JP5052607B2 - Hydrogen sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a hydrogen sensor that detects hydrogen gas from a low concentration to a high concentration. Examples of the relatively low concentration of hydrogen gas include hydrogen gas leaking from various devices such as an automobile fuel cell and a household fuel cell. An example of the relatively high concentration of hydrogen gas is hydrogen gas in an apparatus that handles hydrogen gas. The present hydrogen sensor can be used for detecting these various concentrations of hydrogen gas. In addition to the above applications, the present hydrogen sensor can be used as a handy type hydrogen gas alarm, a stationary type hydrogen gas alarm, or a hydrogen sensor used in a hydrogen gas concentration meter.

  Hydrogen is expected to increase in demand in all industrial fields. Because of such a background, development of a hydrogen sensor used for hydrogen gas leak detection or hydrogen gas concentration measurement is underway.

  The sensor described in Patent Document 1 is a hydrogen sensor that detects hydrogen gas by measuring an electric resistance that changes when a rare earth metal film reacts with hydrogen. The rare earth metal film used in the hydrogen sensor repeatedly deteriorates by reacting with hydrogen gas, and as a result, the output of the hydrogen sensor gradually changes.

  In order to stabilize the output, it is necessary to increase the thickness of the hydrogen detection film from the conventional 30 nm to 50 to 100 nm, preferably 100 nm or more. When the thickness of the rare earth metal film is 100 nm or more, the durability improves as the film thickness increases, but on the other hand, initial characteristics such as sensitivity and responsiveness tend to decrease. The deterioration of the sensor is based on the fact that the volume of the rare earth metal increases when the resistance value changes by reacting with hydrogen.

  For the above reasons, durability, sensitivity and responsiveness are in a trade-off relationship. Therefore, it is difficult to improve both durability, sensitivity, and responsiveness only by adjusting the rare earth metal film thickness.

Paragraph 0061 of Patent Document 2 describes rare earth metals, alloys thereof, and alloys doped with rare earth metals as sensor materials. However, this dopant component (such as copper) is dispersed in rare earth metals at the atomic level, and no sensor material is disclosed in which the dopant component is dispersed in fine particles.
JP 2005-274559 A (Claims) Japanese translation of PCT publication No. 2002-535651 (paragraph 0061)

  The present invention has been made in view of the above circumstances. The object of the present invention is to suppress harmful effects caused by non-hydrogen components and deterioration due to hydrogen. Further, even if high concentration hydrogen gas is repeatedly detected, the detection output is long. An object of the present invention is to provide a hydrogen sensor that is stably maintained for a period of time and a method for manufacturing the same.

  The present invention is described below.

  [1] A substrate; a composite detection film formed on the substrate, the composite detection film comprising a rare earth metal layer and hydrogen-permeable metal particles finely dispersed in the rare earth metal layer; A protective film formed on the composite sensing film, the protective film comprising a ceramic material and a protective film made of hydrogen permeable metal particles dispersed in the ceramic material; Hydrogen sensor.

  [2] The hydrogen sensor according to [1], wherein the composite detection film has a thickness of 5 to 1000 nm and the protective film has a thickness of 5 to 100 nm.

  [3] The hydrogen sensor according to [1], wherein the rare earth metal is composed of at least one selected from the group consisting of yttrium (Y), cerium (Ce), and lanthanum (La).

  [4] The hydrogen sensor according to [1], wherein the content of the hydrogen permeable metal in the rare earth metal is 1 to 25% by mass.

  [5] The hydrogen permeable metal is at least one selected from the group consisting of palladium (Pd), platinum (Pt), niobium (Nb), vanadium (V), and tantalum (Ta). Hydrogen sensor.

  [6] The hydrogen sensor according to [1], wherein the ceramic material is a nitride or oxide of group IVa, Va, VIa.

[7] The ceramic material is AlN _X1 , AlO _X2 , SiN _X3 and SiO _X4 (where 0.5 ≦ X ₁ ≦ 1.0, 0.8 ≦ X ₂ ≦ 1.5, 0.7 ≦ X ₃ ≦ 1.3 The hydrogen sensor according to [1], which is composed of at least one selected from the group consisting of 1 ≦ X ₄ ≦ 2).

