JP2021024924A - Storage phosphor, radiation detection element, personal dosimeter, and imaging plate - Google Patents

Abstract

To provide a novel storage phosphor with good mechanical properties and excellent heat resistance, and a radiation detection element, a personal dosimeter, and an imaging plate that include the storage phosphor.SOLUTION: The storage phosphor comprises a sintered body of sialon and a lanthanoid element. The sialon is one of α-sialon represented by general formula (1): (M)x(Si,Al)12(O,N)16, and β-sialon represented by general formula (2): Si6-zAlzOzN8-z. In the general formula (1), M is one or more elements selected from the group consisting of Li, Mg and Ca and including at least Ca. In the general formula (1), x satisfies 0<x≤2. In the general formula (2), z satisfies 0<z≤4.2.SELECTED DRAWING: None

Description

The present invention relates to a storage phosphor, a radiation detection element containing the storage phosphor, a personal exposure dosimeter containing the storage phosphor, and an imaging plate containing the storage phosphor.

The storage phosphor in the present invention refers to a substance that can undergo some state change by irradiation with radiation and then emit light with an emission intensity according to the irradiation amount by some excitation method, and is photofluorescence (TL) or photostimulation. At least one of the three principles of light emission (OSL) and radiophotoluminescence (RPL) is generated. From these emission principles, the storage phosphor can be used in any application as a radiation detection element. The radiation detection element in the present invention represents an object having a function of detecting radiation. Radiation detection devices using storage phosphors have a wide range of application fields such as medical treatment, security, and radiation protection. For example, personal exposure dosimeters in the field of radiation protection, imaging plates in medical imaging, radiation environment monitoring, etc. are examples of radiation detection elements using typical storage phosphors. Existing storage phosphors include LiF: Mg, Ti mounted on the TL dosimeter, Al ₂ O ₃ : C mounted on the OSL dosimeter, Ag-added phosphate glass mounted on the RPL dosimeter, and an imaging plate. BaFBr: Eu and the like are known.

On the other hand, Sialon powder has been used for LEDs and the like as a phosphor exhibiting good photoluminescence characteristics (for example, Patent Document 1). However, the performance of Sialon as a storage phosphor has not been reported so far. As can be seen from the emission principle, whether or not a certain phosphor produces storage fluorescence is whether or not electrons and holes are accumulated in the capture center by irradiation, or whether or not the valence of the emission center element is changed by irradiation. Determined by. Therefore, there are many phosphors that produce high-intensity photoluminescence, but such phosphors do not always produce high-intensity storage fluorescence. In addition, since a general method for predicting in advance the presence or absence of a capture center in a certain phosphor, its amount, or whether or not a luminescent center element causes a valence change has not been established so far. It is extremely difficult to predict the performance of a fluorescent substance as a storage phosphor without conducting experiments or the like. Therefore, it has not been predicted that Sialon can be used as a storage phosphor.

^{Non-Patent Document 1 describes that BaBrCl: Eu 2+} , which is an alkaline earth metal halide-based phosphor, can be suitably used in medical imaging as a storage phosphor. Non-Patent Document 2 describes that the inorganic phosphor Al ₂ O ₃ : C can be suitably used as a storage phosphor in a personal exposure dosimeter. However, many of these existing storage phosphors do not have sufficient mechanical properties, and it is desired to enrich the storage phosphors having good mechanical properties. Further, as a storage phosphor having good mechanical properties, rare earth-added Si ₃ N ₄ can be mentioned (for example, Patent Document 2), but there is room for improvement in heat resistance, for example, heat resistance as compared with Sialon. Is inferior (Non-Patent Document 3). Since the storage phosphor may be heated at a high temperature when reading the irradiation dose information or initializing the irradiation dose information, it is required to develop a storage phosphor made of a substance having higher heat resistance. Was being done.

JP-A-2002-363554 JP-A-2019-001982

Paul Leblans, Dirk Vandenbroucke and Peter Willems, "Storage Phosphors for Medical Imaging", Materials, 4 (6), 1034-1086 (2011) Bhuwan C. Bhatt, "THERMOLUMINESCENCE, OPTICALLY STIMULATED LUMINESCENCE AND RADIOPHOTOLUMINESCENCE DOSIMETRY: AN OVERALL PERSPECTIVE", Radiation Protection and Environment, 34 (1), 6-16 (2011) Kazuo Kobayashi, Osamu Kimura. Oxidation of non-oxide ceramics. Anticorrosion technology, 1983, 32.6: 331-338.

