WO2016208174A1 - Ceramic, method for producing same, emitter and thermophotovoltaic power generator - Google Patents

Ceramic, method for producing same, emitter and thermophotovoltaic power generator Download PDF

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Publication number
WO2016208174A1
WO2016208174A1 PCT/JP2016/002940 JP2016002940W WO2016208174A1 WO 2016208174 A1 WO2016208174 A1 WO 2016208174A1 JP 2016002940 W JP2016002940 W JP 2016002940W WO 2016208174 A1 WO2016208174 A1 WO 2016208174A1
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ceramic
emitter
rare earth
earth element
composition formula
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PCT/JP2016/002940
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French (fr)
Japanese (ja)
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渋谷　明信
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日本電気株式会社
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/44—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminates
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S10/00—PV power plants; Combinations of PV energy systems with other systems for the generation of electric power
    • H02S10/30—Thermophotovoltaic systems
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • the present invention relates to a thermophotoelectromotive force that converts thermal radiation from an object into electromotive force in a photoelectric conversion cell.
  • thermophotovoltaic power generation is a technology that converts thermal radiation into electricity using a photoelectric conversion cell, and high-efficiency power generation can be expected by controlling the radiation spectrum. Furthermore, thermophotovoltaic power generation is attracting attention as a power generation technology that can use various heat sources and has a high energy density per weight.
  • Fig. 7 shows the basic configuration of a thermophotovoltaic generator.
  • the thermophotovoltaic power generation device 10 shown in FIG. 7 converts heat generated by the combustion device or sunlight condensing into infrared rays by the emitter 13 and makes the emitted infrared rays enter the photoelectric conversion cell 14 to generate electric power. Convert.
  • Various materials for the emitter 13 have been reported. In order to increase the efficiency of the thermophotovoltaic power, it is necessary to narrow the infrared spectrum emitted by the emitter 13 to a wavelength suitable for the photoelectric conversion cell.
  • Patent Document 1 proposes a thermophotovoltaic power generation device in which a photonic crystal is provided on the surface of an emitter for controlling an infrared spectrum in the emitter (FIG. 8).
  • the thermophotovoltaic power generation apparatus 20 shown in FIG. 8 includes an emitter 13 and a photoelectric conversion cell 14, and a photonic crystal 15 in which a large number of cavities are formed in a metal is provided on the infrared radiation side of the emitter 13.
  • the metal cavity deteriorates due to oxidation or recrystallization when used at a high temperature, and the infrared spectrum cannot be controlled as desired.
  • thermophotovoltaic power generator 30 shown in FIG. 9 the optical filter 16 is disposed between the emitter 13 and the photoelectric conversion cell 14.
  • the thermophotovoltaic power generation apparatus 30 shown in FIG. 9 uses an optical filter 16 that reflects and absorbs infrared rays other than the wavelength suitable for the photoelectric conversion cell 14 to the emitter in order to improve efficiency.
  • thermophotovoltaic power generation apparatus 30 shown in FIG. 9 it is difficult to realize the optical filter 16 having high heat resistance.
  • thermophotovoltaic power generation device including a burner device serving as a heat source, a radiant burner screen having a substrate containing a heat-resistant porous or porous material, and a photovoltaic device.
  • the emitter of Patent Document 2 is an infrared emitter in which a compound containing a rare earth element is coated on a radiation burner screen, and ytterbium-substituted yttrium aluminum garnet (Yb: YAG) is used as the coating compound.
  • Yb ytterbium-substituted yttrium aluminum garnet
  • Non-Patent Document 1 a ceramic emitter using a rare earth aluminum garnet is reported in Non-Patent Document 1 or Non-Patent Document 2.
  • Non-Patent Document 1 discloses that a composite coating of alumina or zirconia fiber, erbium aluminum garnet, and Er 3 Al 5 O 12 (ErAG) having a porosity of 50% or more and a thickness of 50 to 500 ⁇ m is formed on SiC ceramic.
  • FIG. 10 is an explanatory diagram showing thermal emission spectra at 1050 ° C. of ErAG composite and SiC ceramic. As shown in FIG. 10, although the selective wavelength radiation near the wavelength of 1600 nm can be confirmed, there is a problem that the radiation intensity is small.
  • Non-Patent Document 2 reports that a melt-grown composite material made of alumina and a rare earth aluminum garnet is used as an emitter, and Er and Yb are selected as the rare earth.
  • Non-Patent Document 2 discloses the wavelength dependence of the emissivity of ceramic emitters by these composite materials, as shown in FIG.
  • the wavelength selectivity of emissivity is defined by the ratio of the emissivity at the peak wavelength to the emissivity at the wavelength of 1750 nm
  • the ratio is a composite of Yb 3 Al 5 O 12 (YbAG) and alumina.
  • the body is 1.7, and the composite of ErAG and alumina is 1.5, which is not very good.
  • the ceramic emitter using the rare earth aluminum garnet described in Non-Patent Documents 1 and 2 has low radiation intensity and insufficient wavelength selectivity.
  • An object of the present invention is to provide a ceramic that realizes thermal radiation having high radiation intensity and excellent wavelength selectivity, as a ceramic used for an emitter of a thermophotovoltaic power generator.
  • One aspect of the ceramic of the present invention is mainly composed of the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element).
  • the sintering temperature of the ceramic mainly composed of the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) is 1350 ° C. to 1400 ° C.
  • the sintering temperature of the ceramic having a composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element) as a main component is 1250 ° C. to 1300 ° C.
  • the material of the emitter that converts heat from the heat source into infrared rays is the above-described ceramic.
  • thermophotovoltaic power generation apparatus of the present invention includes an emitter that converts heat from a heat source into infrared rays, and a photoelectric conversion cell that converts the infrared rays radiated from the emitter into electric power.
  • the material is the ceramic described above.
  • thermophotovoltaic power generator It is a lineblock diagram explaining the thermophotovoltaic power generator concerning a 1st embodiment. It is a schematic diagram which shows a partial cross section of the ceramic used for the emitter of 1st Embodiment. It is a figure which shows the XRD (X-ray diffraction) pattern of the ceramic used for an emitter. It is a figure which shows the thermal radiation spectrum of the ceramic used for an emitter. It is a figure which shows the relationship between the porosity of the ceramic used for an emitter, and sintering temperature. It is a figure showing the comparison of the radiation spectrum in the ceramic used for an emitter. It is a block diagram which shows the basic composition of a thermophotovoltaic power generator.
  • thermophotovoltaic power generator using a photonic crystal. It is a block diagram which shows the thermophotovoltaic power generator using an optical filter. It is a figure which shows the thermal radiation spectrum of the emitter in nonpatent literature 2. It is a figure which shows the emissivity spectrum of the emitter in a nonpatent literature 2.
  • thermophotovoltaic power generator according to the first embodiment of the present invention will be described with reference to FIGS.
  • FIG. 1 is a configuration diagram showing the configuration of the thermophotovoltaic power generation apparatus according to the first embodiment.
  • a thermophotovoltaic power generation device 1 is an Si photoelectric conversion element that converts heat from a heat source into infrared rays and emits them, and an infrared ray emitted from the emitters 2 into electric power. And a photoelectric conversion cell 3 formed.
  • the emitter 2 of the thermophotovoltaic power generator 1 has a compositional formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element). It is a ceramic whose main component is the indicated composition. Although the crystal structure of the emitter 2 is not limited, it is desirable that a K 2 NiF 4 type structure is included.
  • the wavelength selectivity in the thermal emission spectrum is improved by controlling the amount of vacancies and the form of the vacancies in the polycrystal (unnecessary wavelength). (Suppression of radiation) and improvement of radiation intensity at the peak wavelength were confirmed.
  • the improvement of the above characteristics can be confirmed in a ceramic mainly composed of ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element).
  • the ceramic has a porosity of 20% to 40%.
  • FIG. 2 is a schematic diagram showing a part of a cross section of a ceramic applied to the emitter.
  • the ceramic is composed of pores 4 and polycrystalline dense portions 5.
  • the voids 4 in the ceramic include connected but not linearly continuous portions. If the porosity is less than 20%, the wavelength selectivity of the thermal emission spectrum is deteriorated. Further, when the porosity is 40% or more, the mechanical strength becomes small. Further, when the porosity of the ceramic is 40% or more, the mechanical strength of the ceramic becomes small, and it becomes unsuitable for use as the emitter 2 of the thermophotovoltaic power generation device 1. Further, when the porosity of the ceramic is 40% or more, the space formed by connecting the holes becomes linear, and the radiated light from the heat source is transmitted. As a result, the effect of improving the wavelength selectivity in the emitter is affected.
  • the size and shape of the ceramic pores are not limited, but in order to achieve the ceramic porosity and prevent the pores from being connected linearly, the cross-sectional area of the pores must be 5 ⁇ m 2 or less. Is desirable. Note that the optimum value of the hole size based on the relationship between the radiation characteristics and the hole size is not clear.
