JPH0713230B2 - Cerium-activated yttrium phosphate phosphor and fluorescent lamp - Google Patents

Description

Detailed Description of the Invention

[Industrial applications]

The present invention relates to a cerium-activated yttrium phosphate phosphor that emits near-ultraviolet rays when excited by ultraviolet rays, and a fluorescent lamp that uses this phosphor.

[Prior art]

Generally, a fluorescent lamp using an ultraviolet-emitting phosphor that emits near-ultraviolet rays whose main component is near-ultraviolet rays around 350 nm is
It is called a black light fluorescent lamp. This black light fluorescent lamp is used for a wide range of applications such as stage lighting, identification lighting for minerals and gems, flaw detection lighting on metal surfaces, forensic medicine identification lighting, instrument lighting, etc. It is a light source. A lead-activated barium silicate phosphor is known as a phosphor used in this black light fluorescent lamp.

[Problems to be Solved by the Invention]

However, the fluorescent lamp using the lead-activated barium silicate phosphor has a problem that the initial output is low and the output maintenance ratio with respect to the passage of time of this initial output is not sufficient. Therefore, it has been desired to develop a practical phosphor having a sufficient initial output and a sufficient output maintenance rate. Further, near-ultraviolet rays near 350 nm have the effect of irradiating the skin of the human body to cause pigmentation, and therefore a practical phosphor has been desired from the viewpoint of effectively utilizing this characteristic. As a phosphor for preventing this adverse effect, a yttrium orthophosphate phosphor has been developed (JP-A-49-91084). The yttrium orthophosphate phosphor described in this publication contains cerium as an activator and thorium as a sensitizer. The yttrium orthophosphate phosphor described in this publication has a xenotime structure having bipeaks at 336 nm and 352 nm when excited by ultraviolet rays. This phosphor exhibits excellent ultraviolet light emission characteristics as compared with the lead activated barium silicate phosphor. However, this phosphor efficiently emits UV-A ultraviolet light, but cannot efficiently emit UV-B ultraviolet light having a short wavelength. Ultraviolet rays have a wavelength of 320 nm as a boundary, and ultraviolet rays having a longer wavelength than this are UV-A and ultraviolet rays having a shorter wavelength are UV-B. Since UV-A has a long wavelength, it takes a long time to pigment the target skin and has the property of penetrating deep tissues of the skin. There is a high possibility that ultraviolet rays will reach the skin and cause skin cancer.
On the other hand, the ultraviolet rays of UV-B have a short wavelength and therefore have a great influence on the skin, and conversely have a property that they do not penetrate deeply into the skin. Therefore, the combined use of UV-B and UV rays has the effect of shortening the irradiation time of UV rays and makes it difficult to cause skin cancer. Further, it has been proved that irradiation of UV rays of UV-B on the skin improves the production of vitamin D and has a great effect on the disease. However, since the ultraviolet rays of UV-B have a strong effect on the skin, too strong radiation may adversely affect the skin. Therefore, it is important that the phosphor that emits ultraviolet rays emits UV-B and UV-A ultraviolet rays in a well-balanced manner. The present invention has been made in view of the above circumstances,
Its purpose is to provide a cerium-activated yttrium phosphate phosphor having an extremely excellent initial output and output maintenance characteristics, as well as a fluorescent lamp, by improving the shape of the spectrum that emits near-ultraviolet light by ultraviolet excitation. is there.

[Means for Solving the Problems]

The cerium-activated yttrium phosphate phosphor of the present invention,
It emits near-ultraviolet rays having peaks near wavelengths of 320 nm, 336 nm, and 352 nm when excited by ultraviolet rays, and has a composition formula of Y _1- xCexPO ₄ (where x is in the range of 0.08 to 0.6).
It is what Further, the cerium-activated yttrium phosphate phosphor of the present invention is characterized in that the crystal structure is a mixed crystal of a xenotime structure and a monazite structure. Furthermore, the fluorescent lamp of the present invention uses the above phosphor. That is, the cerium-activated yttrium phosphate phosphor of the present invention has a Xenotime structure having peaks at wavelengths of 336 nm and 352 nm and a monazite structure having bipeaks at wavelengths of 320 nm and 340 nm. It is a mixed crystal type. Therefore, the cerium-activated yttrium phosphate phosphor of the present invention has a wavelength of 320 nm and 336 nm.
An ideal emission band spectrum shape is obtained near 352 nm. And, the cerium-activated yttrium phosphate phosphor of the present invention is not only a conventional lead-activated barium silicate phosphor, but also a xenotime structure yttrium orthophosphate phosphor, and a monazite structure cerium phosphate phosphor. It has a very high initial output. Further, the cerium-activated yttrium phosphate phosphor of the present invention has an extremely excellent output retention rate. In the cerium-activated yttrium phosphate phosphor, when the content of cerium is less than 0.08 mol with respect to 1 mol of the phosphor, crystals with a xenotime structure increase. When the content of cerium is increased to 0.6 mol per 1 mol of the phosphor, the monazite structure is increased. The cerium-activated yttrium phosphate phosphor is suitable for near-ultraviolet radiation excellent in initial output and output retention rate, regardless of whether it has a xenotime structure or a monazite structure, unless the crystal structure is a mixed crystal of both. No spectrum is available.

