TW201521685A - Scintillator material, radiation detector, and radiographic examination device - Google Patents

Abstract

This invention provides a scintillator material that comprises either a light-transmitting ceramic consisting primarily of a complex oxide that can be represented by formula (1) or a single crystal of such a complex oxide. When excited by X-rays and/or gamma rays, said scintillator material emits scintillation light having a peak emission wavelength that is further towards the long-wavelength end of the visible-light region than the peak emission wavelengths of existing scintillator materials. This scintillator material also has a high transmittance with respect to the aforementioned scintillation light, has a short decay time, and can be manufactured by heat-treating, at a temperature less than or equal to 1,800 DEG C, a complex oxide having a comparatively simple composition, reducing manufacturing costs. (1) (TbxR1-x-yCey)2B2O7 (In formula (1), 0.2 ≤ x < 1, 0.00001 ≤ y ≤ 0.01, and x+y ≤ 1; R represents one or more rare earth elements selected from among the group consisting of yttrium, gadolinium, lutetium, lanthanum, holmium, thulium, europium, dysprosium, and praseodymium; and B represents one or more elements selected from among the group consisting of titanium, tin, hafnium, silicon, germanium, and zircon (but not silicon only or germanium only).)

Description

Scintillator material, radiation detector, and radiation inspection device

The present invention relates to a scintillator material for detecting an X-ray radiation detector and/or a radiation detector for detecting gamma rays, and more particularly to an X-ray CT apparatus and/or a gamma ray PET. The radiation detector used in the device is a translucent ceramic containing a composite oxide or a scintillator material made of a single crystal, a radiation detector, and a radiation inspection device.

a solid scintillator material capable of releasing light energy in visible light and/or near-visible light regions and a photoelectric conversion circuit for converting optical signals into electrical signals when excited by radiation energy such as X-rays or gamma rays (high-energy electromagnetic photons) It has been used as a radiation detector for various purposes such as resource exploration, security, baggage or food inspection, and high-energy research. Wherein, the solid scintillator material that converts the radiation energy into light energy in the visible light and/or near-visible light region, the photoelectric conversion circuit that converts the light energy into an electrical signal, and the digital signal of the output are digitized and calculated. X-ray CT device or gamma ray PET combined with computerized tomography (CT) system (Positron Emission Tomography, positron emission tomography) device, in recent years, with the progress of the aging society, the medical institution has been rapidly spreading.

The X-ray CT apparatus and the gamma ray PET apparatus not only have different wavelengths of radiation, but also the resulting optical signals and the system for processing them are greatly different. For example, an X-ray CT apparatus is less expensive than a gamma ray PET apparatus, but is exposed to a larger amount than a gamma ray PET apparatus. On the other hand, the gamma ray PET device is capable of high speed photography and is suitable for detecting the position of cancer by detecting a radioactive isotope specifically accumulated by cancer cells, but is a very expensive device. Therefore, the market growth rate and penetration rate of any device are in progress. In other words, in order to promote the spread of radiation medical equipment corresponding to an aging society in the future, it is required to develop a novel emitter material that contributes to a reduction in exposure amount for both a C-ray CT apparatus and a gamma-ray PET apparatus.

Scintillator materials for X-ray CT devices have been known to contain more than half of yttrium oxide (Y ₂ O ₃ ), up to about 50 mol% of cadmium oxide (Gd ₂ O ₃ ), and small amounts of activity (typically about 0.02). Molar %~12 mol%, preferably about 1 mol%~6 mol%, preferably about 3 mol%) rare earth active agent oxide of yttrium cubic structure of light transmissive oxide sintering The body scintillator (U.S. Patent No. 4,421,671 (Patent Document 1)). The ruthenium-active scintillator has been commercially used in the past because of its high luminous efficiency, low residual light, and other preferable characteristics.

For example, Japanese Patent Publication No. Hei 7-97139 (Patent Document 2) discloses a radiation detector including a light-transmitting sintered body scintillator and detecting the flicker. a light-emitting light detector of the body, the light-transmitting sintered body scintillation system is added to a powder scintillator which emits light by radiation, and a sintering aid is added to the powder represented by the following formula, and is filled in a metal container and vacuumed Sealing, hot hydrostatic pressure pressurization, and annealing, a scintillator material (Ln _1-xy Pr _x Ce _y ) ₂ O ₂ S: (X) with high luminous efficiency can be obtained.

(wherein Ln represents at least one element selected from the group consisting of Gd, La, and Y, and X represents at least one element selected from the group consisting of F and Cl, and x is a range of 3 × 10 ^-6 ≦ x ≦ 0.2 The value, y is a value in the range of 1 × 10 ^-6 ≦ x ≦ 5 × 10 ^-3 , and the amount of X is in the range of 2 to 1000 ppm).

Further, the material of the system has been widely used as a scintillator material for an X-ray CT apparatus since the past. For example, Japanese Patent No. 3,741,302 (Patent Document 3) has proposed a continuous improvement.

Further, a scintillator material for other X-ray CT apparatuses is disclosed in Japanese Laid-Open Patent Publication No. 2007-169647 (Patent Document 4).

[Request 1]

A scintillator composition which is provided with a sintered and burnt scintillator composition having a garnet of the formula A ₃ B ₂ C ₃ O ₁₂ before burning, wherein A is composed of Tb , at least one element of the group formed by Ce, and the position of the combination, B is an octahedral position (Al), and C is a tetrahedral position (still Al), and the garnet is selected from the group consisting of At least one substitution: (1) in the above formula, Al of 0.05 atom to 2 atom of the above octahedral B is substituted by Sc, and (2) in the above formula, oxygen of 0.005 atom to 2 atom is substituted with fluorine, and Wherein the above A site is substituted for the same number of Ca atoms, (3) in the above formula, the 0.005 atom to 2 atom of the B site is substituted with Mg, and the same number of oxygen atoms are replaced by fluorine, (4) the above formula, B position An atomic substituent of at least one combination selected from the group consisting of Mg/Si, Mg/Zr, Mg/Ti, and Mg/Hf of 0.005 atoms to 2 atoms, (5) 0.005 atom of the B position in the above formula~ 2 atoms are atomic substitutions of at least one combination selected from the group consisting of Li/Nb and Li/Ta, (6) in the above formula, 0.005 atom to 2 atoms of the above A site are substituted with Ca, and Equal to the number of substituents B or C bits by bit ", conventional scintillator-based ratio of the composition of a shorter decay time was the time of the damage and may reduce the high energy ray exposure.