  [8] A composite sensing film in which hydrogen permeable metal particles are finely dispersed in a rare earth metal is formed on the surface of a substrate by simultaneously vapor-phase-growing or sputtering a hydrogen permeable metal and a rare earth metal, A protective film formed by dispersing hydrogen permeable metal particles in a ceramic material by simultaneously vapor-phase-growing or sputtering a hydrogen permeable metal and a ceramic material on the composite sensing film [1] Method of manufacturing hydrogen sensor.

  As described above, in order to improve the stability of the sensor output when hydrogen gas is repeatedly detected for a long period of time, the conventional hydrogen detection film is made thicker than 100 nm. In this case, the response time of the sensor becomes long. Since the hydrogen sensor of the present invention employs a composite detection film in which hydrogen-permeable metal particles are blended in the detection film, the response time is short and the sensitivity is high even if the thickness of the hydrogen detection film is 100 nm or more.

  Since this composite sensing film has a structure in which hydrogen permeable metal particles are dispersed in a rare earth metal, a gentle concentration gradient of the hydrogen permeable metal is formed in the vicinity of the interface between the protective film and the composite sensing film. As a result, the diffusion of the hydrogen permeable metal from the protective film to the composite detection film becomes difficult. Therefore, the degradation of the performance of the composite sensing film due to diffusion is reduced, and as a result, the hydrogen detection output of the sensor is less likely to decrease.

  Since the composite sensing film of the hydrogen sensor of the present invention has hydrogen permeable metal particles dispersed therein, the sensor response time is short. For this reason, the film thickness can be increased to increase the resistance to high concentration hydrogen and the repetitive stability.

  The protective film of the hydrogen sensor of the present invention has hydrogen permeable metal particles dispersed substantially uniformly in the ceramic material. When the hydrogen permeable metal particles absorb and release hydrogen, the volume of the hydrogen permeable metal particles increases or decreases, and the ceramic material with high rigidity receives the mechanical stress, and the ceramic material takes on the generated mechanical stress. As a result, the hydrogen permeable metal particles are less deteriorated due to hydrogenation, and the durability of the protective film is improved.

  The protective film used in the hydrogen sensor of the present invention is excellent in hydrogen gas permeability. However, gases other than hydrogen (for example, gases such as nitrogen and oxygen) cannot pass through this protective film. Hydrogen gas in the mixed gas selectively permeates the protective film and reaches the composite detection film. For this reason, this sensor has high selectivity for hydrogen gas.

  In the hydrogen sensor of the present invention, the protective film prevents permeation of non-hydrogen gases such as nitrogen, oxygen, and hydrocarbons. As a result, deterioration in performance as a sensor of the composite detection film due to non-hydrogen gas is prevented.

  The hydrogen sensor according to the present invention has a small contact area between the hydrogen permeable metal in the protective film and the rare earth metal constituting the composite sensing film, so that the diffusion of the hydrogen permeable metal to the rare earth metal can be reduced. For this reason, the time-dependent fall of the hydrogen detection performance of the composite detection film resulting from this diffusion can be prevented.

  Since the hydrogen sensor of the present invention can suppress the deterioration of the protective film due to the absorption and release of hydrogen gas, the protective film can be made extremely thin. As a result, hydrogen gas can easily pass through the protective film, and the hydrogen permeability equivalent to that of the conventional thick protective film made of Pd alone can be secured. In addition, since the protective film is thin, the amount of expensive hydrogen permeable metal used for manufacturing the protective film is reduced, and a hydrogen sensor can be manufactured at low cost.

  The composite sensing film used in the present invention can be easily produced by using a film forming process such as simultaneous sputtering of a rare earth metal and a hydrogen permeable metal.

FIG. 1 is a schematic sectional view showing an example of the hydrogen sensor of the present invention. FIG. 2 is an EDX analysis chart showing the Pd concentration in the composite sensing film of the hydrogen sensor of the present invention. FIG. 3 is a chart showing X-ray diffraction measurement results of the composite detection film of the hydrogen sensor of the present invention. FIG. 4 is a state diagram of the Y-Pd system. FIG. 5 is a graph showing the repetitive stability of the hydrogen sensor output of the present invention against high concentration hydrogen.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Hydrogen sensor 2 Board | substrate 4 Composite detection film | membrane 6 Rare earth metal layer 8, 13 Hydrogen permeable metal particle 10 Protective film 15 Ceramic material t4 Thickness of composite detection film t10 Thickness of protective film