【Example】

[First Embodiment] A preferred embodiment of the present invention will be described below. First, a method for producing the cerium-activated yttrium phosphate phosphor of the present invention will be described. 677.4 g Y ₂ O _{3 and} 920.4 g anhydrous Ce ₂ (CO ₃ ) ₃ 30% HC1
Dissolve in 3 liters. Then, 1960 g of 50% H ₃ PO ₄ solution is mixed with this solution. While stirring this mixed solution, 15% aqueous ammonia was gradually added to adjust the pH to 4, and the phosphates of yttrium and cerium were precipitated. The precipitate is filtered, washed with water, dried, and then calcined in an alumina crucible in a weakly reducing atmosphere at a temperature of 1200 ° C. for 4 hours. Next, this fired product is pulverized with a wet ball mill, washed with water, dried, and sieved with a 200-mesh screen. As a result, a cerium-activated yttrium phosphate phosphor is obtained, the composition formula of which is (Y _0.6 Ce _0.4 ) PO ₄ . Next, the shape and emission characteristics of the near-ultraviolet emission spectrum of the cerium-activated yttrium phosphate phosphor thus obtained will be described with reference to FIGS. 1 to 3. In FIG. 1, a 253.7 nm excitation emission spectrum of the cerium-activated yttrium phosphate phosphor (Y _0.6 Ce _0.4 ) PO _{4 having} the above-described composition is shown by a curve a. For comparison,
A similar spectrum of a conventional lead activated barium silicate phosphor is shown by the curve b in FIG. As is apparent from FIG. 1, the active yttrium phosphate phosphor with cerium (Y _0.6 Ce _0.4 ) PO ₄ of the present invention has a band spectrum concentrated around 350 nm. And the spectrum of 350n
In the intensity distribution around m, the conventional activated barium silicate phosphor has a strong initial output of about 20% or more. By the way, the phosphor of the present invention is a mixed crystal type of a xenotime structure having a bipeak at wavelengths of 336 nm and 352 nm and a monazite structure having a bipeak at wavelengths of 320 nm and 340 nm by specifying the addition amount of cerium. With this unique structure, a high initial output and an excellent output maintenance ratio, which could not be realized by the conventional near-ultraviolet emitting phosphor, are realized. That is, the yttrium phosphate phosphor with a small amount of cerium added has a xenotime structure,
Whereas the emission spectrum has an extremely low bipeak near 336 nm as compared to around m, the cerium-activated yttrium phosphate phosphor of the present invention gives a spectrum in which the bipeaks at 336 nm and 352 nm are almost the same. As a result, even if the peak output at 352 nm is lowered, the overall initial output in the wavelength range preferable for the near-ultraviolet emitting phosphor is improved. [Example 2] 10 g of dried nitrocellulose was dissolved in 990 g of butyl acetate to prepare a binder. 100 g of this binder was sampled to obtain the (Y _0.6 Ce _0.4 ) PO ₄ phosphor (Fisher Sub-S) of the present invention.
Mix 100 g of particles by the ieve sizer method (5.3 μ) and stir well to obtain a coating solution. This coating solution is poured from the upper part of a glass tube for standing up to a tube diameter of 32φ40 watts, applied on the inner surface, and then dried. The optimum coating amount of the coating film was 5.3 g. Next, a filament is attached to this glass tube, placed on an exhaust stand, and Ar and Hg are injected to make a FL40S type fluorescent lamp. Place this fluorescent lamp on the lighting stand for 100 hours, 200, 500 for zero hours.
When the peak value of the spectrum after the elapse of time was measured, the results shown in FIG. 2 were obtained. For comparison with the fluorescent lamp of the present invention, a fluorescent lamp using a conventional phosphor was manufactured as a prototype. This fluorescent lamp replaces the (Y _0.6 Ce _0.4 ) PO ₄ phosphor of the present invention with conventional BaSi.
₂ O ₅ : Pb phosphor (similar particle size by FSSS method is 7.1μ)
Was prepared in the same manner as in Example 2 except that the coating amount on the glass tube was changed from 5.3 g to 7.0 g. Phosphor coating amount 5.
