WO2018055925A1 - Hydrogen sensing element and hydrogen sensor - Google Patents

Hydrogen sensing element and hydrogen sensor Download PDF

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Publication number
WO2018055925A1
WO2018055925A1 PCT/JP2017/028109 JP2017028109W WO2018055925A1 WO 2018055925 A1 WO2018055925 A1 WO 2018055925A1 JP 2017028109 W JP2017028109 W JP 2017028109W WO 2018055925 A1 WO2018055925 A1 WO 2018055925A1
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hydrogen sensing
hydrogen
layer
state
sensing element
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PCT/JP2017/028109
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French (fr)
Japanese (ja)
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山田　保誠
吉村　和記
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国立研究開発法人産業技術総合研究所
山田　保誠
吉村　和記
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Priority to JP2018540674A priority Critical patent/JP6697781B2/en
Publication of WO2018055925A1 publication Critical patent/WO2018055925A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C28/00—Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C5/00—Alloys based on noble metals
    • C22C5/04—Alloys based on a platinum group metal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
    • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
    • G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods

Definitions

  • the present invention relates to a hydrogen sensing element and a hydrogen sensor.
  • Alloys based on rare earth metals such as yttrium (Y) and lanthanum (La) (for example, see Patent Document 4), alloys based on magnesium (Mg) (for example, see Patent Documents 5 and 6), tungsten oxide (See, for example, Patent Document 7) and the like are used for hydrogen sensing elements and hydrogen sensors because optical characteristics and electrical resistance characteristics change greatly when hydrogen is occluded or released.
  • a hydrogen sensing element a hydrogen storage layer such as an Mg—Ni alloy is formed on the surface of a transparent substrate such as a glass substrate or a plastic substrate, and palladium or the like is formed on the surface of the hydrogen storage layer.
  • the element in which the catalyst layer is formed is used (for example, refer to Patent Document 8).
  • the hydrogen sensing element can detect hydrogen leakage safely and quickly by detecting a change in light reflectance or light transmittance associated with the hydrogen occlusion layer occludes hydrogen at normal temperature and pressure. Can do.
  • such a hydrogen sensing element has two different types in which when hydrogen leaks, the optical characteristics change by occluding hydrogen, and when hydrogen does not leak, it releases hydrogen and returns to its original state. It has only optical properties. For this reason, when hydrogen is not leaking at the present time, it is not possible to leave a history of hydrogen leaking in the past. In addition, even if it is possible to maintain the state of storing hydrogen without releasing the stored hydrogen so that a history of hydrogen leakage in the past remains, it is not possible to determine whether hydrogen is leaking at this time. .
  • An object of the present invention is to provide a hydrogen sensing element capable of determining the state of being present.
  • a hydrogen sensing layer including a metal whose state changes reversibly between a transparent state by trihydride and a reflection state by dihydride on a transparent substrate; And a catalyst layer containing a metal or an alloy that promotes hydrogenation and dehydrogenation in the hydrogen sensing layer, and the metal contained in the hydrogen sensing layer has non-hydride, dihydride, and trihydrogen having different optical characteristics. Has the state of a compound.
  • a state in which no hydrogen has leaked, a state in which hydrogen has not leaked at the present time, a history of hydrogen leaks in the past, or a state in which hydrogen has leaked is determined.
  • a hydrogen sensing element that can be provided can be provided.
  • a hydrogen sensing element includes a hydrogen sensing layer including a metal whose state reversibly changes between a transparent state by trihydride and a reflection state by dihydride, and a hydrogen sensing layer.
  • stimulates hydrogenation and dehydrogenation in, and a transparent base material are provided.
  • the metal contained in the hydrogen sensing layer has a non-hydride, dihydride, and trihydride state with different optical properties.
  • FIG. 1 shows a configuration example of a hydrogen sensing element according to the first embodiment of the present invention.
  • the hydrogen sensing element 100 includes a hydrogen sensing layer 10 and a catalyst layer 20, and further includes a transparent substrate (transparent substrate) 40 on the opposite side of the hydrogen sensing layer 10 from the catalyst layer 20.
  • the metal contained in the hydrogen sensing layer 10 includes a non-hydrogenated (metal) state that has not been hydrogenated after film formation, and a trihydride state that has become transparent due to the hydrogenation of a non-hydride or dihydride. , Having a dihydride state that is in a reflective state by dehydrogenation of the trihydride.
  • the hydrogen sensing layer 10 preferably contains a rare earth metal, more preferably a rare earth metal or an alloy based on a rare earth metal.
  • the rare earth metal (X) is not particularly limited as long as it has a state of non-hydride (X), dihydride (XH 2 ) and trihydride (XH 3 ) having different optical characteristics. Absent.
  • the rare earth metal is preferably selected from the group consisting of Sc, Y, La, Gd, and Ce in view of availability, cost, and stability in the atmosphere.
  • the alloy based on rare earth metal preferably contains a Group 2 metal.
  • the rare earth metal or the alloy based on the rare earth metal is preferably yttrium, yttrium / magnesium alloy or yttrium / magnesium / scandium alloy.
  • the yttrium-magnesium alloy has a clear difference in optical properties between the hydride of yttrium (Y) and the yttrium dihydride (YH 2 ) dehydrogenated after yttrium is once hydrogenated, the general formula Y 1-x Mg x (0 ⁇ x ⁇ 0.4) (1) And a compound represented by the general formula Y 1-x Mg x (0 ⁇ x ⁇ 0.25) (2) It is more preferable that it is a compound represented by these.
  • the magnesium-yttrium alloy is preferably a compound represented by the general formula (1) in order to exhibit stable hydrogen sensing characteristics of 1000 times or more, that is, repeated durability.
  • the yttrium-magnesium-scandium alloy has the general formula Y 1-xy Mg x Sc y (0 ⁇ x ⁇ 0.4, 0 ⁇ y ⁇ 0.6, x + y ⁇ 1) for the same reason as above. ... (3) It is preferable that it is a compound represented by these.
  • the thickness of the hydrogen sensing layer 10 is selected in consideration of light transmittance, light reflectance, and the like, and is not particularly limited, but is preferably 10 nm or more and 1000 nm or less. When the thickness of the hydrogen sensing layer 10 is 10 nm or more, the light reflectance in the reflective state of the hydrogen sensing layer 10 can be improved. On the other hand, when the thickness of the hydrogen sensing layer 10 is 1000 nm or less, the light transmittance in the transparent state of the hydrogen sensing layer 10 can be improved.
  • the method for forming the hydrogen sensing layer 10 is not particularly limited. For example, general film formation such as sputtering, vacuum deposition, electron beam deposition, chemical vapor deposition (CVD), plating, and the like. The method can be used.
  • the catalyst layer 20 is formed on the hydrogen sensing layer 10 and has a function of promoting hydrogenation and dehydrogenation in the hydrogen sensing layer 10. For this reason, a sufficient switching speed from the transparent state to the reflective state of the hydrogen sensing layer 10 and a sufficient switching speed from the reflective state to the transparent state of the hydrogen sensing layer 10 are ensured.
  • the metal or alloy contained in the catalyst layer 20 is not particularly limited as long as it has a function of promoting hydrogenation and dehydrogenation in the hydrogen sensing layer 10.
  • the metal or alloy contained in the catalyst layer 20 is preferably at least one selected from the group consisting of palladium, palladium alloy, platinum and platinum alloy, and has high hydrogen permeability, so palladium or palladium-ruthenium alloy. More preferably.
  • the palladium-ruthenium alloy has a general formula Pd 1-x Ru x (0 ⁇ x ⁇ 0.7) (4) from the viewpoint of cost and dehydrogenation speed. It is preferable that it is a compound represented by these.
  • the thickness of the catalyst layer 20 is appropriately selected depending on the reactivity of the hydrogen sensing layer 10 and the catalytic ability of the metal or alloy contained in the catalyst layer 20, and is not particularly limited, but is 1 nm or more and 20 nm or less. It is preferable that The function of the catalyst layer 20 can be improved as the thickness of the catalyst layer 20 is 1 nm or more. On the other hand, when the thickness of the catalyst layer 20 is 20 nm or less, the light transmittance of the catalyst layer 20 can be improved.
  • the method for forming the catalyst layer 20 is not particularly limited.
  • a general film forming method such as a sputtering method, a vacuum evaporation method, an electron beam evaporation method, a chemical vapor deposition method (CVD), or a plating method is used.
  • CVD chemical vapor deposition method
  • a plating method is used.
  • the transparent substrate 40 has a function as a base of the hydrogen sensing element 100.
  • the transparent substrate 40 preferably has a function of preventing the hydrogen sensing layer 10 from being oxidized by water or oxygen.
  • the shape of the transparent substrate 40 may be, for example, a sheet shape or a film shape.
  • the shape of the transparent base material 40 is not specifically limited, You may have flexibility.
  • the material constituting the transparent substrate 40 is not limited as long as it has a light transmittance of 50% or more in the visible light region having a wavelength of 380 nm to 780 nm, but glass or plastic is used. preferable.
  • PET polyethylene terephthalate
  • PEN polyethylene naphthalate
  • nylon acrylic or the like
  • the hydrogen sensing element 200 may be formed by inserting a diffusion prevention layer 50 between the hydrogen sensing layer 10 and the catalyst layer 20 of the hydrogen sensing element 100.
  • the material constituting the catalyst layer 20 is prevented from diffusing into the hydrogen sensing layer 10, and the hydrogen permeated through the catalyst layer 20 can effectively diffuse into the hydrogen sensing layer 10.
  • the material constituting the catalyst layer 20 is prevented from diffusing into the hydrogen sensing layer 10, and the hydrogen permeated through the catalyst layer 20 can effectively diffuse into the hydrogen sensing layer 10.
  • it will not specifically limit if it has this, It is preferable to use niobium, vanadium, titanium, and a tantalum.
  • a method for forming the diffusion preventing layer 50 is not particularly limited, and for example, a general film formation such as a sputtering method, a vacuum evaporation method, an electron beam evaporation method, a chemical vapor deposition method (CVD), or a plating method. The method can be used.
  • the hydrogen sensing elements 100 and 200 are provided with the hydrogen sensing layer 10 so that, unlike the conventional hydrogen sensing elements, no hydrogen is leaking, or hydrogen is leaking at this time. However, it is possible to determine a state indicating a history of hydrogen leakage in the past and a state where hydrogen is leaking at the present time.
  • the hydrogen sensing element according to the second embodiment of the present invention is a stack of hydrogen sensing layers having two or more different composition ratios as the hydrogen sensing layer in the hydrogen sensing element according to the first embodiment of the present invention. Is provided.
  • FIG. 3 shows a configuration example of the hydrogen sensing element according to the second embodiment of the present invention.
  • the hydrogen sensing element 300 includes a stack of hydrogen sensing layers 12 and 14 having two different composition ratios instead of the hydrogen sensing layer 10 in the hydrogen sensing element 200.
  • the configuration of the hydrogen sensing element 300 other than the hydrogen sensing layers 12 and 14 is the same as that of the hydrogen sensing element 200, and thus the description of the configuration of the hydrogen sensing element 300 other than the hydrogen sensing layers 12 and 14 is omitted.
  • the hydrogen sensing layers 12 and 14 preferably include a rare earth metal, and more preferably include a rare earth metal or an alloy based on a rare earth metal.
  • the alloy based on rare earth metal preferably contains a second group metal.
  • the rare earth metal or rare earth metal based alloy contained in the hydrogen sensing layers 12 and 14 is preferably yttrium, yttrium / magnesium alloy or yttrium / magnesium / scandium alloy.
  • the metal or alloy contained in the hydrogen sensing layer 12 (or 14) is a rare earth metal or an alloy based on a rare earth metal
  • the metal or alloy contained in the hydrogen sensing layer 14 (or 12) is a rare earth metal. It may be a metal or alloy obtained by removing a rare earth metal from a base alloy.
  • the hydrogen sensing element 300 includes the hydrogen sensing layers 12 and 14 having different composition ratios, the optical characteristics of the metal non-hydride, dihydride, and trihydride states included in the hydrogen sensing layers 12 and 14 are different. .
  • the hydrogen sensing element 300 has a higher optical property in the state of metal non-hydride, dihydride, and trihydride than the hydrogen sensing element 100 including one type of hydrogen sensing layer 10 due to the interference effect. Large differences can be expressed. For this reason, the metal or alloy contained in each of the hydrogen sensing layers 12 and 14 is not particularly limited as long as an interference effect occurs, but it is preferable that the difference in the composition ratio is large.
  • magnesium, yttrium, or a magnesium yttrium alloy is used as the metal or alloy contained in each of the hydrogen sensing layers 12 and 14 will be described more specifically.
  • yttrium or yttrium-magnesium alloy contained in the hydrogen sensing layer 12 is represented by the general formula Y 1-x Mg x (0 ⁇ x ⁇ 0.25) (5)
  • the magnesium or yttrium-magnesium alloy contained in the hydrogen sensing layer 14 has the general formula Y 1-x Mg x (0.35 ⁇ x ⁇ 1) (6)
  • the general formula Y 1-x Mg x (0.35 ⁇ x ⁇ 0.5) It is more preferable that it is a compound represented by these.
  • the magnesium or yttrium-magnesium alloy contained in the hydrogen sensing layer 12 is represented by the general formula Y 1-x Mg x (0.5 ⁇ x ⁇ 1) (8)
  • the case where it is set as the compound represented by is demonstrated.
