JPH10259374A - Production of infrared-excited illuminant improved in moisture resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared-excited illuminant sufficiently improved in moisture resistance. SOLUTION: The moisture resistance of an infrared-excited illuminant represented by the formula: R1x R2(1-x) Baz Cl(3+2z) (R1 is a rare earth element; 0.01<x<=1 R2 is a rare earth element other than R1; and 1<z<4) is sufficiently improved by treating the surface thereof with a gaseous fluorinating agent, etc., to form a fluoride layer on the surface. Examples of the fluorinating agent are a hydrogen fluoride gas and a fluorine gas. In the above formula, R1 is pref. at least one element selected from among Er, Tm, Ho, Nd, Pr, and Dy; and R2 is pref. at least one element selected from among Yb, Gd, Y, Lu, Eu, Ce, and La.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorinated luminous body which emits visible light by infrared excitation, and a method for improving the moisture resistance of an infrared-excited luminous body by fluorine treatment.

[0002]

2. Description of the Related Art At present, semiconductor lasers have been put into practical use as light sources for optical communications. However, semiconductor lasers used in optical communications have a wavelength of 1.33 μm, which has a small optical loss in a quartz fiber.
It is configured to oscillate at 1.55 μm. Wavelengths of 780 are also used for digital audio and laser printers.
Semiconductor lasers of about nm are widely used. On the other hand,
Since infrared light having a wavelength of 780 nm or more is invisible, a laser oscillator having a short wavelength has been developed so that the laser light can be used in the visible light region. However, the wavelength of a semiconductor laser currently in practical use is red laser light of about 650 nm, and a light emitting element that emits green or blue laser light having a shorter wavelength than this has not been put to practical use.

Therefore, development of an up-conversion laser that converts infrared semiconductor laser light into blue and green light using the up-conversion phenomenon is expected. Up-conversion refers to a phenomenon in which light having a wavelength shorter than the excitation wavelength is emitted. Some rare earth ions have this emission characteristic. In this method, a rare earth ion is excited by two or more photons, and emits light having energy larger than that of the excitation light.

A light emitting element of this type is YLiF ₄ : E
r using materials such as fluoride single crystal or heavy metal fluoride glass represented by ZBLAN glass (Wilfried Lenth et al., Optics & Photonics News, 3,
[3], pp. 3-15 (1992)), rare earth chloride materials (Japanese Unexamined Patent Publication No. 7-97
572) have been reported, and among them, rare earth chloride materials are particularly attracting attention because of their high light conversion efficiency and extremely high luminous intensity.

However, chlorides, particularly rare earth chloride phosphors, have a high deliquescent (hygroscopicity) property, and when left in the air without any surface treatment, they immediately absorb moisture and deteriorate. Processing needs to be performed.

Generally, surface treatment methods for improving moisture resistance include ion implantation, ion plating, PVD and CVD for inorganic fluorides represented by fluoride glass.
A method of covering the surface with an oxide or a fluoride layer having higher moisture resistance is adopted.

[0007] On the other hand, in materials having a much more severe deliquescent than fluorides such as inorganic chlorides, bromides and iodides, oxides, sulfides and fluorides having high moisture resistance by vapor deposition and the like are used. The surface is coated with an inorganic substance such as, or a technique of impregnating with a polymer solution and then drying to coat the surface.

However, these methods are all methods of surface-coating a base material with another material, and have problems such as uneven coating, insufficient effect of improving moisture resistance, and poor versatility. .

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an infrared-excited light-emitting device having a greatly improved moisture resistance by directly fluorinating only the surface layer of the infrared-excited light-emitting device having a large deliquescent property. An object of the present invention is to provide a surface treatment method for improving the property.

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the surface treatment of an infrared-excited luminescent material with a gaseous fluorinating agent significantly improves the moisture resistance. Thus, an infrared-excited luminescent material with improved moisture resistance and a surface treatment method for improving moisture resistance according to the present invention have been completed. Here, the present invention is as follows.

(1) An infrared-excited luminescent material having a fluoride layer on its surface. (2) The infrared-excited luminescent material according to the above (1), wherein the fluoride layer on the surface is obtained by a reaction between the gaseous fluorinating agent and the parent infrared-excited luminescent material. (3) The infrared-excited luminescent material according to the above (2), wherein the gaseous fluorinating agent is a fluorine gas. (4) The infrared-excited luminescent material according to (2), wherein the gaseous fluorinating agent is hydrogen fluoride gas. (5) The infrared-excited luminescent material according to any one of (1) to (4), wherein the surface fluoride layer has a thickness of 1 μm to 100 μm. (6) The infrared-excited luminescent material is represented by the general formula: R1 _X R2 _(1-X) Ba
_Z Cl _{3 + 2Z} (R1 is a rare earth element, 0.01 <x ≦ 1, R
2. The infrared-excited luminescent material according to any one of (1) to (5), wherein 2 is a rare earth element other than R1 and 1 <z <4). (7) In the general formula described in (6), R1 is Er, T
The infrared-excited luminescent material according to (6), wherein the luminescent material is one or two or more rare earth elements selected from m, Ho, Nd, Pr, and Dy. (8) In the general formula described in (6), R2 is Yb, G
1 selected from d, Y, Lu, Ce, La or Eu
The infrared-excited luminescent material according to any one of the above (6) or (7), which is a kind or two or more kinds of rare earth elements. (9) The method for producing an infrared-excited luminescent material according to any one of the above (1) to (8), wherein the surface of the infrared-excited luminescent material is treated with a gaseous fluorinating agent. (10) The method for producing an infrared-excited luminescent material according to (9), wherein the surface is treated with a gaseous fluorinating agent at a pressure of 1 to 760 Torr. (11) The method for producing an infrared-excited luminescent material according to any of (9) or (10), wherein the gaseous fluorinating agent is a fluorine gas. (12) The method for producing an infrared-excited luminescent material according to any one of (9) and (10), wherein the gaseous fluorinating agent is hydrogen fluoride gas.

