JP5692727B2 - Ultraviolet light emitting phosphor and light emitting device using the same - Google Patents

Description

  The present invention relates to an ultraviolet light-emitting phosphor that emits ultraviolet light and a light-emitting element using the same.

  In general, a phosphor is a substance that is excited by electromagnetic wave energy such as ultraviolet rays, electron beams, and X-rays and emits light from the ultraviolet region to the infrared region. And since various spectral distributions can be given according to the kind of fluorescent substance, various light emitting elements are developed by combining with an appropriate excitation source.

Phosphors that are frequently used are those that emit red, green, and blue, which are the three primary colors of light, and many phosphors have been developed and put to practical use.
Such a phosphor is selected and used depending on what is used as an excitation source. For example, phosphors for electron beam excitation used in cathode ray tubes include Y ₂ O ₂ S: Eu, ZnS: Cu, Al, ZnS: Ag, Al, and the like. Examples of phosphors for ultraviolet excitation used in fluorescent lamp illumination and cold cathode tubes include Y ₂ O ₃ : Eu, LaPO ₄ : Tb, BaMgAl ₁₀ O ₁₇ : Eu, and the like. (YGd) BO ₃ : Eu, Zn ₂ SiO ₄ : Mn, BaMgAl ₁₀ O ₁₇ : Eu, and the like.

  Ultraviolet light emitting phosphors that emit ultraviolet light have also been developed. Ultraviolet rays are classified into near ultraviolet rays (wavelengths 200 to 380 nm), far ultraviolet rays (wavelengths 10 to 200 nm: generally called vacuum ultraviolet rays, hereinafter referred to as “vacuum ultraviolet rays”), and extreme ultraviolet rays (wavelengths 10 nm or less). . Near-ultraviolet rays are further divided into UV-A (wavelengths 315 to 380 nm), UV-B (wavelengths 280 to 315 nm), and UV-C (wavelengths 200 to 280 nm). These ultraviolet rays are selected and used according to applications such as an insect repellent device, sterilization, deodorization, stain prevention, exposure and skin treatment.

For example, SrB ₄ O ₇ F: Eu or BaSi ₂ O ₅ : Pb is known to emit UV-A as the ultraviolet light emitting phosphor. _Further, YBO 3: _Gd, Pr (see Patent Document _1), YF 3: Gd (see Patent Document _{2), YB m O n:} Gd ( see Patent Document _{2), (Y 1-m} Gd m) Al 3 ( BO ₃ ) ₄ (see Patent Document 2), (Y _1-m Gd _m ) Al _{3 -n} Sc _m (BO ₃ ) ₄ (see Patent Document 3), Sr _1-m Gd _m Al _12-n Mg _n O ₁₉ (see Patent Document _4), etc. _{(La 1-m-n-} z Gd m Y n Ce z) PO 4 ( see Patent Document 5) it has been reported as a phosphor emitting UV-B. LaPO ₄ : Pr, YPO ₄ : Bi, LuPO ₄ : Pr (refer to Patent Document 6), Sr (Al, Mg) ₁₂ O ₁₉ : Pr (refer to Patent Document 7), etc. are phosphors that emit UV-C. As reported. In the above structural formulas, m, n, and z generally represent a number of 1 or less.

Among phosphors emitting UV-B, Y (yttrium) is composed of a matrix composed of YAl ₃ (BO ₃ ) ₄ and part of Y (yttrium) is substituted with Gd (gadolinium) (Y _1-m Gd _m ) Al ₃ (BO ₃ ) ₄ and (Y _1-m Gd _m ) Al _{3 -n} Sc _n (BO ₃ ) ₄ are excellent ultraviolet rays exhibiting light emission with a narrow half-value width due to the ff transition of Gd ³⁺ near 313 nm. Non-Patent Document 1 describes that it is effective to use vacuum ultraviolet rays as an excitation source of (Y _1-m Gd _m ) Al ₃ (BO ₃ ) ₄ .

  As a method for generating vacuum ultraviolet rays, Xe discharge used in plasma displays is generally used. The ratio of the wavelengths of 147 nm and 172 nm generated at that time and the generation efficiency of vacuum ultraviolet rays (the amount of generation of vacuum ultraviolet rays are determined). Since it is easier to measure by emitting the phosphor than direct measurement, it is often discussed as luminous efficiency.) Depends on the Xe concentration. When the Xe concentration is low, the generation rate at 147 nm is high. However, as the Xe concentration increases, the generation rate at 172 nm increases. Patent Document 8 describes the generation ratios of 147 nm and 172 nm in the Xe concentration. When the Xe concentration is 10 mol%, the intensity ratio of 172 nm is 3.1 times as high as 147 nm, and when the Xe concentration is 12 mol%, 3 of 147 nm. .8 times. Further, it is known that the higher the Xe concentration, the higher the generation efficiency of vacuum ultraviolet rays. In the plasma display panels currently on the market, the Xe concentration is set higher from the viewpoint of light emission efficiency. For this reason, when using vacuum ultraviolet rays generated by Xe discharge, it is desired that excitation is not performed more efficiently than either wavelength of 147 nm or 172 nm, but is performed efficiently by both wavelengths.