The scintillator material having a garnet structure of the system is a novel invention, and a similar invention has been frequently proposed recently (for example, Japanese Laid-Open Patent Publication No. 2012-72331 (Patent Document 5) and Japanese Patent Laid-Open No. 2012-184397 (Patent Literature) 6) etc.).

The flagship model of the latest X-ray CT apparatus is progressing with the appearance of the scintillator material.

On the other hand, scintillator materials for gamma ray PET devices have utilized Bi ₄ Ge ₃ O ₁₂ single crystals (commonly known as BGO) since ancient times. Since BGO has a certain degree of luminescence intensity, a certain degree of decay time is short, the melting point is low, and the manufacturing cost is not high, it is required as a relatively inexpensive PET device material. Then, Gd ₂ SiO ₅ :Ce (commonly known as GSO) single crystal with an increase in luminescence amount and a short decay time has been developed, and is used in a high-end model of a gamma ray PET device (for example, Japanese Patent Publication No. 62-8472) (Patent Document 7)).

Subsequently, a Lu ₂ SiO ₅ :Ce (commonly known as LSO) single crystal having a larger amount of luminescence and a shorter decay time was developed, even though it is still mounted in the flagship machine of the gamma ray PET device (for example, Japanese Patent Laid-Open 9- Bulletin No. 118593 (Patent Document 8)).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] US Patent No. 4,421,671

[Patent Document 2] Japanese Patent Publication No. 7-97139

[Patent Document 3] Japanese Patent No. 3741302

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2007-169647

[Patent Document 5] Japanese Laid-Open Patent Publication No. 2012-72331

[Patent Document 6] Japanese Patent Laid-Open Publication No. 2012-184397

[Patent Document 7] Japanese Patent Publication No. 62-8472

[Patent Document 8] Japanese Patent Laid-Open No. Hei 9-118593

However, regarding the X-ray CT apparatus, the problem of the (Y over _{half amount of} Gd ≦ _0.5 ) ₂ O ₃ :Eu-based scintillator material disclosed in the above Patent Document 1 is that the decay time is long and the density is as small as less than 6.0 g/ Cm ³ must be used in thick film.

Further, the problem of the (Gd _1-xy Pr _x Ce _y ) ₂ O ₂ S-based scintillator material disclosed in the above Patent Documents 2 and 3 is that the transmittance of the scintillator light is as low as about 30% due to the monoclinic crystal. And the damage caused by exposure to high energy lines is large.

Further, the (Tb _1-xy Lu _x Ce _y ) ₃ (Al _1-x Sc _z ) ₂ Al ₃ O ₁₂ -based scintillator material disclosed in the above Patent Documents 4, 5, and 6 has a characteristic that the decay time is short, Because of the cubic crystal, the transmittance of the scintillator light is as high as 80% or more, and the damage when the high-energy line is exposed is very small, and it is an extremely suitable material for the scintillator material for the X-ray CT apparatus. However, since it is necessary to process at a high temperature and to produce a composite oxide having a very complicated composition, it is extremely expensive. Alternatively, although an embodiment in which the sintering treatment temperature is lowered depending on the composition is disclosed, since there are many types of constituent elements, there is a problem that the yield is relatively low when manufactured in a desired composition.

On the other hand, regarding the gamma ray PET apparatus, the manufacturing cost for the BGO single crystal is reasonable, but the luminescence intensity and the decay time are insufficient. Further, GSO single crystal and LSO single crystal are very suitable as scintillator materials for gamma ray PET devices because of their high luminous intensity and short decay time. However, since the melting point is extremely high and it is 2000 ° C or higher, it is also a particularly expensive problem compared with other scintillator materials.

The present invention has been made in view of the above problems, and an object thereof is to provide a scintillation light having an emission peak wavelength in a visible light region longer than a conventional wavelength by excitation of X-rays and/or gamma rays. The light transmittance is high and the decay time is also short. The composite oxide having a simple composition can be produced by heat treatment at 1800 ° C or lower, and the novel scintillator material, the radiation detector, and the radiation inspection device can be suppressed.

In order to achieve the above object, the present invention provides a scintillator material, a radiation detector, and a radiation inspection apparatus.

[1] A scintillator material characterized by comprising a light-transmitting ceramic containing a composite oxide represented by the following formula (1) as a main component or a single crystal of a composite oxide represented by the following formula (1). (Tb _x R _1-xy Ce _y ) ₂ B ₂ O ₇ (1)

(wherein x is a range of 0.2 or more and less than 1, and y is a range of 0.00001 or more and 0.01 or less, x + y ≦ 1, and R is selected from the group consisting of ruthenium, cadmium, osmium, iridium, osmium, iridium, osmium, iridium And at least one rare earth element of the group consisting of strontium, and the B system is at least one element selected from the group consisting of titanium, tin, antimony, bismuth, antimony, and zirconium (however, 矽 and 锗 are separate for the element) Except in case)).

[2] The scintillator material according to [1], which is excited by X-rays and/or gamma rays, emits light having an emission peak in a wavelength range of 610 to 700 nm.

[3] The scintillator material according to [1] or [2], wherein the light transmittance at a wavelength of 633 nm at a thickness of 1 mm is 70% or more.

[4] The scintillator material according to any one of [1] to [3], wherein a cubic crystal having a pyrochlore crystal lattice is used as a main phase.

[5] A radiation detector comprising the scintillator material according to any one of [1] to [4].

[6] A radiation inspection apparatus characterized by being equipped with the radiation detector described in [5].

According to the present invention, by using a scintillator material containing terbium and being a ruthenium active type and a cubic rare earth oxide different from the garnet phase as a main component, X-rays and/or Or the excitation of the gamma ray and the scintillation light having the luminescence peak wavelength in the visible light region on the longer wavelength side than the conventional one, and the transmittance of the scintillation light is high, and the decay time is also short, and the manufacturing temperature is 1800 ° C. The following is also a novel scintillator material which suppresses the manufacturing cost.

10‧‧‧radiation detector

11‧‧‧Sparkling board

12‧‧‧Reflecting material

13‧‧‧Light-receiving components

14‧‧‧ Container

Fig. 1 is a schematic view showing the configuration of a radiation detector of the present invention, wherein (a) is a plan view and (b) is a cross-sectional view taken along line A-A in (a).

[Scintillator material]

Hereinafter, the scintillator material of the present invention will be described.

