Phosphors and their manufacturing methods

Abstract

This fluorescent object (10) comprises luminescent phases (11) which convert radiation into visible light to emit the light and light-transmitting phases (12) which transmit the visible light, and has a thickness in the range of 5-200 μm. The luminescent phases (11) include an activation element. The luminescent phases (11) and the light-transmitting phases (12) have been alternately arranged in a direction crossing the direction of the thickness.

Description

[Technical Field]

[0001] The present invention relates to a phosphor and a method for producing the same. This application claims priority based on Japanese Patent Application No. 2021-131653, filed in Japan on August 12, 2021, and the contents of that application are incorporated herein by reference. [Background technology]

[0002] Scintillators are used in scintillation detectors to detect gamma rays, X-rays, alpha rays, beta rays, neutrons, and other radiation. Scintillation detectors are used in a wide range of fields, including medical imaging devices such as X-ray CT, positron emission tomography (PET), and in vivo imaging devices, as well as various radiation measurement devices for high-energy physics and resource exploration devices. Generally, a scintillation detector consists of a scintillator and a photodetector that receives scintillation light and converts it into an electrical signal.

[0003] Medical imaging devices are equipped with photodetectors such as position-detection type avalanche photodiode arrays (APD arrays), silicon photomultiplier arrays (Si-PM arrays), and photomultiplier tubes (PMTs) to identify the position of radionuclides in a subject. These photodetectors have a wavelength range of 400-600 nm in which high detection sensitivity can be obtained, and it is desirable to combine them with scintillators that have a peak wavelength in this wavelength range.

[0004] Scintillators are required to have high density and effective atomic number (high photoelectric absorption ratio) for detection efficiency, a short fluorescence lifetime for fast response, and high luminescence for high energy resolution and reduced inspection time. Inorganic scintillators with a garnet structure are known to have desirable characteristics in terms of fluorescence lifetime and luminescence, and are applied to various radiation detectors. Inorganic scintillators with a garnet structure are chemically stable and easy to handle because they are not cleavable or deliquescent. For example, in Patent Documents 1 and 2 and Non-Patent Document 1, Pr is used as the activating element. 3+ or Ce3+ This document discloses lutetium-aluminum-garnet scintillators fabricated using rare earth elements such as , by melt growth or sintering processes. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-105064 (A) [Patent Document 2] Japanese Patent Application Publication No. 2015-030662 (A) [Non-patent literature]

[0006] [Non-Patent Document 1] M. Nikl, A. Yoshikawa, K. Kamada, K. Nejezchleb, CR Stanek, JA Mares, and K. Blazek: Progress in Crystal Growth and Characterization of Materials 59 (2013) 47-72 [Non-Patent Document 2] S. Witkiewicz-Lukaszek, V. Gorbenko, T. Zorenko, O. Sidletskiy, P. Arhipov, A. Fedorov, JA Mares, R. Kucerkova, M. Nikl, and Y. Zorenko: CrystEngComm 22 (2020) 3713-3724 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Many inorganic scintillators are made of materials with melting points exceeding 2000°C. When formed using common single crystal growth methods, a super-high temperature process is required, resulting in high manufacturing costs and long production times. Additionally, in thick inorganic scintillators formed using single crystal growth methods, some of the irradiated radiation is self-absorbed, reducing the amount of visible light emitted after conversion. Moreover, since energy migration occurs within the phosphor, the fluorescence lifetime becomes longer.

[0008] Non-Patent Document 2 reports that a scintillator crystal with a thickness of 10 to 20 μm was grown by the liquid phase epitaxy method. However, in this method, impurity elements such as Pb 2+ derived from the flux liquid phase (especially transition metal elements) are mixed in during the synthesis process, making it difficult to obtain a sufficient emission amount due to their influence.

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a phosphor that realizes a high emission amount and high-speed responsiveness, and a method for manufacturing the phosphor that enables easy production of the phosphor.

Means for Solving the Problems

[0010] To solve the above problems, the present invention employs the following means.

