JPS6121182A - Fluorescent substance and its preparation - Google Patents

Abstract

NEW MATERIAL:A cerium activated rare earth element halide fluorescent substance shown by the formula I (Ln is rare earth element of Y, La, Gd, or Lu; MI is alkali metal of Li, Na, K, Cs, or Rb; X and X' are Cl, Br, or I; a is in 0<a<= 10.0; x is in 0<x<=0.2). EXAMPLE:A compound shown by the formula II. USE:Showing stimulable emission when the fluorescent substance is irradiated with radiation, and excited with electromagnetic wave, useful as a fluorescent substance for a panel for converting radiation image, such as medical radiation photograhing e.g., X-ray photographing, industrial radiation photographing, e.g., nondestructive examination of material, and a fluorescent substance for radiation sensitized screen. PREPARATION:A raw material mixture of a fluorescent substance to provide a relative ratio corresponding to the formula III is prepared, and the mixture is calcined in a weak reducing atmosphere at 500-1,300 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a phosphor and a method for manufacturing the same. More specifically, the present invention relates to a rare earth halide phosphor activated by cerium and a method for producing the same.

[Technical Background of the Invention] As a type of cerium-activated halide phosphor, cerium-activated rare earth oxyhalide phosphor (LnOX:Ce, where Ln is selected from the group consisting of Y, La, Gd, and Lu) has conventionally been used as a type of cerium-activated halide phosphor. X is at least one kind of halogen selected from the group consisting of Cl and Br).

For example, as disclosed in Japanese Unexamined Patent Publication No. 55-12144, K, this phosphor emits near-ultraviolet light when excited by radiation such as X-rays, electron beams, and ultraviolet rays, and then by electromagnetic waves in the visible to infrared region. It has been found that the stimulable phosphor exhibits stimulable luminescence) and is useful as a stimulable phosphor used in radiation image conversion methods.

[Summary of the Invention] An object of the present invention is to provide a novel cerium-activated rare earth halide phosphor different from the cerium-activated rare earth oxyhalide phosphor described in -1- and a method for producing the same.

The phosphor of the invention has the compositional formula (I): L n X 3 ++ a M ” X ′: x
Ce 3+ (I) (wherein Ln is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; MII is Li, Na, K, Cs and R
b is at least one kind of alkali metal selected from the group consisting of; X and Xo are each at least one kind of halogen selected from the group consisting of CKL, Br, and (where X is a numerical value in the range of O<x≦0.2) This is a cerium-activated rare earth halide fluorescent material.

In addition, the method for producing the cerium-activated rare earth halide phosphor of the present invention has a stoichiometric compositional formula (II): L nX3 a aM "X':xCe
(II) (However, Ln is Y, La, Gd and L
u is at least one rare earth element selected from the group consisting of; MII is at least one alkali metal selected from the group consisting of Li, Na, K, Cs and Rb; X and Xo are CI, Br and I, respectively; at least one kind of halogen selected from the group consisting of; and a is a numerical value in the range of 0<a≦10,0, and X is 0
<x≦0.2) After preparing a phosphor raw material mixture so as to have a relative ratio corresponding to It is characterized by

The cerium-activated rare earth halide phosphor of the present invention represented by the composition formula (I) exhibits near-ultraviolet to Shows stimulated luminescence in the blue region.

Furthermore, the cerium-activated rare earth halide phosphor of the present invention represented by the composition formula (I) emits light in the near-ultraviolet to blue region ( (instantaneous light emission).

[Configuration of the Invention] The cerium-activated rare earth halide phosphor of the present invention comprises:
For example, it can be manufactured by the manufacturing method described below.

First, as phosphor raw materials: 1) YCJL3, YB r3, YI3, LaCu3, L
aBr3, LaI3, G d CJl 3, GdBr3
, Gdl3, LuCu3. At least one rare earth element halide selected from the group consisting of LuBr3 and Lul3, 2) LiCJl, LiBr, LiI, NaCu, NaB
r, NaI, KCu, KBr, KI, CsCl, CsB
at least one alkali metal halide selected from the group consisting of r, CsI, RbCl, RbBr, and RbI; at least one selected from the group consisting of cerium compounds such as (l, 3) halides, oxides, nitrates, and sulfates; Prepare the compound. In some cases, ammonium halide (NH4x''; where X'' is Cl, Br or I) may also be used as a flux.