  • the yttrium or yttrium-magnesium alloy contained in the hydrogen sensing layer 14 has the general formula Y 1-x Mg x (0 ⁇ x ⁇ 0.5) (9)
  • the general formula Y 1-x Mg x (0 ⁇ x ⁇ 0.25) 10 It is more preferable that it is a compound represented by these.
  • the thickness of the hydrogen sensing layer 12 is selected in consideration of light transmittance, light reflectance, and the like, and is not particularly limited, but is preferably 1 nm to 100 nm.
  • the thickness of the hydrogen sensing layer 12 is 1 nm or more, compared with the hydrogen sensing element 100 including one type of hydrogen sensing layer 10, the optical characteristics of the metal non-hydride, dihydride, and trihydride states. Greater differences can be developed.
  • the thickness of the hydrogen sensing layer 12 is 100 nm or less, the light transmittance in the transparent state of the hydrogen sensing layer 12 can be improved.
  • the thickness of the hydrogen sensing layer 14 is selected in consideration of light transmittance, light reflectance, and the like, and is not particularly limited, but is preferably 10 nm to 1000 nm. When the thickness of the hydrogen sensing layer 14 is 10 nm or more, the light reflectance in the reflection state can be improved. On the other hand, when the thickness of the hydrogen sensing layer 14 is 1000 nm or less, the light transmittance in a transparent state can be improved.
  • the formation method of the hydrogen sensing layers 12 and 14 is the same as the formation method of the hydrogen sensing layer 10, the description of the formation method of the hydrogen sensing layers 12 and 14 is omitted.
  • diffusion prevention layer 50 may not be inserted between the hydrogen sensing layer 14 and the catalyst layer 20 in the same manner as the hydrogen sensing element 100.
  • the hydrogen sensing element according to the third embodiment of the present invention further includes one or more protective layers on the surface of the hydrogen sensing element according to the first embodiment of the present invention.
  • FIG. 4 shows a configuration example of the hydrogen sensing element according to the third embodiment of the present invention.
  • the hydrogen sensing element 400 further includes a protective layer 30 on the surface of the hydrogen sensing element 100.
  • the configuration of the hydrogen sensing element 400 other than the protective layer 30 is the same as that of the hydrogen sensing element 100, the description of the configuration other than the protective layer 30 of the hydrogen sensing element 400 is omitted.
  • the protective layer 30 is formed on the surface of the catalyst layer 20 opposite to the hydrogen sensing layer 10 and has hydrogen permeability and water repellency.
  • the protective layer 30 has a function of preventing oxidation of the catalyst layer 20 by water and oxygen and a function of preventing oxidation of the hydrogen sensing layer 10 by water and oxygen in cooperation with the catalyst layer 20.
  • the material constituting the catalyst layer 20 is usually a noble metal, it is difficult to oxidize.
  • the protective layer 30 having a function of preventing the oxidation of the catalyst layer 20, the catalytic ability can be maintained for a long time. It becomes possible.
  • the catalyst layer 20 also has a function of preventing the hydrogen sensing layer 10 from being oxidized.
  • the formation of the protective layer 30 can enhance the function of preventing the hydrogen sensing layer 10 from being oxidized.
  • the protective layer 30 has permeability to hydrogen (hydrogen ions) (hydrogen permeability) and non-permeability to water (water repellency).
  • the material constituting the protective layer 30 is not particularly limited as long as it has hydrogen permeability and water repellency.
  • fluororesin polyvinyl acetate, polyvinyl chloride, polystyrene, cellulose acetate, etc.
  • inorganic materials such as titanium oxide are used.
  • a general film forming method such as a method of applying a dispersion liquid in which a polymer is dispersed and then drying, a method of forming an inorganic thin film by a sputtering method, or a vacuum evaporation method, etc. Can be used.
  • oxidation of the catalyst layer 20 and the hydrogen sensing layer 10 by water or oxygen can be prevented. For this reason, deterioration of the catalyst layer 20 and the hydrogen sensing layer 10 can be prevented, and durability can be enhanced.
  • the hydrogen sensing element further including one or more protective layers on the surface of the hydrogen sensing element according to the first embodiment of the present invention has been described.
  • the hydrogen sensing element may further include one or more protective layers on the surface of the hydrogen sensing element. That is, as shown in FIG. 5, in the hydrogen sensing element 300, the hydrogen sensing element 500 in which the protective layer 30 is formed on the surface of the catalyst layer 20 opposite to the hydrogen sensing layer 14 may be used. In this case, as described in the hydrogen sensing element 400, the catalyst layer 20 and the hydrogen sensing layers 12 and 14 can be prevented from being deteriorated and the durability can be improved.
  • Example 1 In this embodiment, a hydrogen sensing layer 10 made of yttrium or an yttrium-magnesium alloy, a diffusion prevention layer 50 made of tantalum, and a catalyst layer 20 made of palladium are sequentially laminated on a glass substrate as the transparent substrate 40. A hydrogen sensing element 200 was produced.
  • a glass substrate transparent base material 40 having a thickness of 1 mm
  • an yttrium thin film with a changed film thickness or an yttrium-magnesium alloy thin film with a changed film thickness and composition ratio hydrogen sensing layer 10
  • a tantalum thin film (diffusion prevention layer 50) having a thickness of 2 nm
  • a palladium thin film (catalyst layer 20) having a thickness of 3 nm were formed.
  • the tantalum thin film of the diffusion preventing layer 50, and the palladium thin film of the catalyst layer 20 a magnetron sputtering apparatus capable of multi-element film formation was used.
  • metal yttrium, metal magnesium, metal tantalum, and metal palladium were set as targets on the four sputter guns, respectively.
  • the glass substrate was set in a vacuum apparatus, and the inside of the chamber was evacuated.
  • sputtering was performed by setting the argon gas pressure during sputtering to 0.3 Pa and applying a predetermined power to each target for a predetermined time by a direct current sputtering method.
  • composition ratio of the thin film (hydrogen sensing layer 10) to be formed can be controlled by the power applied to each target. Further, the film thickness of the thin film (hydrogen sensing layer 10) to be formed can be controlled by the time during which power is applied to the target.
  • An yttrium-magnesium alloy thin film represented by the following formula was formed as the hydrogen sensing layer 10 in the hydrogen sensing element 200 of Examples 1-1 to 1-18.
  • a calibration curve showing the relationship of the composition ratio of the yttrium-magnesium alloy thin film to the ratio of the power applied to the metal yttrium target and the metal magnesium target was created by Rutherford backscattering method.
  • the composition ratio of the formed yttrium-magnesium alloy thin film was estimated based on the calibration curve.
  • Table 1 shows the power applied to the target and the application time, the composition ratio and the film thickness of the hydrogen sensing layer 10 when forming the hydrogen sensing layer 10 in the hydrogen sensing elements 200 of Examples 1-1 to 1-18. Indicates.
  • a power of 20 W is applied to the metal tantalum target to form a tantalum thin film (diffusion prevention layer 50), and then a metal palladium target.
  • a hydrogen thin film (catalyst layer 20) was formed by applying a power of 30 W to the hydrogen sensing element 200.
  • the hydrogen sensing element 200 manufactured by the above procedure is in a reflective state with metallic luster, but the surface of the palladium thin film is diluted to 4% by volume with argon (hereinafter referred to as “hydrogen-containing gas”). ),
  • the yttrium thin film or the yttrium-magnesium alloy thin film was hydrogenated to produce yttrium trihydride (and magnesium dihydride), which changed to a transparent state.
  • yttrium trihydride and magnesium dihydride
  • yttrium dihydride and magnesium
  • the hydrogen sensing element 200 is in a state containing yttrium trihydride (hereinafter referred to as “trihydride state”) from a state containing yttrium that is not hydrogenated (hereinafter referred to as “non-hydride state”). ) And a state containing yttrium dihydride (hereinafter referred to as “dihydride state”).
  • trihydride state a state containing yttrium trihydride
  • dihydride state a state containing yttrium dihydride
  • the hydrogen sensing element 200 is then switched between a trihydride state and a dihydride state by hydrating the yttrium dihydride and dehydrogenating the yttrium trihydride. It was confirmed to change reversibly.
  • the optical characteristics of the hydrogen sensing element 200 were evaluated using a spectrophotometer. Specifically, each state of the hydrogen sensing element 200 in a non-hydride state (reflection state) (X), a dihydride state (reflection state) (XH 2 ), and a trihydride state (transparent state) (XH 3 ). The light transmittance (T) at a wavelength of 550 nm and the light reflectance (Rb) at a wavelength of 550 nm from the transparent substrate 40 side were measured.
  • Table 2 shows the evaluation results of the optical characteristics of the hydrogen sensing element 200.
  • the difference in reflectance ( ⁇ Rb) is also shown in Table 2.
  • the hydrogen sensing elements 200 of Examples 1-1 to 1-18 show the difference in light transmittance ( ⁇ T) and / or the difference in light reflectance ( ⁇ Rb) between the non-hydride state and the dihydride state. It can be seen that the difference in light transmittance ( ⁇ T) and / or the difference in light reflectance ( ⁇ Rb) between the dihydride state and the trihydride state is 5% or more, respectively. For this reason, the hydrogen sensing elements 200 of Examples 1-1 to 1-18 are in a state in which no hydrogen leaks, no hydrogen leaks at the present time, but a state indicating a history of hydrogen leaks in the past, Thus, it is possible to visually determine the state of hydrogen leakage.
  • Example 2 In this embodiment, instead of the hydrogen sensing layer 10 made of yttrium or yttrium-magnesium alloy, a laminate of a hydrogen sensing layer 12 made of magnesium (or yttrium) and a hydrogen sensing layer 14 made of yttrium (or yttrium-magnesium alloy).
  • a hydrogen sensing element 300 was fabricated in the same manner as in Example 1 except that was used. That is, a hydrogen sensing layer 12 made of magnesium (or yttrium), a hydrogen sensing layer 14 made of yttrium (or yttrium-magnesium alloy), a diffusion prevention layer 50 made of tantalum, and palladium on a glass substrate as a transparent substrate 40.
  • a hydrogen sensing element 300 in which the catalyst layers 20 made of the layers were sequentially stacked was manufactured.
  • a magnesium thin film (or yttrium thin film) (hydrogen sensing layer 12) whose thickness is changed sequentially on a glass substrate (transparent substrate 40) having a thickness of 1 mm, and an yttrium thin film whose thickness is changed.
  • a glass substrate transparent substrate 40
  • an yttrium thin film whose thickness is changed.
  • an yttrium / magnesium alloy thin film with a changed film thickness and composition ratio hydrogen sensing layer 14
  • a tantalum thin film with a thickness of 2 nm diiffusion prevention layer 50
  • a palladium thin film with a thickness of 3 nm catalyst layer 20.
  • the magnesium thin film (or yttrium thin film) of the hydrogen sensing layer 12 When forming the magnesium thin film (or yttrium thin film) of the hydrogen sensing layer 12, the yttrium thin film (or yttrium-magnesium alloy thin film) of the hydrogen sensing layer 14, the tantalum thin film of the diffusion preventing layer 50, and the palladium thin film of the catalyst layer 20.
  • a magnetron sputtering apparatus capable of multi-element film formation was used.
  • metal yttrium, metal magnesium, metal tantalum, and metal palladium were set as targets on the four sputter guns, respectively.
  • the glass substrate was set in a vacuum apparatus and the chamber was evacuated.
  • sputtering was performed by setting the argon gas pressure during sputtering to 0.3 Pa and applying a predetermined power to each target for a predetermined time by a direct current sputtering method.
  • composition ratio of the thin films (hydrogen sensing layers 12 and 14) to be formed can be controlled by the power applied to each target.
  • film thickness of the thin film (hydrogen sensing layers 12 and 14) to be formed can be controlled by the time during which power is applied to the target.
  • a magnesium thin film (or yttrium thin film) was formed so as to have a film thickness of 12 nm to 25 nm, and used as the hydrogen sensing layer 12 in the hydrogen sensing element 300 of Examples 2-1 to 2-5.
  • an yttrium thin film (or composition formula Y 0.55 Mg 0.45 is used so that the film thickness is 80 nm to 150 nm.
  • a calibration curve of the composition ratio of the yttrium-magnesium alloy to be formed with respect to the ratio of the power applied to the metal yttrium target and the metal magnesium target was created by Rutherford backscattering method.
  • the composition ratio of the formed yttrium-magnesium alloy thin film was estimated based on the calibration curve.
  • Table 3 shows the power applied to the target and the application time, the hydrogen sensing layer 12 and the hydrogen sensing layer 12 and the hydrogen sensing layer 14 in the hydrogen sensing elements 300 of Examples 2-1 to 2-5.
  • the composition ratio and film thickness of the hydrogen sensing layer 14 are shown.
  • a tantalum thin film (diffusion prevention layer 50) by applying a power of 20 W to a metal tantalum target under the same vacuum conditions as those for forming the hydrogen sensing layer 12 and the hydrogen sensing layer 14.
  • a hydrogen thin film (catalyst layer 20) was formed by applying a power of 30 W to a metallic palladium target, and a hydrogen sensing element 300 was produced.
  • the hydrogen sensing element 300 manufactured by the above procedure is in a metallic glossy reflecting state, but when the surface of the palladium thin film is exposed to a hydrogen-containing gas at 1 atm diluted to 4% by volume with argon, the yttrium thin film, magnesium When the thin film or the yttrium-magnesium alloy thin film was hydrogenated, yttrium trihydride and magnesium dihydride were produced and changed to a transparent state. When the surface of the palladium thin film was exposed to the atmosphere in this state, yttrium trihydride and magnesium dihydride were dehydrogenated to produce yttrium dihydride and magnesium, which returned to the reflective state. .