However, although YAl ₃ (BO ₃ ) ₄ shows strong light emission at a wavelength of 170 nm or less as described in Non-Patent Document 1, a light source using Xe discharge is extremely weak at a wavelength of 170 nm or more. In the case of using, the wavelength of 147 nm can be used effectively, but the wavelength of 172 nm cannot be used effectively. In addition, (Y _1-m Gd _m ) Al _3-n Sc _n (BO ₃ ) ₄ described in Patent Document 3 is obtained by substituting a part of the Al site of the phosphor with Sc. Although the emission characteristics of the excitation are improved, there is no description about the change in the emission characteristics of the 147 nm excitation, and Sc used for improving the emission characteristics is classified as a rare earth, and the extraction method is difficult due to its nature. Since the production amount is small and the material is very expensive, it becomes quite expensive.

Japanese Patent No. 3683143 Japanese Patent No. 4266706 Japanese Patent No. 4109995 JP 2007-238938 Special table 2006-525404 gazette JP 2003-022783 A JP 2006-342336 A JP 2009-029407 A

Jpn.J.Appl.Phys.Vol.42 (2003) pp.5656-5659

The present invention is an ultraviolet light emitting phosphor composed of a matrix composed of YAl ₃ (BO ₃ ) ₄ , in which a part of Y is substituted with Gd, regardless of the excitation wavelength of 147 nm or 172 nm generated by Xe discharge. It aims at improving so that it can light-emit efficiently.

As a result of sincerity studies, the present inventors have found that Y part of YAl ₃ (BO ₃ ) ₄ UV-emitting phosphor is partially substituted with Bi (bismuth) by adding a part of Y to Gd, thereby reducing the 147 nm excitation characteristics. The present invention was derived by finding that the 172 nm excitation characteristics can be greatly improved with a minimum.

That is, the present invention has a composition represented by the general formula Y _1-xy Gd _x Bi _y Al ₃ (BO ₃ ) ₄ (0 <x <0.6, 0 <y <0.03). It is the fluorescent substance which light-emits the ultraviolet-ray characterized by these.
In addition, the present invention is a light-emitting element using this phosphor.

The ultraviolet light-emitting phosphor of the present invention is a new type of phosphor that emits ultraviolet light by being efficiently excited by an excitation light source having a wide range of wavelengths including 147 nm and 172 nm generated by Xe discharge. The light emitting element used can obtain good light emission of 313 nm due to the df transition of Gd ³⁺ .

The excitation spectrum data of the fluorescent substance of the Example of this invention and the fluorescent substance of a comparative example are shown.

In the present invention, Y _1-x Gd _x Al ₃ (BO ₃ ) ₄ is further substituted with Bi for the general formula Y _1-xy Gd _x Bi _y Al ₃ (BO ₃ ) ₄ (0 < It is a fluorescent substance that emits ultraviolet rays consisting of x <0.6, 0 <y <0.03).

  The amount x of gadolinium as an activator is 0 <x <0.6, preferably 0.1 ≦ x <0.6, and more preferably 0.2 ≦ x ≦ 0.5. Is the time. If the amount of gadolinium exceeds 0.6, a compound other than the target compound is likely to be produced, and although the emission at 313 nm is observed, the characteristics are deteriorated. Also, when the amount of gadolinium is less than 0.1, the characteristics at 147 nm excitation are good, but the characteristics at 172 nm excitation are low.

  The amount y of Bi substituting a part of the Y site is 0 <y <0.03, preferably 0 <y <0.02, and more preferably 0.0005 ≦ y ≦ 0.02. is there. When the amount of Bi exceeds 0.03, other compounds than the target compound are likely to be produced, and the 147 nm excitation characteristics are significantly deteriorated. Moreover, since the improvement rate of the characteristic of 172 nm excitation falls, the Bi addition effect cannot be utilized.

  Next, a method for producing the ultraviolet light emitting phosphor according to the present invention will be described. As starting materials, oxides, nitrates, sulfates, organic substances, and the like of each constituent element can be used. The required amounts of these starting materials are weighed and mixed. A known method can be employed as the mixing method, and examples thereof include wet mixing and dry mixing. Moreover, when using a soluble starting material, chemical reactions, such as a sol-gel method and a coprecipitation method, can also be utilized.

  Note that a fluxing agent such as a halogen compound or a boron compound may be added together in order to control the particle diameter or improve the luminous efficiency. Addition can be performed together during mixing or after mixing.

  The raw material mixture is put in a heat-resistant container such as an alumina crucible and baked in the atmosphere at, for example, 800 ° C. to 1200 ° C. for 1 to 50 hours, whereby the ultraviolet light emitting phosphor according to the present invention can be obtained. The atmosphere may be nitrogen or a reducing atmosphere other than air. Then, if necessary, pulverization, washing with water, drying and sieving are performed to adjust the ultraviolet light-emitting phosphor to a desired particle size. In order to obtain a uniform ultraviolet light emitting phosphor powder, the baking may be performed twice or more.