When producing a phosphor, the above rare earth element halide (1), alkali metal halide (2) and cerium compound (3) are used to obtain stoichiometric K, compositional formula (II
): L nX3 m aM IX':xCe (II
) (However, Ln is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; M
II is at least one kind of alkali metal selected from the group consisting of Li, Na, K, Cs and Rb; X and Xo are each at least one kind of halogen selected from the group consisting of CI, Br and I; and a is 0
<a≦10.0, and X is O<x≦0.
A mixture of phosphor raw materials is prepared by weighing and mixing the phosphor materials in a relative ratio corresponding to 2).

In the method for producing a phosphor of the present invention, from the viewpoint of stimulated luminance and instantaneous luminance, Ln representing a rare earth element in compositional formula (II) is preferably at least one of Y and La, and an alkali metal MII representing is preferably at least one of Cs and Rb. Further, X and Xo representing halogen are preferably either Cl or Br, respectively, and X and X
Preferably, o are different. The a value representing the content of alkali metal halide is preferably in the range of 0.1≦a≦2.0, particularly preferably in the range of 0.2≦a≦1.0. Similarly, from the viewpoint of stimulated luminance and instantaneous luminance, the X value representing the activation amount of cerium in the compositional formula (If) is preferably in the range of 10-'≦X≦10''.

The phosphor raw material mixture may be prepared by i) simply mixing the phosphor raw materials in 1), 2) and 3) above, or ii) first, the phosphor raw materials in 1) and 2) above. After heating this mixture at a temperature of 100''C or more for several hours, the phosphor raw material of 3) above may be mixed with the obtained heat-treated product, or 1ii) First, The above phosphor raw materials 1) and 2) are mixed in a solution state, and this solution is heated (preferably
It may be carried out by drying under reduced pressure, vacuum drying, spray drying, etc. at a temperature of 0 to 200° C., and then mixing the phosphor raw material in 3) above with the obtained dried product.

In addition, as a modification of the method ii) above, the above method l), 2)
Alternatively, the method of 3) in which the phosphor raw materials are mixed and the resulting mixture is subjected to the heat treatment described above may be used. In addition, the above 1i
As a modification of method i), a method may be used in which the phosphor raw materials of 1), 2) and 3) above are mixed in a solution state and this solution is dried.

In any of the above methods 1), 11), and 1ii), common mixers such as various mixers, V-type blenders, ball mills, and rod mills are used for mixing.

Next, the phosphor raw material mixture obtained as described above is filled into a heat-resistant container such as a quartz port, an alumina crucible, or a quartz crucible, and fired in an electric furnace. Firing temperature is 50
A range of 0 to 1300°C is appropriate, preferably 700°C.
~1000°C. Although the firing time varies depending on the filling amount of the phosphor raw material mixture and the firing temperature, 0.5 to 6 hours is generally appropriate. As the firing atmosphere, a weakly reducing atmosphere such as a nitrogen gas atmosphere containing a small amount of hydrogen gas or a carbon dioxide atmosphere containing -carbon oxide is used. Generally, a cerium compound in which the valence of cerium is tetravalent is used as the phosphor raw material in 2) above, but in that case, in the firing process, the tetravalent cerium is converted to trivalent cerium due to the weakly reducing atmosphere mentioned above. will be returned.

The phosphor of the present invention in powder form is obtained by the above baking.

The obtained powdered phosphor may be subjected to various common operations in the production of phosphors, such as drying, washing, drying, and sieving, as necessary.