The scintillator material of the present invention is formed of a single crystal containing a transparent ceramic having a composite oxide represented by the following formula (1) as a main component or a composite oxide represented by the following formula (1): (Tb _x R _1-xy Ce _y ) ₂ B ₂ O ₇ (1)

(wherein x is a range of 0.2 or more and less than 1, and y is a range of 0.00001 or more and 0.01 or less, x + y ≦ 1, and R is selected from the group consisting of ruthenium, cadmium, osmium, iridium, osmium, iridium, osmium, iridium And at least one rare earth element of the group consisting of strontium, and the B system is at least one element selected from the group consisting of titanium, tin, antimony, bismuth, antimony, and zirconium (however, 矽 and 锗 are separate for the element) Except in case)).

In the above formula (1), 鋱 is a skeleton material which is efficiently excited by X-ray and/or gamma ray irradiation, and the excitation energy has an efficient energy transfer to the excitation level of the erbium ion of the active material, and further The excitation energy of the energy transfer is a wavelength of light that can be photoelectrically converted by the Si light-emitting diode, and can be adjusted to a level that can emit light at a light having a light-emitting peak in a visible light region on the long wavelength side of the past. The element is an essential element in the present invention. It is preferred because the energy can be efficiently transferred to the cerium ions of the active material and the luminescence intensity is improved. Further, if the photoelectric conversion can be performed by the Si light-emitting diode, it is preferable to manufacture the radiation detector at a low cost lower than that of the photomultiplier tube. In addition, if it is possible to emit light having a luminescence peak in the visible light region on the long wavelength side in the past In the case of light, a radiation detector using a Si light-emitting diode can reduce the bias voltage, so that the circuit can be simplified and preferably.

Moreover, although the luminescence peak of the light emitted by the scintillator material in the past varies with several compositions, it is in the wavelength range of 510 to 590 nm.

The lanthanide rapidly receives the X-ray and/or gamma ray energy absorbed by the lanthanum and further rare earth elements to become an excited state, and rapidly migrates to an element of a low energy state, which is necessary in the present invention. An element. When hydrazine is used in the active agent, the decay time is preferably shortened compared to other active agents such as hydrazine.

R is an element group having an effect of increasing the material density and increasing the absorption cross-sectional area of X-rays and/or gamma ray energy, and further includes an element group having a function of resonating with the electron transport state of ruthenium to improve luminous efficiency.

As such an element, cerium, cadmium, cerium, lanthanum, cerium, lanthanum, cerium, lanthanum, cerium can be preferably used.

Further, Tb, Ce, and R are collectively referred to as elements of the A site position.

The B system has an element which defines the crystal structure of the scintillator material as a cubic crystal of the pyrochlore type, and is an important element in the present invention. As a result, the scintillator material of the present invention has a cubic crystal (vitreous-type cubic crystal) having a pyrochlore crystal lattice as a main phase, and preferably a pyrochlore-type cubic crystal. In addition, the term "main phase" means that the pyrochlore type cubic crystal as a crystal structure accounts for 90% by volume or more, preferably 95% by volume or more, more preferably 99% by volume or more, and most preferably 99.9% by volume or more. When the crystal structure is cubic, there is no scattering due to birefringence It is preferable to increase the transmittance of the scintillation light which is output when excited by X-rays and/or gamma rays, and the transmittance of light having a wavelength of 633 nm at a thickness of 1 mm is preferably 70% or more.

Such an element can preferably utilize titanium, tin, antimony, bismuth, antimony or zirconium. Except where 矽 and 锗 are separate for this element.

Further, an element that enters the position is referred to as an element of the position of the B portion. Further, the above Tb, Ce, and R are collectively referred to as elements of the A site position. That is, the scintillator material of the present invention contains a composite oxide of the A ₂ B ₂ O ₇ type as a main component.

The above formula (1) is composed of at least one rare earth element containing lanthanum and cerium, and a group selected from the group consisting of lanthanum, cadmium, lanthanum, cerium, lanthanum, cerium, lanthanum, cerium, lanthanum, and containing The B is at least one element selected from the group consisting of titanium, tin, antimony, bismuth, bismuth, and zirconium (except that yttrium and lanthanum are excluded as the element alone), but may further contain other elements. Other elements may be exemplified by ytterbium, and various impurity groups are typically exemplified by calcium, aluminum, phosphorus, tungsten, molybdenum, and the like.

The content of the other element is preferably 10 or less, more preferably 0.1 or less, and most preferably 0.001 or less (substantially zero) when the total amount of lanthanum is 100.

In the formula (1), x is 0.2 or more and less than 1.0. In the formula (1), when x is less than 0.2, the strongest peak wavelength when excited by X-rays and/or gamma rays is on the short-wavelength side in the wavelength range estimated in the present invention, and the emission wavelength is toward the short-wavelength side. Offset, there is also a tendency for the decay time to slow down, which is not good. Conversely, when x is 0.2 or more and less than 1.0, It is preferable to make the strongest peak wavelength when excited by X-rays and/or gamma rays into the wavelength range estimated in the present invention, and also to increase the decay time.

In the formula (1), y is 0.00001 or more and 0.01 or less, preferably 0.0001 or more and 0.01 or less. When y is less than 0.00001, the excited state is rapidly received by the absorbed X-ray energy and/or gamma ray, and the concentration of the active agent that rapidly migrates to the low-energy state becomes too thin, so that the luminescence intensity is lowered and attenuated. Time is getting longer and it is not good. When y exceeds 0.01, the luminescence intensity starts to decrease again, which is not preferable. Also, x+y≦1.

The scintillator material of the present invention contains a composite oxide represented by the above formula (1) as a main component. In other words, the scintillator material of the present invention may contain a composite oxide represented by the above formula (1) as a main component, and may contain other components as an accessory component.

Here, the term "main component" means a composite oxide represented by the above formula (1), which is contained in an amount of 50% by mass or more. The content of the composite oxide represented by the formula (1) is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 99% by mass or more, and most preferably 99.9% by mass or more.

Other subcomponents generally exemplified are dopants doped during single crystal growth, fluxes, and sintering aids added during the manufacture of ceramics.

The method for producing the scintillator material of the present invention may be a single crystal production method such as a floating zone method or a micro-downdraw method, or a ceramic production method, and any of the methods may be used. However, the general single crystal manufacturing method has a certain degree of limitation on the concentration ratio of the solid solution. In the invention, the ceramic manufacturing method is better.

Hereinafter, the ceramic production method which is an example of the method for producing the scintillator material of the present invention will be described in detail, but the single crystal production method according to the technical idea of the present invention is not excluded.