  • the hydrogen sensing element 300 changes from the non-hydride state to the trihydride state and the dihydride state.
  • the hydrogen sensing element 300 can then be switched between a trihydride state and a dihydride state by hydrogenating the yttrium dihydride and dehydrogenating the yttrium trihydride. It was confirmed to change reversibly.
  • Table 4 shows the evaluation results of the optical characteristics of the hydrogen sensing element 300.
  • the hydrogen sensing elements 300 of Examples 2-1 to 2-5 have the difference in light transmittance ( ⁇ T) and / or the difference in light reflectance ( ⁇ Rb) between the non-hydride state and the dihydride state. It can be seen that the difference in light transmittance ( ⁇ T) and / or the difference in light reflectance ( ⁇ Rb) between the dihydride state and the trihydride state is 5% or more, respectively. For this reason, the hydrogen sensing elements 300 of Examples 2-1 to 2-5 are in a state in which no hydrogen leaks, no hydrogen is leaking at the present time, but a state indicating a history of hydrogen leak in the past, Thus, it is possible to visually determine the state of hydrogen leakage.
  • Example 3 a hydrogen sensing element 200 was produced in the same manner as in Example 1 except that a palladium-ruthenium alloy thin film was used as the catalyst layer 20. That is, a hydrogen sensing layer in which a hydrogen sensing layer 10 made of yttrium / magnesium alloy, a diffusion prevention layer 50 made of tantalum, and a catalyst layer 20 made of palladium / ruthenium alloy are sequentially laminated on a glass substrate as a transparent substrate 40. Element 200 was produced.
  • a yttrium / magnesium alloy thin film (hydrogen sensing layer 10) having a thickness of 100 nm and a tantalum thin film having a thickness of 2 nm (diffusion prevention layer 50) are sequentially formed on a glass substrate (transparent substrate 40) having a thickness of 1 mm. Then, a palladium-ruthenium alloy thin film (catalyst layer 20) having a thickness of 3 nm with a changed composition ratio was formed.
  • the tantalum thin film of the diffusion preventing layer 50, and the palladium thin film of the catalyst layer 20 a magnetron sputtering apparatus capable of multi-element film formation was used.
  • metal magnesium, metal yttrium, metal tantalum, metal palladium, and metal ruthenium were set as targets on the five sputter guns, respectively.
  • the glass substrate was set in a vacuum apparatus and the chamber was evacuated.
  • a tantalum thin film (diffusion prevention layer 50) was formed by applying a power of 20 W to a metal tantalum target under the same vacuum conditions as those for forming the hydrogen sensing layer 10.
  • Table 5 shows the power applied to the target, the composition ratio and the film thickness of the catalyst layer 20 when forming the catalyst layer 20 in the hydrogen sensing elements 200 of Examples 3-1 to 3-3.
  • the hydrogen sensing element 200 manufactured by the above procedure is in a metallic glossy reflection state, but when the surface of the palladium-ruthenium alloy thin film is exposed to a hydrogen-containing gas at 1 atm diluted to 4% by volume with argon, it is yttrium.
  • a hydrogen-containing gas at 1 atm diluted to 4% by volume with argon
  • yttrium trihydride and magnesium dihydride were produced and changed to a transparent state. In this state, when the surface of the palladium-ruthenium alloy thin film is exposed to the atmosphere, yttrium trihydride and magnesium dihydride are dehydrogenated to produce yttrium dihydride and magnesium, which is in a reflective state. Returned to.
  • the hydrogen sensing element 200 changes from the non-hydride state to the trihydride state and the dihydride state.
  • the hydrogen sensing element 200 is then switched between a trihydride state and a dihydride state by hydrating the yttrium dihydride and dehydrogenating the yttrium trihydride. It was confirmed to change reversibly.
  • Table 6 shows the evaluation results of the optical characteristics of the hydrogen sensing element 200.
  • the hydrogen sensing elements 200 of Examples 3-1 to 3-3 have the difference in light transmittance ( ⁇ T) and / or the difference in light reflectance ( ⁇ Rb) between the non-hydride state and the dihydride state. It can be seen that the difference in light transmittance ( ⁇ T) and / or the difference in light reflectance ( ⁇ Rb) between the dihydride state and the trihydride state is 5% or more, respectively. For this reason, the hydrogen sensing elements 200 of Examples 3-1 to 3-3 are in a state in which no hydrogen is leaking, no hydrogen is leaking at the present time, but a state indicating a history of hydrogen leakage in the past, Thus, it is possible to visually determine the state of hydrogen leakage.

Abstract

In one mode of embodiment of the present invention, a hydrogen sensing element is provided on a transparent substrate with: a hydrogen sensing layer containing a metal the state of which changes reversibly between a transparent state resulting from a trihydride and a reflecting state resulting from a dihydride; and a catalyst layer containing a metal or an alloy which promotes hydrogenation and dehydrogenation in the hydrogen sensing layer. The metal contained in the hydrogen sensing layer has an anhydride state, a dihydride state and a trihydride state, each having mutually different optical characteristics.

Description

水素感知素子及び水素センサーHydrogen sensing element and hydrogen sensor
　本発明は、水素感知素子及び水素センサーに関する。 The present invention relates to a hydrogen sensing element and a hydrogen sensor.
　近年、クリーンなエネルギー源である水素を用いた燃料電池が注目されている。 In recent years, fuel cells using hydrogen, which is a clean energy source, have attracted attention.
　しかしながら、水素は、分子が小さいため、透過性が高い。さらに、水素は、爆発の危険性があるため、燃料電池を実用化する際に、水素を取り扱う方法が重要になる。水素を安全に取り扱うためには、水素の漏洩を安全かつ迅速に検出する水素感知素子や水素センサーが必須であり、多くの研究が進められている（例えば、特許文献１～３参照）。 However, hydrogen has high permeability because of its small molecule. Furthermore, since hydrogen has a risk of explosion, a method for handling hydrogen becomes important when a fuel cell is put into practical use. In order to handle hydrogen safely, a hydrogen sensing element and a hydrogen sensor that detect leakage of hydrogen safely and quickly are indispensable, and many studies have been made (for example, see Patent Documents 1 to 3).
　イットリウム（Ｙ）やランタン（Ｌａ）などの希土類金属をベースとした合金（例えば、特許文献４参照）や、マグネシウム（Ｍｇ）をベースとした合金（例えば、特許文献５、６参照）、酸化タングステン（例えば、特許文献７参照）等は、水素を吸蔵又は放出した際に、光学特性や電気抵抗特性が大きく変化するため、水素感知素子や水素センサーに用いられている。具体的には、水素感知素子として、ガラス基材、プラスチック基材等の透明基材の表面に、Ｍｇ－Ｎｉ合金等の水素吸蔵層が形成されており、水素吸蔵層の表面に、パラジウム等の触媒層が形成されている素子が用いられている（例えば、特許文献８参照）。 Alloys based on rare earth metals such as yttrium (Y) and lanthanum (La) (for example, see Patent Document 4), alloys based on magnesium (Mg) (for example, see Patent Documents 5 and 6), tungsten oxide (See, for example, Patent Document 7) and the like are used for hydrogen sensing elements and hydrogen sensors because optical characteristics and electrical resistance characteristics change greatly when hydrogen is occluded or released. Specifically, as a hydrogen sensing element, a hydrogen storage layer such as an Mg—Ni alloy is formed on the surface of a transparent substrate such as a glass substrate or a plastic substrate, and palladium or the like is formed on the surface of the hydrogen storage layer. The element in which the catalyst layer is formed is used (for example, refer to Patent Document 8).
　このような水素感知素子は、常温常圧において、水素吸蔵層が可逆的に水素を吸蔵又は放出することに伴い、水素吸蔵層の光反射率又は光透過率が大きく変化する。このため、水素感知素子は、常温常圧において、水素吸蔵層が水素を吸蔵することに伴う光反射率又は光透過率の変化を検知することで、水素の漏洩を安全かつ迅速に検出することができる。 In such a hydrogen sensing element, as the hydrogen storage layer reversibly absorbs or releases hydrogen at normal temperature and pressure, the light reflectance or light transmittance of the hydrogen storage layer changes greatly. For this reason, the hydrogen sensing element can detect hydrogen leakage safely and quickly by detecting a change in light reflectance or light transmittance associated with the hydrogen occlusion layer occludes hydrogen at normal temperature and pressure. Can do.
特開２００４－３４６４１８号公報JP 2004-346418 A 特開２０１１－２１９８４１号公報JP 2011-219841 A 特開２０１３－２４５３７０号公報JP 2013-245370 A 米国特許第６００６５８２号明細書US Pat. No. 6,0065,882 米国特許第５９０５５９０号明細書US Pat. No. 5,905,590 米国特許第６６４７１６６号明細書US Pat. No. 6,647,166 国際公開第２００９／１３３９９７号International Publication No. 2009/133997 米国特許第８７５８６９１号明細書US Pat. No. 8,758,691
　しかしながら、このような水素感知素子は、水素が漏洩すると、水素を吸蔵することで光学特性が変化し、水素が漏洩しなくなると、水素を放出して元の状態に戻るという、異なる２種類の光学特性のみを有する。このため、現時点で水素が漏洩していない場合に、過去に水素が漏洩した履歴を残すことができない。また、過去に水素が漏洩した履歴が残るように、吸蔵した水素を放出しないで水素を吸蔵した状態を維持することができても、現時点でも水素が漏洩しているかどうかを判断することができない。 However, such a hydrogen sensing element has two different types in which when hydrogen leaks, the optical characteristics change by occluding hydrogen, and when hydrogen does not leak, it releases hydrogen and returns to its original state. It has only optical properties. For this reason, when hydrogen is not leaking at the present time, it is not possible to leave a history of hydrogen leaking in the past. In addition, even if it is possible to maintain the state of storing hydrogen without releasing the stored hydrogen so that a history of hydrogen leakage in the past remains, it is not possible to determine whether hydrogen is leaking at this time. .
　本発明の一態様は、上記の点に鑑み、全く水素が漏洩していない状態、現時点では水素が漏洩していないが、過去に水素が漏洩した履歴を示す状態、現時点で水素が漏洩している状態を判断することが可能な水素感知素子を提供することを目的とする。 In one aspect of the present invention, in view of the above points, hydrogen is not leaking at all, hydrogen is not leaking at the present time, but hydrogen is leaking in the past, a state indicating a history of hydrogen leakage in the past, An object of the present invention is to provide a hydrogen sensing element capable of determining the state of being present.
　本発明の一態様は、水素感知素子において、透明基材上に、三水素化物による透明状態と二水素化物による反射状態との間で状態が可逆的に変化する金属を含む水素感知層と、前記水素感知層における水素化及び脱水素化を促進する金属又は合金を含む触媒層とを備え、前記水素感知層に含まれる金属は、光学特性の異なる、無水素化物、二水素化物及び三水素化物の状態を有する。 In one embodiment of the present invention, in the hydrogen sensing element, a hydrogen sensing layer including a metal whose state changes reversibly between a transparent state by trihydride and a reflection state by dihydride on a transparent substrate; And a catalyst layer containing a metal or an alloy that promotes hydrogenation and dehydrogenation in the hydrogen sensing layer, and the metal contained in the hydrogen sensing layer has non-hydride, dihydride, and trihydrogen having different optical characteristics. Has the state of a compound.
　本発明の一態様によれば、全く水素が漏洩していない状態、現時点では水素が漏洩していないが、過去に水素が漏洩した履歴を示す状態、現時点で水素が漏洩している状態を判断することが可能な水素感知素子を提供することができる。 According to one aspect of the present invention, a state in which no hydrogen has leaked, a state in which hydrogen has not leaked at the present time, a history of hydrogen leaks in the past, or a state in which hydrogen has leaked is determined. A hydrogen sensing element that can be provided can be provided.
本発明の第１の実施形態に係る水素感知素子の構成例を示す断面図である。It is sectional drawing which shows the structural example of the hydrogen sensing element which concerns on the 1st Embodiment of this invention. 本発明の第１の実施形態に係る水素感知素子の変形例を示す断面図である。It is sectional drawing which shows the modification of the hydrogen sensing element which concerns on the 1st Embodiment of this invention. 本発明の第２の実施形態に係る水素感知素子の構成例を示す断面図である。It is sectional drawing which shows the structural example of the hydrogen sensing element which concerns on the 2nd Embodiment of this invention. 本発明の第３の実施形態に係る水素感知素子の構成例を示す断面図である。It is sectional drawing which shows the structural example of the hydrogen sensing element which concerns on the 3rd Embodiment of this invention. 本発明の第３の実施形態に係る水素感知素子の変形例を示す断面図である。It is sectional drawing which shows the modification of the hydrogen sensing element which concerns on the 3rd Embodiment of this invention.
　以下、本発明を実施するための形態について図面を参照して説明するが、本発明は、下記の実施形態に制限されることはなく、本発明の範囲を逸脱することなく、下記の実施形態に種々の変形及び置換を加えることができる。 DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and the following embodiments are not departed from the scope of the present invention. Various modifications and substitutions can be made.
　［第１の実施形態］
　本実施形態では、本発明の第１の実施形態に係る水素感知素子について説明する。 [First Embodiment]
In the present embodiment, a hydrogen sensing element according to the first embodiment of the present invention will be described.