[0011] (1) The phosphor according to one aspect of the present invention includes a light-emitting phase that converts radiation into visible light and emits light, and a light-transmitting phase that transmits the visible light, has a thickness in the range of 5 μm or more and 200 μm or less, the light-emitting phase contains an activating element, and the light-emitting phase and the light-transmitting phase are alternately arranged in a direction intersecting the thickness direction.

[0012] (2) In the phosphor according to (1) above, it is preferable that the thickness is 0.8 times or more and 1.2 times or less of the thickness at which the emission amount per unit thickness is maximized.

[0013] (3) In the phosphor described in either (1) or (2) above, the luminescent phase preferably contains the activating element in a ratio of 0.01 mol% to 20 mol%.

[0014] (4) In the phosphor described in any one of (1) to (3) above, it is preferable that the width of the luminescent phase is 0.2 μm or more and 3 μm or less in the overlapping direction in which the luminescent phase and the light-transmitting phase are alternately arranged and overlapping.

[0015] (5) In the phosphor described in any one of (1) to (4) above, it is preferable that the width of the light-transmitting phase in the overlapping direction is 0.2 μm or more and 3 μm or less.

[0016] (6) In the phosphor described in any one of (1) to (5) above, it is preferable that the luminescent phase has a crystalline structure which is a combination of one or more of the following: garnet structure, bixbite structure, perovskite structure, casspidin structure, orthosilicate structure, pyrosilicate structure, and pyrochlore structure.

[0017] (7) In the phosphor described in any one of (1) to (6) above, it is preferable that the light-transmitting phase contains as a main component an oxide made by combining one or more of the metal elements that constitute the light-emitting phase.

[0018] (8) A method for producing a phosphor according to one aspect of the present invention is a method for producing a phosphor according to any one of (1) to (7) above, wherein the phosphor is formed using a laser CVD method on one surface of a substrate such that the thickness direction is perpendicular to the substrate surface. [Effects of the Invention]

[0019] The phosphor of the present invention has a thickness set in the range of 5 μm to 200 μm. By setting the thickness of the phosphor within this range, the transmittance of irradiated radiation and the self-absorption rate of converted visible light can be reduced in the thickness direction, thereby achieving a high emission amount. Furthermore, by setting the thickness of the phosphor within the above range, it is possible to add activating elements that activate the excitation of visible light at a high concentration, thereby achieving a fast response.

[0020] Furthermore, the phosphor of the present invention is composed of alternating luminescent phases and translucent phases in a direction intersecting the thickness direction. Therefore, the ratio of the length of the luminescent phase included in the visible light propagation path is reduced, and the propagation distance of visible light within the luminescent phase can be reduced. As a result, the decrease in the amount of light emitted due to self-absorption can be suppressed, and as a result, a high amount of light emitted in the direction intersecting the thickness direction can be achieved. Moreover, by setting the length and thickness of the luminescent phase within the above range, energy transfer within and between luminescent phases can be suppressed, and high-speed response can be achieved.

[0021] The present invention's method for manufacturing phosphors eliminates the need for ultra-high temperature processes and minimizes the influence of impurity elements, thus enabling the easy production of phosphors that achieve high luminescence and fast response. [Brief explanation of the drawing]

[0022] [Figure 1] This is a cross-sectional view of a phosphor according to one embodiment of the present invention. [Figure 2] Figure 1 is a schematic cross-sectional view showing the configuration of a laser CVD apparatus used for manufacturing phosphors. [Figure 3A] This is an SEM image of a cross-section of the phosphor in Example 1. [Figure 3B] This is an SEM image of the surface of the phosphor in Example 1. [Figure 4] This graph shows the luminescence characteristics of the phosphors in Example 1 and Comparative Examples 1 and 2. [Figure 5]This graph shows the fluorescence lifetime characteristics of the phosphor in Example 1. [Figure 6] This graph shows the relationship between the thickness of the phosphor and the amount of light emitted. [Modes for carrying out the invention]

[0023] The following describes in detail, with reference to the drawings, a phosphor and a method for producing the same as an embodiment to which the present invention is applied. Note that, for the sake of clarity, the drawings used in the following description may show enlarged versions of characteristic parts, and the dimensional ratios of each component may not be the same as those in reality. Furthermore, the materials, dimensions, etc., exemplified in the following description are merely examples, and the present invention is not limited to these; it can be implemented with appropriate modifications without altering its essence.

