JP7007666B2 - Luminous body and method for manufacturing the luminous body - Google Patents

Description

The present invention relates to a light emitter and a method for producing the light emitter.

A light emitter such as a scintillator is used in a photon detector or a radiation detector that detects gamma rays, X-rays, α rays, β rays, neutron rays and the like. These detectors are expected to be widely applied to positron emission tomography (PET) equipment, medical imaging equipment such as X-ray CT, various radiation measurement equipment for high-energy physics, resource exploration equipment, and the like.

As an example of a light emitting body used in these detectors, for example, a light emitting body having a garnet structure shown in Patent Document 1 is disclosed.

Patent Document 1 discloses a light emitter having a garnet structure using light emission from the 4f5d level of Ce ³⁺ and a method for producing the same. The illuminant is the general formula Ce _x RE _3-x M _{5 + y} O _{12 + 3y / 2} (where 0.0001 ≤ x ≤ 0.3, 0 ≤ y ≤ 0.5 or 0 ≤ y ≤ -0.5, M is Al, Lu, A garnet structure represented by one or more selected from Ga, Sc, and RE is one or more selected from La, Pr, Gd, Tb, Yb, Y, Lu). Have. Further, as a method for producing the luminous body, a Czochralski (CZ: Czochralski) method and an EFG (Edge-defined Film-fed. Growth) method are disclosed.

Further, when these light emitters are used for high energy physical detector applications, it is disclosed in Non-Patent Document 1, for example, that a radiation length of 20 is desired as a characteristic.

International Publication No. 2015/166999

M. Niiyama, "Hadron physics with GeV photons at SPring-8 / LEPS II", 2014, EPJ Web of Conferences 73, 08001, p.3

However, the CZ method has a low crystallization rate with respect to the melt of the raw material, and is not suitable for mass production of illuminants. Further, due to the diffusion of atoms by convection in the melt, a high-concentration melt remains as the crystal growth progresses, and the crystal composition of the luminescent material to be grown and formed fluctuates. For example, the segregation coefficient of Ce, which is the central element of light emission, is as small as about 0.05 to 0.3, and the Ce concentration increases as the crystal grows, causing fluctuations in the amount of light emitted in the direction of crystal pulling, resulting in a decrease in the yield of the illuminant.

Further, there is no disclosure of specific technical contents such as how to produce a light emitting body having a characteristic of 20 radiation length in the EFG method, and it has not been realized yet.

The present invention has been made in view of the above problems, and provides a light emitting body capable of emitting light with a uniform amount of light emitted over the longitudinal direction and realizing a characteristic of 20 radiation lengths and a method for manufacturing the same. ..

The above problems are solved by the following invention. That is, in the method for producing a light emitting body of the present invention, a crucible is formed of at least one of Mo, W, Ir, Re, Ru, Pt, and Rh, and a die having a slit and arranged in parallel in the width direction is used as a crucible. Atomic gas is used as the atmosphere gas, a carbon heater and a heat insulating material are used, and the heat insulating material surrounds the crucible, the heater and the die, and the raw material of the luminescent material is put into the crucible and heated by the heater . By melting the raw material of the illuminant in a crucible to prepare a melt, a melt pool is formed in the upper part of the slit through the slit, and the seed crystal is brought into contact with the melt in the upper part of the slit to pull up the seed crystal. , It consists of a single crystal, has a main surface and a longitudinal dimension of 280 mm or more , and contains at least one atom of Mo, W, Ir, Re, Ru, Pt, and Rh at 5000 ppm or less (but does not include 0 ppm). It is characterized by growing the contained luminescent material.

In one embodiment of the method for producing a luminescent material of the present invention, the composition formula is (Ce, Mg) _x R _3-x M ₅ O ₁₂ (where 0.0001 ≤ x ≤ 0.3, R is La, Pr, Gd, Tb, The illuminant has a garnet structure represented by one or more selected from Yb, Y, Lu, and M is one or more selected from Al, Lu, Ga, Sc), and at least Ce or Mg. It is preferable that one species is distributed in the longitudinal direction.

According to the light emitting body and the method for producing a light emitting body according to the present invention, the light emitting body can be made to emit light with a uniform amount of light emitted over the longitudinal direction thereof. Therefore, it is possible to realize the characteristic of 20 radiation length.

