JP2015148563A - hydrogen sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a more practical hydrogen sensor.SOLUTION: A hydrogen sensor comprises: a proton conductor having a perovskite crystal structure represented by a composition formula ABB'O; a detection electrode that is disposed in contact with the proton conductor and has a catalytic action in which hydrogen gas is transmitted, hydrogen is oxidized, and protons are generated; and a reference electrode disposed in contact with the proton conductor. The element of A is an alkaline earth metal, and the value of a showing a composition ratio of the element is included in the range of 0.4<a<0.9. The element of B' is trivalent elements in groups 3 and 13, and the value of x showing a composition ratio of the element is included in the range of 0.2<x<0.6.

Description

  The present disclosure relates to hydrogen sensors. The present disclosure particularly relates to a hydrogen sensor comprising a proton conductor.

Among the proton conductive solid electrolytes, a number of perovskite proton conductive oxides represented by the composition formula AB _1-x B ′ _x O _3-δ have been reported. Here, A is an alkaline earth metal, B is a tetravalent group 4 transition metal element or a tetravalent lanthanoid element Ce, B ′ is a trivalent group 3 or group 13 element, and O is oxygen. x is the composition ratio of the B ′ element that replaces the B element, and satisfies 0 <x <1.0. δ is a value representing oxygen deficiency or oxygen excess. The basic configuration of the perovskite structure will be briefly described later with reference to the drawings.

Non-Patent Document 1 discloses an oxide having a perovskite structure. The oxide of Non-Patent Document 1 has the composition formula BaZr _1-x Y _x O _3-δ or the composition formula BaCe _1-x Y _x O _3-δ . Here, A is barium (Ba), B is Zr or Ce, and B ′ is an oxide of Y.

Patent Document 1 discloses a proton conductive membrane having a perovskite structure. The proton conductive membrane of Patent Document 1 has the chemical formula AL _1-X M _X O _3-α . A is an alkaline earth metal. L is one or more elements selected from cerium, titanium, zirconium and hafnium. M is one or more elements selected from neodymium, gallium, aluminum, yttrium, indium, ytterbium, scandium, gadolinium, samarium and praseodymium. Here, X is the composition ratio of the M element that replaces the L element, and α is the atomic ratio of oxygen deficiency. In the proton conductive membrane of Patent Document 1, 0.05 <X <0.35 and 0.15 <α <1.00.

  The proton conductor is used for a hydrogen sensor, for example. Patent Document 2 discloses a hydrogen sensor including a proton conductor made of tetravalent barium metal acid to which yttria is added.

JP 2008-23404 A JP 2007-066885 A

Nature materials Vol9 (October 2010) 846-852 Solid State Ionics 110 (1998) 103-110

  There is a need to provide more practical hydrogen sensors.

One aspect of the hydrogen sensor of the present disclosure is disposed in contact with a proton conductor having a perovskite crystal structure represented by _a composition formula A _a B _1-x B ′ _x O _3−δ , A detection electrode that has a catalytic action to transmit hydrogen gas and oxidize hydrogen to generate protons, and a reference electrode disposed in contact with the proton conductor, and the A is made of an alkaline earth metal At least one selected, B is a tetravalent group 4 transition metal or Ce, B ′ is a trivalent group 3 or group 13 element, and 0.4 <a < 0.9 and 0.2 <x <0.6.

  According to the embodiment of the present disclosure, a more practical hydrogen sensor is provided.

It is a diagram showing a general perovskite structure represented by the composition formula ABO _3. 3 is a graph showing proton conductivity in a temperature range of 100 ° C. to 600 ° C. in Example 1. FIG. It is a typical sectional view showing an example of a hydrogen sensor by an embodiment of this indication. It is a typical sectional view showing other examples of a hydrogen sensor by an embodiment of this indication.

(About hydrogen sensor)
A conventional hydrogen sensor utilizes changes in physical properties of palladium, which is a hydrogen storage metal, or a hydrogen storage alloy containing it. Specifically, the hydrogen storage metal or hydrogen storage alloy measures the electrical resistivity, light transmittance, light reflectance, etc. of the metal or alloy produced by storing or releasing hydrogen contained in the gas to be detected, Changes in the physical property values are converted to hydrogen concentration. Since the physical properties of the hydrogen storage metal and hydrogen storage alloy change depending on the temperature, it is difficult to accurately measure the hydrogen concentration in a wide temperature range.