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a conceptual diagram showing an example of the hydrogen sensor of the present invention. In FIG. 1, 100 is a hydrogen sensor, and 2 is a substrate. A composite detection film 4 is formed on the upper surface of the substrate 2. The composite sensing film 4 includes a rare earth metal layer 6 serving as a matrix and fine hydrogen permeable metal particles 8 dispersed in the rare earth metal layer 6. The hydrogen-permeable metal concentration in the composite sensing film is a hydrogen-permeable metal concentration that is smaller than the concentration range in which a solid solution is formed. Therefore, there is no doubt that the composite sensing film 4 has a structure in which fine hydrogen permeable metal particles 8 are dispersed in the rare earth metal layer 6. A protective film 10 is formed on the upper surface of the composite detection film 4. The protective film 10 is composed of a ceramic material 15 as a matrix and a large number of hydrogen permeable metal particles 13 dispersed substantially uniformly in the ceramic material 15.

(Composite detection film)
The composite detection film 4 is mainly composed of a rare earth metal having a hydrogen detection function. The rare earth metal is preferably at least one metal selected from the group consisting of yttrium, cerium, and lanthanum because of its excellent hydrogen detection capability. The composite detection film can be manufactured, for example, by forming a rare earth metal and a hydrogen permeable metal on a substrate by a vapor deposition method in a vacuum atmosphere. Alternatively, a composite detection film can be manufactured by forming a film on the surface of the substrate 2 by the simultaneous sputtering method of these metals in an inert gas atmosphere such as argon.

  The thickness of the composite detection film is preferably 5 to 1000 nm. When this thickness is less than 5 nm, the strength of the composite detection film may be insufficient. On the other hand, when the thickness exceeds 1000 nm, the manufacturing cost increases.

  The thickness of the composite detection film is preferably determined according to the purpose. When the hydrogen gas concentration to be measured is a relatively low concentration, for example, less than 1% by volume, particularly less than 5000 ppm, the preferred thickness is less than 100 nm, more preferably 50 nm or less, and particularly preferably 10-40 nm. In FIG. 1, t4 indicates the thickness of the composite detection film 4. As an application for detecting such a low concentration hydrogen gas, for example, a hydrogen gas leak detector can be cited.

  When the hydrogen gas to be measured has a relatively high concentration of, for example, 1% by volume or more, particularly 5% by volume or more, the preferable thickness of the composite detection film is 100 nm or more, more preferably 300 nm or more. As an application for detecting high-concentration hydrogen gas, for example, a hydrogen sensor for controlling the hydrogen gas concentration in the apparatus can be mentioned.

  The content of the hydrogen permeable metal in the rare earth metal is preferably 1 to 25% by mass, and more preferably 5 to 20% by mass. Within this range, the hydrogen permeable metal is dispersed in the form of particles in the rare earth metal.

(Protective film)
A protective film 10 shown in FIG. 1 is a thin film in which hydrogen permeable metal particles 13 are dispersed in a ceramic material 15. The content ratio of the hydrogen permeable metal particles in the protective film is preferably 30 to 70% by mass, more preferably 35 to 65% by mass, and particularly preferably 40 to 60% by mass. When the content ratio is less than 30% by mass, the amount of hydrogen gas that permeates the protective film is insufficient, and the performance of supplying hydrogen gas to the composite detection film becomes insufficient. On the other hand, when the content ratio exceeds 70% by mass, the deterioration of the protective film accompanying hydrogenation of the protective film becomes significant. Furthermore, the diffusion transfer of the hydrogen permeable metal to the composite detection film becomes remarkable, and as a result, the hydrogen detection performance of the composite detection film is significantly lowered.

  If the protective film in which the content ratio of the hydrogen permeable metal particles exceeds 70% by mass is thinned, the mechanical strength of the protective film becomes insufficient. For this reason, it becomes difficult to produce a highly durable protective film having a thickness of 5 to 40 nm.

  The particle diameter of the hydrogen permeable metal particles 13 is 1 to 10 nm, preferably 2 to 6 nm. Moreover, the particle diameter is smaller than the thickness t10 of the protective film 10.

  The hydrogen permeable metal particles constituting the protective film are made of at least one metal selected from the group consisting of palladium (Pd), platinum (Pt), niobium (Nb), vanadium (V) and tantalum (Ta). Particles are preferred. The hydrogen permeable metal particles contained in the protective film and the hydrogen permeable metal particles contained in the composite detection film are preferably the same element. The hydrogen permeable metal particles may be an alloy of the above metals. Of these, Pd and Pd alloys are particularly preferred.

