JP3396264B2 - Infrared blue light wavelength up-converting phosphor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared blue light wavelength up-conversion phosphor having a high conversion efficiency, and can be applied to a full color laser display, an infrared light detecting sensor, etc. In other words, it can be applied as an oscillation element of a short-wavelength solid-state laser using an infrared semiconductor laser as an excitation source, for example, by thinning or making it transparent, and a highly efficient infrared blue containing Tm ³⁺ ions. Wavelength up-conversion fluorescent material.

[0002]

2. Description of the Related Art In recent years, wavelength up-conversion materials utilizing electronic transitions between a plurality of energy levels of rare earth ions are blue,
Since it can be applied to various fields such as a green solid-state laser, a full-color display, an infrared light sensor, etc., it is attracting much interest. As a full color display,
Currently, there are cathode ray tube type, LED type and thin film liquid crystal type,
Larger size, lighter weight, and cost reduction are being promoted rapidly. However, increasing the size and weight of a cathode ray tube type display and increasing the resolution of LED type and thin film liquid crystal type are not easy at all, and it is speculated that it will take years before they are fully put into practical use. On the other hand, with the rapid development of semiconductor lasers, their application to displays is gradually becoming more practical. The semiconductor laser device is
It is characterized by its long life and high reliability, and is currently used mainly in fields such as compact disc signal reading and optical communication light sources. When considering applications to full-color displays, the three primary colors of red, green, and blue are required, so it is generally considered that with these three-color semiconductor lasers, a large, bright, yet lightweight full-color display can be realized. Have been speculated by. Among them, the red semiconductor laser has already been developed and put into practical use together with a high-power infrared semiconductor laser, and has been applied in various fields. On the other hand, green and blue semiconductor lasers are one of the hottest issues at present, but one that can be used stably at room temperature has not yet been developed, and it is said that it will take considerable time to complete. There is. However, on the other hand, if it is possible to efficiently convert high-power semiconductor laser light of infrared light, which is invisible to the human eye, into blue and green light, by combining infrared and red semiconductor lasers with a high-efficiency infrared-visible conversion material, the same laser display order to Ru can be realized, the development of the current varying of the wavelength converting material may have been rapidly promoted. Conventionally, as a material for converting infrared light into blue light, a fluoride phosphor material containing Tm ³⁺ alone or containing Tm ³⁺ and Yb ³⁺ together is known. However, this fluoride material has a very low conversion efficiency for converting infrared light into blue light (<0.1%), and in consideration of the device application as described above, the conversion efficiency must be greatly improved. I won't.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above problems of the prior art and provides a material having a far higher infrared blue light conversion efficiency than conventional fluoride materials.

[0004]

The gist of the present invention is TmC.
The base is a chloride containing 0.1 to 5 mol% of l ₃ and having no absorption in the visible region, and the chloride is a solid solution of an alkali, a chloride of an alkaline earth metal and a chloride of a heavy metal or a compound thereof. from at least one selected from the group
In the infrared blue light wavelength up-conversion phosphor, the heavy metal chloride is generally CdCl ₂ , PbC.
It is selected from ₁₂ and TlCl ₃ . That is, in the present invention, by introducing Tm ³⁺ into anhydrous chloride, the conversion efficiency is greatly improved as compared with the conventional fluoride material. In the infrared blue light wavelength up-conversion phosphor of the present invention, the TmC
The reason why l ₃ is limited to 0.1 to 5 mol% is that there is no effect of Tm ^{3+ when} it is less than 0.1 mol%, and when it exceeds 5 mol%, Tm ³⁺ ions undergo energy transition with each other. This is because blue light emission is significantly quenched by causing cross relaxation. Among the above-mentioned infrared blue light wavelength up-conversion phosphors of the present invention, the general formula, R ¹ _x R ² _(1-x) Ba _z C
The present inventors have separately proposed l _{3 + 2Z} , R ¹ : rare earth element, R ² : rare earth element other than R ^{1 and} substances represented by 0.01 <x ≦ 1, 1 <z <4. Therefore, I will exclude this.

[0005]

The preferred embodiments of the present invention will be described below. FIG. 1 shows an emission spectrum when irradiated with a YAG laser. In FIG. 1 (a), the main emission peak of chloride is located at 450 nm, whereas in FIG.
In (b), the emission peak of blue light of the fluoride is located at 480 nm, and comparing the emission intensities, the former chloride phosphor is about 550 times that of the latter fluoride, and the chloride phosphor is It is clear that the conversion efficiency of the is significantly improved over the fluoride. Also, due to the difference in the position of the emission wavelength,
Chloride is closer to pure blue light than fluoride.