[0024] Figure 1 is a schematic cross-sectional view showing the structure of a phosphor 10 according to one embodiment of the present invention. The phosphor 10 is a eutectic thick film comprising a plurality of regions of luminescent phases (phosphor phases) 11 and a plurality of regions of translucent phases 12, preferably a eutectic thick film composed only of regions of luminescent phases 11 and translucent phases 12. The luminescent phases 11 and translucent phases 12 are arranged alternately and overlapping in a direction W that intersects (preferably orthogonal to) the thickness direction T of the phosphor 10, in other words, in a direction along the main surface (plane direction) W. In a plan view from the thickness direction T, the luminescent phases 11 and translucent phases 12 are distributed in a streaky manner. In this embodiment, "the luminescent phases 11 and translucent phases 12 are arranged alternately" means that the luminescent phases 11 and translucent phases 12 are arranged alternately such that the order of luminescent phase 11 and translucent phase 12 is repeated two or more times, preferably five or more times, along the direction W.

[0025] Radiation R irradiated onto the phosphor 10 is converted into visible light L inside the phosphor 10 (emission phase 11) and propagates by spreading through the radial stripe. The larger the volume of the phosphor 10, the greater the component of the irradiated radiation R that is converted into visible light L. However, a larger component of the converted visible light L is also absorbed by the body, hindering some of the emission, making it difficult to obtain a high emission amount. Conversely, the smaller the volume of the phosphor 10, the easier it is for the irradiated radiation R to pass through the phosphor 10, and the less is converted into visible light L. In this case, too, it is difficult to obtain a high emission amount.

[0026] Taking these factors into consideration, and from the viewpoint of efficiently increasing the amount of light emitted in the thickness direction T of the phosphor 10, the thickness T of the phosphor 10 in this embodiment is set to a range of 5 μm to 200 μm, which allows for efficient increase in the amount of light emitted. This range is one to two orders of magnitude thinner than the thickness of a typical bulk single crystal.

[0027] While increasing the thickness of the phosphor 10 (emissive phase 11) increases the amount of visible light generated, considering the decrease due to self-absorption, the actual increase in the amount of light emitted is suppressed beyond a certain thickness where the increase and decrease are balanced. In other words, the amount of light emitted per unit thickness (the ratio of the increase in light emitted to the increase in thickness) is maximized at this specific thickness. Therefore, it is preferable that the thickness of the phosphor 10 be between 0.8 and 1.2 times the thickness at which the amount of light emitted per unit thickness is maximized, as this allows for a higher luminous efficiency.

[0028] The luminescent phase 11 is a phase consisting of a scintillator material that exhibits emission mainly in the visible light range when irradiated with a predetermined radiation. The region of the luminescent phase 11 does not contain non-luminescent or light-transmitting materials. The thickness T of the phosphor 10 is determined according to the type of radiation R that is converted to visible light L. For example, when converting alpha rays to visible light and transmitting high-energy radiation such as gamma rays, the suitable range for the phosphor thickness T is 5 μm to 30 μm. When converting gamma rays to visible light, the suitable range for the phosphor thickness T is 50 μm to 200 μm.

[0029] In the overlapping direction W where the light-emitting phase 11 and the light-transmitting phase 12 are arranged alternately and overlap, the width W of the light-emitting phase 11 is determined from the viewpoint of reducing the amount of self-absorption and efficiently increasing the amount of light emitted. 11 It is preferable that the particle size is between 0.2 μm and 3 μm.

[0030] The light-transmitting phase 12 consists mainly of oxides and is made of a transparent ceramic material or the like with a visible light L transmittance of 75% or more. From the viewpoint of ensuring a path for the visible light L converted by the light-emitting phase 11 to reach the outside of the phosphor 10, the width W of the light-transmitting phase 12 in the overlapping direction W is set. 12 It is preferable that the width of the translucent phase 12 is 0.2 μm or more. Furthermore, in order to ensure sufficient conversion to visible light L, the width of the translucent phase 12 in the overlapping direction W should not be made too high. 12 It is preferable that the particle size is 3 μm or less.