The reason for increasing 3 g to 7.0 g is that the particle size of the BaSi ₂ O ₅ : Pb phosphor is larger than that of the (Y _0.6 Ce _0.4 ) PO ₄ phosphor of the present invention. Both of the fluorescent lamps manufactured by the above method have a coating film transmittance of 40.8%. With reference to FIG. 2, a 40 W fluorescent lamp using the cerium-activated yttrium phosphate phosphor of the present invention, and an initial output and an output retention rate of a conventional fluorescent lamp will be described. FIG. 2 shows the output maintenance ratio of the fluorescent lamp using the cerium-activated yttrium phosphate phosphor whose composition formula is (Y _0.6 Ce _0.4 ) PO ₄ in the curve a, and the curve b.
The output maintenance ratio of a fluorescent lamp using a conventional lead-activated barium silicate phosphor is shown in FIG.
The initial output is 100% of the initial output of the conventional fluorescent lamp using the lead activated barium silicate phosphor. As is clear from FIG. 2, first, in the initial output,
The fluorescent lamp using the cerium-activated yttrium phosphate phosphor of the present invention is as high as about 25%, and also in the output maintenance rate after 500 hours. The output of a conventional fluorescent lamp using lead-activated barium silicate phosphor is reduced by about 44%, whereas the fluorescent lamp using the cerium-activated yttrium phosphate phosphor of the present invention is only about 13%. It has not dropped. As a result of X-ray diffraction measurement, the cerium-activated yttrium phosphate phosphor obtained in Example 1 had a zenotime structure having bipeaks at wavelengths of 336 nm and 352 nm, 320 nm and 340 nm.
It was confirmed that it was composed of a mixed crystal type with a monazite structure having a bipeak at the wavelength of. Next, the present inventor made various phosphors with different cerium addition amounts and repeated many experiments to obtain an extremely high emission spectrum in the vicinity of 350 nm which has the pigmentation effect of human skin as shown in FIG. It has been found that the content of cerium may be adjusted to obtain the above. This will be described in detail below with reference to FIG. A curve A in FIG. 3 shows a spectrum of a cerium-activated yttrium phosphate phosphor having a composition formula of (Y _0.94 Ce _0.06 ) PO ₄ . In this spectrum, the peak value near 352 nm is higher than the peak value near 336 nm, but the initial output when used in a fluorescent lamp is inferior to the conventional lead-activated barium silicate phosphor. Note that FIG. 3 is based on the peak value at 352 nm of the cerium-activated yttrium phosphate phosphor (Y _0.94 Ce _0.06 ) PO ₄ (100
%), The spectrum is displayed relatively. A cerium-activated yttrium phosphate phosphor having a cerium content adjusted to 0.08 mol per mol of the phosphor (Y _0.92
The characteristic of Ce _0.08 ) PO ₄ is shown by the curve B in FIG.
In the spectrum of this phosphor, the peak value near 336 nm becomes high, and a slightly wider spectrum is obtained compared to the case of 0.06 mol, and when used in a fluorescent lamp, conventional lead-activated barium silicate is used. The initial output and the output retention rate are higher than those of the phosphor. By increasing the content of cerium in the cerium-activated yttrium phosphate phosphor, the peak around 336 nm was 352
A high spectrum is obtained near 320 nm while approaching the peak of nm. When the content of cerium is 0.4 mol based on 1 mol of the phosphor, a substantially coincident spectrum of bipeaks of 336 nm and 352 nm as shown by the curve C in FIG. 3 is obtained. The spectrum shown by the curve C in FIG. 3 is the same as that of the phosphor shown by the curve a in FIG. The cerium-activated yttrium phosphate phosphor having a further increased cerium content gives a spectrum having one peak near 336 nm, as shown by the curve D in FIG. However, when the content of cerium was 0.8 mol per mol of the phosphor, a spectrum having a peak from 320 nm to 340 nm was obtained as shown by the curve E in FIG. 3, and this spectrum was around 350 nm. It differs from the spectrum that has a peak at. Further, when the phosphor is used in a fluorescent lamp, sufficient output cannot be obtained. The cerium-activated yttrium phosphate phosphor of the present invention is similar to the conventional lead-activated barium silicate phosphor by specifying the content of cerium in the range of 0.08 to 0.6 mol with respect to 1 mol of the phosphor. A spectrum having a peak around 350 nm is realized. In this range, when used in a fluorescent lamp, a phosphor having an initial output and an output retention rate higher than those of the lead-activated barium silicate phosphor of 10 can be obtained.