Ceramic Manufacturing Law [raw material]

The raw material used in the present invention can be preferably used from at least 1 group consisting of lanthanum and cerium, and rare earth element R (R is selected from the group consisting of lanthanum, cadmium, lanthanum, cerium, lanthanum, cerium, lanthanum, cerium, lanthanum, cerium a rare earth element) and a B element (B is selected from at least one element selected from the group consisting of titanium, tin, antimony, bismuth, antimony, and zirconium) to form a metal powder of the scintillator material constituent element of the present invention. Or an aqueous solution of nitric acid, sulfuric acid, uric acid or the like, or a composite oxide powder of the above elements. In particular, each of the oxide powders of the above elements is preferred because it is stable and safe to handle. Further, the purity of the raw materials is preferably 99.9% by mass or more.

Moreover, the shape of the powder of the above-mentioned raw material is not particularly limited, and for example, a powder having an angular shape, a spherical shape or a plate shape can be preferably used. Further, it is also possible to preferably use the secondary agglomerated powder, and it is also possible to preferably use a granulated powder granulated by a granulation treatment such as a spray drying treatment. Further, the adjustment step of the raw material powders is not particularly limited. A raw material powder produced by a coprecipitation method, a pulverization method, a spray pyrolysis method, a sol gel method, an alkoxide hydrolysis method, or all other synthesis methods can be preferably used. In addition, you can also use a suitable wet ball mill, bead mill, jet mill or dry The obtained raw material powder is treated by a jet mill, a honing machine or the like.

A suitable sintering inhibitor (sintering aid) may be added to the composite oxide powder raw material used in the present invention. In particular, in order to obtain high light transmittance, it is preferred to add a preferred sintering inhibiting aid in accordance with a conventional host material. However, the purity thereof is preferably 99.9% by mass or more. Further, when the sintering inhibitor is not added, the raw material powder to be used may be selected such that the primary particle diameter is a nanometer size and the sintering activity is extremely high. This choice is implemented as appropriate.

Further, various organic additives may be added depending on the purpose of quality stability or yield improvement in the production steps. There is no particular limitation on the above in the present invention. That is, various dispersing agents, binders, lubricants, plasticizers, and the like can be preferably used.

[manufacturing steps]

In the present invention, the raw material powder is used, pressed to form a specific shape, and then degreased, followed by sintering to prepare a densified sintered body having a relative density of at least 92%. The hot isostatic pressing (HIP) treatment is preferably carried out as a subsequent step.

(press forming)

In the production method of the present invention, a usual press forming step can be preferably utilized. In other words, it is generally possible to use a pressing step of filling the raw material powder in a mold in a certain direction, or to store the raw material powder in a deformable waterproof container by a hydrostatic pressure CIP (cool pressure pressurization) (Cold Isostatic Pressing)) steps. Also, apply pressure as long as you confirm The relative density of the molded body is appropriately adjusted, and is not particularly limited. For example, when the commercially available CIP device can be managed within a pressure range of about 300 MPa or less, the manufacturing cost can be suppressed. Alternatively, not only the forming step at the time of molding but also the hot pressing step or the discharging plasma sintering step, the microwave heating step, and the like which are performed once before sintering may be preferably used.

(degreased)

In the production method of the present invention, a usual degreasing step can be preferably utilized. That is, it can be subjected to a temperature rising degreasing step using a heating furnace. Further, the type of the environmental gas at this time is not particularly limited, and air, oxygen, hydrogen, or the like can be preferably utilized. The degreasing temperature is also not particularly limited, but if a raw material of a mixed organic additive is used, it is preferred to raise the temperature to a temperature at which the organic component can be decomposed and eliminated.

(sintering)

In the production method of the present invention, a general sintering step can be preferably utilized. That is, a heating and sintering step such as a resistance heating method or an induction heating method can be preferably used. The ambient gas at this time is not particularly limited, but an inert gas, oxygen, hydrogen, vacuum, or the like can be preferably used.

The sintering temperature in the sintering step of the present invention can be suitably adjusted depending on the starting material selected. In general, the selected starting materials are used, and the temperature on the low temperature side of about 10 ° C to 100 ° C or even about 200 ° C lower than the melting point of the various composite oxide sintered bodies to be produced is appropriately selected. Further, when a pyrochlore-type composite oxide sintered body having a temperature band in which a phase other than the crystal lattice is changed is formed in the vicinity of the selected temperature, the temperature band is strictly managed. When it is sintered under other conditions, it is possible to suppress the incorporation of phases other than the cubic crystal, and it is advantageous in that the birefringence is scattered.

The sintering retention time in the sintering step of the present invention is suitably adjusted depending on the selected starting materials. In most cases, it is a few hours or so. However, the relative density of the composite oxide sintered body after the sintering step must be densified to a minimum of 92% or more.

(hot isostatic pressing (HIP))

In the production method of the present invention, a step of performing a hot isostatic pressing (HIP) treatment may be additionally performed after the sintering step.

Further, in this case, the type of the pressurized gas medium can preferably utilize an inert gas such as argon gas or nitrogen or Ar-O ₂ . The pressure applied by the pressurized gas medium is preferably from 50 to 300 MPa, more preferably from 100 to 300 MPa. When the pressure is less than 50 MPa, the effect of improving the light transmittance may not be obtained. When the pressure exceeds 300 MPa, the light transmittance improvement may not be obtained even if the pressure is increased, and the device may be overloaded and the device may be damaged. It is relatively simple and preferable to apply pressure to a commercially available HIP device which can handle 196 MPa or less.

Further, the processing temperature (specific holding temperature) at this time may be appropriately set depending on the type of the material and/or the sintering state, and is set, for example, in the range of 1000 to 2000 ° C, preferably 1300 to 1800 ° C. In this case, it is necessary to be below the melting point of the composite oxide constituting the sintered body and/or the phase transition point, which is the same as in the case of the sintering step, and when the heat treatment temperature exceeds 2000 ° C, the composite oxide sintered body estimated by the present invention exceeds the melting point or exceeds phase Transfer points, and it is difficult to perform proper HIP processing. Further, when the heat treatment temperature is less than 1000 ° C, the effect of improving the light transmittance of the sintered body cannot be obtained. Further, the holding time of the heat treatment temperature is not particularly limited, but can be appropriately adjusted while recognizing the characteristics of the composite oxide constituting the sintered body.

Further, the heating material, the heat insulating material, and the processing container for performing the HIP treatment are not particularly limited, and graphite or molybdenum (Mo) can be preferably used.