[0031] The light-emitting phase 11 preferably has a transmittance of 10% to 90% to a certain extent that it can be detected by a predetermined detection device with respect to visible light L generated by irradiation with a predetermined radiation R. From the viewpoint of increasing the transmittance of visible light L, it is preferable that it has an orientation degree of 50% or more when it has a single crystal structure, and it is most preferable if it has a single crystal structure. The light-emitting phase 11 may have a structure consisting of multiple phases, including a main phase of a single crystal structure, as long as the transmittance of visible light L does not become too low. However, it is preferable that the main phase of the single crystal has a volume of 50% or more of the total.

[0032] Examples of the material for the light-emitting phase 11 include materials containing, as the main component, one or a combination of two or more of 3Al2O3·2SiO2, MgO·Al2O3, Al2O3·TiO2, BaO·6Al2O3, BaO·Al2O3, BeO·3Al2O3, BeO·Al2O3, 3BeO·Al2O3, CaO·TiO2, CaO·Nb2O3, CaO·ZrO2, 2CoO·TiO2, FeAl2O4, MnAl2O4, 3MgO·Y2O3, 2MgO·SiO2, MgCr2O4, MgO·TiO2, MgO·Ta2O5, MnO·TiO2, 2MnO·TiO2, 3SrO·Al2O3, SrO·Al2O3, SrO·2Al2O3SrO·6Al2O3, SrO·TiO3, TiO2·3Nb2O5, TiO2·Nb2O5, 3Y2O3·5Al2O3, 2Y2O3·Al2O3, 2MgO·2Al2O3·5SiO2, LaAlO3, CeAlO3, PrAlO3, NdAlO3, SmAlO3, EuAlO3, GdAlO3, DyAlO3, Yb4Al2O9, Er3Al5O 12 、11Al2O3·La2O3、11Al2O3·Nd2O3、11Al2O3·Pr2O3、EuAl 11 O 18 、2Gd2O3·Al2O3、11Al2O3·Sm2O3、Yb3Al5O 12 、CeAl 11 O 18 、and Er4Al2O9.

[0033] Examples of the material for the light-transmitting phase 12 include materials containing, as the main component, one or a combination of two or more of Al₂O₃, MgO, SiO₂, TiO₂, ZrO₂, CaO, Y₂O₃, BaO, BeO, FeO, Fe₂O₃, MnO, CoO, Nb₂O₅, Ta₂O₅, Cr₂O₃, SrO, ZnO, NiO, Li₂O, Ga₂O₃, HfO₂, ThO₂, UO₂, SnO₂, La₂O₃, Y₂O₃, CeO₂, Pr6O 11 、Nd₂O₃, Sm₂O₃, Gd₂O₃, Eu₂O₃, Tb₄O₇, Dy₂O₃, Ho₂O₃, Er₂O₃, Tm₂O₃, Yb₂O₃, and Lu₂O₃.

[0034] The luminescent phase 11 preferably has one or more combinations of the following structures: garnet structure, bixbite structure, perovskite structure, casspidin structure, orthosilicate structure, pyrosilicate structure, and pyrochlore structure.

[0035] The light-emitting phase 11 is A3B5O 12 When the garnet structure is represented by , it is preferable that the translucent phase 12 has a different crystalline phase containing an oxide represented by B2O3. The luminescent phase 11 may also have a bixbite structure represented by A2O3, a perovskite structure represented by ABO3, or a caspidin structure represented by A4B2O9. In these cases, A can be one or more combinations of, for example, Gd, Sc, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and B can be one or more combinations of, for example, Al and Ga.

[0036] When the light-emitting phase 11 has a Bixbite structure represented by A2O3, the light-transmitting phase 12 is B2O3, A3B5O 12 It is preferable to have different crystalline phases, including an oxide represented by A4B2O9. In these cases, A can be one or more combinations of, for example, Gd, Sc, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and B can be one or more combinations of, for example, Al and Ga.