An object of the present invention is to provide a novel storage phosphor having good mechanical properties and excellent heat resistance, which is composed of a sintered body containing a lanthanoid element and sialon, and to enrich the selection of storage phosphors. To contribute.

Another object of the present invention is to provide a radiation detection element containing the storage phosphor, particularly a personal exposure dosimeter containing the storage phosphor and an imaging plate containing the storage phosphor.

The present invention provides the storage phosphors shown below, and radiation detection elements using the storage phosphors, particularly personal exposure dosimeters and imaging plates.
[1] The storage phosphor is composed of a sintered body containing a lanthanoid element and sialon. The sialon is an α-type sialon represented by the general formula (1): (M) x (Si, Al) ₁₂ (O, N) ₁₆ , or the general formula (2): Si _6-z Al _{z Oz} N ₈ It is one of β-type sialons represented by _−z. M in the general formula (1) is one or more elements containing at least Ca selected from the group consisting of Li, Mg, and Ca, and x in the general formula (1) is 0 <x ≦ 2. Z in the general formula (2) is 0 <z ≦ 4.2.
[2] The lanthanoid elements include cerium (Ce), placeodim (Pr), neodymium (Nd), samarium (Sm), europium (Eu), terbium (Tb), dysprosium (Dy), formium (Ho), and erbium ( The storage phosphor according to [1], which is at least one selected from the group consisting of Er), thulium (Tm), and ytterbium (Yb).
[3] The storage phosphor according to [1] or [2], which comprises a sintered body containing the lanthanoid compound having the lanthanoid element and the sialon.
[4] A radiation detection element containing the storage phosphor according to any one of [1] to [3].
[5] A personal dosimeter containing the storage phosphor according to any one of [1] to [3].
[6] An imaging plate containing the storage phosphor according to any one of [1] to [3].

It is possible to provide a new storage phosphor having good mechanical properties and excellent heat resistance, which is composed of a sintered body containing a lanthanoid element and sialon, and contributes to abundant selection of storage phosphors. be able to. Further, it is possible to provide a radiation detection element containing the storage phosphor, in particular, a personal exposure dosimeter containing the storage phosphor and an imaging plate containing the storage phosphor.

In the present specification, the meanings of the following terms are as follows.
(1) “Storage phosphor” refers to a material that stores the energy of irradiated radiation and then emits light with an intensity corresponding to the irradiation amount.
(2) "Radiation" refers to X-rays, gamma rays, alpha rays, beta rays, neutron rays and the like.
(3) The "lanthanoid element" is usually a general term for 15 elements having atomic numbers 57 to 71, that is, lanthanum (La) to lutetium (Lu), but in the present specification, an atom having no stable isotope. It is a general term for 14 elements excluding the promethium (Pm) element of No. 61.
(4) “Good sinterability” refers to the property that a dense sintered body is easily formed even at a lower sintering temperature, or the property that a denser sintered body is easily formed even at the same sintering temperature.
(5) “A to B” (A and B are numerical values) mean A or more and B or less.
(6) A "radiation detection element" is an object having a function of detecting radiation. Examples of radiation detection elements using storage phosphors include, for example, "personal exposure dosimeter" and "imaging plate". The storage phosphor has a property of accumulating the energy of the irradiated radiation, and the detection unit operates without a power source, so that it is suitable for these radiation detection elements.
(7) The "individual radiation dose meter" is an element that is carried by a radiation worker in a nuclear power plant or the like and that measures the amount of radiation emitted during carrying.
(8) The "imaging plate" is a kind of radiographic image detector, and may be, for example, a form in which a storage phosphor is coated on a support plate such as plastic.
(9) “Ceramics” refers to a sintered product of an inorganic compound or a sintered product of a molded product of an inorganic compound.

<Storage phosphor>
The storage phosphor consists of a sintered body containing a lanthanoid element and sialon. Hereinafter, the lanthanoid element and sialon, and other components (impurities) that may be optionally contained will be described.

(Lanthanoid element)
The lanthanoid element plays a role as an activator. The storage phosphor may contain only one type of lanthanoid element, or may contain two or more types. When the storage phosphor contains a lanthanoid element, the storage phosphor can emit fluorescence associated with the electron orbital transition of the lanthanoid element ion by irradiation.

The lanthanoid element is preferably at least one selected from the above 14 elements. That is, the storage phosphor according to the present invention is at least one selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. It is preferably composed of a sintered body containing a certain lanthanoid element and sialon, and is baked containing sialon and at least one lanthanoid element selected from the group consisting of Ce, Nd, Sm, Eu, Tb and Tm. It is more preferably composed of a body.