  • the crystal grain size in the polycrystalline dense part of the ceramic is not limited, but in order to realize the porosity of the ceramic and the pores not connected linearly, the crystal grain size is 10 ⁇ m or less. It is desirable that
  • the ceramic according to the first embodiment can change the selection wavelength of thermal radiation depending on the type of rare earth element corresponding to R in the composition formula.
  • the rare earth element Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb or the like is selected.
  • the photoelectric conversion element of the photoelectric conversion cell when the photoelectric conversion element of the photoelectric conversion cell is based on Si, it is desirable to use Yb having a peak wavelength of the thermal radiation spectrum of about 1000 nm as the rare earth element constituting the ceramic.
  • the photoelectric conversion element of the photoelectric conversion cell is based on GaSb, it is desirable to use Er having a peak wavelength of about 1500 nm as the rare earth element constituting the ceramic.
  • ARAlO 4 A: Ca, Sr, Ba; R: rare earth element
  • ARGaO 4 A: Ca, Sr, Ba; R: rare earth element
  • Ca, Sr and Ba can be used.
  • the ceramic structure it is preferable to select Ca that stabilizes the K 2 NiF 4 type structure.
  • the outer shape and size of the emitter of the first embodiment are not limited, but from the viewpoint of not connecting the holes linearly and the mechanical strength of the ceramic, the thickness of the emitter is a plate shape. It is desirable that it is 0.8 mm or more. Further, in the case of a rectangular parallelepiped or a cylindrical rod shape, it is desirable that the minimum side size or diameter is 0.8 mm or more.
  • the ceramic manufacturing method of the first embodiment can be manufactured by a solid-phase reaction using ceramic powder as a raw material, it can be manufactured by a simple process based on mixing, molding and firing of raw materials. It is.
  • Patent Document 2 there is a problem that the structure is complicated and difficult to manufacture because of the structure in which a substrate containing a porous or porous material is coated with Yb: YAG. Further, in Non-Patent Document 1, there is a problem that the manufacturing process is complicated because it is necessary to manufacture alumina or zirconia fiber and the coating is formed by the sol-gel method. Further, in Non-Patent Document 2, it is necessary to melt the raw material at a high temperature of 2193K at the time of synthesis, and there is a problem that the production is difficult. However, the ceramic of this embodiment does not have these problems.
  • each powder was weighed so that the stoichiometric ratio after synthesis was CaYbAlO 4 , each powder and ethanol were added, and wet-mixed in an agate mortar.
  • the mixed material was dried and calcined at 1400 ° C. for 8 hours in the air, and a K 2 NiF 4 type crystal of the composition formula CaYbAlO 4 was obtained by solid phase reaction.
  • the mixture was pulverized in an agate mortar, formed into pellets, and then fired in air at 1400 ° C. for 2 hours to obtain disk-shaped ceramic pellets.
  • the pellet size after sintering was 12.7 mm in diameter and 1.2 mm in thickness. From the density measurement by Archimedes method, it was confirmed that the porosity of this ceramic was 27%. In order to prevent water penetration into the pores of the ceramic pellet, the above density measurement was performed by coating the ceramic surface or the like with a cellulosic resin.
  • FIG. 3 is a powder X-ray diffraction pattern of ceramic pellets by a powder X-ray diffractometer.
  • the horizontal axis represents the X-ray incident angle
  • the vertical axis represents the diffraction intensity.
  • One peak along the vertical axis represents one crystal plane.
  • FIG. 3 marked with “C (hkl)” in the diffraction peak shown in FIG. 3 has the same structure as CaYAlO 4 of JCPDS (Joint Committee of Powder Diffraction Standards) card 00-024-0221 having a K 2 NiF 4 type structure. A surface index was added. Thereby, it was confirmed that CaYbAlO 4 having a K 2 NiF 4 type structure could be synthesized by the above-described manufacturing method. Moreover, the peak without the index in FIG. 3 could be identified as Yb 2 O 3 . It was confirmed that the main component of the synthesized ceramic was CaYbAlO 4 .
  • the thermal emission spectrum was measured by heating one surface of a disk-shaped ceramic pellet and inputting light emitted from the other surface to an optical spectrum analyzer.
  • the ceramic pellet is heated by first pressing the SiC plate against the disk-shaped ceramic pellet. In this state, when the surface of the SiC plate pressed against the disc-shaped ceramic pellet was the front side, a halogen lamp was condensed and irradiated from the back side of the SiC plate to heat the SiC plate and conduct heat to the ceramic pellet. .
  • the temperature of the heat radiation surface of the pellet was measured with a K thermocouple, and the temperature of the SiC plate was measured with an R thermocouple. Since the SiC plate has a sufficiently high thermal conductivity, it was estimated to be equivalent to the temperature of the heating surface of the pellet.
  • Fig. 4 shows the measurement results of the thermal emission spectrum of the fabricated ceramic.
  • the horizontal axis indicates the wavelength, and the vertical axis indicates the intensity.
  • the measurement conditions were a ceramic surface (infrared radiation surface) temperature of 942 ° C., a ceramic back surface (heating surface) temperature of 1210 ° C., and an average temperature of 1127 ° C.
  • the thermal radiation spectrum of 1120 degreeC SiC ceramic is also shown as a comparison of a measurement result.
  • SiC is known as a gray body having an emissivity of 0.9, but it was confirmed that the CaYbAlO 4 ceramic of Example 1 showed a radiation intensity comparable to that of SiC at the peak wavelength.
  • Example 2 is a ceramic produced by changing the firing temperature as compared with the production method of Example 1. Regarding the ceramic manufacturing method of Example 2, detailed description of the same parts as those of Example 1 will be omitted.
  • CaYbAlO 4 calcined powder was prepared using the same powder as in Example 1, and after pellet molding, it was fired in air at 1350 ° C. for 2 hours to obtain disk-shaped ceramic pellets.
  • the sintered ceramic pellet size was 12.9 mm in diameter and 1.4 mm in thickness. From the density measurement by Archimedes method, it was confirmed that the porosity of the ceramic of this Example 2 was 36%.
  • Comparative Example 1 Next, the manufacturing method of the ceramic of the comparative example 1 is demonstrated.
  • the ceramic of Comparative Example 1 was produced by changing the firing temperature as compared with the production methods of Examples 1 and 2. Regarding the ceramic manufacturing method of Comparative Example 1, description similar to Example 1 or 2 is omitted.
  • a calcined powder of CaYbAlO 4 was prepared, formed into pellets, and then fired in the atmosphere at 1450 ° C. for 2 hours to obtain a disk-shaped ceramic.
  • the pellet size after sintering was 11.6 mm in diameter and 1.3 mm in thickness. From the density measurement by Archimedes method, it was confirmed that the porosity of this ceramic was 11%.
  • FIG. 5 shows the relationship between the sintering temperature and the porosity calculated from the ceramic density of Example 1, Example 2, and Comparative Example 1. As shown in FIG. 5, the ceramic porosity was 36% at the sintering temperature of 1350 ° C. according to Example 2, and the ceramic porosity was 11% at 1450 ° C. in Comparative Example 1. This confirmed that the porosity of the ceramic could be controlled by changing the sintering temperature during production.
  • the CaYbAlO 4 material is a material that can be expected to have high heat resistance, and the sintering temperature range of 1350 ° C. to 1450 ° C. is lower than the sintering temperature of ceramics having a garnet structure, and is easy to control. There is an advantage.
  • Example 2 the thermal emission spectrum of the ceramic was measured in the same manner as in Example 1.
  • the average temperature of the front and back surfaces was used as the ceramic temperature when calculating the emissivity.
  • the surface temperature of the ceramic at the time of measurement was 947 ° C.
  • the back surface temperature was 1178 ° C.
  • the average temperature was 1062.5 ° C.
  • the surface temperature of the ceramic at the time of measurement was 944 ° C.
  • the back surface temperature was 1110 ° C.
  • the average temperature was 1027 ° C.
  • Example 1 Example 2 and Comparative Example 1
  • the spectrum of the emissivity calculated from the measured radiation intensity spectrum is shown in FIG.
  • the wavelength selectivity of the ceramics of Examples 1 and 2 Has been confirmed to be a sufficient value.
  • the ceramic with a porosity of 36% in Example 2 has a smaller emissivity at the peak wavelength than the ceramic with a porosity of 27% in Example 1.
  • the radiation of wavelengths other than the peak wavelength is scattered by the introduction of ceramic vacancies.
  • the radiation intensity is maintained by the energy transfer between the fb electron levels of Yb.
  • wavelength selectivity appears.