  On the other hand, the hydrogen sensor disclosed in Patent Document 2 includes a detection electrode, a proton conductor, and a reference electrode, and the detection electrode is disposed on the measured gas side. Since a current using protons as carriers flows according to the concentration of hydrogen contained in the gas to be measured, the hydrogen concentration can be measured based on the value of the current flowing between the detection electrode and the reference electrode.

  However, according to the hydrogen sensor disclosed in Patent Document 2, the proton conductor has a high proton conductivity at about 600 ° C. For this reason, it is necessary to operate at a high temperature of about 600 ° C.

  Further, a proton conductive solid polymer membrane is known as a proton conductor, and it is conceivable to use this proton conductive solid polymer membrane for a hydrogen sensor. However, in order for the proton conducting solid polymer membrane to exhibit proton conductivity, it is necessary to wet the membrane itself. For this reason, in the hydrogen sensor using the proton conductive solid polymer membrane, the temperature at which the moisture to be wet is not frozen and the temperature at which the proton conductive solid polymer membrane does not change (generally lower than 120 ° C.). It is considered necessary to operate at a relatively narrow temperature range.

  The present inventor has found a proton conductor that maintains high proton conductivity even in a temperature range of 100 ° C. or more and 500 ° C. or less by intensive research, and conceived a hydrogen sensor using such a proton conductor. did.

  The outline of one embodiment of the present invention is as follows.

A hydrogen sensor which is one embodiment of the present invention is disposed in contact with a proton conductor having a perovskite crystal structure represented by _a composition formula A _a B _1-x B ′ _x O _3-δ and the proton conductor. A detection electrode having a catalytic action of permeating hydrogen gas and oxidizing hydrogen to generate protons, and a reference electrode disposed in contact with the proton conductor, wherein A is an alkaline earth metal At least one selected, B is a tetravalent group 4 transition metal or Ce, B ′ is a trivalent group 3 or group 13 element, and 0.4 <a < 0.9 and 0.2 <x <0.6.

  The A may be at least one selected from Ba and Sr. B may be Zr. B ′ may be Y or In.

  The value of a may be 0.4 <a <0.8. The value of x may be 0.3 <x <0.6.

  The value of a may be 0.4 <a <0.8. The value of x may be 0.4 <x <0.6.

  The value of a may be 0.4 <a <0.6. The value of x may be 0.4 <x <0.6.

  The value of a may be 0.4 <a <0.5. The value of x may be 0.4 <x <0.6.

  The proton conduction activation energy of the proton conductor in a temperature range of 100 ° C. or more and 500 ° C. or less may be 0.1 eV or less.

  The relationship of 0.21 ≦ x ≦ 0.58, a ≧ −0.054x + 0.441, and a ≦ −0.027x + 0.886 may be established.

  The proton conductor may be composed of a single phase having a substantially uniform composition and crystal structure.

  The detection electrode may include a metal or alloy having at least one selected from the group consisting of Ti, Zr, Ta, Zn, Cr, Fe, Co, Al, Ni, Sn, and V.

  The detection electrode may include an oxide having at least one selected from the group consisting of Ti, Zr, Ta, Zn, Cr, Fe, Co, Al, Ni, Sn, and V.

  The detection electrode is at least one selected from the group consisting of Ti, Zr, Ta, Zn, Cr, Fe, Co, Al, Ni, Sn and V, and at least one selected from the group consisting of B, C and N It may contain an intermetallic compound.

  The reference electrode may have a structure that does not transmit hydrogen gas.

  The reference electrode may include a metal having a lower ionization tendency than hydrogen or an alloy including a metal having a lower ionization tendency than hydrogen.

  The reference electrode may include a metal or alloy having at least one selected from the group consisting of Cu, Ir, Pt, and Au.

  The reference electrode may include an intermetallic compound having at least one selected from the group consisting of Cu, Ir, Pt, and Au and at least one selected from the group consisting of B, C, and N.

  Before describing an embodiment of a hydrogen sensor according to the present disclosure, a proton conductive oxide used in the hydrogen sensor will be described. The proton conductive oxide described below is a perovskite proton conductor having a perovskite structure, and has high proton conductivity even in a temperature range of 100 ° C. or higher and 500 ° C. or lower.