The cerium-activated rare earth halide phosphor produced by the production method described above has a composition formula (): % formula % () (where Ln is at least one selected from the group consisting of Y, La, Gd, and Lu). is a rare earth element, and y
1 is at least one kind of alkali metal selected from the group consisting of Li, Na, K, Cs and Rb; X and X' are each at least one kind of halogen selected from the group consisting of Cl, Br and ■; And a is a numerical value in the range of 0<a≦10.0, and X is 0<x≦0
．． It is a numerical value in the range of 2).

The cerium-activated rare earth halide phosphor of the present invention is
When excited with radiation such as UV rays, ultraviolet rays, and electron beams, it emits light in the near-ultraviolet to blue region (emission peak wavelength: approximately 360 to 380 nm).
) shows instantaneous light emission.

FIG. 1 illustrates the instantaneous emission spectrum and its excitation spectrum of the cerium-activated rare earth halide phosphor of the present invention. In FIG. 1, curves 1 to 4 are respectively 1: L a B r 3 * Cs C41:0.
Emission spectrum of 001Ce 3+ phosphor 2: LaBr5sCsCJl: 0.001Ce' Excitation spectrum of phosphor 3: La Cl 3 ・Cs Br : 0.0
Emission spectrum of 01Ce'' phosphor 4: Excitation spectrum of LaCJ13 ecsBr:0.001Ce3+ phosphor.

It is clear from FIG. 1 that the phosphor of the present invention emits instantaneous light in the near-ultraviolet to blue region under ultraviolet excitation. Also, the peak wavelength of its emission spectrum is L a B
r 3 * Cs Cn: 365 nm for 0.001Ce′, LaCl3・CsB
r:0.001Ce'' is 375 nm.

The instantaneous emission spectrum and excitation spectrum of the cerium-activated rare earth halide phosphor of the present invention upon excitation with ultraviolet rays have been explained using the above two types of phosphors as examples. It has been confirmed that the spectrum and excitation spectrum show similar trends as described above. It has also been confirmed that the instantaneous emission spectrum of the phosphor of the present invention when excited by X-rays and electron beams is almost the same as the instantaneous emission spectrum when excited by ultraviolet rays shown in FIG. 1 or 2. There is.

Further, the cerium-activated rare earth halide phosphor of the present invention emits light in the near-ultraviolet to blue region when excited with electromagnetic waves in the visible to infrared region of 500 to 850 nm after irradiation with radiation such as X-rays, ultraviolet rays, and electron beams. Shows exhaustion.

FIG. 2 shows a specific example of the cerium-activated rare earth halide phosphor of the present invention, LaBr3CsCl:O,0
It is a photostimulation excitation spectrum of OICe 3+ phosphor.

From FIG. 2, it can be seen that the phosphor of the present invention has a
It is clear that stimulated luminescence is exhibited when excited with electromagnetic waves in the wavelength range of 50 nm.

The stimulated emission spectrum of the phosphor of the present invention corresponds to the instantaneous emission spectrum (curve 1 in FIG. 1).

Above, the stimulated excitation spectrum and the stimulated emission spectrum of the cerium-activated rare earth halide phosphor of the present invention have been explained by taking the case of the LaBr3 *CsCu:O,0OICe3+ phosphor as an example. It has been confirmed that the stimulated excitation spectrum and the stimulated emission spectrum of the catalytic converter are almost the same as those described above.

FIG. 3 shows the present invention c7) LaBr3 e acscl:
Shows the relationship between the a value and the stimulated emission intensity of the 0.001Ce' phosphor [stimulated emission intensity when excited with He-Ne laser light (632,8 nm) after irradiation with 80KV p X-rays] It is a graph.

As is clear from FIG. 3, the LaBr3/CsCn of the present invention has K and a values in the range of 0<a≦10.0: 0.00
Among 1Ce 3+ phosphors, the a value is 0゜1≦a≦2
．． A phosphor in the range of 0 exhibits high-intensity stimulated luminescence.