　本発明の第１の実施形態に係る水素感知素子は、三水素化物による透明状態と二水素化物による反射状態との間で状態が可逆的に変化する金属を含む水素感知層と、水素感知層における水素化及び脱水素化を促進する金属又は合金を含む触媒層と、透明基材を備える。そして、水素感知層に含まれる金属は、光学特性の異なる、無水素化物、二水素化物及び三水素化物の状態を有する。 A hydrogen sensing element according to the first embodiment of the present invention includes a hydrogen sensing layer including a metal whose state reversibly changes between a transparent state by trihydride and a reflection state by dihydride, and a hydrogen sensing layer. The catalyst layer containing the metal or alloy which accelerates | stimulates hydrogenation and dehydrogenation in, and a transparent base material are provided. The metal contained in the hydrogen sensing layer has a non-hydride, dihydride, and trihydride state with different optical properties.
　図１に、本発明の第１の実施形態に係る水素感知素子の構成例を示す。 FIG. 1 shows a configuration example of a hydrogen sensing element according to the first embodiment of the present invention.
　水素感知素子１００は、水素感知層１０と、触媒層２０を備え、水素感知層１０に対して、触媒層２０とは反対側に、透明基材（透明基板）４０をさらに備える。 The hydrogen sensing element 100 includes a hydrogen sensing layer 10 and a catalyst layer 20, and further includes a transparent substrate (transparent substrate) 40 on the opposite side of the hydrogen sensing layer 10 from the catalyst layer 20.
　水素感知層１０に含まれる金属は、成膜後に水素化されていない無水素化物（金属）の状態と、無水素化物又は二水素化物の水素化により透明状態になった三水素化物の状態と、三水素化物の脱水素化により反射状態になった二水素化物の状態を有する。 The metal contained in the hydrogen sensing layer 10 includes a non-hydrogenated (metal) state that has not been hydrogenated after film formation, and a trihydride state that has become transparent due to the hydrogenation of a non-hydride or dihydride. , Having a dihydride state that is in a reflective state by dehydrogenation of the trihydride.
　水素感知層１０は、希土類金属を含むことが好ましく、希土類金属又は希土類金属をベースとする合金を含むことがより好ましい。 The hydrogen sensing layer 10 preferably contains a rare earth metal, more preferably a rare earth metal or an alloy based on a rare earth metal.
　次に、水素感知層１０に含まれる希土類金属及び希土類金属をベースとする合金について説明する。 Next, the rare earth metal contained in the hydrogen sensing layer 10 and an alloy based on the rare earth metal will be described.
　希土類金属（Ｘ）としては、光学特性の異なる、無水素化物（Ｘ）、二水素化物（ＸＨ２）及び三水素化物（ＸＨ３）の状態を有していれば、特に限定されるものではない。 The rare earth metal (X) is not particularly limited as long as it has a state of non-hydride (X), dihydride (XH 2 ) and trihydride (XH 3 ) having different optical characteristics. Absent.
　希土類金属は、入手の容易さ、コスト、大気中での安定性から、Ｓｃ、Ｙ、Ｌａ、Ｇｄ、Ｃｅからなる群より選択されることが好ましい。 The rare earth metal is preferably selected from the group consisting of Sc, Y, La, Gd, and Ce in view of availability, cost, and stability in the atmosphere.
　希土類金属をベースとする合金は、第２属金属を含むことが好ましい。 The alloy based on rare earth metal preferably contains a Group 2 metal.
　希土類金属又は希土類金属をベースとする合金は、イットリウム、イットリウム・マグネシウム合金又はイットリウム・マグネシウム・スカンジウム合金であることが好ましい。 The rare earth metal or the alloy based on the rare earth metal is preferably yttrium, yttrium / magnesium alloy or yttrium / magnesium / scandium alloy.
　イットリウム・マグネシウム合金は、イットリウムの無水素化物（Ｙ）と、イットリウムを一度水素化した後、脱水素化したイットリウムの二水素化物（ＹＨ２）の光学特性に明瞭な差が生じるため、一般式
　Ｙ１－ｘＭｇｘ（０＜ｘ＜０．４）・・・（１）
で表される化合物であることが好ましく、一般式
　Ｙ１－ｘＭｇｘ（０＜ｘ＜０．２５）・・・（２）
で表される化合物であることがより好ましい。また、マグネシウム・イットリウム合金は、１０００回以上の安定した水素感知特性、即ち、繰り返し耐久性を示すため、一般式（１）で表される化合物であることが好ましい。 Since the yttrium-magnesium alloy has a clear difference in optical properties between the hydride of yttrium (Y) and the yttrium dihydride (YH 2 ) dehydrogenated after yttrium is once hydrogenated, the general formula Y 1-x Mg x (0 <x <0.4) (1)
And a compound represented by the general formula Y 1-x Mg x (0 <x <0.25) (2)
It is more preferable that it is a compound represented by these. Further, the magnesium-yttrium alloy is preferably a compound represented by the general formula (1) in order to exhibit stable hydrogen sensing characteristics of 1000 times or more, that is, repeated durability.
　また、イットリウム・マグネシウム・スカンジウム合金は、上記と同様の理由で、一般式
　Ｙ１－ｘ―ｙＭｇｘＳｃｙ（０＜ｘ＜０．４、０＜ｙ＜０．６、ｘ＋ｙ＜１）・・・（３）
で表される化合物であることが好ましい。 In addition, the yttrium-magnesium-scandium alloy has the general formula Y 1-xy Mg x Sc y (0 <x <0.4, 0 <y <0.6, x + y <1) for the same reason as above. ... (3)
It is preferable that it is a compound represented by these.
　水素感知層１０の厚さは、光透過率、光反射率等を考慮して選択されるものであり、特に限定されるものではないが、１０ｎｍ以上１０００ｎｍ以下であることが好ましい。水素感知層１０の厚さが１０ｎｍ以上であると、水素感知層１０の反射状態における光反射率を向上させることができる。一方、水素感知層１０の厚さが１０００ｎｍ以下であると、水素感知層１０の透明状態における光透過率を向上させることができる。 The thickness of the hydrogen sensing layer 10 is selected in consideration of light transmittance, light reflectance, and the like, and is not particularly limited, but is preferably 10 nm or more and 1000 nm or less. When the thickness of the hydrogen sensing layer 10 is 10 nm or more, the light reflectance in the reflective state of the hydrogen sensing layer 10 can be improved. On the other hand, when the thickness of the hydrogen sensing layer 10 is 1000 nm or less, the light transmittance in the transparent state of the hydrogen sensing layer 10 can be improved.
　水素感知層１０の形成方法としては、特に限定されるものではなく、例えば、スパッタリング法、真空蒸着法、電子ビーム蒸着法、化学気相蒸着法（ＣＶＤ）、めっき法等の一般的な成膜方法を用いることができる。 The method for forming the hydrogen sensing layer 10 is not particularly limited. For example, general film formation such as sputtering, vacuum deposition, electron beam deposition, chemical vapor deposition (CVD), plating, and the like. The method can be used.
　触媒層２０は、水素感知層１０上に形成されており、水素感知層１０における水素化及び脱水素化を促進する機能を有する。このため、水素感知層１０の透明状態から反射状態への十分なスイッチング速度、及び、水素感知層１０の反射状態から透明状態への十分なスイッチング速度が確保される。 The catalyst layer 20 is formed on the hydrogen sensing layer 10 and has a function of promoting hydrogenation and dehydrogenation in the hydrogen sensing layer 10. For this reason, a sufficient switching speed from the transparent state to the reflective state of the hydrogen sensing layer 10 and a sufficient switching speed from the reflective state to the transparent state of the hydrogen sensing layer 10 are ensured.
　触媒層２０に含まれる金属又は合金としては、水素感知層１０における水素化及び脱水素化を促進する機能を有するものであれば、特に限定されるものではない。 The metal or alloy contained in the catalyst layer 20 is not particularly limited as long as it has a function of promoting hydrogenation and dehydrogenation in the hydrogen sensing layer 10.
　触媒層２０に含まれる金属又は合金は、パラジウム、パラジウム合金、白金及び白金合金からなる群より選択される一種以上であることが好ましく、水素透過性が高いことから、パラジウム又はパラジウム・ルテニウム合金であることがより好ましい。 The metal or alloy contained in the catalyst layer 20 is preferably at least one selected from the group consisting of palladium, palladium alloy, platinum and platinum alloy, and has high hydrogen permeability, so palladium or palladium-ruthenium alloy. More preferably.
　パラジウム・ルテニウム合金は、コスト及び脱水素化の速度の観点から、一般式
　Ｐｄ１－ｘＲｕｘ（０＜ｘ＜０．７）・・・（４）
で表される化合物であることが好ましい。 The palladium-ruthenium alloy has a general formula Pd 1-x Ru x (0 <x <0.7) (4) from the viewpoint of cost and dehydrogenation speed.
It is preferable that it is a compound represented by these.
　触媒層２０の厚さは、水素感知層１０の反応性、触媒層２０に含まれる金属又は合金の触媒能により適宜選択されるものであり、特に限定されるものではないが、１ｎｍ以上２０ｎｍ以下であることが好ましい。触媒層２０の厚さが１ｎｍ以上であると、触媒層２０の機能を向上させることができる。一方、触媒層２０の厚さが２０ｎｍ以下であると、触媒層２０の光透過率を向上させることができる。 The thickness of the catalyst layer 20 is appropriately selected depending on the reactivity of the hydrogen sensing layer 10 and the catalytic ability of the metal or alloy contained in the catalyst layer 20, and is not particularly limited, but is 1 nm or more and 20 nm or less. It is preferable that The function of the catalyst layer 20 can be improved as the thickness of the catalyst layer 20 is 1 nm or more. On the other hand, when the thickness of the catalyst layer 20 is 20 nm or less, the light transmittance of the catalyst layer 20 can be improved.
　触媒層２０の形成方法としては、特に限定されるものではなく、例えば、スパッタリング法、真空蒸着法、電子ビーム蒸着法、化学気相蒸着法（ＣＶＤ）、めっき法等の一般的な成膜方法を用いることができる。 The method for forming the catalyst layer 20 is not particularly limited. For example, a general film forming method such as a sputtering method, a vacuum evaporation method, an electron beam evaporation method, a chemical vapor deposition method (CVD), or a plating method is used. Can be used.
　透明基材４０は、水素感知素子１００の土台としての機能を有する。また、透明基材４０は、水や酸素による水素感知層１０の酸化を防止する機能を有することが好ましい。 The transparent substrate 40 has a function as a base of the hydrogen sensing element 100. The transparent substrate 40 preferably has a function of preventing the hydrogen sensing layer 10 from being oxidized by water or oxygen.
　透明基材４０の形状は、例えば、シート状やフィルム状であってもよい。 The shape of the transparent substrate 40 may be, for example, a sheet shape or a film shape.
　なお、透明基材４０の形状は、特に限定されるものではなく、フレキシブル性を有していてもよい。 In addition, the shape of the transparent base material 40 is not specifically limited, You may have flexibility.
　透明基材４０を構成する材料としては、波長が３８０ｎｍ～７８０ｎｍの可視光域で５０％以上の光透過率を有するものであれば、限定されるものではないが、ガラス又はプラスチックを用いることが好ましい。 The material constituting the transparent substrate 40 is not limited as long as it has a light transmittance of 50% or more in the visible light region having a wavelength of 380 nm to 780 nm, but glass or plastic is used. preferable.
　ここで、プラスチックとしては、ポリエチレンテレフタレート（ＰＥＴ）、ポリエチレンナフタレート（ＰＥＮ）、ナイロン、アクリル等を用いることが好ましい。 Here, it is preferable to use polyethylene terephthalate (PET), polyethylene naphthalate (PEN), nylon, acrylic or the like as the plastic.
　また、図２に示すように、水素感知素子１００の水素感知層１０と触媒層２０との間に、拡散防止層５０を挿入して、水素感知素子２００としてもよい。 Further, as shown in FIG. 2, the hydrogen sensing element 200 may be formed by inserting a diffusion prevention layer 50 between the hydrogen sensing layer 10 and the catalyst layer 20 of the hydrogen sensing element 100.
　拡散防止層５０を構成する材料としては、触媒層２０を構成する材料が水素感知層１０に拡散することを防ぐと共に、触媒層２０を透過した水素が水素感知層１０に効果的に拡散する能力を有するものであれば、特に限定されるものではないが、ニオブ、バナジウム、チタン、タンタルを用いることが好ましい。 As a material constituting the diffusion preventing layer 50, the material constituting the catalyst layer 20 is prevented from diffusing into the hydrogen sensing layer 10, and the hydrogen permeated through the catalyst layer 20 can effectively diffuse into the hydrogen sensing layer 10. Although it will not specifically limit if it has this, It is preferable to use niobium, vanadium, titanium, and a tantalum.
　拡散防止層５０の形成方法としては、特に限定されるものではなく、例えば、スパッタリング法、真空蒸着法、電子ビーム蒸着法、化学気相蒸着法（ＣＶＤ）、めっき法等の一般的な成膜方法を用いることができる。 A method for forming the diffusion preventing layer 50 is not particularly limited, and for example, a general film formation such as a sputtering method, a vacuum evaporation method, an electron beam evaporation method, a chemical vapor deposition method (CVD), or a plating method. The method can be used.
　以上に説明してきたように、水素感知素子１００、２００は、水素感知層１０を備えることにより、従来の水素感知素子とは異なり、全く水素が漏洩していない状態、現時点では水素が漏洩していないが、過去に水素が漏洩した履歴を示す状態、現時点で水素が漏洩している状態を判断することができる。 As described above, the hydrogen sensing elements 100 and 200 are provided with the hydrogen sensing layer 10 so that, unlike the conventional hydrogen sensing elements, no hydrogen is leaking, or hydrogen is leaking at this time. However, it is possible to determine a state indicating a history of hydrogen leakage in the past and a state where hydrogen is leaking at the present time.