  The hydrogen permeable metal particles 13 may be dispersed in the ceramic material as particles of a single metal element, or may be dispersed as particles of the alloy. As an alloy of a hydrogen permeable metal, an alloy conventionally used for a hydrogen permeable membrane can be used. For example, examples of alloy elements include calcium, iron, copper, vanadium, nickel, titanium, chromium, and zirconium.

  The protective film can be formed on the surface of the composite detection film using a method in which a ceramic material and a hydrogen permeable metal are simultaneously vapor-grown or a method in which sputtering is performed simultaneously.

If the ceramic material is a protective film which is AlNx ₁ uses the Al metal and the hydrogen permeable metal film-forming material, forming a film under an atmosphere of nitrogen gas. If the ceramic material is a protective film which is AlOx ₂ uses the Al metal and the hydrogen permeable metal film-forming material, forming a film in an atmosphere of oxygen gas. When forming a protective film in which the ceramic material is SiNx ₃ or SiOx ₄ , the film is formed in the same manner as in the case of AlNx ₁ and AlOx ₂ except that silicon is used instead of Al metal as the film forming material.

In forming the protective film, for example, a composite target in which a Pd chip having a smaller area than the aluminum target is placed on the aluminum target is used. First, the substrate on which the detection film is formed is attached above the composite target with the detection film and the composite target facing each other. By sputtering the composite target in this state, a protective film can be formed to cover the detection film formed on the substrate surface. Sputtering is performed in a mixed gas atmosphere of argon and nitrogen. By this method, a protective film made of a mixture (dispersion) of Pd (hydrogen permeable metal) and AlN _X1 (ceramic material) can be formed on the upper surface of the composite detection film.

  The thickness of the protective film is preferably 5 to 100 nm, more preferably 10 to 60 nm, and particularly preferably 15 to 30 nm. When the thickness of the protective film is less than 5 nm, it may not be possible to sufficiently prevent non-hydrogen components such as nitrogen, oxygen, ammonia, and hydrocarbons that are harmful to the composite detection film from reaching the detection film. On the other hand, when the thickness exceeds 100 nm, hydrogen permeability is insufficient. As a result, the measurement accuracy of the hydrogen gas concentration may be insufficient. Alternatively, the response time may be long. Furthermore, the effect of reducing the manufacturing cost is reduced.

  Since Pd has a high separation ability between hydrogen gas and other gases, the thickness of the protective film can be particularly reduced when Pd is used as the hydrogen permeable metal.

  The protective film may be composed of one layer or may be composed of two or more layers. When the protective film is composed of two or more layers, the thickness of each layer is preferably 4 to 40 nm, and more preferably 5 to 20 nm. When the protective film has two or more layers, the composition may be the same or different.

When the protective film is composed of two layers, a protective film in which the first layer close to the detection film is Pd + AlNx ₁ and the second layer far from the detection film is Pd + AlOx ₂ can be exemplified. By providing the Pd + AlOx ₂ film in contact with the outside world, it is possible to improve the water vapor resistance. Furthermore, when forming a Pd + AlOx ₂ film, it is necessary to form the film in an oxygen atmosphere. However, when Pd + AlOx ₂ is formed directly on the hydrogen detection film, the detection film is oxidized and deteriorated. Therefore, when the protective film having the two-layer structure is formed, it is preferable to form the two-layer protective film in the above order.

(Ceramic materials)
As shown in FIG. 1, the matrix layer in which the hydrogen permeable metal particles are dispersed is composed of a ceramic material 15. As the ceramic material, aluminum (Al) or silicon (Si) nitride and / or oxide, or rare earth metal silicide is preferable. Among these ceramic materials, AlNx ₁ , AlOx ₂ , SiNx ₃ , SiOx ₄ (however, 0.5 ≦ x ₁ ≦ _1, 0.8 ≦ x ₂ ≦ 1.5, 0.7 ≦ x ₃ ≦ 1. 3, 1 ≦ x ₄ ≦ 2) is preferred.

Other ceramic materials are preferably nitrides or oxides of group IVa, Va, or VIa metal elements. Specific examples of the ceramic material include TiN _0.3-3.5 , ZrN _0.3-2.5 , HfN _0.3-2.5 , VN _0.3-2.5 , NbN _{0.3-2. .5} , nitrides such as TaN _0.8-2 , CrN _0.5-3 , MoN _0.5-3 , WN _0.5-3 , TiO _0.5-3 , ZrO _1-3 , HfO _{1 -3} , VO _0.5-3 , NbO _0.5-3 , TaO _1-3 , CrO _0.5-5 , MoO _1-4 , and WO _1-4 .