  • an increase in the porosity value of the ceramic means a decrease in the concentration of Yb atoms that transmit energy. For this reason, it is considered that the radiation intensity at the peak wavelength decreases as the porosity value increases as in the second embodiment.
  • the porosity is 40% or more, the mechanical strength of the ceramic is reduced, which is insufficient for use as an emitter. Further, the ceramic of Comparative Example 1 had a smaller ratio of emissivity at the peak wavelength and emissivity above the band gap wavelength than the ceramic of Example 2, and a sufficient value for wavelength selectivity was not obtained. The ceramic of Comparative Example 1 having a porosity of 11% was insufficiently scattered to obtain wavelength selectivity.
  • the composition formula ARAlO 4 (A: Ca, Sr , Ba; R: rare earth element) has shown an example of a ceramic mainly composed of, but is not limited thereto.
  • CaYbGaO 4 which is an example of a ceramic of the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element)
  • CaCO 3 , Yb 2 O 3 and Ga 2 O 3 are used as ceramic raw materials.
  • the sintering temperature of the ceramic mainly composed of the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element) is preferably in the range of 1250 ° C to 1300 ° C.
  • (Appendix 1) It is a ceramic whose main component is the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element),
  • the ceramic has pores with a porosity of 20% to 40%,
  • the pore is a ceramic including a portion which is connected inside the ceramic but is not linearly continuous.
  • the ceramic has a pore cross-sectional area of 5 ⁇ m 2 or less.
  • the ceramic has a region composed of a particle size of 10 ⁇ m or less, The ceramic according to any one of appendices 1 to 3.
  • composition formula ARAlO 4 (R: rare earth element) or the composition A of the composition formula ARGaO 4 (R: rare earth element) is Ca.
  • the rare earth element is Pr. , Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, or Yb, The ceramic according to any one of appendices 1 to 5.
  • Appendix 10 The emitter according to any one of appendices 1 to 7, wherein a material of the emitter that converts heat from the heat source into infrared rays.
  • the thickness between the heat supply surface of the emitter and the infrared radiation surface is 0.8 mm or more, The emitter according to appendix 10.
  • Appendix 12 An emitter that converts heat from a heat source into infrared; A photoelectric conversion cell that converts the infrared radiation emitted from the emitter into electric power, The thermophotovoltaic power generation device, wherein the material of the emitter is the ceramic according to any one of appendices 1 to 7.

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Abstract

Provided is a ceramic which has high radiation intensity and enables heat emission having excellent wavelength selectivity. A ceramic which is mainly composed of a composition formula ARAlO4 (wherein A is Ca, Sr or Ba; and R is a rare earth element) or a composition formula ARGaO4 (wherein A is Ca, Sr or Ba; and R is a rare earth element), and which has pores at a porosity of from 20% to 40% (inclusive). The pores are connected with each other within the ceramic, but have portions that are not linearly continuous.

Description

セラミックとその製造方法、エミッタおよび熱光起電力発電装置CERAMIC AND METHOD FOR MANUFACTURING THE SAME, EMITTER AND THERMAL PHOTOVOLTAIC GENERATION DEVICE
　本発明は、物体からの熱放射を光電変換セルで起電力に変える熱光起電力に関する。 The present invention relates to a thermophotoelectromotive force that converts thermal radiation from an object into electromotive force in a photoelectric conversion cell.
　熱光起電力発電は、熱放射を光電変換セルで電気に変換する技術であり、放射スペクトルを制御することにより高効率な発電が期待できる。更に、熱光起電力発電は、種々の熱源が利用可能であり、重量当たりのエネルギー密度が大きい発電技術として注目されている。 Thermophotovoltaic power generation is a technology that converts thermal radiation into electricity using a photoelectric conversion cell, and high-efficiency power generation can be expected by controlling the radiation spectrum. Furthermore, thermophotovoltaic power generation is attracting attention as a power generation technology that can use various heat sources and has a high energy density per weight.
　図７に熱光起電力発電装置の基本構成を示す。図７に示す熱光起電力発電装置１０は、燃焼装置又は太陽光の集光により発生させた熱をエミッタ１３で赤外線に変換し、放射された赤外線を光電変換セル１４に入射して電力に変換する。エミッタ１３の材質は、種々のものが報告されている。熱光起電力の高効率化のためには、エミッタ１３が放射する赤外線のスペクトルを光電変換セルに適合した波長に絞ることが必要となる。 Fig. 7 shows the basic configuration of a thermophotovoltaic generator. The thermophotovoltaic power generation device 10 shown in FIG. 7 converts heat generated by the combustion device or sunlight condensing into infrared rays by the emitter 13 and makes the emitted infrared rays enter the photoelectric conversion cell 14 to generate electric power. Convert. Various materials for the emitter 13 have been reported. In order to increase the efficiency of the thermophotovoltaic power, it is necessary to narrow the infrared spectrum emitted by the emitter 13 to a wavelength suitable for the photoelectric conversion cell.
　例えば、特許文献１には、エミッタにおける赤外線スペクトルの制御のために、エミッタの表面にフォトニック結晶を設けた熱光起電力発電装置が提案されている（図８）。図８に示す熱光起電力発電装置２０は、エミッタ１３、光電変換セル１４を備え、エミッタ１３の赤外線放射側に、金属に多数のキャビティが形成されたフォトニック結晶１５が設けられている。 For example, Patent Document 1 proposes a thermophotovoltaic power generation device in which a photonic crystal is provided on the surface of an emitter for controlling an infrared spectrum in the emitter (FIG. 8). The thermophotovoltaic power generation apparatus 20 shown in FIG. 8 includes an emitter 13 and a photoelectric conversion cell 14, and a photonic crystal 15 in which a large number of cavities are formed in a metal is provided on the infrared radiation side of the emitter 13.
　しかし、フォトニック結晶が設けられたエミッタは、高温使用時に酸化又は再結晶によって金属製のキャビティが劣化し、赤外線スペクトルに対する所望の制御ができなくなる。 However, in the emitter provided with the photonic crystal, the metal cavity deteriorates due to oxidation or recrystallization when used at a high temperature, and the infrared spectrum cannot be controlled as desired.
　また、熱光起電力の効率化のために熱光起電力発電装置に光学フィルタを設ける構造が提案されている（図９）。図９に示す熱光起電力発電装置３０は、エミッタ１３と光電変換セル１４との間に光学フィルタ１６を配置している。図９に示す熱光起電力発電装置３０は、効率の向上のために、光電変換セル１４に適応する波長以外の赤外線をエミッタに反射して吸収させる光学フィルタ１６を用いている。 Also, a structure has been proposed in which an optical filter is provided in the thermophotovoltaic power generator in order to increase the efficiency of the thermophotovoltaic power (FIG. 9). In the thermophotovoltaic power generator 30 shown in FIG. 9, the optical filter 16 is disposed between the emitter 13 and the photoelectric conversion cell 14. The thermophotovoltaic power generation apparatus 30 shown in FIG. 9 uses an optical filter 16 that reflects and absorbs infrared rays other than the wavelength suitable for the photoelectric conversion cell 14 to the emitter in order to improve efficiency.
　しかし、図９に示す熱光起電力発電装置３０では、耐熱性の高い光学フィルタ１６を実現することが困難である。 However, in the thermophotovoltaic power generation apparatus 30 shown in FIG. 9, it is difficult to realize the optical filter 16 having high heat resistance.
　一方、エミッタの材質として、耐酸化性や耐熱性が良好なセラミックを用いる熱光起電力発電装置の研究開発が活発に行われている。特許文献２には、熱源となるバーナー装置と、耐熱性の多孔性または有孔材料を含む基板を有する輻射バーナースクリーンと、光電池装置とを備える熱光起電力発電装置が報告されている。 On the other hand, research and development of thermophotovoltaic power generators using ceramics with good oxidation resistance and heat resistance as the material of the emitter are being actively conducted. Patent Document 2 reports a thermophotovoltaic power generation device including a burner device serving as a heat source, a radiant burner screen having a substrate containing a heat-resistant porous or porous material, and a photovoltaic device.
　特許文献２のエミッタは、輻射バーナースクリーンに希土類元素を含む化合物を被覆した赤外線エミッタであり、被覆する化合物として、イッテルビウム置換イットリウムアルミニウムガーネット（Ｙｂ：ＹＡＧ）を用いている。 The emitter of Patent Document 2 is an infrared emitter in which a compound containing a rare earth element is coated on a radiation burner screen, and ytterbium-substituted yttrium aluminum garnet (Yb: YAG) is used as the coating compound.
　更に、希土類元素を用いた化合物では、希土類イオンの４ｆ電子遷移吸収に相当する波長に選択的な熱放射が得られることが知られている。このように、希土類アルミニウムガーネットを用いたセラミックエミッタが、非特許文献１又は非特許文献２で報告されている。 Furthermore, it is known that a compound using a rare earth element can obtain selective thermal radiation at a wavelength corresponding to 4f electronic transition absorption of rare earth ions. Thus, a ceramic emitter using a rare earth aluminum garnet is reported in Non-Patent Document 1 or Non-Patent Document 2.