[0037] When the luminescent phase 11 has an orthosilicate structure represented by A2BO5, it is preferable that the light-transmitting phase 12 has a different crystalline phase containing an oxide represented by A2O3. In this case, A can be one or more combinations of, for example, Gd, Y, Yb, and Lu, and B can be, for example, Si.

[0038] When the luminescent phase 11 has a perovskite structure represented by ABO3, it is preferable that the light-transmitting phase 12 has a different crystalline phase containing an oxide represented by BO2. In the case of a perovskite structure, A can be one or more combinations of, for example, Ca, Sr, Ba, and Pb, and B can be one or more combinations of, for example, Ti, Zr, and Hf.

[0039] When the luminescent phase 11 has a pyrosilicate structure or pyrochlore structure represented by A2B2O7, it is preferable that the light-transmitting phase 12 has a different crystalline phase containing an oxide represented by BO2. In the case of a pyrosilicate structure, A can be one or more combinations of Gd, Y, Yb, and Lu, and B can be Si, for example. In the case of a pyrochlore structure, A can be one or more combinations of Gd, Sc, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and B can be one or more combinations of Ti, Zr, and Hf, for example.

[0040] The luminescent phase 11 preferably contains an activating element in a ratio of 0.01 mol% to 20 mol%. Examples of activating elements include Ce. 3+ , Pr 3+ , Nd 3+ Sm 3+ ,EU 3+ , Tb 3+ Dy 3+ Ho 3+ Er 3+ , Tm 3+ Yb 3+ ,EU 2+ You may use one or more combinations of these.

[0041] The luminescent phase 11 adjusts the charge balance and prevents crystal defects, using Mg 2+ Ca 2+ Sr 2+ Ba 2+ Li + Na + , K+ Alkali metals and alkaline earth metals such as , may be added in a range of 1000 ppm or less. In addition, other elements may be added for the purpose of this.

[0042] (Method for manufacturing phosphors) Figure 2 is a schematic cross-sectional view showing an example of the configuration of a laser CVD apparatus 100 used for manufacturing phosphors according to this embodiment. The laser CVD apparatus 100 mainly consists of a chamber 101, a substrate support section 102 for supporting the substrate 10 within the chamber 101, a laser light irradiation section 103 for irradiating the substrate 10 with laser light, and a raw material gas supply section 104 for supplying raw material gas into the chamber 101.

[0043] The substrate support section 102 mainly consists of a stage 102A on which the substrate 10 is placed, and a thermocouple 102B attached to the stage 102A for monitoring the temperature of the substrate 10.

[0044] As the laser irradiated using the laser light irradiation unit 103, for example, a carbon dioxide laser, a semiconductor laser, a solid-state laser, etc., can be used.

[0045] The raw material gas supply unit 104 mainly consists of heater chambers 104B and 104D that heat and vaporize the precursor (organometallic compound) of the phosphor raw material to produce the raw material gas, carrier gas (Ar gas) supply sources (supply units) 104A and 104C, nozzles 104E that introduce the raw material gas and carrier gas into the chamber 101, oxygen gas supply source (supply unit) 104F, and nozzles 104G that introduce the supplied oxygen gas into the chamber 101.

[0046] For example, when manufacturing the phosphor 10 of this embodiment, which consists of LuAG (luminescent phase) and Al2O3 (transparent phase), one heater chamber 104B functions as a source of Lu, and the other heater chamber 104D functions as a source of Al. The number of heater chambers may be increased or decreased depending on the amount of raw materials (activating elements, etc.) required.

[0047] The carrier gas supply sources 104A and 104C are connected to heater chambers 104B and 104D, respectively, and the supplied carrier gas is transported through heater chambers 104B and 104D, and the vaporized raw material gas in heater chambers 104B and 104D is transported into chamber 101. The vaporization temperature of the raw material (raw material precursor) is preferably 150°C or higher and 270°C or lower. The carrier gas supply sources 104A and 104C and the oxygen gas supply source 104F each include a mass flow controller for adjusting the flow rate of the supplied gas. The flow rate of the carrier gas is preferably adjusted to a range of 20 ccm or higher and 500 sccm or lower. The flow rate of the oxygen gas is also preferably adjusted to a range of 20 sccm or higher and 500 sccm or lower.