FIG. 2 shows the energy level of Tm ³⁺ ions and the excitation process by a YAG laser (1.06 μm).
Light emission at 480 nm and 450 nm shown in FIG.
This is due to energy transition between ¹ G ₄ → ³ H ₆ and ¹ D ₂ → ³ H ₄ levels of m ³⁺ ion. By irradiation with a YAG laser, first, the intermediate emission level of ³ H ₅ , the emission level of ³ F ₄ and then the emission levels of ¹ G ₄ , ¹ D ₂ in the order of 3 or 4 levels are obtained. It gets excited. With chloride,
Higher conversion efficiency than that of fluoride can be achieved because the lifetime of each Tm ³⁺ energy level in chloride is longer than that of fluoride. The longer lifetime of the intermediate level is advantageous for higher level excitation (ESA), the blue emission levels ¹ D ₂ and ¹ G ₄ are excited more efficiently, and the energy due to non-radiative transition is increased. The loss of is suppressed. As another cause, in the chloride, the total action of Tm ³⁺ ions is much weaker than in the fluoride, the cross relaxation due to it is suppressed, and the concentration quenching hardly occurs. Therefore, chloride can contain more Tm ³⁺ without concentration quenching. For example, Tm up to 1 mol% for chloride
The emission did not weaken even when added with the addition of, while the concentration quenching appeared with the addition of 0.5 mol% for the fluoride. Thus, the present onset
In accordance with Akira, chloride, which does not have the absorption in the visible region, if example example, alkali, Monoa Rui chloride of an alkaline earth is Cd, Pb,
Heavy metal chlorides, such as Tl, or a solid solution thereof using
When that show a much higher efficiency than the fluoride in the same manner as YCl ₃ shown in the following Reference Example 1.

FIG. 1 and Table 1 show the YAG laser (1064n
The spectra or intensities of the blue emission due to m) excitation are shown respectively, and it is clear from FIG. 2 that the YAG laser is by no means a good excitation light. When the YAG laser is irradiated, the ³ H ₅ level is excited in the first step, but since the level is near 1200 nm, the wavelength 10
The absorption efficiency for 64 nm light is very poor. Furthermore,
1064 for the second, third, and fourth excitations to the upper level
Since the nm light does not match the gap between the energy levels of Tm ³⁺ ions, the excitation efficiency is not good. However, if the light has a wavelength of 1200 nm, not only can the ³ H ₅ level of Tm ³⁺ be excited efficiently, but also the energy gap between the Tm ³⁺ ion levels matches that of the ³ H ₅ level.
It can be easily predicted that the conversion efficiency from infrared to blue light will be much higher if the excitation light near 00 nm is used.

In order to manufacture the infrared blue light wavelength up-conversion phosphor of the present invention, a chloride powder having no absorption in the visible region so that the TmCl ₃ powder has a predetermined mol% and in an inert atmosphere. Weigh out and mix well. The mixture is put in, for example, a glassy carbon crucible and dissolved and reacted in a mixed atmosphere of nitrogen and chlorine gas at a temperature of 800 to 1100 ° C. The homogeneously melted melt is slowly cooled to room temperature and ground.

[0009]

EXAMPLES The present invention and its effects are not limited to the materials, compositions and production methods described in the following examples. For example, when Tm is added as another compound or a single element to the material used in the present invention, the addition concentration is changed, or in addition to these, another impurity which does not have absorption in the visible region is added at the same time. Even when used in the same manner, the same effect can be expected. Needless to say, the following embodiments are merely examples, and various modifications and improvements can be made without departing from the spirit of the present invention. Reference Example 1 Composition 99YCl ₃ 1 TmCl ₃ (mol%)
Then , add anhydrous powder YCl ₃ and TmCl ₃ to the high purity nitrogen gas.
Weigh and mix in the filling glove box and mix. mixture
Place the thing in a glassy carbon crucible and nitrogen at a temperature of 800 degrees.
Dissolve and react for about 1 hour in a mixed atmosphere of chlorine gas and chlorine gas
It Slowly cool the homogeneously dissolved melt to room temperature,
Finely crush. Chloride phosphor obtained in this way
Irradiate with 1060nm YAG laser (3 watts)
The emission spectrum at that time is shown in FIG. 450n
A very strong blue emission was observed in the m and 480 nm wavelength bands.
It was

Comparative Example 1 For comparison, one typical conventionally developed fluoride phosphor (40ZnF ₂ 20BaF ₂ 39.5YF ₃ 0.
5TmF ₂ , mol%) with fluoride powder as the starting material,
It was prepared using a platinum crucible in a nitrogen gas atmosphere. NH ₄ HF ₂ powder was added to the batch to promote fluorination. The emission spectrum when the obtained phosphor was finely pulverized and irradiated with the same YAG laser as in Example 1 is shown in FIG.
It shows in (b). The main emission peak of chloride is located at 450 nm, whereas the emission peak of blue light of fluoride is located at 480 nm. Comparing the emission intensities, the chloride phosphors of Example 1 are compared. It is about 550 times that of the fluoride according to Example 1, and it is clear that the conversion efficiency of the chloride phosphor is significantly improved as compared with the fluoride. In addition, due to the difference in the position of the emission wavelength, chloride is closer to pure blue light than fluoride.