　［第２の実施形態］
　本実施形態では、本発明の第２の実施形態に係る水素感知素子について説明する。 [Second Embodiment]
In the present embodiment, a hydrogen sensing element according to a second embodiment of the present invention will be described.
　本発明の第２の実施形態に係る水素感知素子は、本発明の第１の実施形態に係る水素感知素子において、水素感知層として、２種類以上の異なる組成比を有する水素感知層の積層体を備える。 The hydrogen sensing element according to the second embodiment of the present invention is a stack of hydrogen sensing layers having two or more different composition ratios as the hydrogen sensing layer in the hydrogen sensing element according to the first embodiment of the present invention. Is provided.
　図３に、本発明の第２の実施形態に係る水素感知素子の構成例を示す。 FIG. 3 shows a configuration example of the hydrogen sensing element according to the second embodiment of the present invention.
　水素感知素子３００は、水素感知素子２００において、水素感知層１０の代わりに、異なる２種類の組成比を有する水素感知層１２、１４の積層体を備える。 The hydrogen sensing element 300 includes a stack of hydrogen sensing layers 12 and 14 having two different composition ratios instead of the hydrogen sensing layer 10 in the hydrogen sensing element 200.
　なお、水素感知素子３００の水素感知層１２、１４以外の構成は、水素感知素子２００と同様であるので、水素感知素子３００の水素感知層１２、１４以外の構成の説明を省略する。 The configuration of the hydrogen sensing element 300 other than the hydrogen sensing layers 12 and 14 is the same as that of the hydrogen sensing element 200, and thus the description of the configuration of the hydrogen sensing element 300 other than the hydrogen sensing layers 12 and 14 is omitted.
　次に、水素感知層１２、１４について説明する。 Next, the hydrogen sensing layers 12 and 14 will be described.
　水素感知層１２、１４は、水素感知層１０と同様にして、希土類金属を含むことが好ましく、希土類金属又は希土類金属をベースとする合金を含むことがより好ましい。また、希土類金属をベースとする合金は、第２属金属を含むことが好ましい。 Similarly to the hydrogen sensing layer 10, the hydrogen sensing layers 12 and 14 preferably include a rare earth metal, and more preferably include a rare earth metal or an alloy based on a rare earth metal. The alloy based on rare earth metal preferably contains a second group metal.
　水素感知層１２、１４に含まれる希土類金属又は希土類金属をベースとする合金は、イットリウム、イットリウム・マグネシウム合金又はイットリウム・マグネシウム・スカンジウム合金であることが好ましい。 The rare earth metal or rare earth metal based alloy contained in the hydrogen sensing layers 12 and 14 is preferably yttrium, yttrium / magnesium alloy or yttrium / magnesium / scandium alloy.
　なお、水素感知層１２（又は１４）に含まれる金属又は合金が希土類金属又は希土類金属をベースとする合金である場合、水素感知層１４（又は１２）に含まれる金属又は合金は、希土類金属をベースとする合金から希土類金属を除いた金属又は合金であってもよい。 When the metal or alloy contained in the hydrogen sensing layer 12 (or 14) is a rare earth metal or an alloy based on a rare earth metal, the metal or alloy contained in the hydrogen sensing layer 14 (or 12) is a rare earth metal. It may be a metal or alloy obtained by removing a rare earth metal from a base alloy.
　水素感知素子３００は、組成比が異なる水素感知層１２、１４を備えることにより、水素感知層１２、１４に含まれる金属の無水素化物、二水素化物及び三水素化物の状態の光学特性が異なる。また、水素感知素子３００は、干渉効果により、１種類の水素感知層１０を備える水素感知素子１００と比較して、金属の無水素化物、二水素化物及び三水素化物の状態の光学特性のより大きい差を発現させることができる。このため、水素感知層１２、１４にそれぞれ含まれる金属又は合金は、干渉効果が生じれば、特に限定されるものではないが、組成比の差が大きい方が好ましい。 Since the hydrogen sensing element 300 includes the hydrogen sensing layers 12 and 14 having different composition ratios, the optical characteristics of the metal non-hydride, dihydride, and trihydride states included in the hydrogen sensing layers 12 and 14 are different. . In addition, the hydrogen sensing element 300 has a higher optical property in the state of metal non-hydride, dihydride, and trihydride than the hydrogen sensing element 100 including one type of hydrogen sensing layer 10 due to the interference effect. Large differences can be expressed. For this reason, the metal or alloy contained in each of the hydrogen sensing layers 12 and 14 is not particularly limited as long as an interference effect occurs, but it is preferable that the difference in the composition ratio is large.
　次に、水素感知層１２、１４にそれぞれ含まれる金属又は合金として、マグネシウム、イットリウム又はマグネシウム・イットリウム合金を用いる場合について、より具体的に説明する。 Next, the case where magnesium, yttrium, or a magnesium yttrium alloy is used as the metal or alloy contained in each of the hydrogen sensing layers 12 and 14 will be described more specifically.
　まず、水素感知層１２に含まれるイットリウム又はイットリウム・マグネシウム合金を、一般式
　Ｙ１－ｘＭｇｘ（０≦ｘ＜０．２５）・・・（５）
で表される化合物とする場合について説明する。この場合、水素感知層１４に含まれるマグネシウム又はイットリウム・マグネシウム合金は、一般式
　Ｙ１－ｘＭｇｘ（０．３５≦ｘ≦１）・・・（６）
で表される化合物であることが好ましく、スイッチングの繰り返し耐久性を向上させるためには、一般式
　Ｙ１－ｘＭｇｘ（０．３５≦ｘ＜０．５）・・・（７）
で表される化合物であることがより好ましい。 First, yttrium or yttrium-magnesium alloy contained in the hydrogen sensing layer 12 is represented by the general formula Y 1-x Mg x (0 ≦ x <0.25) (5)
The case where it is set as the compound represented by is demonstrated. In this case, the magnesium or yttrium-magnesium alloy contained in the hydrogen sensing layer 14 has the general formula Y 1-x Mg x (0.35 ≦ x ≦ 1) (6)
In order to improve the switching durability, the general formula Y 1-x Mg x (0.35 ≦ x <0.5) (7)
It is more preferable that it is a compound represented by these.
　次に、水素感知層１２に含まれるマグネシウム又はイットリウム・マグネシウム合金を、一般式
　Ｙ１－ｘＭｇｘ（０．５≦ｘ≦１）・・・（８）
で表される化合物とする場合について説明する。この場合、水素感知層１４に含まれるイットリウム又はイットリウム・マグネシウム合金は、一般式
　Ｙ１－ｘＭｇｘ（０≦ｘ＜０．５）・・・（９）
で表される化合物であることが好ましく、無水素化物、二水素化物及び三水素化物の状態の光学特性の明瞭な差を発現させるためには、一般式
　Ｙ１－ｘＭｇｘ（０≦ｘ＜０．２５）・・・（１０）
で表される化合物であることがより好ましい。 Next, the magnesium or yttrium-magnesium alloy contained in the hydrogen sensing layer 12 is represented by the general formula Y 1-x Mg x (0.5 ≦ x ≦ 1) (8)
The case where it is set as the compound represented by is demonstrated. In this case, the yttrium or yttrium-magnesium alloy contained in the hydrogen sensing layer 14 has the general formula Y 1-x Mg x (0 ≦ x <0.5) (9)
In order to express a clear difference in the optical properties of the non-hydride, dihydride, and trihydride states, the general formula Y 1-x Mg x (0 ≦ x <0.25) (10)
It is more preferable that it is a compound represented by these.
　水素感知層１２の厚さは、光透過率、光反射率等を考慮して選択されるものであり、特に限定されるものではないが、１ｎｍ以上１００ｎｍ以下であることが好ましい。水素感知層１２の厚さが１ｎｍ以上であると、１種類の水素感知層１０を備える水素感知素子１００と比較して、金属の無水素化物、二水素化物及び三水素化物の状態の光学特性のより大きい差を発現させることができる。一方、水素感知層１２の厚さが１００ｎｍ以下であると、水素感知層１２の透明状態における光透過率を向上させることができる。 The thickness of the hydrogen sensing layer 12 is selected in consideration of light transmittance, light reflectance, and the like, and is not particularly limited, but is preferably 1 nm to 100 nm. When the thickness of the hydrogen sensing layer 12 is 1 nm or more, compared with the hydrogen sensing element 100 including one type of hydrogen sensing layer 10, the optical characteristics of the metal non-hydride, dihydride, and trihydride states. Greater differences can be developed. On the other hand, when the thickness of the hydrogen sensing layer 12 is 100 nm or less, the light transmittance in the transparent state of the hydrogen sensing layer 12 can be improved.
　さらに、水素感知層１４の厚さは、光透過率、光反射率等を考慮して選択されるものであり、特に限定されるものではないが、１０ｎｍ以上１０００ｎｍ以下であることが好ましい。水素感知層１４の厚さが１０ｎｍ以上であると、反射状態における光反射率を向上させることができる。一方、水素感知層１４の厚さが１０００ｎｍ以下であると、透明状態における光透過率を向上させることができる。 Furthermore, the thickness of the hydrogen sensing layer 14 is selected in consideration of light transmittance, light reflectance, and the like, and is not particularly limited, but is preferably 10 nm to 1000 nm. When the thickness of the hydrogen sensing layer 14 is 10 nm or more, the light reflectance in the reflection state can be improved. On the other hand, when the thickness of the hydrogen sensing layer 14 is 1000 nm or less, the light transmittance in a transparent state can be improved.
　水素感知層１２、１４の形成方法は、水素感知層１０の形成方法と同様であるため、水素感知層１２、１４の形成方法の説明を省略する。 Since the formation method of the hydrogen sensing layers 12 and 14 is the same as the formation method of the hydrogen sensing layer 10, the description of the formation method of the hydrogen sensing layers 12 and 14 is omitted.
　なお、水素感知素子１００と同様にして、水素感知層１４と触媒層２０との間に拡散防止層５０を挿入しなくてもよい。 Note that the diffusion prevention layer 50 may not be inserted between the hydrogen sensing layer 14 and the catalyst layer 20 in the same manner as the hydrogen sensing element 100.
　［第３の実施形態］
　本実施形態では、本発明の第３の実施形態に係る水素感知素子について説明する。 [Third Embodiment]
In the present embodiment, a hydrogen sensing element according to a third embodiment of the present invention will be described.
　本発明の第３の実施形態に係る水素感知素子は、本発明の第１の実施形態に係る水素感知素子の表面に、１層以上の保護層をさらに備える。 The hydrogen sensing element according to the third embodiment of the present invention further includes one or more protective layers on the surface of the hydrogen sensing element according to the first embodiment of the present invention.
　図４に、本発明の第３の実施形態に係る水素感知素子の構成例を示す。 FIG. 4 shows a configuration example of the hydrogen sensing element according to the third embodiment of the present invention.
　水素感知素子４００は、水素感知素子１００の表面に、保護層３０をさらに備える。 The hydrogen sensing element 400 further includes a protective layer 30 on the surface of the hydrogen sensing element 100.
　なお、水素感知素子４００の保護層３０以外の構成は、水素感知素子１００と同様であるので、水素感知素子４００の保護層３０以外の構成の説明を省略する。 Since the configuration of the hydrogen sensing element 400 other than the protective layer 30 is the same as that of the hydrogen sensing element 100, the description of the configuration other than the protective layer 30 of the hydrogen sensing element 400 is omitted.
　保護層３０は、触媒層２０の水素感知層１０とは反対側の面に形成されており、水素透過性及び撥水性を有する。また、保護層３０は、水や酸素による触媒層２０の酸化を防止する機能及び触媒層２０と協働して、水や酸素による水素感知層１０の酸化を防止する機能を有する。 The protective layer 30 is formed on the surface of the catalyst layer 20 opposite to the hydrogen sensing layer 10 and has hydrogen permeability and water repellency. In addition, the protective layer 30 has a function of preventing oxidation of the catalyst layer 20 by water and oxygen and a function of preventing oxidation of the hydrogen sensing layer 10 by water and oxygen in cooperation with the catalyst layer 20.
　触媒層２０を構成する材料は、通常、貴金属であるため、酸化しにくいが、触媒層２０の酸化を防止する機能を有する保護層３０を形成することで、触媒能を長期間維持することが可能となる。 Since the material constituting the catalyst layer 20 is usually a noble metal, it is difficult to oxidize. However, by forming the protective layer 30 having a function of preventing the oxidation of the catalyst layer 20, the catalytic ability can be maintained for a long time. It becomes possible.
　さらに、触媒層２０は、水素感知層１０の酸化を防止する機能も有するが、保護層３０を形成することで、水素感知層１０の酸化を防止する機能を高めることが可能になる。 Further, the catalyst layer 20 also has a function of preventing the hydrogen sensing layer 10 from being oxidized. However, the formation of the protective layer 30 can enhance the function of preventing the hydrogen sensing layer 10 from being oxidized.
　保護層３０は、上記のように、水素（水素イオン）に対する透過性（水素透過性）及び水に対する非透過性（撥水性）を有する。 As described above, the protective layer 30 has permeability to hydrogen (hydrogen ions) (hydrogen permeability) and non-permeability to water (water repellency).
　保護層３０を構成する材料としては、水素透過性及び撥水性を有するものであれば、特に限定されるものではないが、例えば、フッ素樹脂、ポリ酢酸ビニル、ポリ塩化ビニル、ポリスチレン、酢酸セルロース等のポリマーや、酸化チタン等の無機材料が用いられる。 The material constituting the protective layer 30 is not particularly limited as long as it has hydrogen permeability and water repellency. For example, fluororesin, polyvinyl acetate, polyvinyl chloride, polystyrene, cellulose acetate, etc. And inorganic materials such as titanium oxide are used.