　非特許文献１は、ＳｉＣセラミック上に、空孔率５０％以上で厚み５０～５００μｍとなるアルミナやジルコニアファイバーとエルビウムアルミニウムガーネット、Ｅｒ３Ａｌ５Ｏ１２（ＥｒＡＧ）との複合体被覆を形成して成るエミッタを報告している。図１０は、ＥｒＡＧ複合体およびＳｉＣセラミックの１０５０℃における熱放射スペクトルを示す説明図である。図１０に示すように、波長１６００ｎｍ付近での選択波長放射が確認できるものの、放射強度が小さいという問題がある。 Non-Patent Document 1 discloses that a composite coating of alumina or zirconia fiber, erbium aluminum garnet, and Er 3 Al 5 O 12 (ErAG) having a porosity of 50% or more and a thickness of 50 to 500 μm is formed on SiC ceramic. Has been reported. FIG. 10 is an explanatory diagram showing thermal emission spectra at 1050 ° C. of ErAG composite and SiC ceramic. As shown in FIG. 10, although the selective wavelength radiation near the wavelength of 1600 nm can be confirmed, there is a problem that the radiation intensity is small.
　また、非特許文献２では、アルミナと希土類アルミニウムガーネットからなる溶融成長複合材料をエミッタとし、希土類としてＥｒおよびＹｂを選択したものが報告されている。非特許文献２では、図１０に示すように、これら複合材料によるセラミックエミッタの放射率の波長依存性が開示されている。 Further, Non-Patent Document 2 reports that a melt-grown composite material made of alumina and a rare earth aluminum garnet is used as an emitter, and Er and Yb are selected as the rare earth. Non-Patent Document 2 discloses the wavelength dependence of the emissivity of ceramic emitters by these composite materials, as shown in FIG.
　非特許文献２のエミッタは、放射率の波長選択性をピーク波長での放射率と波長１７５０ｎｍでの放射率の比で定義すると、その比はＹｂ３Ａｌ５Ｏ１２（ＹｂＡＧ）とアルミナの複合体で１．７、ＥｒＡＧとアルミナの複合体で１．５となり、あまり良好ではない。 In the emitter of Non-Patent Document 2, when the wavelength selectivity of emissivity is defined by the ratio of the emissivity at the peak wavelength to the emissivity at the wavelength of 1750 nm, the ratio is a composite of Yb 3 Al 5 O 12 (YbAG) and alumina. The body is 1.7, and the composite of ErAG and alumina is 1.5, which is not very good.
特許第３４７２８３８号公報Japanese Patent No. 3472838 特表２００２－５３７５３７号公報Special Table 2002-537537
　以上説明したように、非特許文献１、２に記載の希土類アルミニウムガーネットを用いたセラミックエミッタは、放射強度が小さく、波長選択性が十分ではない。 As described above, the ceramic emitter using the rare earth aluminum garnet described in Non-Patent Documents 1 and 2 has low radiation intensity and insufficient wavelength selectivity.
　本発明の目的は、熱光起電力発電装置のエミッタに用いるセラミックとして、放射強度が大きく、波長選択性に優れた熱放射を実現するセラミックを提供することにある。 An object of the present invention is to provide a ceramic that realizes thermal radiation having high radiation intensity and excellent wavelength selectivity, as a ceramic used for an emitter of a thermophotovoltaic power generator.
　本発明のセラミックの一態様は、組成式ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）、又は、組成式ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）を主成分とするセラミックであり、前記セラミックは、空孔率２０％以上４０％以下の空孔を有し、前記空孔は、前記セラミックの内部で連結しているが直線的に連続していない部分を含む。 One aspect of the ceramic of the present invention is mainly composed of the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element). A ceramic as a component, wherein the ceramic has pores with a porosity of 20% or more and 40% or less, and the pores are connected within the ceramic but are not linearly continuous portions. including.
　本発明のセラミックの製造方法の一態様は、組成式ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）を主成分とするセラミックの焼結温度が１３５０℃～１４００℃である。 In one embodiment of the method for producing a ceramic of the present invention, the sintering temperature of the ceramic mainly composed of the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) is 1350 ° C. to 1400 ° C.
　本発明のセラミックの製造方法の一態様は、組成式ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）主成分とするセラミックの焼結温度が１２５０℃～１３００℃である。 In one embodiment of the method for producing a ceramic of the present invention, the sintering temperature of the ceramic having a composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element) as a main component is 1250 ° C. to 1300 ° C.
　本発明のエミッタの一態様は、熱源からの熱を赤外線に変換するエミッタの材料が、上述のセラミックである。 In one embodiment of the emitter of the present invention, the material of the emitter that converts heat from the heat source into infrared rays is the above-described ceramic.
　本発明の熱光起電力発電装置の一態様は、熱源からの熱を赤外線に変換するエミッタと、前記エミッタから放射された前記赤外線を電力に変換する光電変換セルと、を備え、前記エミッタの材料が、上述のセラミックである。 One aspect of the thermophotovoltaic power generation apparatus of the present invention includes an emitter that converts heat from a heat source into infrared rays, and a photoelectric conversion cell that converts the infrared rays radiated from the emitter into electric power. The material is the ceramic described above.
　本発明によれば、放射強度が大きく、波長選択性に優れた熱放射が可能なセラミックを提供できる。 According to the present invention, it is possible to provide a ceramic capable of emitting heat with high radiation intensity and excellent wavelength selectivity.
第１の実施の形態に係る熱光起電力発電装置を説明する構成図である。It is a lineblock diagram explaining the thermophotovoltaic power generator concerning a 1st embodiment. 第１の実施の形態のエミッタに用いるセラミックの一部の断面を示す模式図である。It is a schematic diagram which shows a partial cross section of the ceramic used for the emitter of 1st Embodiment. エミッタに用いるセラミックのＸＲＤ（Ｘ‐ｒａｙ　ｄｉｆｆｒａｃｔｉｏｎ）パターンを示す図である。It is a figure which shows the XRD (X-ray diffraction) pattern of the ceramic used for an emitter. エミッタに用いるセラミックの熱放射スペクトルを示す図である。It is a figure which shows the thermal radiation spectrum of the ceramic used for an emitter. エミッタに用いるセラミックの空孔率と焼結温度の関係を示す図である。It is a figure which shows the relationship between the porosity of the ceramic used for an emitter, and sintering temperature. エミッタに用いるセラミックにおける放射スペクトルの比較を表す図である。It is a figure showing the comparison of the radiation spectrum in the ceramic used for an emitter. 熱光起電力発電装置の基本構成を示す構成図である。It is a block diagram which shows the basic composition of a thermophotovoltaic power generator. フォトニクス結晶を用いた熱光起電力発電装置を示す構成図である。It is a block diagram which shows the thermophotovoltaic power generator using a photonic crystal. 光学フィルタを用いた熱光起電力発電装置を示す構成図である。It is a block diagram which shows the thermophotovoltaic power generator using an optical filter. 非特許文献２におけるエミッタの熱放射スペクトルを示す図である。It is a figure which shows the thermal radiation spectrum of the emitter in nonpatent literature 2. 非特許文献２におけるエミッタの放射率スペクトルを示す図である。It is a figure which shows the emissivity spectrum of the emitter in a nonpatent literature 2.
　本発明の第１の実施形態に係るセラミック、エミッタ及び熱光起電力発電装置について、図１、図２を用いて説明する。 The ceramic, emitter, and thermophotovoltaic power generator according to the first embodiment of the present invention will be described with reference to FIGS.
　（熱光起電力発電装置の構成）
　図１は、第１の実施形態に係る熱光起電力発電装置の構成を示す構成図である。図１に示すように、熱光起電力発電装置１は、熱源からの熱を赤外線に変換して放射するエミッタ２と、エミッタ２から放射された赤外線を電力に変換する、Ｓｉ光電変換素子で形成され光電変換セル３とを備える。 (Configuration of thermophotovoltaic power generator)
FIG. 1 is a configuration diagram showing the configuration of the thermophotovoltaic power generation apparatus according to the first embodiment. As shown in FIG. 1, a thermophotovoltaic power generation device 1 is an Si photoelectric conversion element that converts heat from a heat source into infrared rays and emits them, and an infrared ray emitted from the emitters 2 into electric power. And a photoelectric conversion cell 3 formed.
　熱光起電力発電装置１のエミッタ２は、組成式ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）、又は、ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）で示される組成を主成分とするセラミックである。エミッタ２の結晶構造は限定されないが、Ｋ２ＮｉＦ４型構造が含まれていることが望ましい。 The emitter 2 of the thermophotovoltaic power generator 1 has a compositional formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element). It is a ceramic whose main component is the indicated composition. Although the crystal structure of the emitter 2 is not limited, it is desirable that a K 2 NiF 4 type structure is included.