Further, in the present invention, the composition formula of the illuminant is (Ce, Mg) _x R _3-x M ₅ O ₁₂ (where 0.0001 ≤ x ≤ 0.3, R is from La, Pr, Gd, Tb, Yb, Y, Lu. One or more selected species, M is one or more selected from Al, Lu, Ga, Sc), and at least one species of Ce or Mg is distributed in the longitudinal direction of the illuminant by growing by the EFG method. At least one of Mo, W, Ir, Re, Ru, Pt, and Rh is used as the material for forming the lantern used in the production of the luminous body, and the atom of the forming material is 5000 ppm or less (however, 0 ppm is not included). It is contained in the illuminant. By setting such a composition and atomic content, it is possible to produce a luminescent material that emits light with a uniform luminescence amount and can realize a characteristic of 20 radiation lengths by the EFG method.

It is a perspective view which shows typically the light emitting body which concerns on Embodiment and Example of this invention. It is a block diagram which shows schematicly schematicly the manufacturing apparatus of the light emitting body by the EFG method which concerns on Embodiment and Example of this invention. (a) It is a top view which shows an example of the die which concerns on Embodiment and Example of this invention. (b) It is a front view of the figure (a). (c) It is a side view of the figure (a). It is explanatory drawing which shows an example of the seed crystal which concerns on Embodiment and Example of this invention. It is a perspective view which shows typically the positional relationship between a seed crystal and a partition plate in Embodiment and Example of this invention. (a) It is a front view which shows typically the positional relationship between a seed crystal and a partition plate in Embodiment and Example of this invention. (b) It is a front view which shows the state which a part of the seed crystal is melted in Embodiment and Example of this invention. FIG. 3 is a perspective view schematically showing how a light emitting body grows in the embodiments and examples of the present invention. It is a perspective view partially and schematically showing a plurality of light emitters according to an embodiment and an embodiment of the present invention obtained by the EFG method.

The first feature of this embodiment is that the light emitter is made of a single crystal, has a dimension in the longitudinal direction, and the dimension is 280 mm or more.

The second feature is that the composition formula is (Ce, Mg) _x R _3-x M ₅ O ₁₂ (however, 0.0001 ≤ x ≤ 0.3, R is selected from La, Pr, Gd, Tb, Yb, Y, Lu. It has a garnet structure represented by one or more species, M is one or more species selected from Al, Lu, Ga, Sc), and at least one species of Ce or Mg is distributed in the longitudinal direction. It was made into a illuminant.

The third feature is that the illuminant contains at least one atom of Mo, W, Ir, Re, Ru, Pt, and Rh in an amount of 5000 ppm or less (however, 0 ppm is not included).

The fourth feature is that the crucible is formed of at least one of Mo, W, Ir, Re, Ru, Pt, and Rh, has a slit, and the dies arranged in parallel in the width direction are housed in the crucible, and the atmosphere . Argon gas is used as the gas, a carbon heater and a heat insulating material are used, and the heat insulating material surrounds the crucible, the heater, and the die . It consists of a single crystal by melting in a crucible to prepare a melt, forming a melt pool on the upper part of the slit through the slit, and contacting the seed crystal with the melt on the upper part of the slit to pull up the seed crystal. Emissions that have a longitudinal dimension of 280 mm or more with the main surface and contain at least one atom of Mo, W, Ir, Re, Ru, Pt, Rh of 5000 ppm or less (but not including 0 ppm). It is a method of manufacturing a crucible that grows the body.

The fifth feature is that the composition formula is (Ce, Mg) _x R _3-x M ₅ O ₁₂ (however, 0.0001 ≤ x ≤ 0.3, R is selected from La, Pr, Gd, Tb, Yb, Y, Lu. The illuminant has a garnet structure represented by (1 or more, M is one or more selected from Al, Lu, Ga, Sc), and at least one of Ce or Mg is distributed in the longitudinal direction. This is the method of manufacturing the luminous body.

According to these light-emitting bodies and the method for producing the light-emitting body, the light-emitting body can be made to emit light with a uniform amount of light emission over the longitudinal direction thereof. Therefore, it is possible to realize the characteristic of 20 radiation length.

In the present invention, the uniform light emission amount refers to a state in which the fluctuation of the light emission amount over the entire length in the longitudinal direction of the light emitter is within the range of ± 10%.

The sixth feature is that the illuminant is an As-grown single crystal and a method for producing the illuminant.

According to these light-emitting bodies and the method for manufacturing the light-emitting body, it is not necessary to grow the light-emitting body into crystals so as to have a dimension of 280 mm or more in the longitudinal direction, and it is not necessary to perform surface treatment such as grinding or polishing. The reduction of the surface processing process can be achieved. Further, since the grinding allowance or the polishing allowance in the light emitting body is not required, it is possible to improve the crystallization rate with respect to the raw material, adapt to mass productivity, and improve the yield of the light emitting body.