[0048] The method for manufacturing a phosphor comprises the following steps. First, the substrate 10 is placed on the stage 102A, and the chamber 101 is evacuated to a pressure suitable for film formation (for example, 200 Pa or more and 3000 Pa or less) (evacuation step). Next, the substrate 10 is irradiated with laser light L using the laser light irradiation unit 103 to heat the substrate 10 (substrate heating step). The output density of the laser light is 100 W / cm². 2 More than 200W / cm 2 The following is preferable. By supplying the raw material gas together with the carrier gas to the heated substrate 101 while irradiating it with laser light, a phosphor film made of inorganic solid material can be formed (phosphor film formation step). The film formation temperature is preferably 700°C or higher and 1200°C or lower. The film formation rate is preferably 15 μm / h or higher and 200 μm / h or lower.

[0049] Laser irradiation can activate the growth of crystals in inorganic solid materials. Furthermore, laser irradiation enables the synthesis of crystals at a rapid growth rate, thereby reducing the crystal growth temperature. The crystal growth rate is approximately 180 times faster than that of conventional gas-phase processes without laser light. The crystal growth temperature is approximately 50% of that of conventional gas-phase processes.

[0050] In the phosphor film formation process, by supplying multiple types of raw material gases, the phosphor of this embodiment having a self-assembled eutectic structure can be manufactured. By adjusting the content ratio of the raw material gases, the content ratio (composition ratio) of each phase in the formed phosphor, and consequently the width of each phase, can be adjusted. Furthermore, by adjusting the supply time of the raw material gases, i.e., the film formation time, the thickness of the formed phosphor can be adjusted.

[0051] The phosphor of this embodiment, with the configuration described above, can achieve high-speed response and high light emission. The mechanism is as follows.

[0052] The phosphor 10 in this embodiment has a thickness in the range of 5 μm to 200 μm. Therefore, when adding activating elements that activate the excitation of visible light L, segregation is less likely to occur, and they can be added at high concentrations, thus enabling a fast response. In addition, by having sufficient thickness in the phosphor 10, it is possible to suppress the transmission of irradiated radiation R through the emission phase 11 without being converted to visible light L. Furthermore, by not being too thick in the phosphor 10, the probability of the component of visible light L that propagates in the thickness direction T, which is converted in the emission phase 11 and propagates radially toward the outside of the phosphor 10, being self-absorbed by the emission phase 11 can be reduced. Therefore, according to the phosphor 10 of this embodiment, the irradiated radiation R can be efficiently converted to visible light L and emitted in the emission phase 11, and the reduction in the amount of light emitted due to self-absorption can be suppressed, and as a result, a high amount of light emitted in the thickness direction T can be achieved.

[0053] Furthermore, in this embodiment, the phosphor 10 is composed of alternating emitting phases 11 and light-transmitting phases 12 in a direction W intersecting the thickness direction. Of the visible light L propagating from the emitting phase 11, the propagation path of the component propagating in the direction W intersecting the thickness direction becomes longer as it is inclined from the thickness direction T of the phosphor 10, and contains a proportional amount of light-transmitting phase 12. Therefore, compared to the case where the phosphor 10 is composed only of the emitting phase 11, the ratio of the length of the emitting phase 11 included in the propagation path of visible light L becomes smaller, and the propagation distance of visible light L within the emitting phase 11 can be reduced. As a result, the reduction in the amount of light emitted due to self-absorption in the emitting phase 11 can be suppressed, and as a result, a high amount of light emitted in the direction W intersecting the thickness direction can be achieved. In addition, energy circulation within and between the emitting phases can be suppressed, and as a result, high-speed response can be achieved.