(Perovskite structure)
First, the basic configuration of the perovskite structure will be briefly described with reference to FIG. A typical perovskite structure is composed of elements A, B, and O, as illustrated in FIG. 1, and is represented by a composition formula ABO ₃ . Here, A is an element that can be a divalent cation, B is an element that can be a tetravalent cation, and O is oxygen. A unit cell of a crystal having a perovskite structure typically has a shape close to a cube. As shown in the figure, ions of the element A are located at the eight vertices of the unit cell. On the other hand, oxygen O ions are located at the centers of the six faces of the unit cell. In addition, an element B ion is located near the center of the unit cell. The positions occupied by the elements A, B, and O may be referred to as A site, B site, and O site, respectively.

The above structure is a basic structure of the perovskite crystal, and some of the elements A, B, and O may be missing, excessive, or substituted with other elements. For example, a crystal in which an element B ′ other than the element B is located at the B site is a perovskite crystal represented by a composition formula AB _(1-x) B ′ _x O ₃ . Here, x is a composition ratio (mole fraction) of B ′, and may be called a substitution rate. When such element substitution, deficiency, or excess occurs, the structure of the unit cell can be distorted or deformed from the cube. Perovskite crystals are not limited to “cubic crystals”, but broadly include crystals that have phase transitions to “rhombic crystals” and “tetragonal crystals” with lower symmetry.

(Knowledge of the present inventors)
In a conventional proton conductive oxide having a perovskite structure, when B, which is a tetravalent element, is substituted with B ′, which is a trivalent element, oxygen vacancies are generated in the proton conductive oxide. In other words, if a part of the tetravalent cation is replaced with a trivalent cation, the total positive charge of the cation is reduced, so that it is a divalent anion due to charge compensation that maintains electrical neutrality. It is considered that the composition ratio of oxygen ions decreases and oxygen deficiency occurs. In the proton conductive oxide having such a composition, proton conductive carriers are introduced into the proton conductive oxide by introducing water molecules (H ₂ O) into the oxygen deficient position (O site). It is believed that.

  In conventional proton-conductive oxides, it is considered that proton conductivity is expressed by protons hopping around oxygen atoms. In this case, the temperature dependence of proton conductivity is a thermal activation type having an activation energy of about 0.4 to 1.0 eV. Therefore, proton conductivity decreases exponentially with decreasing temperature.

In order to maintain a high proton conductivity of 10 ⁻¹ S / cm (Siemens / centimeter) or more even in a temperature range of 100 ° C. or more and 500 ° C. or less, the proton conductivity is activated. It is desired to suppress a decrease in proton conductivity associated with a decrease in temperature by setting the energy to 0.1 eV or less.

  The inventors of the present invention have tried to increase the concentration or density of proton carriers by increasing the solid solution amount (substitution amount) of the trivalent element B ′ and to create a state in which protons can move more easily than conventional hopping. It was. However, in the conventional perovskite proton conductive oxide, the upper limit of the composition ratio of the B ′ element is about 0.2, and the oxygen deficiency has an upper limit.

  As a method for introducing more proton carriers, the present inventor has focused on the possibility of obtaining the same effect as increasing the composition ratio of the B ′ element by decreasing the composition ratio of the A element. However, as described in Non-Patent Document 2, when the composition ratio a of the element A decreases from 1, the proton conductivity decreases. The reason for this is considered to be that a component having no proton conductivity (heterophase: a phase not having a perovskite crystal structure) is generated in the crystal structure.

  Therefore, the present inventors reduced the composition ratio a of the element A from 1 in the chemical composition region, which is conventionally unsuitable for proton conduction, and set the composition ratio x of the B ′ element to 0. It has been found that the activation energy can be lowered while maintaining a single-phase perovskite structure unexpectedly by making it higher than 2. As a result, a perovskite proton conductive oxide having high proton conductivity was obtained.

(Proton conductive oxide)
Hereinafter, the proton conductive oxide used in the hydrogen sensor according to the embodiment of the present disclosure will be described.