　保護層３０の形成方法としては、例えば、ポリマーが分散している分散液を塗布した後、乾燥させる方法、スパッタリング法、真空蒸着法により無機薄膜を成膜する方法等の一般的な成膜方法を用いることができる。 As a method for forming the protective layer 30, for example, a general film forming method such as a method of applying a dispersion liquid in which a polymer is dispersed and then drying, a method of forming an inorganic thin film by a sputtering method, or a vacuum evaporation method, etc. Can be used.
　保護層３０を形成することによって、水や酸素による触媒層２０及び水素感知層１０の酸化を防止することができる。このため、触媒層２０及び水素感知層１０の劣化を防止し、耐久性を高めることが可能になる。 By forming the protective layer 30, oxidation of the catalyst layer 20 and the hydrogen sensing layer 10 by water or oxygen can be prevented. For this reason, deterioration of the catalyst layer 20 and the hydrogen sensing layer 10 can be prevented, and durability can be enhanced.
　なお、本実施形態では、本発明の第１の実施形態に係る水素感知素子の表面に、１層以上の保護層をさらに備える水素感知素子について説明したが、本発明の第２の実施形態に係る水素感知素子の表面に、１層以上の保護層をさらに備える水素感知素子とすることもできる。すなわち、図５に示すように、水素感知素子３００において、触媒層２０の水素感知層１４とは反対側の面に保護層３０が形成されている水素感知素子５００としてもよい。この場合、水素感知素子４００で説明したように、触媒層２０及び水素感知層１２、１４の劣化を防止し、耐久性を高めることが可能になる。 In the present embodiment, the hydrogen sensing element further including one or more protective layers on the surface of the hydrogen sensing element according to the first embodiment of the present invention has been described. However, in the second embodiment of the present invention, The hydrogen sensing element may further include one or more protective layers on the surface of the hydrogen sensing element. That is, as shown in FIG. 5, in the hydrogen sensing element 300, the hydrogen sensing element 500 in which the protective layer 30 is formed on the surface of the catalyst layer 20 opposite to the hydrogen sensing layer 14 may be used. In this case, as described in the hydrogen sensing element 400, the catalyst layer 20 and the hydrogen sensing layers 12 and 14 can be prevented from being deteriorated and the durability can be improved.
　以下、実施例により本発明を詳細に説明するが、本発明は、実施例に限定されるものではない。 Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples.
　［実施例１］
　本実施例では、透明基材４０としての、ガラス基板上に、イットリウム又はイットリウム・マグネシウム合金からなる水素感知層１０、タンタルからなる拡散防止層５０、パラジウムからなる触媒層２０が順次積層されている水素感知素子２００を作製した。 [Example 1]
In this embodiment, a hydrogen sensing layer 10 made of yttrium or an yttrium-magnesium alloy, a diffusion prevention layer 50 made of tantalum, and a catalyst layer 20 made of palladium are sequentially laminated on a glass substrate as the transparent substrate 40. A hydrogen sensing element 200 was produced.
　具体的には、厚さ１ｍｍのガラス基板（透明基材４０）上に、順次、膜厚を変化させたイットリウム薄膜又は膜厚及び組成比を変化させたイットリウム・マグネシウム合金薄膜（水素感知層１０）、膜厚２ｎｍのタンタル薄膜（拡散防止層５０）、膜厚３ｎｍのパラジウム薄膜（触媒層２０）を成膜した。 Specifically, on a glass substrate (transparent base material 40) having a thickness of 1 mm, an yttrium thin film with a changed film thickness or an yttrium-magnesium alloy thin film with a changed film thickness and composition ratio (hydrogen sensing layer 10). ), A tantalum thin film (diffusion prevention layer 50) having a thickness of 2 nm, and a palladium thin film (catalyst layer 20) having a thickness of 3 nm were formed.
　次に、水素感知層１０、拡散防止層５０、触媒層２０の成膜条件について説明する。 Next, film forming conditions for the hydrogen sensing layer 10, the diffusion prevention layer 50, and the catalyst layer 20 will be described.
　水素感知層１０のイットリウム薄膜又はイットリウム・マグネシウム合金薄膜、拡散防止層５０のタンタル薄膜、触媒層２０のパラジウム薄膜を成膜する際には、多元成膜が可能なマグネトロンスパッタ装置を用いた。このとき、４つのスパッタ銃に、ターゲットとして、それぞれ金属イットリウム、金属マグネシウム、金属タンタル及び金属パラジウムをセットした。 When forming the yttrium thin film or yttrium magnesium alloy thin film of the hydrogen sensing layer 10, the tantalum thin film of the diffusion preventing layer 50, and the palladium thin film of the catalyst layer 20, a magnetron sputtering apparatus capable of multi-element film formation was used. At this time, metal yttrium, metal magnesium, metal tantalum, and metal palladium were set as targets on the four sputter guns, respectively.
　最初に、ガラス基板（透明基材４０）を洗浄した後、真空装置の中にガラス基板をセットして、チャンバー内を真空排気した。 First, after cleaning the glass substrate (transparent base material 40), the glass substrate was set in a vacuum apparatus, and the inside of the chamber was evacuated.
　次に、金属イットリウムのターゲットと、金属マグネシウムのターゲットに同時に電力を印加して、イットリウム・マグネシウム合金薄膜を成膜した。なお、イットリウム薄膜を成膜する際には、金属イットリウムのターゲットだけに電力を印加した。このとき、スパッタ中のアルゴンガス圧を０．３Ｐａとし、直流スパッタ法により、それぞれのターゲットに所定の電力を所定の時間印加することでスパッタした。 Next, power was simultaneously applied to the metal yttrium target and the metal magnesium target to form a yttrium-magnesium alloy thin film. Note that when the yttrium thin film was formed, power was applied only to the metal yttrium target. At this time, sputtering was performed by setting the argon gas pressure during sputtering to 0.3 Pa and applying a predetermined power to each target for a predetermined time by a direct current sputtering method.
　なお、それぞれのターゲットに印加する電力によって、成膜される薄膜（水素感知層１０）の組成比を制御することができる。また、ターゲットに電力を印加する時間によって、成膜される薄膜（水素感知層１０）の膜厚を制御することができる。 Note that the composition ratio of the thin film (hydrogen sensing layer 10) to be formed can be controlled by the power applied to each target. Further, the film thickness of the thin film (hydrogen sensing layer 10) to be formed can be controlled by the time during which power is applied to the target.
　本実施例では、膜厚が１５ｎｍ～１６７ｎｍとなるように、イットリウム薄膜又は組成式
　Ｙ１－ｘＭｇｘ（ｘ＝０．１、０．１５、０．２５）
で表わされるイットリウム・マグネシウム合金薄膜を成膜し、実施例１－１～１－１８の水素感知素子２００における水素感知層１０とした。 In this example, the yttrium thin film or the composition formula Y 1-x Mg x (x = 0.1, 0.15, 0.25) is used so that the film thickness becomes 15 nm to 167 nm.
An yttrium-magnesium alloy thin film represented by the following formula was formed as the hydrogen sensing layer 10 in the hydrogen sensing element 200 of Examples 1-1 to 1-18.
　ここで、ラザフォード後方散乱法により、金属イットリウムのターゲット及び金属マグネシウムのターゲットに印加する電力の比に対する、成膜されるイットリウム・マグネシウム合金薄膜の組成比の関係を示すキャリブレーションカーブを作成した。次に、キャリブレーションカーブに基づいて、成膜されたイットリウム・マグネシウム合金薄膜の組成比を見積もった。 Here, a calibration curve showing the relationship of the composition ratio of the yttrium-magnesium alloy thin film to the ratio of the power applied to the metal yttrium target and the metal magnesium target was created by Rutherford backscattering method. Next, the composition ratio of the formed yttrium-magnesium alloy thin film was estimated based on the calibration curve.
　表１に、実施例１－１～１－１８の水素感知素子２００における水素感知層１０を成膜する際に、ターゲットに印加した電力及びその印加時間、水素感知層１０の組成比及び膜厚を示す。 Table 1 shows the power applied to the target and the application time, the composition ratio and the film thickness of the hydrogen sensing layer 10 when forming the hydrogen sensing layer 10 in the hydrogen sensing elements 200 of Examples 1-1 to 1-18. Indicates.
Figure JPOXMLDOC01-appb-T000001
 　次に、水素感知層１０を成膜するのと同一の真空条件で、金属タンタルのターゲットに２０Ｗの電力を印加して、タンタル薄膜（拡散防止層５０）を成膜した後、金属パラジウムのターゲットに３０Ｗの電力を印加して、パラジウム薄膜（触媒層２０）を成膜し、水素感知素子２００を作製した。
Figure JPOXMLDOC01-appb-T000001
 Next, under the same vacuum conditions as those for forming the hydrogen sensing layer 10, a power of 20 W is applied to the metal tantalum target to form a tantalum thin film (diffusion prevention layer 50), and then a metal palladium target. A hydrogen thin film (catalyst layer 20) was formed by applying a power of 30 W to the hydrogen sensing element 200.
　以上の手順によって作製した水素感知素子２００は、金属光沢の反射状態になっているが、パラジウム薄膜の表面をアルゴンで４体積％に希釈した１気圧の水素ガス（以下、「水素含有ガス」という）に曝すと、イットリウム薄膜又はイットリウム・マグネシウム合金薄膜が水素化されることにより、イットリウムの三水素化物（及びマグネシウムの二水素化物）が生成し、透明状態に変化した。この状態で、パラジウム薄膜の表面を大気に曝すと、イットリウムの三水素化物（及びマグネシウムの二水素化物）が脱水素化されることにより、イットリウムの二水素化物（及びマグネシウム）が生成し、反射状態に戻った。このように、水素感知素子２００は、水素化されていないイットリウムを含む状態（以下、「無水素化物状態」という）から、イットリウムの三水素化物を含む状態（以下、「三水素化物状態」という）、イットリウムの二水素化物を含む状態（以下、「二水素化物状態」という）に変化することを確認した。さらに、水素感知素子２００は、その後、イットリウムの二水素化物が水素化されること及びイットリウムの三水素化物が脱水素化されることにより、三水素化物状態と二水素化物状態の間で状態が可逆的に変化することを確認した。 The hydrogen sensing element 200 manufactured by the above procedure is in a reflective state with metallic luster, but the surface of the palladium thin film is diluted to 4% by volume with argon (hereinafter referred to as “hydrogen-containing gas”). ), The yttrium thin film or the yttrium-magnesium alloy thin film was hydrogenated to produce yttrium trihydride (and magnesium dihydride), which changed to a transparent state. In this state, when the surface of the palladium thin film is exposed to the atmosphere, yttrium trihydride (and magnesium dihydride) is dehydrogenated, and yttrium dihydride (and magnesium) is generated and reflected. Returned to the state. Thus, the hydrogen sensing element 200 is in a state containing yttrium trihydride (hereinafter referred to as “trihydride state”) from a state containing yttrium that is not hydrogenated (hereinafter referred to as “non-hydride state”). ) And a state containing yttrium dihydride (hereinafter referred to as “dihydride state”). In addition, the hydrogen sensing element 200 is then switched between a trihydride state and a dihydride state by hydrating the yttrium dihydride and dehydrogenating the yttrium trihydride. It was confirmed to change reversibly.
　［光学特性］
　分光光度計を用いて、水素感知素子２００の光学特性を評価した。具体的には、水素感知素子２００の無水素化物状態（反射状態）（Ｘ）、二水素化物状態（反射状態）（ＸＨ２）、三水素化物状態（透明状態）（ＸＨ３）の各状態の波長５５０ｎｍの光透過率（Ｔ）、透明基材４０の側からの波長５５０ｎｍの光反射率（Ｒｂ）を測定した。 [optical properties]
The optical characteristics of the hydrogen sensing element 200 were evaluated using a spectrophotometer. Specifically, each state of the hydrogen sensing element 200 in a non-hydride state (reflection state) (X), a dihydride state (reflection state) (XH 2 ), and a trihydride state (transparent state) (XH 3 ). The light transmittance (T) at a wavelength of 550 nm and the light reflectance (Rb) at a wavelength of 550 nm from the transparent substrate 40 side were measured.