[0054] In the method for manufacturing the phosphor 10 of this embodiment, by using the laser CVD method described above, an ultra-high temperature process like that used when using the single crystal growth method is not required, and the influence of impurity elements is less than that when using the liquid-phase epitaxy method. Therefore, according to the method for manufacturing the phosphor 10 of this embodiment, a phosphor 10 that achieves high luminescence and high-speed response can be easily manufactured. [Examples]

[0055] The effects of the present invention will be made clearer by the following examples. However, the present invention is not limited to the following examples and can be modified as appropriate without altering its essence.

[0056] (Example 1) Using the phosphor manufacturing method described above, LuAG(Lu3Al5O) has a garnet structure. 12 ) is the main phase, and Ce is used as the activating element. 3+A phosphor with a eutectic structure, consisting of an emissive phase with 9.0 moles of added material and a translucent phase mainly composed of Al2O3, was formed on one surface of a substrate. The thickness of the phosphor was 6.6 μm. The substrate used was made of alumina (Al2O3). The main manufacturing conditions for the phosphor were set as follows. Laser power density: 79 W / cm² 2 Ar gas flow rate: 100 sccm Oxygen gas flow rate: 100 sccm Raw material vaporization temperature: 190~270℃ Film forming temperature: 860℃ Deposition pressure: 200 Pa Deposition speed: 79μm / h

[0057] (Comparative Example 1) Gd3Al2Ga3O 12 (GAGG) is the main phase, with Ce as the activating element. 3+ Only the luminescent phase with added material was formed using the melt growth method. The thickness of the formed scintillator layer was approximately 1 mm.

[0058] (Comparative Example 2) LuAG(Lu3Al5O) 12 ) is the main phase, and Ce is used as the activating element. 3+ Only the luminescent phase with added material was formed using the melt growth method. The thickness of the formed scintillator layer was approximately 1 mm.

[0059] Figures 3A and 3B show SEM images of the cross-section and surface of the phosphor formed in Example 1. It can be seen that the phosphor has a eutectic structure, with the emissive phase (black portion) and the translucent phase (white portion) overlapping alternately, forming a film with a uniform thickness T of approximately 6.6 μm. The width in the overlapping direction of the emissive and translucent phases is approximately 0.7 μm in both cases.

[0060] The phosphors of Example 1, Comparative Example 1, and Comparative Example 2 were irradiated with radiation including alpha and gamma rays, and the pulsed pulse height spectrum of the visible light converted within each emission phase was measured. Figure 4 is a graph showing the measurement results. The horizontal axis of the graph represents the digital channel value [ch] corresponding to the amount of light emitted, and the vertical axis of the graph represents the light emission intensity.

[0061] The pulse height spectra 201 and 202 of Comparative Examples 1 and 2 both have an edge in the energy region of 700-1100ch, and are significantly attenuated in the higher energy region. Therefore, it can be seen that high emission levels were not obtained with the phosphors of Comparative Examples 1 and 2. This is thought to be because the emission phase is formed thickly in the phosphors of Comparative Examples 1 and 2, which increases the propagation distance of visible light within the emission phase, resulting in a decrease in emission levels due to self-absorption.

[0062] On the other hand, the pulse height spectrum 203 of Example 1 has an edge at the 1500ch energy, and the detection signal is gradually attenuated in the high-energy region above 1500ch. Therefore, it can be seen that a high amount of light emission is obtained with the phosphor of Example 1. This is thought to be because by providing a transparent phase inside the phosphor, the ratio of the length of the emitting phase included in the visible light propagation path is reduced, the propagation distance of visible light within the emitting phase can be reduced, and the decrease in the amount of light emission due to self-absorption is suppressed.

[0063] The phosphor of Example 1 was irradiated with alpha rays, and measurements were performed to investigate its fluorescence lifetime characteristics. Figure 5 is a graph showing the measurement results. The horizontal axis of the graph represents elapsed time [μs], and the vertical axis of the graph represents the voltage [mV] corresponding to the energy state of the phosphor.

[0064] The phosphor's energy state is excited upon absorbing alpha rays irradiated at time 0 [μs], and then transitions to the ground state by emitting visible light over time. The time constant during decay is 17 ns for the fastest component, which is smaller than the 70 ns time constant obtained for typical bulk single-crystal LuAG. By setting the phosphor thickness to a range of 5 μm to 100 μm (6.6 μm in this case) and doping it with a high concentration of Ce, concentration quenching can be promoted, and by including a transparent phase in the phosphor, energy migration within the emitter can be suppressed. As a result, the fluorescence lifetime of the phosphor is shortened, and a fast response can be achieved.