In the present invention, the As-grown single crystal refers to a single crystal that has not been subjected to surface treatment such as grinding or polishing while the crystal has been grown.

Hereinafter, the light emitting body according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, the light emitter 2 in the present invention has dimensions in the longitudinal direction (length L direction), has a rectangular shape in the plane direction, and has a specific dimension such as a width W of about 10 mm and a thickness. It is composed of a single crystal having a T of about 2 mm and a length L of 280 mm or more, which is the dimension in the longitudinal direction. A width W of about 10 mm and a thickness T = 2 mm are desirable because they are highly versatile for radiation detectors and can eliminate the polishing allowance after crystal growth. The upper limit of the length L is not particularly limited and can be set arbitrarily, but in the case of a radiation detector application, the higher the radiation energy, the longer the required length. For example, when absorbing 8 GeV radiation, the standard is about 280 mm with a radiation length of 20.

The illuminant 2 according to the embodiment of the present invention has a composition formula (Ce, Mg) _x R _3-x M ₅ O ₁₂ (where 0.0001 ≤ x ≤ 0.3, R is La, Pr, Gd, Tb, Yb, It has a garnet structure represented by one or more selected from Y and Lu, and M is one or more selected from Al, Lu, Ga, Sc). Furthermore, at least one species of Ce or Mg is distributed in the longitudinal direction.

Further, the illuminant 2 contains at least one atom of Mo, W, Ir, Re, Ru, Pt, and Rh in an amount of 5000 ppm or less (however, 0 ppm is not included).

By setting the composition and the atomic content in this way, the illuminant 2 can emit light from the 4f5d level of Ce ³⁺ when irradiated with light in the ultraviolet region of 254 nm to 365 nm. Further, the light emitting body 2 can emit light with a uniform light emitting amount over the longitudinal direction thereof by setting the composition and the atomic content.

Further, even if the length L is increased to 280 mm or more and set, the characteristic of 20 radiation lengths can be realized over the length L.

In the present invention, the uniform light emission amount means a state in which the fluctuation of the light emission amount over the total length (length L) in the longitudinal direction of the light emitting body 2 is within the range of ± 10%. In order to achieve this state, one or two kinds of Ce or Mg and at least one kind of atom of Mo, W, Ir, Re, Ru, Pt, Rh of 5000 ppm or less (but not including 0 ppm) are added. Distribute over the longitudinal direction.

The content of at least one atom of Mo, W, Ir, Re, Ru, Pt, Rh exceeds 5000 ppm, or Ce or Mg and at least one of Mo, W, Ir, Re, Ru, Pt, Rh. If the distribution of the atoms in the longitudinal direction is biased and the fluctuation of the amount of light emitted over the length L is less than or exceeds the range of ± 10%, a uniform amount of light emitted over the long length L of 280 mm or more is obtained. I can't. Therefore, the characteristic of 20 radiation length is also unrealizable.

Further, the illuminant 2 is preferably an As-grown single crystal. As-grown single crystal refers to a single crystal that has not been subjected to surface treatment such as grinding or polishing while it is in a crystal-grown state. By forming the illuminant 2 with an As-grown single crystal, it is not necessary to perform surface treatment such as grinding or polishing on the illuminant 2 whose crystal has been grown so as to have a dimension of 280 mm or more in the longitudinal direction. The reduction of the surface processing process of the body 2 can be achieved. Further, since the grinding allowance or the polishing allowance in the light emitting body 2 is not required, it is possible to improve the crystallization rate with respect to the raw material, adapt to mass productivity, and improve the yield of the light emitting body 2. Further, the illuminant 2 has a desired main surface 2a.

Examples of the radiation inspection device in which the illuminant 2 is used include a detector for resource exploration, a detector for high energy physics, an environmental radioactivity detector, a gamma camera, a medical image processing device, and the like. As an example of a medical image processing device, applications such as a positron emission tomography (PET) device, an X-ray CT, SPECT, and a PEM device are suitable. Two-dimensional type, three-dimensional type, time-of-flight (TOF) type, and depth detection (DOI) type are preferable as PET embodiments. Further, these may be used in combination. The light emitter 2 can also be used for a large Hadron collider and a calorimeter.