【The invention's effect】

According to the present invention, the spectrum of radiating near-ultraviolet rays by ultraviolet ray excitation has a shape that radiates UV-A and UV-B ultraviolet rays in a well-balanced manner, and is extremely practical and excellent in initial output and output maintenance It is possible to obtain a cerium-activated yttrium phosphate phosphor having a high rate and a fluorescent lamp. That is, the cerium-activated yttrium phosphate phosphor of the present invention, by limiting the activation amount of cerium to a specified range, the crystal structure of the phosphor is a mixed crystal of monazite structure and xenotime structure. is there. The cerium-activated yttrium phosphate phosphor having a monazite structure is excited by ultraviolet rays and emits ultraviolet rays having peak values at 340 nm and 320 nm. Those with xenotime structure are excited by ultraviolet rays,
It emits ultraviolet rays with peak values at 336 nm and 352 nm. Thus, the cerium-activated yttrium phosphate phosphor of the present invention, by forming a mixed crystal of monazite structure and xenotime structure, emits ultraviolet rays having a peak in the vicinity of 320 nm, 336 nm, and 352 nm, thereby, A remarkable effect that the output of near ultraviolet rays can be increased is realized. Furthermore, the cerium-activated yttrium phosphate phosphor of the present invention contains a specific amount of cerium, and is made into a mixed crystal of xenotime structure and monazite structure by UV-
A and UV-B ultraviolet rays can be emitted. For this reason, the phosphor and the fluorescent lamp of the present invention can reduce the irradiation amount of ultraviolet rays and have an effect on the skin at the same time, as compared with the conventional product that irradiates ultraviolet rays of UV-A. In addition, it also realizes the characteristics that the production of vitamin D can be improved and a superior effect on the disease can be expected. Furthermore, since the phosphor and the fluorescent lamp of the present invention specify the content of cerium, they are irradiated with ultraviolet rays of UV-B as shown in FIG. 1 and FIG. Is
It does not become stronger than UV-A, and has the feature that it can radiate UV-B and UV-A ultraviolet rays in a well-balanced manner. Since UV-B ultraviolet rays have a shorter wavelength than UV-A ultraviolet rays, they have a great influence on the skin, and a small amount of irradiation can have a great influence. It also has the feature that it does not penetrate deeply into the skin. Therefore, in addition to UV-A, the phosphor that emits UV-B ultraviolet light has a feature that it can be irradiated with a small amount and have the same effect. However, if the UV intensity of UV-B is too strong, there is a risk that the effect on the skin will be too strong. Since the phosphor of the present invention specifies the amount of cerium, it emits UV-B ultraviolet light, but its intensity is UV.
It is not stronger than the ultraviolet light of -A, and UV-A and UV-
Achieves excellent features of radiating B with a favorable balance.

[Brief description of drawings]

FIG. 1 is a curve diagram comparing the spectral intensity distributions of the cerium-activated yttrium phosphate phosphor obtained by the present invention and the conventional lead-activated barium silicate phosphor, and FIG. A curve diagram showing the initial output and the output maintenance rate of the fluorescent lamp using the active yttrium phosphate phosphor and the conventional lead-activated barium silicate phosphor, and FIG. 3 illustrates the relationship between the cerium content and the spectrum. It is explanatory drawing for doing.

Front page continued (72) Inventor Teruji Yamakawa 491 Kamikachu-cho Oka, Anan City, Tokushima Prefecture 100 Nichia Kagaku Kogyo Co., Ltd. Gaku Kogyo Co., Ltd. (56) Reference JP-A-49-91084 (JP, A) JP-B 39-11601 (JP, B1)

Claims (2)

[Claims] 1. Wavelengths of 320 nm, 336 nm and
It has a peak near 352 nm and its composition formula is represented by Y _1- xCexPO ₄ (where x is in the range of 0.08 to 0.6), and its crystal structure is a mixed crystal of xenotime structure and monazite structure. A cerium-activated yttrium phosphate phosphor characterized by comprising: 2. Wavelengths of 320 nm, 336 nm and
It has a peak near 352 nm and its composition formula is represented by Y _1- xCexPO ₄ (where x is in the range of 0.08 to 0.6), and its crystal structure is a mixed crystal of xenotime structure and monazite structure. A fluorescent lamp characterized by comprising a cerium-activated yttrium phosphate phosphor.