Hereinafter, the structure of the present invention will be described in detail together with its operation. The gaseous fluorinating agent used in the present invention is not particularly limited as long as it can uniformly fluorinate the surface of the infrared-excited luminescent material. Common gaseous fluorinating agents include fluorine gas (F ₂ ), hydrogen fluoride (HF), chlorine trifluoride (ClF ₃ ), sulfur tetrafluoride (SF ₄ ), and boron trifluoride (BF _3). ), Germanium tetrafluoride (GeF
₄ ), arsenic pentafluoride (AsF ₅ ) and the like are known,
F ₂ and HF are preferred from the viewpoint of high reactivity and versatility.

The thickness of the fluoride layer on the surface of the infrared-excited luminescent material obtained by the present invention is determined from the balance between the effect of improving the moisture resistance and the luminous characteristics, particularly the luminous intensity, and is preferably from 1 to 1.
It is good to control it to 00 μm, more preferably 1 to 50 μm. When the thickness of the fluoride layer is 1 μm or less, the improvement of the moisture resistance tends to be insufficient, and the luminescent material has a large deliquescence, which makes it difficult to handle in the air. In some cases, peeling is observed between the base and the fluoride layer.

The infrared-excited luminescent material of the present invention is not particularly limited, but is preferably a complex chloride represented by the following general formula. _{R1 X R2 (1-X)} Ba Z Cl 3 + 2Z (R1 is a rare earth element, 0.01 <x ≦ 1, R2 is a rare earth element other than R1, 1 <z <4) In the above formula, R1 rare earth The element is a light emitting source, and typically includes Er, Tm, and Ho, and also includes Nd, Pr, Dy, and the like. In these, E
r, Tm, Ho, and Nd are preferred. When these rare earth elements are irradiated with infrared light, the energy level of the ions transitions stepwise from the ground level to the excited level, and the transition energy emits visible light. Note that R1
Is not limited to one kind, and two or more kinds may be contained.

In the above general formula, the ratio of R1 as a light emitting source is preferably 0.01 <x ≦ 1. When x <0.01, the content of the light emitting source is too small and the light emitting intensity is insufficient. In addition, since the light emitting source R1 emits light alone, the light emitting auxiliary substance R2 may not necessarily be contained. The rare earth element other than R1 represented by R2 is a light emission auxiliary substance, and typically, Y, Gd, Yb, Lu, La, Ce, Eu and the like are used, and among these, Yb and Gd are preferable. Those containing these rare earth elements alone do not emit light even when irradiated with infrared light, and are therefore used together with R1. The luminescence auxiliary substance of R2 is mainly used for increasing the luminescence intensity.

As the infrared-excited luminescent material other than the above general formula, a chloride glass-based luminescent material or the like can be used.

The form of the infrared-excited luminescent material for fluorination of the present invention is not particularly limited, and may be a bulk material such as a single crystal or a polycrystal or a powder. However, in view of the reactivity and the variety of applications of the luminous body, a powdery one is preferable. When pulverizing a bulk body into powder,
To prevent deliquescence due to moisture in the air, it is necessary to ground in an inert gas such as dry Ar and N _2.

In the surface treatment method adopted in the present invention, in consideration of handling of an object to be treated after the treatment, the wet method requires a process of deagglomeration after drying the object to be treated. There is a possibility that the fluoride layer formed on the surface of the substrate may be destroyed. On the other hand, in the dry method, the process after the surface treatment as described above is not necessary, and thus the dry method is preferable. This dry surface treatment method only needs to perform the surface treatment of the base material uniformly,
A batch system or a fluorinated gas flow system may be used. In the batch method, the inside of the reaction system is evacuated in advance, and a fluorinated gas at a predetermined partial pressure is introduced into the system. In the gas flow method, an inert gas such as N ₂ is flowed into the system in advance for purging, and the fluorinated gas is caused to flow. At that time, the fluorinated gas may be diluted with a dry inert gas such as Ar or N ₂ before use.

The fluorination treatment conditions such as reaction time, temperature, fluorinated gas pressure (partial pressure) and the like are not particularly limited, and depend on the surface treatment method and the form of the infrared-excited luminescent material, particularly the specific surface area.
It is determined so as to obtain a desired thickness of the fluoride layer. However, in general, the fluorinated gas pressure (partial pressure) is preferably 1 to 760 Torr, more preferably 1 to 100 Torr.
It is preferable to perform the surface treatment with r because the degree of reaction progress, that is, the film thickness can be easily controlled.