(optical grinding)

In the production method of the present invention, it is preferred that the light-transmitting composite oxide sintered body (translucent ceramic) subjected to the above-described series of manufacturing steps is polished at both end faces on the axis for optical use. The optical surface accuracy at this time is preferably λ/4 or less, and preferably λ/8 or less at the measurement wavelength λ = 633 nm. Further, it is possible to further reduce the optical loss by forming an appropriate anti-reflection film on the surface of the optical polishing.

The scintillator material of the present invention obtained as described above is mainly composed of a cubic crystal having a pyrochlore crystal lattice, and when excited by X-rays and/or gamma rays, emits scintillation light emitted from a scintillator material in the past. The scintillation light having an emission peak in the visible light region on the longer wavelength side is, for example, preferably having a wavelength range of 610 to 700 nm, more preferably having an emission peak in 630 to 670 nm, and preferably having the strongest wavelength peak in the wavelength range. Further, the light transmittance at a wavelength of 633 nm when the thickness is 1 mm is 70% or more.

[radiation detector]

The scintillator material of the present invention is suitable for X-ray CT apparatus use and/or gamma ray PET apparatus use, and can be preferably arranged in a matrix in the apparatus, and is irradiated by X-rays and/or gamma rays. Excited radiation detector. Further, the X-rays and gamma rays estimated in the present invention are, for example, X-rays generated by an X-ray tube using a target having an electron beam irradiation surface made of tungsten or a tungsten alloy (Re-W alloy), and radiation. A gamma ray produced by a gamma ray source of the isotope cobalt 60.

The radiation detector of the present invention comprises a light-emitting element such as a plate made of the scintillator material of the present invention and a Si light-emitting diode of the latter stage. The configuration is illustrated in Fig. 1. In the radiation detector 10 of the present invention, the scintillator plate 11 made of the scintillator material of the present invention is divided into 36 elements of 6 columns in the vertical direction and 6 rows in the horizontal direction by the reflection material 12, and is further disposed in the subsequent stage of each of the scintillator plates 11. The light receiving element 13 is housed in the container 14. The radioactive detector 10 is configured to excite the scintillator plate 11 by X-rays and/or gamma rays incident from the front, and convert the luminescence energy output from the scintillator plate 11 into an electric signal by the light-receiving element 13, Zoom in and output.

Further, the light-receiving element 13 is a light-detecting region of the region of the emission peak wavelength of the scintillator material of the present invention, and is generally used in an X-ray CT apparatus or a radiation detector mounted on the gamma-ray PET apparatus. It is a Si light emitting diode (PD), a Si-APD (Avalanche Light Diode (Avalanche Phitidiide)), a CCD (Charge Coupled Device) image sensor, a photomultiplier tube (PMT), or the like. As for the light receiving element 13, it is preferably, for example, a sensitivity wavelength range 450 to 1050 nm, the maximum sensitivity wavelength is 550 nm or more, preferably a sensitivity wavelength range of 450 to 800 n, and a Si-APD (avalanche light-emitting diode) having a maximum sensitivity wavelength of 590 nm or more is preferable.

The X-ray CT apparatus is manufactured by combining the radiation detector 10 of the present invention arranged in a matrix form with a computerized tomography (CT) system that digitizes the electrical signals output from the radiation detector 10 and is imaged by calculation processing. Or a radiation inspection device for a gamma ray PET device.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited to the examples. Further, the primary particle diameter of the raw material powder was determined by a laser light diffraction method using a weight average value.

[Example 1 and Comparative Example 1]

In the above formula (1), an example in which titanium, tin or antimony is selected as an element of the B site position will be described.

Obtained cerium oxide powder, cerium oxide powder, cerium oxide powder, cadmium oxide powder, cerium oxide powder, cerium oxide powder, cerium oxide powder, cerium oxide powder, cerium oxide powder, cerium oxide powder and oxidation by Shin-Etsu Chemical Industry Co., Ltd.鐠 powder. Further, titanium oxide powder, tin oxide powder, and cerium oxide powder manufactured by American Elements Co., Ltd., which were manufactured by High Purity Chemical Research Co., Ltd., were obtained, and the purity was 99.9% by mass or more.

Using the above raw materials, a mixing ratio of the final composition as shown in Table 1 was produced. The ratio of each mixed oxide raw material. That is, the sum of the molar ratios of the final elements of 鋱, 铈, and R (i.e., the number of elements in the position of the A site), and the number of moles of titanium, tin, or bismuth (i.e., part B) The molar amount of the element of the position is a mixed powder of the same amount as the molar ratio. Next, dispersion and ‧ mixing treatment were carried out in ethanol using a zirconia ball mill apparatus while preventing mutual test samples from being mixed with each other. The processing time is 24 hours. Subsequently, a spray drying treatment was carried out to prepare a granulated raw material having an average particle diameter of 20 μm. Further, these powders were placed in a crucible, and subjected to a calcination treatment at 1600 ° C for 3 hours in a high-temperature muffle furnace to obtain a calcined raw material containing 28 types of the comparative examples. The diffraction pattern analysis of each of the obtained calcined raw materials was carried out by a powder X-ray diffraction apparatus manufactured by PANalytical Co., Ltd. As a result, it was confirmed that any of the calcined raw materials was an oxide raw material having a pyrochlore type cubic crystal (a cubic crystal having a pyrochlore crystal lattice) as a main phase as a crystal structure.

The obtained various raw materials were again dispersed and mixed with ethanol in a zirconia ball mill apparatus. At this time, a suitable organic dispersant and an organic binder are added. The processing time is 40 hours. Subsequently, a spray drying treatment was carried out to prepare a particulate pyrochlore-type oxide raw material (starting material) having an average particle diameter of 20 μm.

Next, the obtained starting material was filled in a mold having a diameter of 40 nm, and temporarily formed into a rod shape having a thickness of 6 mm by a uniaxial press molding machine, and then hydrostatically pressed at a pressure of 198 MPa to obtain a CIP molded body. Next, the obtained CIP molded body was placed in a muffle furnace, and heat-treated at 800 ° C for 3 hours in the air to carry out degreasing.

Next, the obtained degreased molded body was fed into a vacuum heating furnace, and the temperature was raised to 1500 to 1700 ° C at a heating rate of 100 ° C / h, and after 3 hours, it was cooled at a cooling rate of 600 ° C / h to obtain a sintered body. At this time, the sintering temperature or the holding time was adjusted so that the sintered relative density of the sample became 92% or more.