　表２に、水素感知素子２００の光学特性の評価結果を示す。なお、二水素化物状態（ＸＨ２）と無水素化物状態（Ｘ）の光透過率の差（ΔＴ）、三水素化物状態（ＸＨ３）と二水素化物状態（ＸＨ２）の光透過率の差（ΔＴ）、無水素化物状態（Ｘ）と二水素化物状態（ＸＨ２）の光反射率の差（ΔＲｂ）、二水素化物状態（ＸＨ２）と三水素化物状態（ＸＨ３）の光反射率の差（ΔＲｂ）も併せて表２に示す。 Table 2 shows the evaluation results of the optical characteristics of the hydrogen sensing element 200. The difference in light transmittance between the dihydride state (XH 2 ) and the non-hydride state (X) (ΔT), the light transmittance of the trihydride state (XH 3 ) and the dihydride state (XH 2 ). Difference (ΔT), light reflectance difference (ΔRb) between non-hydride state (X) and dihydride state (XH 2 ), light in dihydride state (XH 2 ) and trihydride state (XH 3 ) The difference in reflectance (ΔRb) is also shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
 　表２から、実施例１－１～１－１８の水素感知素子２００は、無水素化物状態と二水素化物状態の光透過率の差（ΔＴ）及び／又は光反射率の差（ΔＲｂ）と、二水素化物状態と三水素化物状態の光透過率の差（ΔＴ）及び／又は光反射率の差（ΔＲｂ）が、それぞれ５％以上であることがわかる。このため、実施例１－１～１－１８の水素感知素子２００は、全く水素が漏洩していない状態、現時点では水素が漏洩していないが、過去に水素が漏洩した履歴を示す状態、現時点で水素が漏洩している状態を目視で判断することができる。
Figure JPOXMLDOC01-appb-T000002
 From Table 2, the hydrogen sensing elements 200 of Examples 1-1 to 1-18 show the difference in light transmittance (ΔT) and / or the difference in light reflectance (ΔRb) between the non-hydride state and the dihydride state. It can be seen that the difference in light transmittance (ΔT) and / or the difference in light reflectance (ΔRb) between the dihydride state and the trihydride state is 5% or more, respectively. For this reason, the hydrogen sensing elements 200 of Examples 1-1 to 1-18 are in a state in which no hydrogen leaks, no hydrogen leaks at the present time, but a state indicating a history of hydrogen leaks in the past, Thus, it is possible to visually determine the state of hydrogen leakage.
　［実施例２］
　本実施例では、イットリウム又はイットリウム・マグネシウム合金からなる水素感知層１０の代わりに、マグネシウム（又はイットリウム）からなる水素感知層１２及びイットリウム（又はイットリウム・マグネシウム合金）からなる水素感知層１４の積層体を用いた以外は、実施例１と同様にして、水素感知素子３００を作製した。すなわち、透明基材４０としての、ガラス基板上に、マグネシウム（又はイットリウム）からなる水素感知層１２、イットリウム（又はイットリウム・マグネシウム合金）からなる水素感知層１４、タンタルからなる拡散防止層５０、パラジウムからなる触媒層２０が順次積層されている水素感知素子３００を作製した。 [Example 2]
In this embodiment, instead of the hydrogen sensing layer 10 made of yttrium or yttrium-magnesium alloy, a laminate of a hydrogen sensing layer 12 made of magnesium (or yttrium) and a hydrogen sensing layer 14 made of yttrium (or yttrium-magnesium alloy). A hydrogen sensing element 300 was fabricated in the same manner as in Example 1 except that was used. That is, a hydrogen sensing layer 12 made of magnesium (or yttrium), a hydrogen sensing layer 14 made of yttrium (or yttrium-magnesium alloy), a diffusion prevention layer 50 made of tantalum, and palladium on a glass substrate as a transparent substrate 40. A hydrogen sensing element 300 in which the catalyst layers 20 made of the layers were sequentially stacked was manufactured.
　具体的には、厚さ１ｍｍのガラス基板（透明基材４０）上に、順次、膜厚を変化させたマグネシウム薄膜（又はイットリウム薄膜）（水素感知層１２）、膜厚を変化させたイットリウム薄膜（又は膜厚及び組成比を変化させたイットリウム・マグネシウム合金薄膜）（水素感知層１４）、膜厚２ｎｍのタンタル薄膜（拡散防止層５０）、膜厚３ｎｍのパラジウム薄膜（触媒層２０）を成膜した。 Specifically, a magnesium thin film (or yttrium thin film) (hydrogen sensing layer 12) whose thickness is changed sequentially on a glass substrate (transparent substrate 40) having a thickness of 1 mm, and an yttrium thin film whose thickness is changed. (Or an yttrium / magnesium alloy thin film with a changed film thickness and composition ratio) (hydrogen sensing layer 14), a tantalum thin film with a thickness of 2 nm (diffusion prevention layer 50), and a palladium thin film with a thickness of 3 nm (catalyst layer 20). Filmed.
　次に、水素感知層１２、１４、拡散防止層５０、触媒層２０の成膜条件について説明する。 Next, film forming conditions for the hydrogen sensing layers 12 and 14, the diffusion preventing layer 50, and the catalyst layer 20 will be described.
　水素感知層１２のマグネシウム薄膜（又はイットリウム薄膜）、水素感知層１４のイットリウム薄膜（又はイットリウム・マグネシウム合金薄膜）、拡散防止層５０のタンタル薄膜、触媒層２０のパラジウム薄膜を成膜する際には、多元成膜が可能なマグネトロンスパッタ装置を用いた。このとき、４つのスパッタ銃に、ターゲットとして、それぞれ金属イットリウム、金属マグネシウム、金属タンタル及び金属パラジウムをセットした。 When forming the magnesium thin film (or yttrium thin film) of the hydrogen sensing layer 12, the yttrium thin film (or yttrium-magnesium alloy thin film) of the hydrogen sensing layer 14, the tantalum thin film of the diffusion preventing layer 50, and the palladium thin film of the catalyst layer 20. A magnetron sputtering apparatus capable of multi-element film formation was used. At this time, metal yttrium, metal magnesium, metal tantalum, and metal palladium were set as targets on the four sputter guns, respectively.
　最初に、ガラス基板（透明基材４０）を洗浄した後、真空装置の中にガラス基板をセットしてチャンバー内を真空排気した。 First, after cleaning the glass substrate (transparent base material 40), the glass substrate was set in a vacuum apparatus and the chamber was evacuated.
　次に、金属マグネシウム（又は金属イットリウム）のターゲットに電力を印加して、マグネシウム薄膜（又はイットリウム薄膜）を成膜した。なお、イットリウム・マグネシウム合金薄膜を成膜する際には、金属イットリウムのターゲットと、金属マグネシウムのターゲットに同時に電力を印加した。このとき、スパッタ中のアルゴンガス圧を０．３Ｐａとし、直流スパッタ法により、それぞれのターゲットに所定の電力を所定の時間印加することでスパッタした。 Next, power was applied to the target of metal magnesium (or metal yttrium) to form a magnesium thin film (or yttrium thin film). When the yttrium / magnesium alloy thin film was formed, power was simultaneously applied to the metal yttrium target and the metal magnesium target. At this time, sputtering was performed by setting the argon gas pressure during sputtering to 0.3 Pa and applying a predetermined power to each target for a predetermined time by a direct current sputtering method.
　なお、それぞれのターゲットに印加する電力によって、成膜される薄膜（水素感知層１２、１４）の組成比を制御することができる。また、ターゲットに電力を印加する時間によって、成膜される薄膜（水素感知層１２、１４）の膜厚を制御することができる。 Note that the composition ratio of the thin films (hydrogen sensing layers 12 and 14) to be formed can be controlled by the power applied to each target. Moreover, the film thickness of the thin film (hydrogen sensing layers 12 and 14) to be formed can be controlled by the time during which power is applied to the target.
　本実施例では、膜厚が１２ｎｍ～２５ｎｍとなるように、マグネシウム薄膜（又はイットリウム薄膜）を成膜し、実施例２－１～２－５の水素感知素子３００における水素感知層１２とした。また、膜厚が８０ｎｍ～１５０ｎｍとなるように、イットリウム薄膜（又は組成式
　Ｙ０．５５Ｍｇ０．４５
で表わされるイットリウム・マグネシウム合金薄膜）を成膜し、実施例２－１～２－５の水素感知素子３００における水素感知層１４とした。 In this example, a magnesium thin film (or yttrium thin film) was formed so as to have a film thickness of 12 nm to 25 nm, and used as the hydrogen sensing layer 12 in the hydrogen sensing element 300 of Examples 2-1 to 2-5. In addition, an yttrium thin film (or composition formula Y 0.55 Mg 0.45 is used so that the film thickness is 80 nm to 150 nm.
And a hydrogen sensing layer 14 in the hydrogen sensing element 300 of Examples 2-1 to 2-5.
　ここで、ラザフォード後方散乱法により、金属イットリウムのターゲット及び金属マグネシウムのターゲットに印加する電力の比に対する、成膜されるイットリウム・マグネシウム合金の組成比のキャリブレーションカーブを作成した。次に、キャリブレーションカーブに基づいて、成膜されたイットリウム・マグネシウム合金薄膜の組成比を見積もった。 Here, a calibration curve of the composition ratio of the yttrium-magnesium alloy to be formed with respect to the ratio of the power applied to the metal yttrium target and the metal magnesium target was created by Rutherford backscattering method. Next, the composition ratio of the formed yttrium-magnesium alloy thin film was estimated based on the calibration curve.
　表３に、実施例２－１～２－５の水素感知素子３００における水素感知層１２及び水素感知層１４を成膜する際に、ターゲットに印加した電力及びその印加時間、水素感知層１２及び水素感知層１４の組成比及び膜厚を示す。 Table 3 shows the power applied to the target and the application time, the hydrogen sensing layer 12 and the hydrogen sensing layer 12 and the hydrogen sensing layer 14 in the hydrogen sensing elements 300 of Examples 2-1 to 2-5. The composition ratio and film thickness of the hydrogen sensing layer 14 are shown.
Figure JPOXMLDOC01-appb-T000003
 　次に、水素感知層１２及び水素感知層１４を成膜するのと同一の真空条件で、金属タンタルのターゲットに２０Ｗの電力を印加して、タンタル薄膜（拡散防止層５０）を成膜した後、金属パラジウムのターゲットに３０Ｗの電力を印加して、パラジウム薄膜（触媒層２０）を成膜し、水素感知素子３００を作製した。
Figure JPOXMLDOC01-appb-T000003
 Next, after forming a tantalum thin film (diffusion prevention layer 50) by applying a power of 20 W to a metal tantalum target under the same vacuum conditions as those for forming the hydrogen sensing layer 12 and the hydrogen sensing layer 14. A hydrogen thin film (catalyst layer 20) was formed by applying a power of 30 W to a metallic palladium target, and a hydrogen sensing element 300 was produced.
　以上の手順によって作製した水素感知素子３００は、金属光沢の反射状態になっているが、パラジウム薄膜の表面をアルゴンで４体積％に希釈した１気圧の水素含有ガスに曝すと、イットリウム薄膜、マグネシウム薄膜又はイットリウム・マグネシウム合金薄膜が水素化されることにより、イットリウムの三水素化物及びマグネシウムの二水素化物が生成し、透明状態に変化した。この状態で、パラジウム薄膜の表面を大気に曝すと、イットリウムの三水素化物及びマグネシウムの二水素化物が脱水素化されることにより、イットリウムの二水素化物及びマグネシウムが生成し、反射状態に戻った。このように、水素感知素子３００は、無水素化物状態から、三水素化物状態、二水素化物状態に変化することを確認した。さらに、水素感知素子３００は、その後、イットリウムの二水素化物が水素化されること及びイットリウムの三水素化物が脱水素化されることにより、三水素化物状態と二水素化物状態の間で状態が可逆的に変化することを確認した。 The hydrogen sensing element 300 manufactured by the above procedure is in a metallic glossy reflecting state, but when the surface of the palladium thin film is exposed to a hydrogen-containing gas at 1 atm diluted to 4% by volume with argon, the yttrium thin film, magnesium When the thin film or the yttrium-magnesium alloy thin film was hydrogenated, yttrium trihydride and magnesium dihydride were produced and changed to a transparent state. When the surface of the palladium thin film was exposed to the atmosphere in this state, yttrium trihydride and magnesium dihydride were dehydrogenated to produce yttrium dihydride and magnesium, which returned to the reflective state. . Thus, it was confirmed that the hydrogen sensing element 300 changes from the non-hydride state to the trihydride state and the dihydride state. In addition, the hydrogen sensing element 300 can then be switched between a trihydride state and a dihydride state by hydrogenating the yttrium dihydride and dehydrogenating the yttrium trihydride. It was confirmed to change reversibly.
　［光学特性］
　前述と同様にして、得られた水素感知素子３００の光学特性を評価した。 [optical properties]
In the same manner as described above, the optical characteristics of the obtained hydrogen sensing element 300 were evaluated.
　表４に、水素感知素子３００の光学特性の評価結果を示す。 Table 4 shows the evaluation results of the optical characteristics of the hydrogen sensing element 300.
Figure JPOXMLDOC01-appb-T000004
 　表４から、実施例２－１～２－５の水素感知素子３００は、無水素化物状態と二水素化物状態の光透過率の差（ΔＴ）及び／又は光反射率の差（ΔＲｂ）と、二水素化物状態と三水素化物状態の光透過率の差（ΔＴ）及び／又は光反射率の差（ΔＲｂ）が、それぞれ５％以上であることがわかる。このため、実施例２－１～２－５の水素感知素子３００は、全く水素が漏洩していない状態、現時点では水素が漏洩していないが、過去に水素が漏洩した履歴を示す状態、現時点で水素が漏洩している状態を目視で判断することができる。
Figure JPOXMLDOC01-appb-T000004
 From Table 4, the hydrogen sensing elements 300 of Examples 2-1 to 2-5 have the difference in light transmittance (ΔT) and / or the difference in light reflectance (ΔRb) between the non-hydride state and the dihydride state. It can be seen that the difference in light transmittance (ΔT) and / or the difference in light reflectance (ΔRb) between the dihydride state and the trihydride state is 5% or more, respectively. For this reason, the hydrogen sensing elements 300 of Examples 2-1 to 2-5 are in a state in which no hydrogen leaks, no hydrogen is leaking at the present time, but a state indicating a history of hydrogen leak in the past, Thus, it is possible to visually determine the state of hydrogen leakage.