Incidentally, the relationship between the a value and the instantaneous emission intensity for the phosphor "-" is similar to that shown in FIG. 3. SaraK, LaB
It was confirmed that for the phosphors of the present invention other than the r3 *CsCl:0.0OICe3') phosphor, the relationships between the a value and the stimulated luminescence intensity and instantaneous luminescence intensity tended to be the same as in Figure 3. has been done.

Due to the luminescent properties explained above, the phosphor of the present invention can be used particularly in medical radiography such as X-ray photography for the purpose of medical diagnosis, and industrial radiography for the purpose of non-destructive inspection of materials. It is used as a phosphor for radiation image conversion panels used in radiation image conversion methods using stimulable phosphors, or in radiography used for radiography for the purposes of medical diagnosis and non-destructive testing. Very useful as a phosphor for radiation intensifying screens.

Next, examples of the present invention will be described. However, these examples do not limit the present invention.

[Example 1] 378.9 g of lanthanum bromide (LaBr3), 168.4 g of cesium chloride (CsCJl) and cerium oxide (C
eO2) 0.172g distilled water (H20) 800 m
1 and mixed to form an aqueous solution. This aqueous solution
After vacuum drying at 0°C for 3 hours, vacuum drying was further carried out at 150°C for 3 hours.Next, the obtained phosphor raw material mixture was filled into an aluminum crucible, and this was placed in a high-temperature electric furnace for firing. I did it. Firing is carried out at 900°C in a carbon dioxide atmosphere containing carbon oxide.
The test was carried out at a temperature of 2 hours. After the firing was completed, the fired product was taken out of the furnace and cooled. In this way, powdered cerium-activated lanthanum bromide phosphor (LaBr3
・CsCl:0.001Ce 3+) was obtained.

[Example 2] In Example 1, lanthanum chloride (LaC 3) 245.
Powdered cerium-activated lanthanum chloride phosphor (LaCl3*CsBr:0 .001C
e3+) was obtained.

[Example 3] In Example 1, yttrium bromide (YBr3) 328 was used instead of lanthanum bromide and cesium chloride, respectively.
．． A powdered cerium-activated yttrium bromide phosphor (YB r 3 e Li Cl :0.00
1Ce3+) was obtained.

Next, the emission spectrum and the excitation spectrum of each of the phosphors obtained in Examples 1 and 2 when excited with ultraviolet rays were measured. The results are shown in FIG.

As mentioned above, curves 1 to 4 in FIG. 1 are respectively 1: L a B r 3 * Cs Cl : 0.
Emission spectrum 2 of 001Ce'' phosphor (Example 1): LaB r3 @ C5cJ1:O,0OIC
Excitation spectrum 3 of e3+ phosphor (Example 1): L a Cl 3 * Cs B r :0.
Emission spectrum of 0OICe 3+ phosphor (Example 2) 4: L a Cl 3 m Cs B r :0.
The excitation spectrum of 001Ce 3+ phosphor (Example 2) is shown.

In addition, LaBr3・C3C41:0 obtained in Example 1
．． When the 001Ce 3+ phosphor was irradiated with X-rays at a tube voltage of 80 KVp and then excited with light in the wavelength range of 500 to 850 nm, the photostimulation excitation spectrum at the peak wavelength (365 nm) of the photostimulated product was measured. The results are shown in FIG.

Furthermore, the tube voltage of 80 was applied to each of the phosphors obtained in Examples 1 to 3.
After irradiating KVp X-rays, a He-Ne laser (wavelength:
The stimulated emission intensity when excited at 632.8 nm) was measured. The results are shown in Table 1.

Table 1 Relative stimulated luminescence intensity Example 1 100 Example 2 95 Example 3 50 [Example 4] In Example 1, the amount of cesium chloride was changed to lanthanum bromide 1
Various cerium-activated lanthanum bromide-based phosphors with different cesium chloride contents were prepared by performing the same operation as in Example 1 except that the amount was varied in the range of 0 to 10.0 moles. (LaBr3 e acscJl
:0.001Ce3')) was obtained.

Next, a tube voltage of 80 KVP was applied to each phosphor obtained in Example 4.
After irradiating with X-rays, a He-Ne laser (wavelength: 632
．． The stimulated luminescence intensity was measured when excited at 8 nm). The results are shown in FIG.