　上記エミッタに用いるＡＲＡｌＯ4またはＡＲＧａＯ4を主成分とするセラミックにおいて、多結晶体中の空孔の量および空孔の形態を制御することにより、熱放射スペクトルにおける波長選択性の向上（不要な波長放射の抑制）とピーク波長での放射強度の向上を確認した。 In the ceramic mainly composed of ARAlO 4 or ARGaO 4 used for the emitter, the wavelength selectivity in the thermal emission spectrum is improved by controlling the amount of vacancies and the form of the vacancies in the polycrystal (unnecessary wavelength). (Suppression of radiation) and improvement of radiation intensity at the peak wavelength were confirmed.
　ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）、又は、ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）を主成分とするセラミックにおいて、上記特性の向上が確認できたセラミックは、空孔率が２０％以上４０％以下である。 The improvement of the above characteristics can be confirmed in a ceramic mainly composed of ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element). The ceramic has a porosity of 20% to 40%.
　図２は、エミッタに適用するセラミックの断面の一部を示す模式図である。図２に示すように、セラミックは、空孔４と多結晶緻密部５で構成されている。セラミック中の空孔４は、連結しているが直線的に連続していない部分を含む。空孔率が２０％未満では、熱放射スペクトルの波長選択性が劣化する。また、空孔率が４０％以上では、機械的強度が小さくなる。また、セラミックの空孔率が４０％以上では、セラミックの機械的強度が小さくなり、熱光起電力発電装置１のエミッタ２として使用に適さなくなる。また、セラミックの空孔率が４０％以上では、空孔が連結されて形成された空間が直線的になり、熱源からの放射光が透過される。これによりエミッタにおける波長選択性の向上効果に影響を与えることになる。 FIG. 2 is a schematic diagram showing a part of a cross section of a ceramic applied to the emitter. As shown in FIG. 2, the ceramic is composed of pores 4 and polycrystalline dense portions 5. The voids 4 in the ceramic include connected but not linearly continuous portions. If the porosity is less than 20%, the wavelength selectivity of the thermal emission spectrum is deteriorated. Further, when the porosity is 40% or more, the mechanical strength becomes small. Further, when the porosity of the ceramic is 40% or more, the mechanical strength of the ceramic becomes small, and it becomes unsuitable for use as the emitter 2 of the thermophotovoltaic power generation device 1. Further, when the porosity of the ceramic is 40% or more, the space formed by connecting the holes becomes linear, and the radiated light from the heat source is transmitted. As a result, the effect of improving the wavelength selectivity in the emitter is affected.
　セラミックの空孔のサイズや形状は限定されないが、上記セラミックの空孔率を実現し、直線的に空孔が連結しないようにするために、空孔の断面積は、５μｍ２以下となることが望ましい。なお、放射特性との空孔のサイズとの関連に基づく、空孔のサイズの最適値は明らかとなっていない。 The size and shape of the ceramic pores are not limited, but in order to achieve the ceramic porosity and prevent the pores from being connected linearly, the cross-sectional area of the pores must be 5 μm 2 or less. Is desirable. Note that the optimum value of the hole size based on the relationship between the radiation characteristics and the hole size is not clear.
　また、セラミックの多結晶緻密部における結晶粒径についても制限されるものではないが、上記セラミックの空孔率と、直線的に連結しない空孔を実現するためには、結晶粒径は１０μｍ以下となることが望ましい。 Further, the crystal grain size in the polycrystalline dense part of the ceramic is not limited, but in order to realize the porosity of the ceramic and the pores not connected linearly, the crystal grain size is 10 μm or less. It is desirable that
　第１の実施形態におけるセラミックは、上記組成式のＲに相当する希土類元素の種類により熱放射の選択波長を変化させることが可能である。希土類元素は、Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ等が選択される。ここで熱光起電力装置の効率化のためには、エミッタからの放射スペクトルを光電変換セルの感度波長に適合させる必要がある。 The ceramic according to the first embodiment can change the selection wavelength of thermal radiation depending on the type of rare earth element corresponding to R in the composition formula. As the rare earth element, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb or the like is selected. Here, in order to improve the efficiency of the thermophotovoltaic device, it is necessary to adapt the radiation spectrum from the emitter to the sensitivity wavelength of the photoelectric conversion cell.
　例えば、光電変換セルの光電変換素子がＳｉベースの場合、セラミックを構成する希土類元素として、熱放射スペクトルのピーク波長が約１０００ｎｍとなるＹｂを使用することが望ましい。光電変換セルの光電変換素子がＧａＳｂベースの場合、セラミックを構成する希土類元素として、熱放射スペクトルのピーク波長が約１５００ｎｍとなるＥｒを使用することが望ましい。 For example, when the photoelectric conversion element of the photoelectric conversion cell is based on Si, it is desirable to use Yb having a peak wavelength of the thermal radiation spectrum of about 1000 nm as the rare earth element constituting the ceramic. When the photoelectric conversion element of the photoelectric conversion cell is based on GaSb, it is desirable to use Er having a peak wavelength of about 1500 nm as the rare earth element constituting the ceramic.
　また、組成式ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）または組成式ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）において、Ａで示されるアルカリ土類金属においては、Ｃａ，Ｓｒ，Ｂａを用いることができる。セラミックの構造として、Ｋ２ＮｉＦ４型構造が安定となるＣａを選択することが好適である。 In the alkaline earth metal represented by A in the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element). Ca, Sr and Ba can be used. As the ceramic structure, it is preferable to select Ca that stabilizes the K 2 NiF 4 type structure.
　また、第１の実施形態のエミッタの外形、サイズについては制限されないが、空孔が直線的に連結しないこと及びセラミックの機械的強度の観点から、エミッタが板状の形態の場合、板厚が０．８ｍｍ以上であることが望ましい。また、直方体あるいは円柱の棒状の場合、その最小の辺サイズあるいは、直径が０．８ｍｍ以上であることが望ましい。 In addition, the outer shape and size of the emitter of the first embodiment are not limited, but from the viewpoint of not connecting the holes linearly and the mechanical strength of the ceramic, the thickness of the emitter is a plate shape. It is desirable that it is 0.8 mm or more. Further, in the case of a rectangular parallelepiped or a cylindrical rod shape, it is desirable that the minimum side size or diameter is 0.8 mm or more.
　また、第１の実施形態のセラミックの製造方法は、セラミック粉末を原料とした固相反応で製造可能であるため、原料の混合・成型と焼成を基本とした簡単なプロセスで製造することが可能である。 In addition, since the ceramic manufacturing method of the first embodiment can be manufactured by a solid-phase reaction using ceramic powder as a raw material, it can be manufactured by a simple process based on mixing, molding and firing of raw materials. It is.
　前述の特許文献２では、多孔性または有孔材料を含む基板にＹｂ：ＹＡＧを被膜する構造のため、構成が複雑で製造が困難である問題もあった。また非特許文献１では、アルミナやジルコニアファイバーの製造が必要な上に、ゾルゲル法で上記被覆を形成しているため、製造工程が複雑になる問題もあった。また非特許文献２では、合成時に原料を２１９３Ｋもの高温で溶融する必要があり、製造が困難な問題もあった。しかし本実施形態のセラミックではこれらの問題はない。 In the above-mentioned Patent Document 2, there is a problem that the structure is complicated and difficult to manufacture because of the structure in which a substrate containing a porous or porous material is coated with Yb: YAG. Further, in Non-Patent Document 1, there is a problem that the manufacturing process is complicated because it is necessary to manufacture alumina or zirconia fiber and the coating is formed by the sol-gel method. Further, in Non-Patent Document 2, it is necessary to melt the raw material at a high temperature of 2193K at the time of synthesis, and there is a problem that the production is difficult. However, the ceramic of this embodiment does not have these problems.
　［実施例］
　（実施例１）
　次に、上述した熱光起電力発電装置のエミッタに用いるセラミックについて詳細に説明する。 [Example]
(Example 1)
Next, the ceramic used for the emitter of the thermophotovoltaic power generator described above will be described in detail.
　（製造方法）
　以下、実施例１におけるセラミックの製造方法について説明する。セラミックの原料は、ＣａＣＯ３、Ｙｂ２Ｏ３およびＡｌ２Ｏ３の各粉末を用いた。 (Production method)
Hereinafter, the manufacturing method of the ceramic in Example 1 is demonstrated. As the ceramic raw material, CaCO 3 , Yb 2 O 3 and Al 2 O 3 powders were used.