[0065] (Examples 2-6) Under the same manufacturing conditions as in Example 1, phosphors of Examples 2-6 were formed, differing in thickness from the phosphor of Example 1. Aside from the thickness, the composition was the same as that of the phosphor of Example 1.

[0066] Alpha rays were irradiated onto the phosphors of Examples 1 to 6, and the amount of light emitted from each phosphor was measured. A radioactive isotope of Am (mass number 241) was used as the alpha ray source, and pulse height distribution spectra were measured. The relationship between the thickness of the obtained phosphors and the amount of light emitted is shown in Table 1 and Figure 6.

[0067] [Table 1]

[0068] Figure 6 is a graph showing the relationship between phosphor thickness and luminescence. The horizontal axis of the graph represents the phosphor thickness [μm], and the vertical axis represents the luminescence (Light Yield) normalized by the maximum value (saturation value).

[0069] Under the conditions of this embodiment, when the thickness is 9 μm or more, the increase in light emission due to the increase in the light-emitting region balances out with the decrease in light emission due to the increase in the self-absorption region, and the resulting value of light emission saturates at its maximum value. In other words, the amount of light emission per unit thickness is maximized when the thickness is 9 μm or more. From this result, it can be seen that the luminescence efficiency can be further increased if the thickness of the phosphor is between 0.8 and 1.2 times the thickness at which the amount of light emission per unit thickness is maximized. [Industrial applicability]

[0070] According to the present invention, it is possible to provide a phosphor that achieves high luminescence and fast response, and a method for manufacturing the phosphor that enables easy production of the phosphor. [Explanation of Symbols]

[0071] 10 Phosphors 11. Emitting Phase 12 Translucent phase 100 Laser CVD equipment 101 Chamber 102 Base material support part 102A Stage 102B Thermocouple 103 Laser beam irradiation area 104 Raw Material Gas Supply Department 104A Carrier gas supply source (supply unit) 104B Heater room (source of raw material precursors) 104C Carrier gas supply source (supply unit) 104D Heater room (source of raw material precursors) 104E Supply nozzle for raw material precursor gas 104F Oxygen gas supply source 104G Oxygen Gas Supply Nozzle

Claims

1. A light-emitting phase that converts radiation into visible light and causes it to emit light, The light-transmitting phase that transmits the visible light, The thickness is in the range of 5 μm to 200 μm. The luminescent phase contains an activating element, The light-emitting phase and the light-transmitting phase are arranged alternately in a direction intersecting the thickness direction. A phosphor characterized in that, in the overlapping direction in which the light-emitting phase and the light-transmitting phase are alternately arranged and overlapping, the width of the light-emitting phase is 0.2 μm or more and 3 μm or less.

2. The phosphor according to claim 1, characterized in that the thickness is 0.8 times or more and 1.2 times or less the thickness at which the amount of light emitted per unit thickness is maximized.

3. The phosphor according to either claim 1 or 2, characterized in that the luminescent phase contains the activating element in a ratio of 0.01 mol% to 20 mol%.

4. (delete)

5. The phosphor according to either claim 1 or 2, characterized in that the width of the light-transmitting phase in the overlapping direction is 0.2 μm or more and 3 μm or less.

6. The phosphor according to either claim 1 or 2, characterized in that the luminescent phase has a crystal structure which is a combination of one or more of the following: garnet structure, bixbite structure, perovskite structure, casspidin structure, orthosilicate structure, pyrosilicate structure, and pyrochlore structure.

7. The phosphor according to either claim 1 or 2, characterized in that the light-transmitting phase mainly contains an oxide made from one or more of the metal elements constituting the light-emitting phase.

8. A method for producing a phosphor according to either claim 1 or 2, A method for producing a phosphor, characterized by forming the phosphor using a laser CVD method so that the thickness direction is perpendicular to one surface of a substrate.

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