The film thickness of the fluoride layer on the surface of the infrared-excited luminescent material treated with the fluorinated gas was evaluated by the cross-section polishing after the treatment and the distribution of the elemental fluorine in the cross section.

The luminous intensity of the luminous body immediately after the treatment was 50%.
Irradiation with a mW semiconductor laser (wavelength: 650 to 980 nm), 発 光 indicates that light emission can be sufficiently confirmed by visual observation, 発 光 indicates that light emission intensity decreases before processing, and extremely difficult or impossible to confirm light emission. Were qualitatively evaluated as x.

The moisture resistance of the infrared-excited luminescent material was evaluated as follows. That is, 0.5 g of a luminous body after fluorination treatment in 50 ml of ethanol containing about 200 ppm of water.
And emitted light using the same semiconductor laser as used above, and evaluated by the time until light emission could not be visually confirmed. Although this method is strictly a method for evaluating water resistance, the above method was adopted as a method for evaluating moisture resistance because the results corresponded to the results obtained under high temperature and high humidity conditions of 30 ° C./70%. did.

[0023]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the scope of the present invention is not limited to the examples unless it exceeds the gist thereof.

Examples 1 to 18 and Comparative Examples 1 to 8 (batch system) will be described. 1.0 g of the infrared-excited luminescent material shown in Table 1 was introduced into the reaction system, and the system was kept at a vacuum.
A fluorinated infrared-excited luminescent material was obtained under the fluorination treatment conditions shown in (1). The results of the evaluation of the thickness of the fluoride layer on the surface of the obtained luminous body, the luminous intensity immediately after the treatment, and the moisture resistance of the luminous body as described above are shown together with the processing conditions.

[0025]

[Table 1]

Examples 19 to 33 and Comparative Examples 9 to 13 (fluorinated gas flow system) will be described. 1.0 g of the infrared-excited luminescent material shown in Table 2 was introduced into the reaction system, and N was introduced into the system.
After purging completely with _two gases for 30 minutes, a fluorinated infrared-excited luminescent material was obtained under the fluorination treatment conditions shown in Table 2.
In Example 24, the fluorination treatment was performed while grinding using ZrO2 beads as a grinding medium. The results of the evaluation of the thickness of the obtained fluoride layer on the surface of the phosphor, the emission intensity immediately after the treatment, and the moisture resistance of the phosphor as described above are shown together with the treatment conditions.

[0027]

[Table 2]

[0028]

As can be seen from Table 1 and Table 2, according to the present invention, according to the present invention, F ₂ and HF surface infrared excitation light emitter, such a very low complex chlorides moisture resistance fluorination gas as such It can be seen that the treatment improves the moisture resistance, which was about 15 minutes before the treatment, to one week or more.

Correspondingly, in Comparative Examples shown in Tables 1 and 2, some of them were insufficiently fluorinated on the surface and had insufficient effect of improving moisture resistance, while others were too fluorinated. The emission intensity was extremely reduced, the visibility was poor, and the utility was poor.

Claims (12)

[Claims] 1. An infrared-excited luminous body having a fluoride layer on its surface. (2) 2. The infrared-excited luminescent material according to claim 1, which is obtained by reacting a fluorinating agent with a parent infrared-excited luminescent material. 3. The infrared-excited luminescent material according to claim 2, wherein the gaseous fluorinating agent is a fluorine gas. 4. The infrared-excited luminescent material according to claim 2, wherein the gaseous fluorinating agent is hydrogen fluoride gas. 5. The fluoride layer on the surface has a thickness of 1 μm to 100 μm.
The infrared-excited luminescent material according to any one of claims 1 to 4, wherein the thickness is μm. 6. The infrared excitation light emitters _{formula, R1 X R2 (1-X} ) Ba Z Cl 3 + 2Z (R1 is a rare earth element, 0.01 <x ≦ 1, R2 is a rare earth element other than R1, The infrared-excited luminescent material according to any one of claims 1 to 5, wherein 1 <z <4). 7. The method according to claim 6, wherein R is
7. The infrared-excited luminescent material according to claim 6, wherein 1 is one or more rare earth elements selected from Er, Tm, Ho, Nd, Pr, and Dy. 8. 8. The compound according to claim 6, wherein R is
8. The infrared-excited luminescent material according to claim 6, wherein 2 is one or more rare earth elements selected from Yb, Gd, Y, Lu, Ce, La, and Eu. 9. The method for producing an infrared-excited luminescent material according to claim 1, wherein the surface of the infrared-excited luminescent material is treated with a gaseous fluorinating agent. 10. The method for producing an infrared-excited luminescent material according to claim 9, wherein the surface is treated with a gaseous fluorinating agent at a pressure of 1 to 760 Torr. 11. The method according to claim 9, wherein the gaseous fluorinating agent is fluorine gas. 12. The method according to claim 9, wherein the gaseous fluorinating agent is hydrogen fluoride gas.