　はじめに、合成後の量論比がＣａＹｂＡｌＯ4となるように各粉末を秤量し、各粉末とエタノールを加えてメノウ乳鉢中で湿式混合した。混合した材料を乾燥後、大気中１４００℃で８時間仮焼成し、固相反応で組成式ＣａＹｂＡｌＯ4のＫ２ＮｉＦ４型構造の結晶を得た。 First, each powder was weighed so that the stoichiometric ratio after synthesis was CaYbAlO 4 , each powder and ethanol were added, and wet-mixed in an agate mortar. The mixed material was dried and calcined at 1400 ° C. for 8 hours in the air, and a K 2 NiF 4 type crystal of the composition formula CaYbAlO 4 was obtained by solid phase reaction.
　その後、メノウ乳鉢中で粉砕、ペレット成型後、大気中１４００℃で２時間焼成して円盤状のセラミックペレットを得た。 Thereafter, the mixture was pulverized in an agate mortar, formed into pellets, and then fired in air at 1400 ° C. for 2 hours to obtain disk-shaped ceramic pellets.
　焼結後のペレットサイズは、直径１２．７ｍｍ、厚み１．２ｍｍであった。アルキメデス法による密度測定から、このセラミックの空孔率は２７％であることを確認した。なお、セラミックペレットの空孔への水侵入を防ぐため、上記密度測定はセラミック表面等にセルロース系の樹脂をコートして実施した。 The pellet size after sintering was 12.7 mm in diameter and 1.2 mm in thickness. From the density measurement by Archimedes method, it was confirmed that the porosity of this ceramic was 27%. In order to prevent water penetration into the pores of the ceramic pellet, the above density measurement was performed by coating the ceramic surface or the like with a cellulosic resin.
　次に、セラミックペレットを均一な粉末にして粉末Ｘ線回折装置で試料同定を実施した。図３は、粉末Ｘ線回折装置によるセラミックペレットの粉末Ｘ線回折パターンである。図３中、横軸はＸ線の入射角を示し、縦軸は回折強度を示す。また、縦軸に沿った１つのピークが１つの結晶面を表す。 Next, the ceramic pellets were made into a uniform powder and sample identification was performed with a powder X-ray diffractometer. FIG. 3 is a powder X-ray diffraction pattern of ceramic pellets by a powder X-ray diffractometer. In FIG. 3, the horizontal axis represents the X-ray incident angle, and the vertical axis represents the diffraction intensity. One peak along the vertical axis represents one crystal plane.
　図３に示す回折ピークに「Ｃ（ｈｋｌ）」でマークしたものは、Ｋ２ＮｉＦ４型構造をもつＪＣＰＤＳ（Joint Committee of Powder Diffraction Standards）カード００－０２４－０２２１のＣａＹＡｌＯ4と同様の構造に面指数付けができた。これにより、上述の製造方法により、Ｋ２ＮｉＦ４型構造のＣａＹｂＡｌＯ４が合成できたことを確認した。また、図３中で指数がついていないピークはＹｂ２Ｏ３と同定できた。合成したセラミックの主成分はＣａＹｂＡｌＯ4であることが確認された。 3 marked with “C (hkl)” in the diffraction peak shown in FIG. 3 has the same structure as CaYAlO 4 of JCPDS (Joint Committee of Powder Diffraction Standards) card 00-024-0221 having a K 2 NiF 4 type structure. A surface index was added. Thereby, it was confirmed that CaYbAlO 4 having a K 2 NiF 4 type structure could be synthesized by the above-described manufacturing method. Moreover, the peak without the index in FIG. 3 could be identified as Yb 2 O 3 . It was confirmed that the main component of the synthesized ceramic was CaYbAlO 4 .
　（熱放射スペクトルの測定）
　次に、合成したセラミックの熱放射スペクトルの測定法について説明する。熱放射スペクトルは、円盤状のセラミックペレットの一方の面を熱し、他方の面から放射される光を光スペクトラムアナライザに入力して測定した。 (Measurement of thermal emission spectrum)
Next, a method for measuring the thermal emission spectrum of the synthesized ceramic will be described. The thermal emission spectrum was measured by heating one surface of a disk-shaped ceramic pellet and inputting light emitted from the other surface to an optical spectrum analyzer.
　セラミックペレットの加熱法は、まず、ＳｉＣ板を円盤状のセラミックペレットに押し当てる。その状態で、ＳｉＣ板に円盤状のセラミックペレットを押し当てた面を表側としたときに、ＳｉＣ板の裏側からハロゲンランプを集光照射してＳｉＣ板を加熱しセラミックペレットに熱を伝導させた。 The ceramic pellet is heated by first pressing the SiC plate against the disk-shaped ceramic pellet. In this state, when the surface of the SiC plate pressed against the disc-shaped ceramic pellet was the front side, a halogen lamp was condensed and irradiated from the back side of the SiC plate to heat the SiC plate and conduct heat to the ceramic pellet. .
　その際、該ペレットの熱放射面の温度をＫ熱電対で測定し、ＳｉＣ板の温度をＲ熱電対で測定した。ＳｉＣ板は十分に熱伝導率が大きいので、該ペレットの加熱面の温度と等価であると推定した。 At that time, the temperature of the heat radiation surface of the pellet was measured with a K thermocouple, and the temperature of the SiC plate was measured with an R thermocouple. Since the SiC plate has a sufficiently high thermal conductivity, it was estimated to be equivalent to the temperature of the heating surface of the pellet.
　図４に、作製したセラミックの熱放射スペクトルの測定結果を示す。図４中、横軸は波長を示し、縦軸は強度を示す。測定条件は、セラミックの表面（赤外線の放射面）温度９４２℃、セラミックの裏面（加熱面）温度１２１０℃、平均温度１１２７℃であった。なお、図４には、測定結果の比較として、１１２０℃のＳｉＣセラミックの熱放射スペクトルも示す。 Fig. 4 shows the measurement results of the thermal emission spectrum of the fabricated ceramic. In FIG. 4, the horizontal axis indicates the wavelength, and the vertical axis indicates the intensity. The measurement conditions were a ceramic surface (infrared radiation surface) temperature of 942 ° C., a ceramic back surface (heating surface) temperature of 1210 ° C., and an average temperature of 1127 ° C. In addition, in FIG. 4, the thermal radiation spectrum of 1120 degreeC SiC ceramic is also shown as a comparison of a measurement result.
　実施例１のＣａＹｂＡｌＯ4セラミックの熱放射スペクトルは、Ｙｂ３＋の４ｆ電子の２Ｆ５／２→２F７／２遷移に相当する波長約１０００ｎｍにピークが確認された。これにより、光電変換セルを構成するＳｉ光電変換素子のバンドギャップに相当する波長１１２０ｎｍに対して選択性を有することが確認された。 In the thermal radiation spectrum of the CaYbAlO 4 ceramic of Example 1, a peak was confirmed at a wavelength of about 1000 nm corresponding to the 2 F 5/2 → 2 F 7/2 transition of 4f electrons of Yb 3+ . Thereby, it was confirmed that it has selectivity with respect to a wavelength of 1120 nm corresponding to the band gap of the Si photoelectric conversion element constituting the photoelectric conversion cell.
　また、ＳｉＣは、放射率０．９の灰色体（grey body）として知られているが、実施例１のＣａＹｂＡｌＯ4セラミックはピーク波長においてＳｉＣと同程度の放射強度を示すことが確認できた。 Further, SiC is known as a gray body having an emissivity of 0.9, but it was confirmed that the CaYbAlO 4 ceramic of Example 1 showed a radiation intensity comparable to that of SiC at the peak wavelength.
　（実施例２）
　次に、実施例２のセラミックの製造方法について説明する。実施例２は、実施例１の製造方法と比べて焼成温度を変えて製造したセラミックである。実施例２のセラミックの製造方法に関し、実施例１と同様な部分について詳細な説明を省略する。 (Example 2)
Next, the manufacturing method of the ceramic of Example 2 is demonstrated. Example 2 is a ceramic produced by changing the firing temperature as compared with the production method of Example 1. Regarding the ceramic manufacturing method of Example 2, detailed description of the same parts as those of Example 1 will be omitted.
　まず、実施例１と同じ粉末を用いてＣａＹｂＡｌＯ4の仮焼粉を作製し、ペレット成型後、大気中１３５０℃で２時間焼成して、円盤状のセラミックペレットを得た。焼結後のセラミックペレットサイズは、直径１２．９ｍｍ、厚み１．４ｍｍであった。アルキメデス法による密度測定から、この実施例２のセラミックの空孔率は３６％であることを確認した。 First, CaYbAlO 4 calcined powder was prepared using the same powder as in Example 1, and after pellet molding, it was fired in air at 1350 ° C. for 2 hours to obtain disk-shaped ceramic pellets. The sintered ceramic pellet size was 12.9 mm in diameter and 1.4 mm in thickness. From the density measurement by Archimedes method, it was confirmed that the porosity of the ceramic of this Example 2 was 36%.