Further, the sintered body was subjected to HIP treatment at a HIP heat treatment temperature of 1500 to 1750 ° C and a pressure of 190 MPa for 3 hours using Ar gas as a pressurizing medium.

Each of the ceramic sintered bodies thus obtained was cut into a width of 2 mm × 2 mm and a thickness of 1 mm, and subjected to grinding and polishing treatment to form a scintillator plate. Next, a reflective material (made of magnesium oxide powder dispersed in the cerium oxide paste, followed by drying) is disposed between the scintillator plates, and is cut into 36 elements of 6 columns in the vertical direction and 6 rows in the horizontal direction. The final optical polishing of the optical both end faces of the sample was carried out with an optical surface precision λ/4 (measurement wavelength λ = 633 nm).

The transmittance of each obtained scintillator plate was measured using a HeNe laser (wavelength: 633 nm) in the following manner. At this time, care should be taken not to irradiate the laser beam between the scintillator plate and the scintillator plate.

(Measurement method of transmittance)

The transmittance is measured by the intensity when light having a wavelength of 633 nm is transmitted, and is obtained by the following equation.

Transmission rate (%) = 1 / Io × 100

(In the formula, I represents the transmitted light intensity (intensity of light transmitted through a sample having a thickness of 1 mm), and Io represents incident light intensity).

Subsequently, each of the scintillator plates 11 is placed on the light receiving element 13 to form the radiation detector 10 of FIG. Then, using the light output measuring device which is formed by combining the X-ray tube of the radiation detector 10 and the tungsten target, the X-ray tube is irradiated with X-rays at a tube voltage of 120 kV, and the current flowing into the light-receiving element 13 is obtained. The value is output as light. Further, Si-APD (short wavelength type manufactured by Hamamatsu Photonics Co., Ltd., model number S5343, sensitivity wavelength range of 550 to 800 nm, maximum sensitivity wavelength of 590 nm) was used as the light receiving element 13. Further, the sensitivity of the Si-APD at a wavelength of 540 nm (the peak wavelength of the CdWO ₄ single crystal (CWO single crystal) scintillator of the reference sample) and the sensitivity at a wavelength of 650 nm (corresponding to the luminescence peak wavelength of the sample of the example) To the same extent.

At this time, the emission peak wavelength, the light output, and the decay time of the scintillator plate 11 are obtained as follows.

(Method for measuring the peak wavelength of luminescence)

Before the light output was evaluated by the X-ray irradiation evaluation system, photoluminescence was measured by a fluorescence lifetime measuring device (Quantaurus-Tau: Model C11367-1, manufactured by Hamamatsu Photonics Co., Ltd.). As a result, the luminescence peak wavelength was obtained. That is, the excitation light is excited by a light having a wavelength of 280 nm, the emitted fluorescent light is subjected to gratings, and the fluorescence wavelength spectrum is detected by a CCD camera, and the maximum wavelength of the fluorescence output is regarded as an emission peak when X-ray irradiation is performed. wavelength. Further, the light having an excitation wavelength of 280 nm is the shortest wavelength that can be incident on the fluorescence lifetime measuring device, that is, the ultraviolet light having the maximum energy, for example, does not cause vibration of the skeleton material during X-ray irradiation, but when the scintillator plate is excited, The excitation energy of the order relaxation can confirm the sufficient excitation wavelength at the wavelength of the last emission, and the excitation light for the X-ray for measuring the peak wavelength of the emission at the time of X-ray irradiation can be used.

(Method of measuring light output)

Here, for the purpose of comparison, the CdWO ₄ single crystal (CWO single crystal) scintillator which is separately obtained is placed in the radiation detector 10 instead of the scintillator plate 11, and the time is obtained by the evaluation method using the light output measuring device. Light output, and the light output ratio (for CWO ratio) of the sample when the value was set to "1" was displayed as the light output value of each sample.

(Method of measuring decay time)

In the light output measuring apparatus described above, the state in which the X-rays are irradiated and the light output of each sample is stabilized is set to 100%, and then the X-ray irradiation is stopped, and the light output intensity of each sample is attenuated to 5% of the stable state after the measurement is stopped. Time (decay time during X-ray irradiation).

Further, in the above-described fluorescence lifetime measuring device, the light having an excitation wavelength of 280 nm is irradiated and the light output of each sample is stabilized. After 100%, the light irradiation was stopped, and the time until the light output intensity of each sample was attenuated to 5% of the stable state after the stop (the decay time at the time of ultraviolet irradiation) was measured.

The above series of evaluation results are shown in Table 2.

From the above results, the scintillator material having the pyrochlore-type composite oxide as a main component formed by the group of the examples has a transmittance of 70% or more and a transparency of light having a wavelength of 633 nm at a thickness of 1 mm. Therefore, the light emitted as the scintillator material has no unnecessary scattering loss in the interior thereof, and the strongest emission peak wavelength when excited by X-rays is in the wavelength range of 638 to 661 nm, so that it can be used as the Si light-emitting diode of the light-receiving element. The photoelectric conversion is carried out without problems, and the light output is not inferior to that of the past materials, and the decay time of the residual light output by X-ray irradiation is 5%, which is 5 ms or less. Further, the decay time when the residual light of the ultraviolet irradiation is 5% is 1 ns of the lower limit of measurement (device performance limit). In this way, when the scintillator material of the present invention is used in a radiation inspection apparatus such as an X-ray CT apparatus or a gamma ray PET apparatus, the switching cycle can be speeded up, so that operability and safety in a short time and a low exposure amount can be achieved. Excellent radiation inspection device.

Further, in the compositions of Comparative Examples 1-1 to 1-3, since the strongest emission peak wavelength at the time of X-ray excitation was shifted to the short wavelength side of less than 600 nm, the photoelectric conversion efficiency of the Si light-emitting diode was lowered. Further, in the composition of Comparative Example 1-4, since the concentration of ruthenium of the active agent was too low, the light output was low. On the contrary, in the composition of Comparative Example 1-5, since the concentration of ruthenium of the active agent was too high, a concentration extinction phenomenon occurred to lower the light output.

[Example 2, Comparative Example 2]

In the above formula (1), the element which is the position of the B site is selected from the group consisting of ruthenium, osmium, and zirconium.

Acquired cerium oxide powder, cerium oxide powder, cerium oxide powder, and cadmium oxide powder manufactured by Shin-Etsu Chemical Co., Ltd. Further, cerium oxide powder, cerium oxide powder, and zirconia powder of the first rare element chemical industry (stock) manufactured by High Purity Chemical Research Institute Co., Ltd. were obtained. The purity was 99.9% by mass or more.