Among these, as nitrides, TaN _0.8-2 , TiN _0.3-2.5 , ZrN _0.3-2.5 , HfN _0.3-2.5 , WN _0.5-3 Etc. are preferred. As the oxide, HfO _1-3 , TiO _0.5-3 , TaO _1-3 , WO _{1-4 and the} like are preferable.

  Examples of rare earth metal silicides include silicides such as yttrium (Y) and lanthanum (La).

Among these ceramic materials, since AlNx ₁ has high hardness and high strength, it is possible to effectively suppress powdering of the hydrogen permeable metal when hydrogen permeable metal particles in the protective film are hydrogenated, Particularly preferred.

(Method for manufacturing hydrogen sensor)
In the hydrogen sensor of the present invention, the composite sensing film 4 is formed on at least one surface of the substrate by vapor deposition or sputtering, and then the protective film 10 is formed on the upper surface of the composite sensing film 4 by vapor deposition or sputtering. It can be manufactured by forming a film.

  As the substrate, a glass plate, a ceramic plate, sapphire, quartz crystal, silicon, silicon nitride ceramics, or the like can be used. It is preferable to provide a heater on the surface opposite to the sensor forming surface of the substrate. The heater is preferably a thin film resistor in which a predetermined pattern is formed on the substrate surface with a thin film of platinum, ruthenium oxide, silver-palladium alloy or the like.

  In FIG. 1, for simplicity of explanation, the side surface of the composite detection film 4 is shown exposed to the outside world. However, in practice, a certain shielding layer is formed and blocked from the outside world. Preferably it is. Alternatively, it is preferable that the side surface is also covered with a protective layer.

  Next, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

Example 1
The hydrogen sensor shown in FIG. 1 was produced using a sputtering apparatus having a biaxial or more cathode. Y was used for the rare earth metal target and Pd was used for the hydrogen permeable metal target. Argon gas is introduced into the apparatus, the pressure is 9.3 × 10 ⁻¹ Pa, the substrate temperature is kept at room temperature, and two targets are simultaneously sputtered to form a composite detection film 4 having a thickness of 1 μm on the quartz substrate 2. did. The sputtering time was 1430 seconds. The thickness of the quartz substrate 2 was 1.5 mm. The ratio of the sputtering output of Y and the sputtering output of Pd during sputtering was set to 15: 2. In this case, the content ratio of Pd in Y was 15% by mass. The film thickness of the detection film 4 was measured using a stylus type surface shape roughness measuring instrument.

Next, palladium and tantalum were used as targets. Argon gas and nitrogen gas (volume ratio 40:60 Pa) were introduced into the apparatus, and sputtering was performed for 1 minute at a pressure of 9.3 × 10 ⁻¹ Pa at room temperature. As a result, a protective film having a thickness of 20 nm was formed on the upper surface of the composite detection film. The formed protective film was a TaN matrix in which Pd was uniformly dispersed with a particle diameter of 2 to 6 nm. The Pd content in the protective film was 45% by mass.

  FIG. 2 shows an analysis result obtained by analyzing the Pd concentration in the composite detection film by EDX using the hydrogen sensor of the present invention produced in Example 1 as a sample.

FIG. 3 is a chart obtained by X-ray diffraction measurement of the composite detection film using the hydrogen sensor of the present invention produced in Example 1 as a sample. The peak of Pd was not observed, and it was found to be mainly Y polycrystal. As a result of X-ray diffraction measurement of the hydrogenated composite sensing film, a peak of YH ₂ (Y dihydride) was observed.

  FIG. 4 shows a state diagram of Y and Pd. From EDX analysis, X-ray analysis measurement, and phase diagram, it can be considered that a structure in which Pd particles are finely dispersed in Y is formed. In order to obtain such a structure, it can be seen from the phase diagram that the Pd concentration is limited to 1 to 25% by mass.

Example 2
A hydrogen sensor was produced in the same manner as in Example 1. However, a detection film having a thickness of 144 nm was obtained with a simultaneous sputtering time of 205 seconds.