Next, the apparatus for manufacturing the light emitting body 2 according to the embodiment of the present invention will be described with reference to FIGS. 2 to 8. The description of the parts and contents that overlap with the description of the light emitting body 2 will be simplified or omitted.

As shown in FIG. 2, the illuminant manufacturing apparatus 1 is composed of a growth container 3 for growing the illuminant 2 and a pull-up container 4 for pulling up the illuminant 2 that has been cultivated, and grows and grows the illuminant 2 by the EFG method. do.

The growing container 3 includes a crucible 5, a crucible drive unit 6, a heater 7, an electrode 8, a die 9, and a heat insulating material 10. The crucible 5 is formed by at least one of Mo, W, Ir, Re, Ru, Pt, and Rh. Among these materials, Mo is preferable because it can reduce impurities such as Cr to the ICP analysis level or lower. The raw material is melted in this crucible 5. The crucible drive unit 6 rotates the crucible 5 about its vertical direction. The heater 7 heats the crucible 5. Further, the electrode 8 energizes the heater 7. The die 9 is installed in the crucible 5 and determines the liquid level shape of the melt 21 when the light emitting body 2 is pulled up. Further, the heat insulating material 10 surrounds the crucible 5, the heater 7, and the die 9. Both the heater 7 and the heat insulating material 10 are made of carbon.

Further, the growing container 3 includes an atmospheric gas introduction port 11 and an exhaust port 12. The atmosphere gas introduction port 11 is an introduction port for introducing argon gas as an atmosphere gas into the growing container 3, and prevents the crucible 5, the heater 7, and the die 9 from being consumed by oxidation. On the other hand, the exhaust port 12 is provided for exhausting the inside of the growing container 3.

The pull-up container 4 includes a shaft 13, a shaft drive unit 14, a gate valve 15, and a substrate entrance / exit 16, and pulls up a plurality of flat plate-shaped light emitters 2 grown and grown from the seed crystal 17. The shaft 13 holds the seed crystal 17. Further, the shaft drive unit 14 raises and lowers the shaft 13 toward the crucible 5, and rotates the shaft 13 about the raising and lowering direction. The gate valve 15 separates the growing container 3 and the pulling container 4. Further, the substrate inlet / outlet 16 takes in and out the seed crystal 17.

The manufacturing apparatus 1 also has a control unit (not shown), which controls the rotation of the crucible drive unit 6 and the shaft drive unit 14.

The die 9 is made of Mo and has a large number of dividers 18 as shown in FIG. FIG. 3 shows a case where 30 partition plates 18 are formed and 15 dies 9 are formed as an example of dies. The partition plates 18 have the same flat plate shape and are arranged in parallel with each other so as to form a minute gap (slit) 19 to form one die 9. The slit 19 is provided over almost the entire width of the die 9. Further, since the plurality of dies 9 have the same shape and are arranged in parallel at predetermined intervals so that their width directions are parallel to each other, a plurality of slits 19 are provided. A slope 30 is formed on the upper portion of each partition plate 18, and an opening 20 is formed by arranging the slopes 30 so as to face outward. Further, the slit 19 has a role of raising the melt 21 from the lower end of each die 9 to the opening 20 by the capillary phenomenon.

The width WD of the die 9 is set according to the width W of the light emitter 2. In this embodiment, WD = 10 mm is set from the W value. The width TS of the slit is set to be equal to or less than the thickness T of the light emitter 2.

The raw material charged into the crucible 5 melts (raw material melt) based on the temperature rise of the crucible 5 to become the melt 21. The raw material is a compound containing an atom represented by the composition formula of the light emitter 2. An oxide raw material can be used as a starting material, but when the illuminant 2 is used as a single crystal for a scintillator, it is particularly preferable to use a high-purity raw material of 99.99% or more (4N or more). At the time of production, these starting materials are weighed and mixed so as to have the desired composition at the time of forming the melt 21. It is particularly preferable that these raw materials have as few impurities as possible (for example, 1 ppm or less) other than the target composition.

A part of the melt 21 invades the slit 19 of the die 9, rises in the slit 19 based on the capillary phenomenon as described above, is exposed from the opening 20, and the melt pool 22 (in the opening 20). (See FIG. 6 (b)) is formed. In the EFG method, the illuminant 2 grows according to the shape of the melt surface formed by the melt pool 22. In the die 9 shown in FIG. 3, since the shape of the melt surface is an elongated rectangle, a flat plate-shaped light emitter 2 is manufactured.