The lanthanoid element can be contained in the storage phosphor as a lanthanoid compound such as a metal lanthanoid or a lanthanoid oxide. From the viewpoint of obtaining a storage phosphor having good sinterability, the storage phosphor preferably contains a lanthanoid compound having a lanthanoid element. That is, the storage phosphor according to the present invention is preferably a storage phosphor composed of a sintered body containing a lanthanoid compound having a lanthanoid element and sialon.

(Sialon)
Sialon is widely applied to bearings, turbine blades and cutting tools, and has high mechanical properties and thermal shock resistance. Sialon is usually contained in the storage phosphor as a sintered body (Sialon ceramics). Therefore, when the storage phosphor contains Sialon, a storage phosphor having excellent mechanical properties and thermal shock resistance can be obtained. In addition, Sialon is suitable from the viewpoint of resources because it does not contain rare elements.

The sialon is an α-type sialon represented by the general formula (1): (M) x (Si, Al) ₁₂ (O, N) ₁₆ , or the general formula (2): Si _6-z Al _{z Oz} N ₈ It is one of β-type sialons represented by _−z. M in the general formula (1) is one or more elements containing at least Ca selected from the group consisting of Li, Mg, and Ca, and x in the general formula (1) is 0 <x ≦ 2. Z in the general formula (2) is 0 <z ≦ 4.2.

(Other ingredients that can be optionally included)
The storage phosphor may further contain other components (impurities) other than the lanthanoid element and sialon. Examples of other components include unavoidable impurities that are unintentionally contained in the production process, additives that are intentionally added, and the like. The unavoidable impurities and additives may contain impurity elements such as oxygen (O), carbon (C), and magnesium (Mg).

Examples of the additive include a sintering aid for obtaining a storage phosphor having good sinterability. The storage phosphor can contain one or more sintering aids. The sintering aid, _MgO, a known sintering aid such as Y 2 _{O 3} and the like.

<Manufacturing method of storage phosphor>
The method for producing a storage phosphor according to the present disclosure includes the following steps (1) to (3). Hereinafter, steps (1) to (3) will be described.
(1) A step of mixing a lanthanoid compound having a lanthanoid element and Sialon to obtain a mixture containing the lanthanoid compound and Sialon (first step).
(2) A step of molding the mixture obtained in the above step to obtain a molded product of the mixture (second step), and
(3) A step (third step) of sintering the molded product obtained in the above step to obtain a sintered body (storage phosphor) of the molded product.

<< First step >>
This step is a step of obtaining a mixture containing a lanthanoid compound and sialon by mixing a lanthanoid compound having a lanthanoid element and sialon. The mixture containing the lanthanoid compound and sialon may be in the form of powder (hereinafter, the powdery mixture containing the lanthanoid compound and sialon is also referred to as "raw material powder").
As an example of the lanthanoid element, the example of the lanthanoid element mentioned in the description of the storage phosphor is applied.

(Content of lanthanoid compound in the mixture)
The content of the lanthanoid compound contained in the mixture may be, for example, 0.01 part by mass to 20 parts by mass with respect to 100 parts by mass of the total amount of the lanthanoid compound and Sialon contained in the mixture.

(Additional amount of other components that can be optionally contained)
The raw material powder may further contain components (impurities) other than the lanthanoid compound and sialon. Examples of other components include unavoidable impurities that are unintentionally contained in the production process, additives that are intentionally added, and the like. Examples of the additive include a sintering aid for obtaining a storage phosphor having good sinterability. The storage phosphor can contain one or more sintering aids. The sintering aid, _MgO, a known sintering aid such as Y 2 _{O 3} and the like. The amount of the sintering aid added to the raw material powder may be, for example, 25 parts by mass or less with respect to 100 parts by mass of the total amount of the lanthanoid compound and sialon contained in the raw material powder.

The particle size and particle shape of the raw material powder may be adjusted in order to obtain a storage phosphor having good sinterability. Examples of the adjusting method include crushing and granulation. The crushing method and the granulating method may be any method.

<< Second step >>
This step is a step of molding the mixture obtained in the first step to obtain a molded product. By molding a mixture of the lanthanoid compound and Sialon, the sinterability can be improved in the third step described later.

The molded product can be obtained by press molding (press molding) the raw material crushed in the first step by, for example, a mechanical press, a hydraulic press, a hydraulic press, a cold isotropic press (CIP), or the like. it can. The molding method is not limited to press molding, and general molding methods such as injection molding and tape molding may be used.