Figure 3 shows L a B r 3 @ a Cs Cl
:0.001Ce3+ is a graph showing the relationship between the content of cesium chloride (a value) and the stimulated luminescence intensity in the phosphor.

[Brief explanation of the drawing]

FIG. 1 shows a specific example of the cerium-activated rare earth halide phosphor of the present invention, LaBr3.C8CJl:0.
001Ce” phosphor and LaCu3*CsB r
:0.001Ce'' Figure 2 shows the instantaneous emission spectrum and its excitation spectrum (curves 1, 2.3 and 4, respectively) of the phosphor of the present invention. A specific example of LaBr3/CsCl: 0.
001Ce" phosphor. FIG. 3 is a diagram showing the photostimulation spectrum of the 001Ce" phosphor. FIG.
It is a graph showing the relationship between the a value and the stimulated luminescence intensity in a 0.001Ce 3+ phosphor.

Claims (15)

[Claims] 1. Composition formula (I): LnX_3・aM^IIX':xCe^3^+(I) (However, Ln is at least one rare earth element selected from the group consisting of Y, La, Gd, and Lu; M^II is at least one alkali metal selected from the group consisting of Li, Na, K, Cs and Rb;
are at least one kind of halogen selected from the group consisting of Cl, Br, and I, respectively; and a is 0<a≦
10.0, x is a numerical value in the range 0<x≦0.2) A cerium-activated rare earth halide phosphor. 2. The phosphor according to claim 1, wherein a in the compositional formula (I) is a numerical value in the range of 0.1≦a≦2.0. 3. The phosphor according to claim 2, wherein a in compositional formula (I) satisfies 0.2≦a≦1.0. 4. The phosphor according to claim 1, wherein Ln in compositional formula (I) is at least one of Y and La. 5. The phosphor according to claim 1, wherein M^II in compositional formula (I) is at least one of Cs and Rb. 6. In compositional formula (I), X and X' are each Cl
and Br, and X≠X'. 7. x in compositional formula (I) is 10^-^5≦x≦10
The phosphor according to claim 1, wherein the phosphor has a numerical value in the range of ^-^2. 8. Stoichiometrically, compositional formula (II): LnX_3・aM^IIX':xCe(II) (however, L
n is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; M^I is Li, N
is at least one kind of alkali metal selected from the group consisting of a, K, Cs and Rb; X and x' are each at least one kind of halogen selected from the group consisting of CL, Br and I; and a is 0< a≦10.0
(x is a numerical value in the range of 0<x≦0.2) After preparing a phosphor raw material mixture to have a relative ratio corresponding to Compositional formula (I) characterized by firing at a temperature in the range of 500 to 1300°C: LnX_3・aM^IX':xCe^3^+(I) (However, Ln, M^I, X, X' , a and x have the same definitions as above) A method for producing a cerium-activated rare earth halide phosphor. 9. Claim 8, wherein a in compositional formula (II) is a numerical value in the range of 0.1≦a≦2.0.
Method for producing the phosphor described in Section 1. 10. a in compositional formula (II) is 0.2≦a≦1.0
A method for producing a phosphor according to claim 9, characterized in that: 11. 9. The method for producing a phosphor according to claim 8, wherein Ln in compositional formula (II) is at least one of Y and La. 12. M^I in compositional formula (II) is Cs and Rb
9. The method for producing a phosphor according to claim 8, wherein the phosphor is at least one of the following. 13. 9. The method for producing a phosphor according to claim 8, wherein x and x' in compositional formula (II) are each Cl or Br, and X≠X'. 14. x in compositional formula (II) is 10^-^5≦x≦
9. The method for producing a phosphor according to claim 8, wherein the numerical value is in the range of 10^-^2. 15. Firing the phosphor raw material mixture at 700 to 1000℃
9. A method for producing a phosphor according to claim 8, characterized in that the method is carried out at a temperature in the range of .