Next, the seed crystal 17 will be described. As shown in FIGS. 2 and 4 to 6, in the present embodiment, it is preferable to use a seed crystal 17 having the same or similar composition as that of the light emitter 2. Specifically, the composition formula was (Ce, Mg) _x R _3-x M ₅ O ₁₂ (however, 0.0001 ≤ x ≤ 0.3, R was selected from La, Pr, Gd, Tb, Yb, Y, Lu. A single crystal having a garnet structure represented by one or more kinds, M is one or more kinds selected from Al, Lu, Ga, Sc) and containing at least one kind of Ce or Mg is referred to as a seed crystal 17. ..

As the seed crystal 17, a flat plate-shaped substrate is used. Further, the seed crystal 17 is arranged so that the plane direction of the seed crystal 17 and the width direction of the die 9 are orthogonal to each other at an angle of 90 °. Further, since the seed crystal 17 and the illuminant 2 are also orthogonal to each other at an angle of 90 °, the side surface of the illuminant 2 is shown in FIG. By making the positional relationship between the plane direction of the seed crystal 17 and the width direction of the partition plate 18 vertical (crossing the seed crystal 17 with the partition plate 18), the contact area between the melt 21 and the seed crystal 17 is minimized. It becomes possible to do. Therefore, the contact portion of the seed crystal 17 becomes easily compatible with the melt 21, and the occurrence of crystal defects in the light emitter 2 is reduced or eliminated.

The seed crystal 17 has a substrate shape that can be securely fixed to the substrate holder.

Next, a method of manufacturing the light emitting body 2 using the manufacturing apparatus 1 will be described. First, a predetermined amount of the raw material powder (purity 99.99%) of the illuminant 2 is charged into the crucible 5 containing the die 9 and filled.

Subsequently, in order not to oxidatively consume the crucible 5, the heater 7, or the die 9, the inside of the growing container 3 is replaced with argon gas, and the oxygen concentration is set to a predetermined value or less.

Next, the crucible 5 is heated to a predetermined temperature by heating with the heater 7, and the raw material powder is melted. Since the melting point of the raw material of the illuminant 2 is 2000 ° C. or higher (about 2150 ° C.), the heating temperature of the crucible 5 is set to a temperature equal to or higher than the melting point. After a while after heating, the raw material powder melts and the melt 21 is prepared. Further, a part of the melt 21 rises through the slit 19 of the die 9 due to the capillary phenomenon and reaches the surface of the die 9, and a melt pool 22 is formed on the upper portion of the slit 19.

Next, as shown in FIGS. 5 and 6, the seed crystal 17 is lowered while being held at an angle perpendicular to the width direction of the melt pool 22 above the slit 19, and the seed crystal 17 is melted in the melt pool 22. Contact the liquid surface. The seed crystal 17 is introduced into the pulling container 4 from the substrate entrance / exit 16 in advance. In FIG. 5, the melt 21 and the melt pool 22 are not shown in order to give priority to the visibility of the slit 19 and the opening 20.

FIG. 5 is a diagram showing the positional relationship between the seed crystal 17 and the partition plate 18. As described above, by making the plane direction of the seed crystal 17 orthogonal to the width direction of the partition plate 18, it is possible to reduce the contact area between the seed crystal 17 and the melt 21. Therefore, the contact portion of the seed crystal 17 becomes familiar with the melt 21, and crystal defects are less likely to occur in the luminescent material 2 that is grown and grown. Therefore, the yield of the light emitting body 2 can be improved.

When the seed crystal 17 is brought into contact with the melt surface, the lower part of the seed crystal 17 may be brought into contact with the upper part of the partition plate 18 to be melted. FIG. 6B is a diagram showing how a part of the seed crystal 17 is melted. By melting a part of the seed crystal 17 in this way, the temperature difference between the seed crystal 17 and the melt 21 can be quickly eliminated, and the occurrence of crystal defects in the illuminant 2 can be further reduced. It becomes.

Subsequently, the substrate holder is pulled up by the shaft 13 at a predetermined ascending speed to start pulling up the seed crystal 17, and the illuminant 2 is formed as shown in FIG. FIG. 7 is an explanatory diagram showing how the light emitting body 2 grows. As described above, the light emitting body 2 is grown by the width WD of the die 9 (that is, the width W of the light emitting body 2), and the light emitting body 2 is pulled up to a predetermined length (length L) at a predetermined speed to form a flat plate shape. 2 is obtained.