　（比較例１）
　次に、比較例１のセラミックの製造方法について説明する。比較例１のセラミックは、実施例１、２の製造方法と比べて焼成温度を変えて製造した。比較例１のセラミックの製造方法に関し、実施例１又は２と同様な説明については、その説明を省略する。 (Comparative Example 1)
Next, the manufacturing method of the ceramic of the comparative example 1 is demonstrated. The ceramic of Comparative Example 1 was produced by changing the firing temperature as compared with the production methods of Examples 1 and 2. Regarding the ceramic manufacturing method of Comparative Example 1, description similar to Example 1 or 2 is omitted.
　実施例１と同様にして、ＣａＹｂＡｌＯ4の仮焼粉を作製、ペレット成型後、大気中１４５０℃で２時間焼成して、円盤状のセラミックを得た。焼結後のペレットサイズは、直径１１．６ｍｍ、厚み１．３ｍｍであった。アルキメデス法による密度測定から、このセラミックの空孔率は１１％であることを確認した。 In the same manner as in Example 1, a calcined powder of CaYbAlO 4 was prepared, formed into pellets, and then fired in the atmosphere at 1450 ° C. for 2 hours to obtain a disk-shaped ceramic. The pellet size after sintering was 11.6 mm in diameter and 1.3 mm in thickness. From the density measurement by Archimedes method, it was confirmed that the porosity of this ceramic was 11%.
　（セラミックの空孔率）
　図５に、実施例１、実施例２、比較例１の焼結温度とセラミック密度から算出した空孔率の関係を示す。図５に示すように、実施例２による焼結温度１３５０℃では、セラミックの空孔率が３６％となり、比較例１の１４５０℃では、セラミックの空孔率が１１％となった。これにより、作製時の焼結温度を変えることでセラミックの空孔率が制御できることを確認した。 (Ceramic porosity)
FIG. 5 shows the relationship between the sintering temperature and the porosity calculated from the ceramic density of Example 1, Example 2, and Comparative Example 1. As shown in FIG. 5, the ceramic porosity was 36% at the sintering temperature of 1350 ° C. according to Example 2, and the ceramic porosity was 11% at 1450 ° C. in Comparative Example 1. This confirmed that the porosity of the ceramic could be controlled by changing the sintering temperature during production.
　ＣａＹｂＡｌＯ4の材料は、高い耐熱性が期待できる材料であるとともに、焼結温度となる１３５０℃－１４５０℃の範囲は、ガーネット構造を備えるセラミックの焼結温度と比べて低く、制御も容易であるという利点がある。 The CaYbAlO 4 material is a material that can be expected to have high heat resistance, and the sintering temperature range of 1350 ° C. to 1450 ° C. is lower than the sintering temperature of ceramics having a garnet structure, and is easy to control. There is an advantage.
　次に、セラミックの空孔率と、セラミックの放射率の波長依存性との関連について説明する。実施例２及び比較例１について、実施例１と同様にセラミックの熱放射スペクトルを測定した。放射率を計算した際のセラミックの温度は、表面と裏面の平均温度を使用した。実施例２は、測定時のセラミックの表面温度は９４７℃、裏面温度は１１７８℃、平均温度１０６２．５℃であった。また、比較例１は、測定時のセラミックの表面温度は９４４℃、裏面温度は１１１０℃、平均温度１０２７℃であった。実施例１、実施例２、比較例１において、測定した放射強度スペクトルから計算した放射率のスペクトルを図６に示す。 Next, the relationship between the porosity of the ceramic and the wavelength dependence of the emissivity of the ceramic will be described. For Example 2 and Comparative Example 1, the thermal emission spectrum of the ceramic was measured in the same manner as in Example 1. The average temperature of the front and back surfaces was used as the ceramic temperature when calculating the emissivity. In Example 2, the surface temperature of the ceramic at the time of measurement was 947 ° C., the back surface temperature was 1178 ° C., and the average temperature was 1062.5 ° C. In Comparative Example 1, the surface temperature of the ceramic at the time of measurement was 944 ° C., the back surface temperature was 1110 ° C., and the average temperature was 1027 ° C. In Example 1, Example 2, and Comparative Example 1, the spectrum of the emissivity calculated from the measured radiation intensity spectrum is shown in FIG.
　Ｓｉ光電変換素子の吸収帯に対応するピーク波長での放射率とＳｉ光電変換素子のバンドギャップ波長１１２０ｎｍ以上での波長での放射率の比から、本実施例１、２のセラミックの波長選択性が十分な値であることが確認できた。 From the ratio of the emissivity at the peak wavelength corresponding to the absorption band of the Si photoelectric conversion element and the emissivity at the band gap wavelength of 1120 nm or more of the Si photoelectric conversion element, the wavelength selectivity of the ceramics of Examples 1 and 2 Has been confirmed to be a sufficient value.
　しかし、図６に示すように、実施例２の空孔率３６％のセラミックは、実施例１の空孔率２７％のセラミックよりもピーク波長での放射率が小さい値となっている。 However, as shown in FIG. 6, the ceramic with a porosity of 36% in Example 2 has a smaller emissivity at the peak wavelength than the ceramic with a porosity of 27% in Example 1.
　セラミックの空孔の導入によりピーク波長以外の波長の放射光は散乱される。実施例１、実施例２、比較例１におけるピーク波長は、Ｙｂのｆ電子準位間のエネルギー伝達により放射強度が維持される。この結果、波長選択性が出現すると考えられる。ここで、セラミックの空孔率の値が大きくなることは、エネルギーを伝達するＹｂ原子濃度の低下を意味する。このため、実施例２のように空孔率の値が大きくなるとピーク波長の放射強度が低下すると考えられる。 The radiation of wavelengths other than the peak wavelength is scattered by the introduction of ceramic vacancies. In the peak wavelengths in Example 1, Example 2, and Comparative Example 1, the radiation intensity is maintained by the energy transfer between the fb electron levels of Yb. As a result, it is considered that wavelength selectivity appears. Here, an increase in the porosity value of the ceramic means a decrease in the concentration of Yb atoms that transmit energy. For this reason, it is considered that the radiation intensity at the peak wavelength decreases as the porosity value increases as in the second embodiment.
　なお、空孔率を４０％以上とするとセラミックの機械的強度が小さくなり、エミッタとして使用するのに不十分となってしまう。また、比較例１のセラミックは、実施例２のセラミックと比べて、ピーク波長の放射率及びバンドギャップ波長以上での放射率の比が小さく、波長選択性に関する十分な値は得られなかった。空孔率１１％である比較例１のセラミックは、波長選択性を得るための散乱が不十分であった。 Note that if the porosity is 40% or more, the mechanical strength of the ceramic is reduced, which is insufficient for use as an emitter. Further, the ceramic of Comparative Example 1 had a smaller ratio of emissivity at the peak wavelength and emissivity above the band gap wavelength than the ceramic of Example 2, and a sufficient value for wavelength selectivity was not obtained. The ceramic of Comparative Example 1 having a porosity of 11% was insufficiently scattered to obtain wavelength selectivity.
　（その他）
　上記実施例１、２は、組成式ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）を主成分とするセラミックの例を示したが、これに限られるものではない。例えば、組成式ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）のセラミックの一例であるＣａＹｂＧａＯ4を作製する場合、セラミックの原料として、ＣａＣＯ３、Ｙｂ２Ｏ３およびＧａ２Ｏ３を用いて実施例１、２と同様な条件で作製することができる。但し、組成式ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）主成分とするセラミックの焼結温度は、１２５０℃～１３００℃の範囲が好ましい。 (Other)
The first and second embodiments, the composition formula ARAlO 4 (A: Ca, Sr , Ba; R: rare earth element) has shown an example of a ceramic mainly composed of, but is not limited thereto. For example, when producing CaYbGaO 4 , which is an example of a ceramic of the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element), CaCO 3 , Yb 2 O 3 and Ga 2 O 3 are used as ceramic raw materials. Can be produced under the same conditions as in Examples 1 and 2. However, the sintering temperature of the ceramic mainly composed of the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element) is preferably in the range of 1250 ° C to 1300 ° C.
　以上、実施形態（及び実施例）を参照して本願発明を説明したが、本願発明は上記実施形態（及び実施例）に限定されものではない。本願発明の構成や詳細には、本願発明のスコープ内で当業者が理解し得る様々な変更をすることができる。 Although the present invention has been described with reference to the embodiments (and examples), the present invention is not limited to the above embodiments (and examples). Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.
　上記の実施形態の一部又は全部は、以下の付記のように記載されうるが、以下には限られない。 Some or all of the above embodiments may be described as in the following supplementary notes, but are not limited to the following.