The press conditions in the press molding are not particularly limited, but in the case of mechanical press molding using a mold, for example, the conditions can be ^{about 150 to 200 kgf / cm 2.} In the case of CIP, for example, it can be carried out under the condition of ^{1000 to 2000 kgf / cm 2.} A molded product can be obtained by the above method.

<< Third step >>
This step is a step of sintering the molded product obtained in the second step. The sintering method may be any sintering method such as normal pressure sintering, gas pressure sintering, hot press sintering, hot hydrostatic pressure pressure sintering, and pulse energization pressure sintering. The sintering atmosphere is preferably an inert gas atmosphere such as nitrogen or argon from the viewpoint of preventing the oxidation of silicon contained in Sialon.

The conditions for gas pressure sintering are preferably set appropriately according to the composition of the molded product and the sintering apparatus used. The conditions for gas pressure sintering are, for example, a sintering temperature of 1700 to 1800 ° C. and a sintering time of 0.5 to 2 hours in a nitrogen atmosphere of 50 to 300 MPa.

The conditions for atmospheric sintering are preferably set appropriately according to the composition of the molded product and the sintering apparatus used. The conditions for atmospheric sintering are, for example, a sintering temperature of 1700 to 1800 ° C. and a sintering time of 1 to 10 hours (for example, about 6 hours) in a nitrogen atmosphere of 0.2 to 5 MPa (for example, 0.8 MPa).

The sintered body obtained by sintering (that is, the storage phosphor) may be processed. Examples of the processing process include a cutting process and a shape adjusting process such as a polishing process. By the above method, a storage phosphor composed of a sintered body containing a lanthanoid element and sialon can be produced.

<Use of storage phosphor>
Since the fluorescence amount of the storage phosphor changes according to the irradiated radiation amount, the irradiated radiation amount can be detected by measuring the fluorescence amount. The principle of fluorescence includes, for example, TL, OSL, and RPL. The storage phosphor according to the present invention can be suitably used, for example, in the following radiation detection elements, particularly personal exposure dosimeters and imaging plates.

<Radiation detection element>
The storage phosphor according to the present invention may be included in the radiation detection element. The storage phosphor according to the present invention has a radiation detection ability and can be suitably used in a radiation detection element using any conventionally known technique. Among the radiation detection elements, it can be particularly preferably used for personal dosimeters and imaging plates.

<Personal dose meter>
The storage phosphor according to the present invention may be included in a personal dosimeter. Known techniques related to personal exposure dosimeters containing storage phosphors include, for example, filter techniques. Filter technology is a personal dosimeter containing a storage phosphor that uses an open window without a filter, a window with a single or multiple plastic filters, and a personal dosimeter with a single or multiple thin metal filter windows. This is a method of changing the energy of the radiation emitted to the storage phosphor and obtaining the energy information of the irradiated radiation from the comparison of the measurement results. The storage phosphor according to the present invention can be suitably used, for example, in a personal exposure dosimeter using such a known technique.

<Imaging plate>
The storage phosphor according to the present invention may be contained in an imaging plate. The configuration of the imaging plate may be a conventionally known configuration including, for example, a storage phosphor layer formed on a flat plastic substrate and a transparent protective layer for preventing stains and scratches on the surface of the storage phosphor. .. In the imaging plate having such a configuration, the flexibility of the plastic substrate cushions the physical impact, and the transparent protective layer can take out light emission and prevent stains and scratches. The storage phosphor according to the present invention can be suitably used, for example, in an imaging plate using such a conventionally known known technique.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples.

<Examples 1 to 77>
_{(1) Production of storage phosphor (sintered body) Various lanthanoid oxides (CeO 2} , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm) manufactured by High Purity Chemical Laboratory Co., Ltd. as lanthanoid compounds (lanthanoid element supply sources) ₂ O ₃ , Eu ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , all with a purity of 99.9% by mass and in powder form. ) Was prepared. As a sialon, an α-type sialon manufactured by Combustion Synthesis Co., Ltd. was prepared. Each lanthanoid compound was mixed with Sialon to obtain a powdery mixture (raw material powder). The content of the lanthanoid compound contained in the raw material powder is 0.01 part by mass, 0.5 part by mass, 1 part by mass, and 5 parts by mass with respect to 100 parts by mass of the total amount of the lanthanoid compound and Sialon contained in the raw material powder. It was set to 10 parts by mass, 15 parts by mass, or 20 parts by mass. To each raw material powder, silicon nitride balls having a particle size of 10 mm were added so as to have the same volume as the raw material powder, and ethanol was further added so as to have a total volume of about 1.5 times that of the raw material powder. Time mixed. Each of the obtained slurries was dried by an evaporator and then pulverized using a mortar and a pestle. Then, each pulverized raw material was obtained by classifying through a sieve having an opening of 425 μm. Then, each of the crushed raw materials was ^{press-molded under the condition of 200 kgf / cm 2} to obtain a molded product having a cylindrical shape (diameter 10 mm × height 4 mm). The obtained molded product was sintered under normal pressure under the conditions of 0.9 MPa, 1700 ° C., and 4 hours in a nitrogen atmosphere to obtain a storage phosphor (sintered product) according to Examples 1 to 77.