After that, the obtained illuminant 2 is cooled, the gate valve 15 is opened, the gate valve 15 is moved to the pulling container 4, and the light emitter 2 is taken out from the substrate entrance / exit 16. The appearance of the obtained flat plate-shaped light emitter 2 is shown in FIG.

As shown in FIGS. 2 and 5 to 8, it is preferable to grow a plurality of light emitters 2 from the common seed crystal 17 at the same time because the manufacturing cost of the light emitter 2 per sheet can be reduced. .. When manufacturing a plurality of light emitters 2 at the same time, the plurality of dies 9 are housed in the crucible 5, and the width directions of the dies 9 are arranged in parallel. By pulling up the seed crystal 17, it is possible to prepare a plurality of illuminants 2 as an As-grown single crystal having a desired main surface 2a and a dimension L in the longitudinal direction.

The die 9 including the seed crystal 17 and the partition plate 18 needs to be precisely positioned. Therefore, as shown in FIG. 2, the manufacturing apparatus 1 is provided with a crucible drive unit 6 for rotating the crucible 5 on which the die 9 is installed, and a control unit (not shown) for controlling the rotation thereof. Further, the shaft 13 is also provided with a shaft drive unit 14 that rotates the shaft 13 and a control unit (not shown) that controls the rotation thereof. That is, the positioning of the seed crystal 17 with respect to the die 9 is adjusted by rotating the shaft 13 or the crucible 5 by the control unit.

By arbitrarily setting the crystal plane 28 of the seed crystal 17, the plane direction of the main surface 2a of the light emitter 2 can also be arbitrarily changed.

The pulling speed of the illuminant 2 can be set to a constant width W / thickness T from the time when the crystal growth is disclosed by the start of pulling the seed crystal 17 to the end of the crystal growth with the desired length L. It is preferable because the fluctuation ratio of is suppressed.

In the present invention, by using at least one of Mo, W, Ir, Re, Ru, Pt, and Rh as the forming material of the crucible 5, the melt is melted from the crucible 5 while the illuminant 2 is pulled up and grown by the EFG method. The illuminant 2 can contain at least one atom of Mo, W, Ir, Re, Ru, Pt, and Rh as it is via 21. However, the content should be 5000 ppm or less (however, 0 ppm is not included) as described above.

Therefore, in the present invention, argon gas is used as the atmosphere gas, and the heater 7 and the heat insulating material 10 are both made of carbon. With such a configuration, the atmosphere in the growing container 3 becomes reducible, the reaction between the atmosphere and the crucible 5 forming material can be suppressed, and the content of the crucible 5 forming material in the light emitting body 2 can also be suppressed. The applicant has found it after verification. Since the EFG method is adopted in the present invention, the melt 21 is raised from the lower end of each die 9 to the opening 20 through the slit 19 by the capillary phenomenon. In the present invention, the melt 21 is thinly raised and supplied through the slit 19 in a state where the reaction between the atmosphere and the crucible 5 forming material is further suppressed, so that the melt pool 22 is always provided with a uniform composition and concentration. It becomes possible to form. Therefore, it has become possible to form a content of 5000 ppm or less and a uniform luminescence amount over the length L by pulling up the growth from the melt pool 22. Further, with respect to Ce or Mg, the uniform composition and concentration formation of the melt pool 22 enables the formation of a uniform light emission amount in the longitudinal direction.

In the verification process, verification was also performed by the EFG method in which the atmosphere gas was a nitrogen atmosphere. However, in this case, for example, Mo and nitrogen react with each other, and the reaction promotes the inclusion of the crucible 5 forming material in the illuminant 2. As a result, the Mo content in the light emitter 2 exceeded 5000 ppm, and the characteristic of 20 radiation length could not be realized.

Furthermore, the composition formula of the illuminant 2 is selected from (Ce, Mg) _x R _3-x M ₅ O ₁₂ (where 0.0001 ≤ x ≤ 0.3, R is La, Pr, Gd, Tb, Yb, Y, Lu. At least one species, M is one or more species selected from Al, Lu, Ga, Sc), and at least one species of Ce or Mg is distributed in the longitudinal direction of the illuminant 2 by growing by the EFG method. At least one of Mo, W, Ir, Re, Ru, Pt, and Rh is used as the forming material of the sword 5 used in the production of the illuminant 2, and the atom of the forming material is 5000 ppm or less (however, 0 ppm is not included). It is contained in the light emitting body 2. By setting the composition and the atomic content in this way, it is possible to produce a light emitter 2 capable of emitting light with a uniform amount of light emission and realizing a characteristic of 20 radiation lengths by the EFG method.