  Table 1 shows the measurement results of the response time of the sensor produced in Example 2 when it was in contact with 100% hydrogen gas. In this measurement, the hydrogen sensor element was kept at 150 ° C., and hydrogen gas having a concentration of 100% was blown onto the sensor with a nozzle, and the response time was measured.

  FIG. 5 shows a set of a mixed gas of 79% by volume of nitrogen and 21% by volume of oxygen (0% by volume of hydrogen) and a gas having a hydrogen concentration of 100% by volume. The test results after repeated exposure are shown. This test was conducted with the aim of confirming the repeated stability of the hydrogen sensor output for high concentrations of hydrogen. From the test results, it was confirmed that this composite sensing film had durability.

Example 3
A hydrogen sensor was produced in the same manner as in Example 1. However, the co-sputtering time of the detection film was 44 seconds, and a detection film with a thickness of 30 nm was obtained.

Comparative Example 1
A Y single-layer film having a thickness of 100 nm was used as a detection film, and the same protective film as the protective film of Example 1 was formed on the upper surface of the detection film. The other operations were the same as in Example 1.

Comparative Example 2
The same hydrogen sensor as that of Comparative Example 1 was produced except that the thickness of the detection film was 1000 nm.

  The sensitivity and response time of the sensor of Example 2 and the sensor of Comparative Example 1 were compared. As shown in Table 1, the response time was the rare earth metal single layer film (100 nm) of Comparative Example 1> the composite detection film (144 nm) of Example 2.

本センサーにおいては、複合検知膜に水素透過性金属が配合されているので、希土類金属内部の水素の拡散が迅速になる。その為、膜全体に水素が容易に拡散する。その結果、水素に対する応答時間の減少、及び複合検知膜が初期状態へ戻る脱水素時間の減少が達成される。

In this sensor, since hydrogen permeable metal is blended in the composite sensing film, the diffusion of hydrogen inside the rare earth metal is accelerated. Therefore, hydrogen easily diffuses throughout the film. As a result, a reduction in response time to hydrogen and a reduction in dehydrogenation time for the composite sensing membrane to return to the initial state are achieved.

  Even when the thickness of the hydrogen detection part is increased to 100 nm or more in order to increase the durability, the composite detection film according to the present invention contains a hydrogen permeable metal, so that the initial characteristics such as response time are reduced. Can be suppressed.

Claims (8)

A composite sensing film formed on the substrate, the composite sensing film comprising a rare earth metal layer and hydrogen permeable metal particles finely dispersed in the rare earth metal layer; and the composite A hydrogen sensor, comprising: a protective film formed on a detection film, the protective film comprising a ceramic material and a hydrogen permeable metal particle dispersed in the ceramic material. The hydrogen sensor according to claim 1, wherein the composite sensing film has a thickness of 5 to 1000 nm and the protective film has a thickness of 5 to 100 nm. The hydrogen sensor according to claim 1, wherein the rare earth metal is composed of at least one selected from the group consisting of yttrium (Y), cerium (Ce), and lanthanum (La). The hydrogen sensor according to claim 1, wherein the content ratio of the hydrogen-permeable metal in the rare earth metal is 1 to 25% by mass. 2. The hydrogen sensor according to claim 1, wherein the hydrogen permeable metal is at least one selected from the group consisting of palladium (Pd), platinum (Pt), niobium (Nb), vanadium (V), and tantalum (Ta). 2. The hydrogen sensor according to claim 1, wherein the ceramic material is a nitride or oxide of group IVa, Va, VIa elements. The ceramic material is AlN _X1 , AlO _X2 , SiN _X3 and SiO _X4 (however, 0.5 ≦ X ₁ ≦ 1.0, 0.8 ≦ X ₂ ≦ 1.5, 0.7 ≦ X ₃ ≦ 1.3 The hydrogen sensor according to claim 1, comprising at least one selected from the group consisting of 1 ≦ X ₄ ≦ 2). By simultaneously vapor-phase-growing or sputtering a hydrogen permeable metal and a rare earth metal, a composite sensing film in which hydrogen permeable metal particles are finely dispersed in the rare earth metal is formed on the surface of the substrate, and then the composite sensing film 2. The hydrogen sensor according to claim 1, wherein a protective film is formed by dispersing hydrogen permeable metal particles in a ceramic material by simultaneously vapor-phase-growing or sputtering a hydrogen permeable metal and a ceramic material on the substrate. Manufacturing method.

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