[0011] in the same manner as in Comparative Example 2 Comparative Example 1 method to prepare fluoride phosphor having the same composition as in Comparative Example 1 containing 0.2 mol% TmF _3. The blue emission upon irradiation with a YAG laser having a wavelength of 1064 nm is shown in Table 1, and it can be seen that blue emission at 480 nm is stronger than emission at 450 nm, as in Comparative Example 1.

[0012] Reference Example 2-3 Reference Example 1 In the same manner as in TMCL ₃ 0.5 mol% or chloride containing 2 mol% (YCl ₃₎ phosphor samples were prepared, respectively, was excited by YAG laser 1064nm The blue visible light emission intensity at that time was put together with the result of Reference Example 1 and summarized in the following table. Any chloride phosphor is 1 more than fluoride
It exhibited blue light emission of 00 times or more.

[0013]

[Table 1] I ₃₆₅ , I ₄₅₀ , and I ₄₈₀ have wavelengths of 365 nm and 4 respectively.
It is a relative intensity of light emission having peaks at 50 nm and 480 nm, and its unit is arbitrary.

Example 1 A chloride phosphor having the composition 99NaCl1TmCl ₃ (mol%) was prepared in the same manner as in Reference Example 1. When the obtained phosphor was irradiated with a YAG laser having a wavelength of 1060 nm, strong blue light emission was observed. In this example, solid phase reaction
I made it, but vacuum deposition method and sputtering deposition method,
Materials are created by chemical vapor deposition such as chemical vapor deposition
However, the same effect can be obtained.

Example 2 A chloride phosphor having the composition 99PbCl ₂ 1TmCl ₃ (mol%) was prepared in the same manner as in Reference Example 1. When the obtained phosphor was irradiated with a YAG laser having a wavelength of 1060 nm, strong blue light emission was observed. In this example, solid phase reaction
Although the material was created, vacuum deposition method and sputtering deposition method
Materials by chemical vapor deposition such as chemical vapor deposition and chemical vapor deposition
Even if it goes, the same effect can be obtained.

Reference Example 4 A chloride phosphor having a composition of 99GdCl ₃ 1TmCl ₃ (mol%) was prepared in the same manner as in Reference Example 1. When the obtained phosphor was irradiated with a YAG laser having a wavelength of 1060 nm, strong blue light emission was observed. Examples 1 and 2 and Reference Example
4 , the emission spectrum had the same intensity as that of Reference Example 1 and the shape was the same.

[0017]

According to the present invention, a phosphor material having high infrared blue light conversion efficiency can be obtained by incorporating Tm ³⁺ in chloride, and the material according to the present invention can be procured at low cost.
In addition, since the infrared light can be efficiently up-converted into blue light, it can be applied to a short-wavelength solid-state laser using an infrared semiconductor laser as excitation light, a full-color laser display, an infrared light detection sensor, and the like.

[Brief description of drawings]

FIG. 1 shows emission spectra of Reference Example 1 and Comparative Example 1 of an infrared-visible wavelength up-conversion material according to the present invention when excited with YAG laser light having a wavelength of 1060 nm, and (a) shows Reference Example 1
Tm ³⁺ added chloride according to, (b) Tm according to Comparative Example 1
³⁺ added fluoride is shown.

FIG. 2 is an energy level diagram of Tm ³⁺ ions and 1064.
7 shows a wavelength up-conversion process by exciting a YAG laser of nm.

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Claims (2)

(57) [Claims] 1. A base material is a chloride containing 0.1 to 5 mol% of TmCl ₃ and having no absorption in the visible region, and the chloride is an alkali, an alkaline earth metal chloride and a heavy metal chloride, or a chloride thereof. Infrared blue light wavelength up-conversion phosphor (provided that R ¹ _x R ^{2 has the} general formula: R ¹ _x R ²⁾ comprising at least one selected from the group consisting of compound solid solutions of
_(1-x) Ba _z Cl _{3 + 2Z} , R ¹ : Rare earth element, R ² : R ¹
Other than rare earth elements, except for substances represented by 0.01 <x ≦ 1, 1 <z <4). 2. The heavy metal chloride is CdCl ₂ , PbCl ₂
And TlCl ₃ are infrared blue light wavelengths according to claim 1.
Up-converting phosphor.