Further, by setting the composition and the atomic content, the light emitting body 2 can realize the characteristics of the light emitting amount of less than 60,000 photons / MeV.

The present invention is not limited to the above-described embodiment, and can be modified by a configuration within a range that does not deviate from the scope of the technical idea.

Each embodiment of the present invention will be described below, but the present invention is not limited to the following examples.

Hereinafter, the light emitters of Examples 1 and 2 and the method for producing the same according to the present invention will be described. As the luminescent material manufacturing apparatus according to this embodiment, the manufacturing apparatus 1 by the EFG method shown in FIG. 2 was used. The material for forming the crucible 5 was made of Mo, argon gas was used as the atmosphere gas, and both the heater 7 and the heat insulating material 10 were made of carbon.

The illuminant to be pulled up and grown is a single crystal, and its composition formula is Ce _0.05 Lu _2.95 Al ₅ O ₁₂ in both Example 1 and Example 2, and Ce is grown in the longitudinal direction (length) of the illuminant by pulling up and growing by the EFG method. It was distributed over the L direction).

As shown in FIG. 1, the illuminant has dimensions in the longitudinal direction, and the shape in the plane direction is rectangular. The width W was set to 10 mm in Example 1 and 8 mm in Example 2. The thickness T was set to 2 mm in Example 1 and 8 mm in Example 2. Further, the length L was set to 280 mm in both of the two examples.

The light-emitting body after being pulled up and grown was not subjected to surface treatment such as grinding or polishing, and was made into an As-grown single crystal, and the Mo content was measured. The Mo content was measured by ICP-AES. As a result, Example 1 was 221 ppm and Example 2 was 13 ppm.

On the other hand, as Comparative Example 1 and Comparative Example 2, a light emitting body was produced by using the manufacturing apparatus 1 by the EFG method shown in FIG. The only difference between the two comparative examples from the above-mentioned Examples is that the atmosphere gas is a nitrogen atmosphere. In other cases, Comparative Example 1 is the same as Example 1 and Comparative Example 2 is the same as Example 2. .. As a result of measuring the Mo content of the raised and grown illuminant, it was 5005 ppm in Comparative Example 1 and 5011 ppm in Comparative Example 2.

The light emitters of Examples 1 and 2 and Comparative Examples 1 and 2 were both irradiated with light in the ultraviolet region of 254 nm to 365 nm, and it was confirmed whether or not the characteristics of 20 radiation lengths were realized. As a result, it was confirmed that 20 radiation lengths were achieved in Examples 1 and 2. On the other hand, it was confirmed that 20 radiation lengths were not achieved in Comparative Examples 1 and 2.

Next, the light emitting body of Example 3 according to the present invention and a method for producing the same will be described. As the illuminant manufacturing apparatus according to the third embodiment, the manufacturing apparatus 1 by the EFG method shown in FIG. 2 was used. The material for forming the crucible 5 was made of Mo, argon gas was used as the atmosphere gas, and both the heater 7 and the heat insulating material 10 were made of carbon.

The illuminant to be pulled up and grown is a single crystal, and its composition formula is Mg _0.0006 Ce _0.0294 Lu _2.97 Al ₅ O ₁₂ , and by pulling up and growing by the EFG method, Mg and Ce are grown in the longitudinal direction (length L direction) of the illuminant. It was distributed over.

As shown in FIG. 1, the illuminant has dimensions in the longitudinal direction, and the shape in the plane direction is rectangular. The width W was set to 10 mm, the thickness T was set to 2 mm, and the length L was set to 300 mm.

The illuminant after being pulled up and grown was not subjected to surface treatment such as grinding or polishing, and was made into an As-grown single crystal.

On the other hand, as Comparative Example 3, a luminescent material made of a single crystal was produced by the CZ (Czochralski) method. The difference between Comparative Example 3 and Example 3 is whether the method for producing the illuminant is the EFG method or the CZ method, and the composition formula, width W, thickness T, and length L of the illuminant are the same.

The light emitters of Example 3 and Comparative Example 3 were both irradiated with light in the ultraviolet region of 254 nm to 365 nm, and fluctuations in the amount of light emitted (photons / MeV) over the length L were confirmed. At the same time, fluctuations in Ce concentration (mol%) and Mg concentration (mol%) over length L were also confirmed by ICP-AES.