The difference between the examples is the type of the lanthanoid compound contained in the raw material powder and the content of the lanthanoid compound contained in the raw material powder. In each example, the type of the lanthanoid compound contained in the raw material powder and the content (parts by mass) of the lanthanoid compound contained in the raw material powder with respect to 100 parts by mass of the total amount of the lanthanoid compound and Sialon contained in the raw material powder. , As shown in Table 1.

<Examples 78 to 81>
_{The content of Y 2} O ₃ which is a sintering aid is 5 parts by mass (Example 78) and 10 parts by mass (Example 79) with respect to 100 parts by mass of the total amount of the lanthanoid compound and sialon contained in the raw material powder. ), so that 20 parts by weight (example 80) and 25 parts by weight (example 81), except further that the addition of Y ₂ O ₃ raw material powder, storage under the same conditions as in example 32 A phosphor was prepared to obtain a storage phosphor according to Examples 78 to 81.

(2) Evaluation of Emission Performance of Storage Fluorescent Body Whether or not the storage phosphor according to each example emits light with sufficiently high intensity by thermal stimulation after irradiation is examined (hereinafter, also referred to as "emission performance"). Therefore, it was evaluated whether or not it functions as a storage phosphor. The specific evaluation method is as follows.

An X-ray generator (Monoblock XRB80P & N200X4550 manufactured by Spellman) is used as a radiation source, the tube voltage is 40 kV, the tube current is 5.2 mA, and the amount of X-rays equivalent to 10 Gy (gray) in air absorbed dose is stored. The phosphor was irradiated.

The thermal fluorescence (TL) intensity of the irradiated sample (storage phosphor) was measured using a thermoluminescence measuring device (manufactured by nanoGray, TL-2000) while raising the temperature. The applied temperature range when the TL intensity was measured was 50 ° C. to 490 ° C., the temperature rising rate was 1 ° C./sec, and the graph (glow curve) based on the applied temperature and the emission intensity was measured. In the measurement result of the glow curve obtained in this way, the horizontal axis represents the applied temperature (° C.) and the vertical axis represents the electric charge (nC). The unit on the vertical axis, nC, represents nanocoulomb and means 10 minus 9 coulomb. One coulomb is an electric charge (electric energy) carried by a current of 1 ampere per second, and depends on the current value measured by a photomultiplier tube, which is a receiver of this measuring device. This current value increases according to the amount of background noise in addition to the thermal fluorescence (TL) intensity of the storage phosphor. Therefore, from the obtained measurement results, the result of measurement without a sample is the background noise. By subtracting the amount of background noise, the influence of background noise was removed, and the horizontal axis was the applied temperature (° C.) and the vertical axis was the TL intensity (nC) glow curve graph. Further, the values on the vertical axis of the glow curve thus obtained were summed in the range of the applied temperature of 50 ° C. to 490 ° C. to obtain the integrated value of the TL intensity. The integrated values of the obtained TL intensities are shown in Table 1 for Examples 1 to 77 and Table 2 for Examples 78 to 81. The higher the integrated value, the better the light emission performance.

(3) Evaluation of Mechanical Strength of Storage Fluorescent Material It was evaluated whether or not the storage phosphor according to each example had sufficient mechanical strength as the storage phosphor. As a specific evaluation method, the storage phosphor according to each example was rubbed against paper, and it was observed whether the storage phosphor collapsed. The storage phosphor according to each embodiment did not collapse even when rubbed against paper, or even if it collapsed, it was extremely finely collapsed. This indicates that the storage phosphor according to the present application has good mechanical properties.

