth is performed by the floating zone method in which this melting zone is scanned in the direction of the raw material fired body at 5 to 10 mm / h, a colorless and transparent single crystal can be produced. It was.
When this single crystal is irradiated with black light with a wavelength of 254 nm or 365 nm, the pure LuVO ₄ part not coated with the activator emits blue light, the part coated with Eu ₂ O ₃ emits red light, and Dy ₂ O ₃ The applied part emitted yellow light. That is, a single LuVO ₄ single crystal emitting three colors of light could be produced.

(Color development test)
Figures 2-4 show the Luo ₄ single crystal temperature maintained at room temperature (absolute temperature = 295K) and the emission obtained when it is irradiated with He-Cd laser light (wavelength = 325 nm). It is the result. The horizontal axis represents the wavelength of light (unit: nm), and the vertical axis represents the emission intensity of light of that wavelength.
First, FIG. 2 shows an emission spectrum of a pure LuVO ₄ single crystal. A feature of this spectrum is that a wide emission band centered around the wavelength = 500 nm is observed. The presence of this band is the reason why the sample emits blue light when observed with the naked eye. The light emission mechanism of this wide light emission band is considered to be light emission from an acid group called VO ₄ ³⁻ . As shown in FIG. 2, in addition to the wide emission band, some sharp emission lines are observed. All of them are considered to emit light from impurity elements present in a minute amount in the sample. For example, the strongest emission line is observed in the vicinity of the wavelength = 620 nm, but the impurity type is considered to be Eu.

FIG. 3 shows an emission spectrum of a LuVO ₄ single crystal doped with Eu. A characteristic of this spectrum is that several sharp emission lines are observed. All of these emission lines are considered to be emission from Eu present in the sample. In particular, the strongest emission line is observed in the vicinity of the wavelength = 620 nm. The reason why the emission of this sample looks red when observed with the naked eye is the presence of this emission line.
FIG. 4 shows an emission spectrum of a LuVO ₄ single crystal doped with Dy. A characteristic of this spectrum is that several sharp emission lines are observed. All of these emission lines are considered to be emission from Dy present in the sample. In particular, the strongest emission line is observed in the vicinity of the wavelength = 575 nm, but the cause of the yellow color when the emission of this sample is observed with the naked eye is the presence of this emission line.

All the light emitting materials of the LuVO ₄ compound of the present invention can produce three primary colors, and if this is incorporated into a display device, color display can be achieved.
Further, since the light-emitting element of the present invention is solid, it can be used as a display device that is strong against vibration and has few failures.

Schematic diagram of an infrared heating crystal growth furnace Luminescence spectrum of pure LuVO ₄ (blue emission) PL spectrum of LuVO ₄ doped with Eu (red light emission) PL spectrum of LuVO ₄ doped with Dy (yellow emission)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Quartz tube 2 Condensing spheroid mirror 3 Heat source 4 Monitoring window 5 Lens 6 Screen

Claims (6)

LuVO ₄ light-emitting material with an activator added to the chemical formula LuVO ₄ The LuVO ₄ light emitting material according to claim 1, wherein the LuVO ₄ light emitting material is either single crystal or polycrystalline. The LuVO ₄ light emitting material according to claim 1 or 2, wherein Dy, Eu, is used as an activator. The lu ₂ O ₃ and V ₂ O ₅ 1: were mixed in a 1, molded to create a LuVO ₄ feed rod and fired at 1000 to 1300 ° C., portions without the activator to LuVO ₄ feed rod or A raw material fired body in which Eu ₂ O ₃ and / or Dy ₂ O ₃ powder dissolved in a solvent is attached in a spot shape is prepared, and this raw material fired body is melted in a crystal furnace, and this molten zone is fired as a raw material. A method for producing a light-emitting material in which crystal growth is performed by a floating zone method in which the body is scanned at 5 to 10 mm / h in the body direction. A light emitting device in which a single crystal includes a LuVO ₄ crystal, a crystal composed of LuVO ₄ and Dy, and a crystal composed of LuVO ₄ and Eu. The lu ₂ O ₃ and V ₂ O ₅ 1: were mixed in a 1, molded to create a LuVO ₄ feed rod and fired at 1000 to 1300 ° C., and a portion without a activator to LuVO ₄ feed rod The Eu ₂ O ₃ and Dy ₂ O ₃ powders dissolved in the solvent are attached in a spot shape to produce a raw material fired body having three zones, which is melted in a crystal furnace using this raw material fired body. A method for manufacturing a light-emitting element in which crystal growth is performed by a floating zone method in which a band is scanned in the direction of a raw material fired body at 5 to 10 mm / h.

Images