As a result, it was confirmed that both light emitters had a characteristic of a light emission amount of less than 60,000 photons / MeV over a length L = 300 mm. However, in Comparative Example 3, the amount of light emitted from the end of the illuminant at L = 10 mm is 30,000 photons / MeV, the amount of light emitted at L = 100 mm is 27,000 photons / MeV, and the amount of light emitted at L = 200 mm is 15,000 photons / MeV. The amount of light emitted at L = 300 mm was 9000 photons / MeV. From the above results, it was confirmed that in Comparative Example 3, the variation in the amount of light emitted over the entire length of the illuminant in the longitudinal direction was not within the range of ± 10%, and a uniform amount of light emitted in the longitudinal direction could not be realized. Was done.

On the other hand, in Example 3, the amount of light emitted from the end of the illuminant at L = 10 mm is 30500 photons / MeV, the amount of light emitted at L = 100 mm is 30200 photons / MeV, and the amount of light emitted at L = 200 mm is 29500 photons / MeV. The amount of light emitted at L = 300 mm was 30400 photons / MeV. From the above results, in Example 3, the variation in the amount of light emitted over the entire length of the light emitter in the longitudinal direction is within the range of ± 10%, and a uniform amount of light emitted can be realized in the longitudinal direction. confirmed.

The fluctuations in the Ce concentration and the Mg concentration in Example 3 were as follows: Ce concentration 0.99 mol% at L = 10 mm portion, Mg concentration 0.022 mol%, Ce concentration 1.00 mol% at L = 100 mm portion, and so on. The Mg concentration was 0.022 mol%, the Ce concentration was 1.01 mol% and the Mg concentration was 0.022 mol% at the L = 200 mm portion, and the Ce concentration was 1.01 mol% and the Mg concentration was 0.022 mol% at the L = 300 mm portion.

On the other hand, the fluctuations in the Ce concentration and the Mg concentration in Comparative Example 3 were such that the Ce concentration was 0.12 mol% at the portion L = 10 mm from the end of the illuminant, the Mg concentration was 0.002 mol%, and the Ce concentration was 0.24 mol% at the portion L = 100 mm. The Mg concentration was 0.005 mol%, the Ce concentration was 0.68 mol% and the Mg concentration was 0.009 mol% at the L = 200 mm portion, and the Ce concentration was 2.20 mol% and the Mg concentration was 0.029 mol% at the L = 300 mm portion.

From the above results, it was confirmed that the fluctuation value of the Ce concentration and the fluctuation value of the Mg concentration in the longitudinal direction were both larger in Comparative Example 3 than in Example 3.

1 Luminous body manufacturing equipment 2 Luminescent body
2a Main surface 3 Growing container 4 Pulling container 5 Crucible 6 Crucible drive 7 Heater 8 Electrode 9 Die
10 Insulation
11 Atmospheric gas inlet
12 Exhaust port
13 shaft
14 Shaft drive
15 Gate valve
16 Board doorway
17 seed crystals
18 divider
19 slit
20 openings
21 Melt
22 Melt pool
28 Crystal plane
30 Slope L Length of illuminant W Width of illuminant T Thickness of illuminant
TS slit width
WD die width

Claims (3)

A crucible is formed with at least one of Mo, W, Ir, Re, Ru, Pt, and Rh.
Dies that have slits and are arranged in parallel in the width direction are housed in a crucible.
Argon gas is used as the atmosphere gas, a carbon heater and heat insulating material are used, and the heat insulating material surrounds the crucible, the heater, and the die.
The raw material of the illuminant is put into the crucible and heated by a heater, and the raw material of the illuminant is melted in the crucible to prepare a melt.
A melt pool is formed on the upper part of the slit through the slit,
By contacting the seed crystal with the melt on the upper part of the slit and pulling up the seed crystal, it is composed of a single crystal and has a longitudinal dimension of 280 mm or more with the main surface, Mo, W, Ir, Re, Ru, Pt. , A method for producing a luminescent material for growing a luminescent material containing at least one atom of Rh in an amount of 5000 ppm or less (however, 0 ppm is not included). The composition formula is (Ce, Mg) _{x x} R _3-x M _Five O ₁₂ (However, 0.0001 ≤ x ≤ 0.3, R is one or more selected from La, Pr, Gd, Tb, Yb, Y, Lu, and M is one or more selected from Al, Lu, Ga, Sc. The illuminant has a garnet structure represented by).
The method for producing a luminescent material according to claim 1, wherein at least one of Ce or Mg is distributed in the longitudinal direction. The method for producing a luminescent material according to any one of claims 1 or 2, wherein the luminescent material is an As-grown single crystal.

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