Using the above raw materials, each mixed oxide raw material which is a mixing ratio of the final composition of Table 3 was produced. That is, the total ratio of the molar ratios of the final tantalum, niobium, and tantalum or cadmium (i.e., the number of moles of the element at the A site position) to the molar ratio of niobium and zirconium, or hafnium and zirconium, respectively. The total amount, or the number of moles of yttrium, lanthanum or zirconium (i.e., the number of moles of the element at the position of the B site) is a mixed powder of the same molar ratio. Next, dispersion and ‧ mixing treatment were carried out in ethanol using a zirconia ball mill apparatus while preventing mutual test samples from being mixed with each other. The processing time is 24 hours. Subsequently, a spray drying treatment was carried out to prepare a granulated raw material having an average particle diameter of 20 μm.

Further, these powders were placed in a crucible, and calcined at 1600 ° C for 3 hours in a high-temperature muffle furnace to obtain a calcined raw material containing seven types of comparative examples. The diffraction pattern analysis of each of the obtained calcined raw materials was carried out by a powder X-ray diffraction apparatus manufactured by PANalytic Co., Ltd. As a result, it was confirmed that the pyrochlore type cubic crystal (the cubic crystal having the pyrochlore crystal lattice) as the crystal structure is the oxide raw material of the main phase, and the examples are 2-1, 2-2, and 2-3. Group of 2-4. Further, although it is a pyrochlore type, the raw material of the crystal is orthorhombic is a group of Comparative Examples 2-1 and 2-2. Further, the raw materials of other fluorite-type tetragonal crystals other than the pyrochlore-type cubic crystals were the examples 2-5.

Each of the materials thus obtained was again subjected to dispersion and mixing treatment in ethanol using a zirconia ball mill apparatus. At this time, a suitable organic dispersant and an organic binder are added. The processing time is 40 hours. Subsequently, a spray drying treatment was carried out to prepare a particulate pyrochlore-type oxide raw material (starting material) having an average particle diameter of 20 μm.

Next, the obtained starting material was filled in a mold having a diameter of 40 nm, and temporarily formed into a rod shape having a thickness of 6 mm by a uniaxial press molding machine, and then hydrostatically pressed at a pressure of 198 MPa to obtain a CIP molded body. Next, the obtained CIP molded body was placed in a muffle furnace, and heat-treated at 800 ° C for 3 hours in the air to carry out degreasing.

Next, the obtained degreased molded body was fed into a vacuum heating furnace, and the temperature was raised to 1500 to 1700 ° C at a heating rate of 100 ° C / h, and after 3 hours, it was cooled at a cooling rate of 600 ° C / h to obtain a sintered body. At this time, the sintering temperature is adjusted or maintained so that the sintered relative density of the sample becomes 92% or more. time.

Further, the sintered body was subjected to HIP treatment using Ar gas as a pressurizing medium at a HIP heat treatment temperature of 1500 to 1750 ° C and a pressure of 190 MPa for 3 hours.

Next, each of the obtained ceramic sintered bodies was cut to have a growth width of 2 mm × 2 mm and a thickness of 1 mm, and subjected to grinding and polishing treatment. Then, the transmissive reflective material is processed into a scintillator material composed of 36 elements of 6×6, and the final optical end of the optical both ends of the sample is performed with an optical surface precision of λ/4 (measurement wavelength λ=633 nm). Grinding.

The transmittance of each obtained scintillator plate was measured in the same manner as in Example 1 using a HeNe laser (wavelength: 633 nm). At this time, care should be taken not to irradiate the laser beam between the scintillator plate and the scintillator plate.

Subsequently, in the same manner as in the first embodiment, each of the scintillator plates 11 is placed on the light receiving element 13 to form the radiation detector 10 of Fig. 1 . Then, a light output measuring apparatus was produced in the same manner as in the first embodiment, and X-rays were applied to the scintillator plate 11 at a tube voltage of 120 kV of the X-ray tube of the tungsten target, and the current value flowing to the light receiving element 13 was obtained as a light output. At this time, in the same manner as in the first embodiment, the emission peak wavelength, the light output, and the decay time of the scintillator plate 11 were obtained.

The results of the above series of evaluations are shown in Table 4.

From the above results, the transmittance of light having a wavelength of 633 nm at a thickness of 1 mm, which is a scintillator material having a pyrochlore-type composite oxide as a main component, is in the range of 65% or more, especially in the examples. 2-1~2-4 is 79% or more and transparent. Therefore, the light emitted as a scintillator material has no unnecessary scattered loss inside, and the strongest luminescence peak wavelength when excited by X-ray is 656~661nm. In the wavelength range, the Si light-emitting diode as the light-receiving element can be photoelectrically converted without any problem. Moreover, the light output is not inferior to the material in the past, and the decay time of the residual light output by X-ray irradiation is 5% is very short. It is 6ms or less. Further, the decay time when the residual light of the ultraviolet irradiation was 5% was 1 nm of the lower limit of measurement (device performance limit). Further, in Examples 2 to 5, the light output was slightly lower than that of the other examples, because in the composition of Example 2-5, the fluorite-type tetragonal phase was mixed in addition to the pyrochlore-type cubic crystal. Thereby increasing the light scattering. In this way, when the scintillator material of the present invention is used in a radiation inspection apparatus such as an X-ray CT apparatus or a gamma ray PET apparatus, the switching cycle can be speeded up, so that operability in a short time and a low exposure amount can be achieved. A radiation inspection device with excellent safety.

Further, in the compositions of Comparative Examples 2-1 and 2-2, since the crystal system was orthorhombic, the transmittance was lowered, and thus the light output was lowered.

[Example 3, Comparative Example 3]

In the above formula (1), an example in which zirconium or hafnium is selected as the element of the B site position and the sintering temperature is adjusted is described.

Obtained cerium oxide powder, cerium oxide powder, cadmium oxide powder, and cerium oxide powder manufactured by Shin-Etsu Chemical Co., Ltd. Further, zirconia powder manufactured by the first rare element chemical industry (share) and cerium oxide powder manufactured by American Elements Co., Ltd. were obtained. The purity was 99.9% by mass or more.