<Discussion>
From the results of each example in Table 1, it can be understood that the storage phosphor composed of a sintered body containing a lanthanoid element and sialon has sufficient luminescence performance as a storage phosphor. Further, as described above, the storage phosphor according to each example had sufficient mechanical strength. Further, since the storage phosphor according to each example contains sialon, it has excellent heat resistance (Non-Patent Document 3). That is, the storage phosphor according to the present application is a novel storage phosphor having good mechanical properties and excellent heat resistance (Non-Patent Document 3), and abundance of storage phosphors has been achieved.

In Table 1, Examples 2 to 6 in which the content of the lanthanoid compound contained in the raw material powder is 0.5 to 15 parts by mass with respect to 100 parts by mass of the total amount of the lanthanoid compound and Sialon contained in the raw material powder. The storage phosphors according to 9 to 13, 16 to 20, 23 to 27, 30 to 34, 37 to 41, 44 to 48, 51 to 55, 58 to 62, 65 to 69, 72 to 76 have excellent light emission. Examples showing that the raw material powder has performance, the content of the lanthanoid compound contained in the raw material powder is 1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the lanthanoid compound and Sialon contained in the raw material powder. The storage phosphors according to 3, 18, 19, 31, 32 and 40 have been shown to have particularly excellent luminescence performance. It is not clear why the integrated value of TL strength changes depending on the content of the lanthanoid compound contained in the raw material powder, but the change in the sinterability of sialon caused by the addition of the lanthanoid element has an effect. There may be.

In addition, Table 1 shows that the optimum content at which the integrated value of TL intensity is maximized differs for each lanthanoid compound. Specifically, when the lanthanoid compound is Nd ₂ O ₃ , Tb ₄ O ₇ , and Ho ₂ O ₃ , the content of the lanthanoid compound contained in the raw material powder is the same as that of the lanthanoid compound and sialon contained in the raw material powder. The integrated value of the TL strength became the maximum when the total amount was 10 parts by mass with respect to 100 parts by mass. When the lanthanoid compound is Sm ₂ O ₃ and Eu ₂ O ₃ , the content of the lanthanoid compound contained in the raw material powder is 5% by mass with respect to 100 parts by mass of the total amount of the lanthanoid compound and sialon contained in the raw material powder. The integrated value of the TL strength became the maximum when it was a part. When the lanthanoid compound is CeO ₂ , Pr ₂ O ₃ , Dy ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , and Yb ₂ O ₃ , the content of the lanthanoid compound contained in the raw material powder is the raw material powder. The integrated value of the TL intensity became the maximum when the total amount of the contained lanthanoid compound and sialon was 1 part by mass with respect to 100 parts by mass.

As shown in Table 2, the integrated values of the TL intensities of Examples 78 to 81 were 210, 206, 198 and 188 (nC), respectively. In Examples 78 to 81, the integrated value of TL intensity did not decrease significantly. From this, in the method for producing a storage phosphor in the present invention, a conventionally known sintering aid is contained in an amount of 25 parts by mass or less with respect to 100 parts by mass of the total amount of the lanthanoid compound and sialon contained in the raw material powder. It was shown that it may be contained in an amount of 10 parts by mass or less, or may be contained in an amount of 5 parts by mass or less.

The storage phosphor according to the present invention has good mechanical properties and excellent heat resistance in place of ^{BaBrCl: Eu 2+} , which is an alkaline earth metal halide-based phosphor, and _{Al 2} O ₃ : C, which is an inorganic phosphor. It is expected as a new storage phosphor that can have.

Claims (6)

Consists of a sintered body containing lanthanoid elements and sialon,
The Sialon has the following general formula (1):
(M) x (Si, Al) ₁₂ (O, N) ₁₆ (1)
[In the formula, M is one or more elements containing at least Ca selected from the group consisting of Li, Mg, and Ca, and 0 <x≤2].
Α-type sialon represented by, or the following general formula (2):
Si _6-z Al _{z Oz} N _8-z (2)
[In the formula, 0 <z ≦ 4.2]
A storage fluorophore that is one of the β-type sialons represented by. The storage phosphor according to claim 1, wherein the lanthanoid element is at least one selected from the group consisting of cerium, praseodymium, neodymium, samarium, europium, terbium, dysprosium, holmium, erbium, thulium, and ytterbium. The storage phosphor according to claim 1 or 2, which comprises a sintered body containing the lanthanoid compound having the lanthanoid element and the sialon. A radiation detection element comprising the storage phosphor according to any one of claims 1 to 3. A personal dosimeter containing the storage phosphor according to any one of claims 1 to 3. An imaging plate comprising the storage phosphor according to any one of claims 1 to 3.