　［実施例３］
　本実施例では、触媒層２０として、パラジウム・ルテニウム合金薄膜を用いた以外は、実施例１と同様にして、水素感知素子２００を作製した。すなわち、透明基材４０としての、ガラス基板上に、イットリウム・マグネシウム合金からなる水素感知層１０、タンタルからなる拡散防止層５０、パラジウム・ルテニウム合金からなる触媒層２０が順次積層されている水素感知素子２００を作製した。 [Example 3]
In this example, a hydrogen sensing element 200 was produced in the same manner as in Example 1 except that a palladium-ruthenium alloy thin film was used as the catalyst layer 20. That is, a hydrogen sensing layer in which a hydrogen sensing layer 10 made of yttrium / magnesium alloy, a diffusion prevention layer 50 made of tantalum, and a catalyst layer 20 made of palladium / ruthenium alloy are sequentially laminated on a glass substrate as a transparent substrate 40. Element 200 was produced.
　具体的には、厚さ１ｍｍのガラス基板（透明基材４０）上に、順次、厚さ１００ｎｍのイットリウム・マグネシウム合金薄膜（水素感知層１０）、厚さ２ｎｍのタンタル薄膜（拡散防止層５０）、組成比を変化させた厚さ３ｎｍのパラジウム・ルテニウム合金薄膜（触媒層２０）を成膜した。 Specifically, a yttrium / magnesium alloy thin film (hydrogen sensing layer 10) having a thickness of 100 nm and a tantalum thin film having a thickness of 2 nm (diffusion prevention layer 50) are sequentially formed on a glass substrate (transparent substrate 40) having a thickness of 1 mm. Then, a palladium-ruthenium alloy thin film (catalyst layer 20) having a thickness of 3 nm with a changed composition ratio was formed.
　次に、水素感知層１０、拡散防止層５０、触媒層２０の成膜条件について説明する。 Next, film forming conditions for the hydrogen sensing layer 10, the diffusion prevention layer 50, and the catalyst layer 20 will be described.
　水素感知層１０のイットリウム・マグネシウム合金薄膜、拡散防止層５０のタンタル薄膜、触媒層２０のパラジウム薄膜を成膜する際には、多元成膜が可能なマグネトロンスパッタ装置を用いた。このとき、５つのスパッタ銃に、ターゲットとして、それぞれ金属マグネシウム、金属イットリウム、金属タンタル、金属パラジウム及び金属ルテニウムをセットした。 When forming the yttrium / magnesium alloy thin film of the hydrogen sensing layer 10, the tantalum thin film of the diffusion preventing layer 50, and the palladium thin film of the catalyst layer 20, a magnetron sputtering apparatus capable of multi-element film formation was used. At this time, metal magnesium, metal yttrium, metal tantalum, metal palladium, and metal ruthenium were set as targets on the five sputter guns, respectively.
　最初に、ガラス基板（透明基材４０）を洗浄した後、真空装置の中にガラス基板をセットしてチャンバー内を真空排気した。 First, after cleaning the glass substrate (transparent base material 40), the glass substrate was set in a vacuum apparatus and the chamber was evacuated.
　次に、金属イットリウムと、金属マグネシウムのターゲットに、それぞれ６０Ｗ及び４．７Ｗの電力を同時に印加して、組成式
　Ｙ０．８５Ｍｇ０．１５
で表わされるイットリウム・マグネシウム合金薄膜（水素感知層１０）を成膜した。このとき、スパッタ中のアルゴンガス圧を０．３Ｐａとし、直流スパッタ法により、それぞれのターゲットに６３０秒間印加することでスパッタした。 Next, 60 W and 4.7 W of electric power were simultaneously applied to the metallic yttrium and metallic magnesium targets, respectively, so that the composition formula Y 0.85 Mg 0.15
An yttrium-magnesium alloy thin film (hydrogen sensing layer 10) represented by At this time, the argon gas pressure during sputtering was 0.3 Pa, and sputtering was performed by applying 630 seconds to each target by a direct current sputtering method.
　次に、水素感知層１０を成膜するのと同一の真空条件で、金属タンタルのターゲットに２０Ｗの電力を印加して、タンタル薄膜（拡散防止層５０）を成膜した。 Next, a tantalum thin film (diffusion prevention layer 50) was formed by applying a power of 20 W to a metal tantalum target under the same vacuum conditions as those for forming the hydrogen sensing layer 10.
　次に、金属パラジウムと、金属ルテニウムのターゲットに同時に電力を印加して、組成式
　Ｐｄ１－ｘＲｕｘ（ｘ＝０．２、０．４、０．６）
で表わされるパラジウム・ルテニウム合金薄膜（触媒層２０）を成膜し、実施例３－１～３－３の水素感知素子２００を作製した。 Next, power is simultaneously applied to the metallic palladium and metallic ruthenium targets, and the composition formula Pd 1-x Ru x (x = 0.2, 0.4, 0.6)
A palladium-ruthenium alloy thin film (catalyst layer 20) represented by the following formula was formed to produce hydrogen sensing elements 200 of Examples 3-1 to 3-3.
　表５に、実施例３－１～３－３の水素感知素子２００における触媒層２０を成膜する際に、ターゲットに印加した電力、触媒層２０の組成比及び膜厚を示す。 Table 5 shows the power applied to the target, the composition ratio and the film thickness of the catalyst layer 20 when forming the catalyst layer 20 in the hydrogen sensing elements 200 of Examples 3-1 to 3-3.
Figure JPOXMLDOC01-appb-T000005
 　以上の手順によって作製した水素感知素子２００は、金属光沢の反射状態になっているが、パラジウム・ルテニウム合金薄膜の表面をアルゴンで４体積％に希釈した１気圧の水素含有ガスに曝すと、イットリウム・マグネシウム合金薄膜が水素化されることにより、イットリウムの三水素化物及びマグネシウムの二水素化物が生成し、透明状態に変化した。この状態で、パラジウム・ルテニウム合金薄膜の表面を大気に曝すと、イットリウムの三水素化物及びマグネシウムの二水素化物が脱水素化されることにより、イットリウムの二水素化物及びマグネシウムが生成し、反射状態に戻った。このように、水素感知素子２００は、無水素化物状態から、三水素化物状態、二水素化物状態に変化することを確認した。さらに、水素感知素子２００は、その後、イットリウムの二水素化物が水素化されること及びイットリウムの三水素化物が脱水素化されることにより、三水素化物状態と二水素化物状態の間で状態が可逆的に変化することを確認した。
Figure JPOXMLDOC01-appb-T000005
 The hydrogen sensing element 200 manufactured by the above procedure is in a metallic glossy reflection state, but when the surface of the palladium-ruthenium alloy thin film is exposed to a hydrogen-containing gas at 1 atm diluted to 4% by volume with argon, it is yttrium. -When the magnesium alloy thin film was hydrogenated, yttrium trihydride and magnesium dihydride were produced and changed to a transparent state. In this state, when the surface of the palladium-ruthenium alloy thin film is exposed to the atmosphere, yttrium trihydride and magnesium dihydride are dehydrogenated to produce yttrium dihydride and magnesium, which is in a reflective state. Returned to. Thus, it was confirmed that the hydrogen sensing element 200 changes from the non-hydride state to the trihydride state and the dihydride state. In addition, the hydrogen sensing element 200 is then switched between a trihydride state and a dihydride state by hydrating the yttrium dihydride and dehydrogenating the yttrium trihydride. It was confirmed to change reversibly.
　［光学特性］
　前述と同様にして、得られた水素感知素子２００の光学特性を評価した。 [optical properties]
In the same manner as described above, the optical characteristics of the obtained hydrogen sensing element 200 were evaluated.
　表６に、水素感知素子２００の光学特性の評価結果を示す。 Table 6 shows the evaluation results of the optical characteristics of the hydrogen sensing element 200.
Figure JPOXMLDOC01-appb-T000006
 　表６から、実施例３－１～３－３の水素感知素子２００は、無水素化物状態と二水素化物状態の光透過率の差（ΔＴ）及び／又は光反射率の差（ΔＲｂ）と、二水素化物状態と三水素化物状態の光透過率の差（ΔＴ）及び／又は光反射率の差（ΔＲｂ）が、それぞれ５％以上であることがわかる。このため、実施例３－１～３－３の水素感知素子２００は、全く水素が漏洩していない状態、現時点では水素が漏洩していないが、過去に水素が漏洩した履歴を示す状態、現時点で水素が漏洩している状態を目視で判断することができる。
Figure JPOXMLDOC01-appb-T000006
 From Table 6, the hydrogen sensing elements 200 of Examples 3-1 to 3-3 have the difference in light transmittance (ΔT) and / or the difference in light reflectance (ΔRb) between the non-hydride state and the dihydride state. It can be seen that the difference in light transmittance (ΔT) and / or the difference in light reflectance (ΔRb) between the dihydride state and the trihydride state is 5% or more, respectively. For this reason, the hydrogen sensing elements 200 of Examples 3-1 to 3-3 are in a state in which no hydrogen is leaking, no hydrogen is leaking at the present time, but a state indicating a history of hydrogen leakage in the past, Thus, it is possible to visually determine the state of hydrogen leakage.
　本国際出願は、２０１６年９月２３日に出願された日本国特許出願２０１６－１８５５６４号に基づく優先権を主張するものであり、日本国特許出願２０１６－１８５５６４号の全内容を本国際出願に援用する。 This international application claims priority based on Japanese Patent Application No. 2016-185564 filed on September 23, 2016. The entire contents of Japanese Patent Application No. 2016-185564 are incorporated herein by reference. Incorporate.
　１０、１２、１４　　水素感知層
　２０　　触媒層
　３０　　保護層
　４０　　透明基材
　５０　　拡散防止層
　１００、２００、３００、４００、５００　　水素感知素子 10, 12, 14 Hydrogen sensing layer 20 Catalyst layer 30 Protective layer 40 Transparent substrate 50 Diffusion prevention layer 100, 200, 300, 400, 500 Hydrogen sensing element

Claims (11)

  1. 　透明基材上に、三水素化物による透明状態と二水素化物による反射状態との間で状態が可逆的に変化する金属を含む水素感知層と、前記水素感知層における水素化及び脱水素化を促進する金属又は合金を含む触媒層とを備え、
    　前記水素感知層に含まれる金属は、光学特性の異なる、無水素化物、二水素化物及び三水素化物の状態を有することを特徴とする水素感知素子。     A hydrogen sensing layer including a metal whose state changes reversibly between a transparent state by trihydride and a reflection state by dihydride on a transparent substrate, and hydrogenation and dehydrogenation in the hydrogen sensing layer A catalyst layer comprising a promoting metal or alloy,
    2. The hydrogen sensing element according to claim 1, wherein the metal contained in the hydrogen sensing layer has a non-hydride state, a dihydride state, and a trihydride state having different optical characteristics.
  2. 　前記水素感知層が希土類金属を含むことを特徴とする請求項１に記載の水素感知素子。 The hydrogen sensing element according to claim 1, wherein the hydrogen sensing layer includes a rare earth metal.
  3. 　前記水素感知層が、イットリウム又は一般式
    　Ｙ１－ｘＭｇｘ（０＜ｘ＜０．４）
    で表されるイットリウム・マグネシウム合金を含むことを特徴とする請求項２に記載の水素感知素子。     The hydrogen sensing layer is yttrium or a general formula Y 1-x Mg x (0 <x <0.4)
    The hydrogen sensing element according to claim 2, comprising an yttrium-magnesium alloy represented by:
  4. 　前記触媒層は、パラジウム、パラジウム合金、白金及び白金合金からなる群より選択される一種以上を含むことを特徴とする請求項１に記載の水素感知素子。 The hydrogen sensing element according to claim 1, wherein the catalyst layer includes one or more selected from the group consisting of palladium, a palladium alloy, platinum, and a platinum alloy.
  5. 　前記触媒層が、パラジウム又は一般式
    　Ｐｄ１－ｘＲｕｘ（０＜ｘ＜０．７）
    で表されるパラジウム・ルテニウム合金を含むことを特徴とする請求項４に記載の水素感知素子。     The catalyst layer is composed of palladium or the general formula Pd 1-x Ru x (0 <x <0.7)
    The hydrogen sensing element according to claim 4, comprising a palladium-ruthenium alloy represented by:
  6. 　前記水素感知層と前記触媒層との間に、拡散防止層をさらに備えることを特徴とする請求項１に記載の水素感知素子。 The hydrogen sensing element according to claim 1, further comprising a diffusion prevention layer between the hydrogen sensing layer and the catalyst layer.
  7. 　前記触媒層に対して、前記水素感知層とは反対側に、保護層をさらに備えることを特徴とする請求項１に記載の水素感知素子。 The hydrogen sensing element according to claim 1, further comprising a protective layer on the opposite side of the catalyst layer from the hydrogen sensing layer.
  8. 　前記水素感知層の厚さが、１０ｎｍ以上１０００ｎｍ以下であることを特徴とする請求項１に記載の水素感知素子。 The hydrogen sensing element according to claim 1, wherein the thickness of the hydrogen sensing layer is 10 nm or more and 1000 nm or less.
  9. 　前記触媒層の厚さが、１ｎｍ以上２０ｎｍ以下であることを特徴とする請求項１に記載の水素感知素子。 The hydrogen sensing element according to claim 1, wherein the thickness of the catalyst layer is 1 nm or more and 20 nm or less.
  10. 　前記透明基材は、ガラス基材又はプラスチック基材であることを特徴とする請求項１に記載の水素感知素子。 2. The hydrogen sensing element according to claim 1, wherein the transparent substrate is a glass substrate or a plastic substrate.
  11. 　請求項１に記載の水素感知素子を備えることを特徴とする水素センサー。 A hydrogen sensor comprising the hydrogen sensing element according to claim 1.
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