Using the above raw materials, each mixed oxide raw material which is a mixing ratio of the final composition of Table 5 was produced. That is, the sum of the molar ratios of the final 鋱, 铈, and R elements (that is, the elemental molar number at the A site position), and the molar number of zirconium or yttrium (ie, the position of the B site) The elemental molar number is a mixed powder of the same amount as the molar ratio. Next, dispersion and ‧ mixing treatment were carried out in ethanol using a zirconia ball mill apparatus while preventing mutual test samples from being mixed with each other. The processing time is 24 hours. Subsequently, a spray drying treatment was carried out to prepare a granulated raw material having an average particle diameter of 20 μm. Further, these powders were placed in a crucible, and subjected to a calcination treatment at 1600 ° C for 3 hours in a high-temperature muffle furnace to obtain a calcined raw material containing 12 types of the comparative examples. The diffraction pattern analysis of each of the obtained calcined raw materials was carried out by a powder X-ray diffraction apparatus manufactured by PANalytic Co., Ltd. As a result, any of the calcined raw materials was confirmed to be a pyrochlore type cubic crystal as a crystal structure. (Cubic crystal with pyrochlore crystal lattice) is the oxide raw material of the main phase.

Each of the obtained raw materials was again subjected to dispersion and mixing treatment in ethanol using a zirconia ball mill apparatus. At this time, a suitable organic dispersant and an organic binder are added. The processing time is 40 hours. Subsequently, a spray drying treatment was carried out to prepare a particulate pyrochlore-type oxide raw material (starting material) having an average particle diameter of 20 μm.

Next, the obtained starting material was filled in a mold having a diameter of 40 nm, and temporarily formed into a rod shape having a thickness of 6 mm by a uniaxial press molding machine, and then hydrostatically pressed at a pressure of 198 MPa to obtain a CIP molded body. Next, the obtained CIP molded body was placed in a muffle furnace, and heat-treated at 800 ° C for 3 hours in the air to carry out degreasing.

Next, the obtained degreased molded body was fed into a vacuum heating furnace, and the temperature was raised to 1650 to 1750 ° C at a heating rate of 100 ° C / h, and after 10 hours, it was cooled at a cooling rate of 600 ° C / h to obtain a sintered body. At this time, the sintering temperature or the holding time is adjusted so that the sintered relative density of the sample becomes 99.2% or more.

Further, the sintered body was subjected to HIP treatment using Ar gas as a pressurizing medium at a HIP heat treatment temperature of 1500 to 1750 ° C and a pressure of 190 MPa for 3 hours.

Next, each of the ceramic sintered bodies thus obtained was cut into a length of 2 mm × 2 mm and a thickness of 1 mm, and subjected to grinding and polishing to form a scintillator plate. Next, a reflective material (made of magnesium oxide powder dispersed in the bismuth oxide paste, followed by drying) is disposed between the scintillator plates, and is cut into 36 elements in 6 rows and 6 rows in the horizontal direction, and then The optical surface precision λ/4 (when the measurement wavelength λ = 633 nm) was subjected to final optical polishing on the optical both end faces of the sample.

The transmittance of each obtained scintillator plate was measured in the same manner as in Example 1 using a HeNe laser (wavelength: 633 nm). At this time, care should be taken not to irradiate the laser beam between the scintillator plate and the scintillator plate.

Subsequently, in the same manner as in the first embodiment, each of the scintillator plates 11 is placed on the light receiving element 13 to form the radiation detector 10 of Fig. 1 . Then, a light output measuring apparatus was produced in the same manner as in the first embodiment, and X-rays were applied to the scintillator plate 11 at a tube voltage of 120 kV of the X-ray tube of the tungsten target, and the current value flowing to the light receiving element 13 was obtained as a light output. At this time, in the same manner as in the first embodiment, the emission peak wavelength, the light output, and the attenuation of the scintillator plate 11 are obtained. between.

The results of the above series of evaluations are shown in Table 6.

From the above results, the scintillator material having the pyrochlore-type composite oxide as a main component formed by the group of the examples has a transmittance of light of 633 nm at a thickness of 1 mm of 80% or more and is highly transparent. Therefore, the light emitted as the scintillator material has no unnecessary scattered loss in the interior thereof, and the wavelength of the strongest emission peak when excited by ultraviolet rays is in the wavelength range of 649 to 656 nm, so that it can be used as the Si light-emitting diode of the light-receiving element. The photoelectric conversion is carried out without any problem, and the light output is not inferior to that of the past materials, and the decay time of the residual light output by the ultraviolet light is 5%. Examples 3-8 are 15 ns, and the other examples are extremely short and are the lower limit of measurement (device performance limit). The decay time is expected to exhibit at least the same value as that of Examples 1 and 2 in the case of X-ray irradiation or gamma ray irradiation. Therefore, when the scintillator material of the present invention is used in a radiation inspection apparatus such as an X-ray CT apparatus or a gamma ray PET apparatus, the switching cycle can be greatly increased, and the operability of a short time and a low exposure amount can be completed. A radiation inspection device with excellent safety.

Further, in the compositions of Comparative Examples 3-1 and 3-2, since the concentration of ruthenium of the active agent was too low, the light output was low.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be modified within a range that can be thought of by other persons, such as other embodiments, additions, changes, and reductions. The effects of the present invention are all included in the scope of the present invention.

10‧‧‧radiation detector

11‧‧‧Sparkling board

12‧‧‧Reflecting material

13‧‧‧Light-receiving components

14‧‧‧ Container

Claims (6)

A scintillator material characterized by comprising a translucent ceramic having a composite oxide represented by the following formula (1) as a main component or a single crystal of a composite oxide represented by the following formula (1), (Tb _x R _1-xy Ce _y ) ₂ B ₂ O ₇ (1) (wherein x is 0.2 or more and not up to 1, and y is 0.00001 or more and 0.01 or less, x + y ≦ 1, R is selected from At least one rare earth element of the group consisting of lanthanum, cadmium, lanthanum, cerium, lanthanum, cerium, lanthanum, cerium, lanthanum, and B is selected from the group consisting of titanium, tin, lanthanum, cerium, lanthanum, zirconium 1 element (except for the case where 矽 and 锗 are separate for this element)). The scintillator material of claim 1, which emits light having an emission peak in a wavelength range of 610 to 700 nm when excited by X-rays or gamma rays. The scintillator material of claim 1 or 2, which has a light transmittance of 70% or more at a wavelength of 633 nm at a thickness of 1 mm. The scintillator material according to any one of claims 1 to 3, which has a cubic crystal having a pyrochlore crystal lattice as a main phase. A radiation detector characterized by being provided with a scintillator material according to any one of claims 1 to 4. A radiation inspection apparatus characterized by being equipped with a radiation detector as claimed in claim 5.