  The light emitting device using the ultraviolet light emitting phosphor of the present invention can be used as an excitation source using an electron beam or vacuum ultraviolet light, but the most preferable is a light emitting device using vacuum ultraviolet light using Xe discharge as a light source. is there.

〔Example〕
Next, the present invention will be described with reference to the following examples, but the present invention is not limited to these examples.
Example 1
Y ₂ O ₃ , Gd ₂ O ₃ , Bi ₂ O ₃ , Al ₂ O ₃ , H ₃ BO ₃ are used as raw materials, and the final Y: Gd: Bi: Al: B molar ratio is 0.695: 0.3. : 0.005: 3: 4 and weighed and mixed using a mortar. This mixture was placed in an alumina crucible and baked in an electric furnace at 1200 ° C. in the atmosphere for 10 hours. The fired product was washed with warm water, dried and crushed in a mortar to obtain the intended ultraviolet light-emitting phosphor Y _0.695 Gd _0.3 Bi _0.005 Al ₃ (BO ₃ ) ₄ .

Example 2-Example 10
Y ₂ O ₃ , Gd ₂ O ₃ , Bi ₂ O ₃ , Al ₂ O ₃ , H ₃ BO ₃ are used as raw materials, and the final Y: Gd: Bi: Al: B molar ratio is 0.795: 0.2. : 0.005: 3: 4 (Example 2), 0.595: 0.4: 0.005: 3: 4 (Example 3), 0.495: 0.5: 0.005: 3: 4 (Example 4), 0.6975: 0.3: 0.0025: 3: 4 (Example 5), 0.6925: 0.3: 0.0075: 3: 4 (Example 6),. 69: 0.3: 0.01: 3: 4 (Example 7), 0.68: 0.3: 0.02: 3: 4 (Example 8), 0.699: 0.3: 0. 001: 3: 4 (Example 9), 0.6995: 0.3: 0.0005: 3: 4 (Example 10) were weighed and mixed using a mortar. This mixture was placed in an alumina crucible and baked in an electric furnace at 1200 ° C. in the atmosphere for 10 hours. The fired product was washed with warm water, dried and crushed in a mortar to obtain an ultraviolet light-emitting phosphor having the desired composition.

As a comparative example raw material, Y ₂ O ₃ , Gd ₂ O ₃ , Al ₂ O ₃ , and H ₃ BO ₃ were used at a final Y: Gd: Al: B molar ratio of 0.7: 0.3: 3: 4 And weighed and mixed using a mortar. This mixture was placed in an alumina crucible and kept at 1200 ° C. for 10 hours in the atmosphere for firing. The fired product was washed with hot water, dried and crushed in a mortar to obtain the target phosphor Y _0.7 Gd _0.3 Al ₃ (BO ₃ ) ₄ .

The emission characteristics of the phosphors obtained in Examples 1 to 10 and the comparative example were measured using a deuterium lamp (manufactured by Hamamatsu Photonics) as a light source and a photomultiplier tube (R374: manufactured by Hamamatsu Photonics) as a detector. That is, the excitation spectrum was measured by changing the wavelength of the excitation light while detecting 313 nm emission resulting from the ff transition of Gd ³⁺ . The values in Table 1 show the emission peak intensities of the respective examples by standardizing the emission peak intensities of 147 nm excitation and 172 nm excitation of the comparative example as 100%. FIG. 1 exemplifies an excitation spectrum in a region with an excitation wavelength of 130 nm to 300 nm.

  As is apparent from Table 1, the ultraviolet light emitting phosphors obtained by substituting part of Y with Bi in the examples have significantly improved emission characteristics at 172 nm excitation compared to the ultraviolet light emitting phosphors shown in the comparative examples. Yes. The light emission characteristics with 172 nm excitation were most improved when Bi = 0.005 shown in Example 6 and an improvement of about 1.9 times was observed compared to the comparative example. At that time, the emission characteristic at 147 nm excitation was only about 3% lower than the comparative example.

  Further, as is clear from FIG. 1, the ultraviolet light emitting phosphor of the example according to the present invention has not only the characteristic of excitation at 172 nm but also the light emission characteristic in most of the region from 170 nm to 300 nm as compared with the comparative example. It can be seen that it has improved. For this reason, the present invention can use a light source other than vacuum ultraviolet light emission using Xe discharge as a light source (for example, 185 nm and 254 nm of a low-pressure mercury lamp or 222 nm of a KrCl excimer laser), which is highly industrially useful phosphor. And a light-emitting element using the same.

Note that the terms and expressions used in this specification are merely explanatory and are not restrictive, and do not exclude terms and expressions equivalent to the above terms and expressions.

Claims (2)

It has a composition represented by the general formula Y _1-xy Gd _x Bi _y Al ₃ (BO ₃ ) ₄ (0 <x <0.6, 0.0005 <y < 0.01 ). A phosphor that emits ultraviolet light when excited by vacuum ultraviolet light.   A light-emitting element using the phosphor according to claim 1.