　　（付記１）
　組成式ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）、又は、組成式ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）を主成分とするセラミックであり、
　前記セラミックは、空孔率２０％以上４０％以下の空孔を有し、
　前記空孔は、前記セラミックの内部で連結しているが直線的に連続していない部分を含むセラミック。 (Appendix 1)
It is a ceramic whose main component is the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element),
The ceramic has pores with a porosity of 20% to 40%,
The pore is a ceramic including a portion which is connected inside the ceramic but is not linearly continuous.
　　（付記２）
　前記セラミックは、Ｋ２ＮｉＦ４型構造を有する、付記１に記載のセラミック。 (Appendix 2)
It said ceramic has a K 2 NiF 4 -type structure, ceramic according to Appendix 1.
　　（付記３）
　前記セラミックは、空孔の断面積が５μｍ２以下である、
付記１又は２に記載のセラミック。 (Appendix 3)
The ceramic has a pore cross-sectional area of 5 μm 2 or less.
The ceramic according to Appendix 1 or 2.
　　（付記４）
　　　前記セラミックは、粒径１０μｍ以下の粒径で構成された領域を有する、
付記１から３のいずれか１つに記載のセラミック。 (Appendix 4)
The ceramic has a region composed of a particle size of 10 μm or less,
The ceramic according to any one of appendices 1 to 3.
　　（付記５）
　前記組成式ＡＲＡｌＯ4（Ｒ：希土類元素）又は、前記組成式ＡＲＧａＯ4（Ｒ：希土類元素）の組成ＡがＣａである、
　　（付記６）
　前記組成式ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）、又は、前記組成式ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）のうち、前記希土類元素は、Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，又は、Ｙｂから選択される、
付記１から５のいずれか１つに記載のセラミック。 (Appendix 5)
The composition formula ARAlO 4 (R: rare earth element) or the composition A of the composition formula ARGaO 4 (R: rare earth element) is Ca.
(Appendix 6)
In the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or in the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element), the rare earth element is Pr. , Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, or Yb,
The ceramic according to any one of appendices 1 to 5.
　　（付記７）
　前記組成Ｒの前記希土類元素が、Ｅｒ又はＹｂである、
付記６に記載のセラミック。 (Appendix 7)
The rare earth element of the composition R is Er or Yb;
The ceramic according to appendix 6.
　　（付記８）
　組成式ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）を主成分とするセラミックの焼結温度が１３５０℃～１４００℃であるセラミックの製造方法。 (Appendix 8)
A method for producing a ceramic, wherein the sintering temperature of the ceramic mainly composed of the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) is 1350 ° C. to 1400 ° C.
　　（付記９）
　組成式ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）を主成分とするセラミックの焼結温度が１２５０℃～１３００℃であるセラミックの製造方法。 (Appendix 9)
A method for producing a ceramic, wherein the sintering temperature of the ceramic mainly comprising the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element) is 1250 ° C to 1300 ° C.
　　（付記１０）
　熱源からの熱を赤外線に変換するエミッタの材料が、付記１～７のいずれか１つに記載のセラミックであるエミッタ。 (Appendix 10)
The emitter according to any one of appendices 1 to 7, wherein a material of the emitter that converts heat from the heat source into infrared rays.
　　（付記１１）
　前記エミッタの熱供給面と赤外線放射面との間の厚みが０．８ｍｍ以上である、
付記１０に記載のエミッタ。 (Appendix 11)
The thickness between the heat supply surface of the emitter and the infrared radiation surface is 0.8 mm or more,
The emitter according to appendix 10.
　　（付記１２）
　熱源からの熱を赤外線に変換するエミッタと、
　前記エミッタから放射された前記赤外線を電力に変換する光電変換セルと、を備え、
　前記エミッタの材料が、付記１～７のいずれか１つに記載のセラミックである熱光起電力発電装置。 (Appendix 12)
An emitter that converts heat from a heat source into infrared;
A photoelectric conversion cell that converts the infrared radiation emitted from the emitter into electric power,
The thermophotovoltaic power generation device, wherein the material of the emitter is the ceramic according to any one of appendices 1 to 7.
　この出願は、２０１５年６月２６日に出願された日本出願特願２０１５－１２８７８８を基礎とする優先権を主張し、その開示の全てをここに取り込む。 This application claims priority based on Japanese Patent Application No. 2015-128788 filed on June 26, 2015, the entire disclosure of which is incorporated herein.
１　熱光起電力発電装置
２　エミッタ
３　光電変換セル
４　空孔
５　多結晶緻密部
１０　熱光起電力発電装置
１３　エミッタ
１４　光電変換セル
１５　フォトニック結晶
１６　光学フィルタ
２０　熱光起電力発電装置
３０　熱光起電力発電装置 DESCRIPTION OF SYMBOLS 1 Thermophotovoltaic power generator 2 Emitter 3 Photoelectric conversion cell 4 Hole 5 Polycrystalline dense part 10 Thermophotovoltaic power generator 13 Emitter 14 Photoelectric conversion cell 15 Photonic crystal 16 Optical filter 20 Thermophotovoltaic power generator 30 Heat Photovoltaic power generator

Claims (10)

  1. 　組成式ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）、又は、組成式ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）を主成分とするセラミックであり、
    　前記セラミックは、空孔率２０％以上４０％以下の空孔を有し、
    　前記空孔は、前記セラミックの内部で連結しているが直線的に連続していない部分を含むセラミック。     It is a ceramic whose main component is the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element),
    The ceramic has pores with a porosity of 20% to 40%,
    The pore is a ceramic including a portion which is connected inside the ceramic but is not linearly continuous.
  2. 　前記セラミックは、Ｋ２ＮｉＦ４型構造を有する、請求項１に記載のセラミック。 The ceramic of claim 1, wherein the ceramic has a K 2 NiF 4 type structure.
  3. 　前記セラミックは、前記空孔の断面積が５μｍ２以下である、
    請求項１又は２に記載のセラミック。     The ceramic is a cross-sectional area of the holes is 5 [mu] m 2 or less,
    The ceramic according to claim 1 or 2.
  4. 　前記組成式ＡＲＡｌＯ4（Ｒ：希土類元素）、又は、前記組成式ＡＲＧａＯ4（Ｒ：希土類元素）の組成ＡがＣａである、
    請求項１から３のいずれか１項に記載のセラミック。     The composition formula ARAlO 4 (R: rare earth element) or the composition A of the composition formula ARGaO 4 (R: rare earth element) is Ca.
    The ceramic according to any one of claims 1 to 3.
  5. 　前記組成式ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）、又は、前記組成式ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）のうち、前記希土類元素は、Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，又は、Ｙｂから選択される、
    請求項１から４のいずれか１項に記載のセラミック。     In the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) or in the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element), the rare earth element is Pr. , Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, or Yb,
    The ceramic according to any one of claims 1 to 4.
  6. 　組成式ＡＲＡｌＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）を主成分とするセラミックの焼結温度が１３５０℃～１４００℃であるセラミックの製造方法。 A method for producing a ceramic, wherein the sintering temperature of the ceramic mainly composed of the composition formula ARAlO 4 (A: Ca, Sr, Ba; R: rare earth element) is 1350 ° C. to 1400 ° C.
  7. 　組成式ＡＲＧａＯ4（Ａ：Ｃａ，Ｓｒ，Ｂａ；Ｒ：希土類元素）を主成分とするセラミックの焼結温度が１２５０℃～１３００℃であるセラミックの製造方法。 A method for producing a ceramic, wherein the sintering temperature of the ceramic mainly comprising the composition formula ARGaO 4 (A: Ca, Sr, Ba; R: rare earth element) is 1250 ° C to 1300 ° C.
  8. 　熱源からの熱を赤外線に変換するエミッタの材料が、請求項１～５のいずれか１つに記載のセラミックであるエミッタ。 The emitter according to any one of claims 1 to 5, wherein an emitter material for converting heat from a heat source into infrared rays is used.
  9. 　前記エミッタの熱供給面と赤外線放射面との間の厚みが０．８ｍｍ以上である、
    請求項８に記載のエミッタ。     The thickness between the heat supply surface of the emitter and the infrared radiation surface is 0.8 mm or more,
    The emitter according to claim 8.
  10. 　熱源からの熱を赤外線に変換するエミッタと、
    　前記エミッタから放射された前記赤外線を電力に変換する光電変換セルと、を備え、
    　前記エミッタの材料が、請求項１～５のいずれか１つに記載のセラミックである熱光起電力発電装置。     An emitter that converts heat from a heat source into infrared;
    A photoelectric conversion cell that converts the infrared radiation emitted from the emitter into electric power,
    The thermophotovoltaic power generation device, wherein the material of the emitter is ceramic according to any one of claims 1 to 5.
PCT/JP2016/002940 2015-06-26 2016-06-20 Ceramic, method for producing same, emitter and thermophotovoltaic power generator WO2016208174A1 (en)

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