The proton conductive oxide used in the hydrogen sensor according to the embodiment of the present disclosure is a metal oxide having a perovskite crystal structure represented by _a composition formula A _a B _1−x B ′ _x O _3−δ . The element A is an alkaline earth metal. The value of a indicating the composition ratio of the A element is the atomic ratio of the A element when the sum of B and B ′ is 1, and is in the range of 0.4 <a <0.9. The element B ′ is a trivalent group 3 or group 13 element. The value of x indicating the composition ratio of the B element is in the range of 0.2 <x <0.6. The composition ratio will be described in detail in Examples described later. Note that δ represents oxygen deficiency or oxygen excess as described above. In the following examples, the value of δ is not measured, but oxygen deficiency occurs, and it is considered that the relationship 0 <δ <3.0 is satisfied.

<Element of A>
An example of the element A is an alkaline earth metal. The perovskite structure is stable. A specific example of the element A is at least one element selected from barium (Ba), strontium (Sr), calcium (Ca), and magnesium (Mg). A proton conductive oxide in which the element A is at least one selected from barium (Ba) and strontium (Sr) is desirable because it has high proton conductivity. The element A includes at least barium (Ba) and may include at least one element selected from strontium (Sr), calcium (Ca), and magnesium (Mg). For example, elements A is _{Ba y A '1-y (} 0 <y ≦ 1).

  If the element of A is an alkaline earth metal element that is divalent, by reducing the composition ratio of the element of A, an effect similar to the increase of the composition ratio of the element of B ′ can be obtained, and oxygen deficiency can be reduced. This is likely to occur, and the effect of increasing the proton carrier concentration is obtained.

<B element>
An example of the element of B is a group 4 element. Specific examples of the element of B are zirconium (Zr), cerium (Ce), titanium (Ti), or hafnium (Hf). When the element of B is zirconium (Zr), the perovskite structure becomes stable, so that generation of a tissue component having no proton conductivity is reduced. As a result, a proton conductive oxide having high proton conductivity is obtained, which is desirable.

  If the element of B is tetravalent group 4 zirconium (Zr), titanium (Ti), hafnium (Hf) and cerium (Ce), the perovskite structure becomes stable, and the tissue component has no proton conductivity Is reduced, and high proton conductivity is obtained.

<B 'element>
The element of B ′ is a group 3 element, a group 13 element, or a trivalent lanthanoid. The element B ′ is preferably a group 3 element, a group 13 element, or a trivalent lanthanoid having an ionic radius larger than 0.5 Å and smaller than 1.02 Å. As a result, even when the value of x is larger than 0.2, a proton conducting oxide having a stable perovskite structure and high proton conductivity can be obtained. A proton conductive oxide in which the element of B ′ is yttrium (Y) or indium (In) is more desirable because the perovskite structure is stable and it has high proton conductivity.

  The element of B ′ is a trivalent group 3 element, a trivalent group 13 element, or a trivalent lanthanoid element that has an ionic radius greater than 0.5 Å and less than 1.02 Å. For example, even when the value of x is larger than 0.2, oxygen deficiency is likely to occur in a state where the perovskite structure is stably maintained, and the effect of increasing the proton carrier concentration can be obtained.

(About a, x, and δ)
The value of a indicating the composition ratio of the element A is in the range of 0.4 <a <0.9. An oxide having a value of less than 0.4 is not desirable because the perovskite structure becomes unstable and a phase having no proton conductivity is generated in the proton conductive oxide.

  The value x indicating the composition ratio of the element B ′ is in the range of 0.2 <x <0.6. An oxide having a value greater than 0.6 is not preferable because the perovskite structure becomes unstable and a phase having no proton conductivity is generated.

  An oxide in which 0.9 ≦ a <1.1 and 0 ≦ x ≦ 0.2 has an activation energy of 0.1 eV or more, and proton conduction in a temperature range of 100 ° C. or more and 500 ° C. or less. This is not desirable because the properties are reduced.

  An oxide satisfying 0.9 ≦ a <1.1 and 0.2 <x <0.6 is not desirable because a phase having no proton conductivity is generated.

  An oxide with a> 1.1 is not desirable because the perovskite structure becomes unstable and the proton conductivity decreases.

Therefore, in the proton conductive oxide in which 0.4 <a <0.9 and 0.2 <x <0.6, a perovskite structure can be stably obtained, and the proton conductivity is 10 ⁻¹ S. / Cm or more, which is desirable. An oxide satisfying 0.4 <a <0.9 and 0.0 ≦ x ≦ 0.2 has a perovskite structure, which is desirable because proton conductivity is less than 10 ⁻¹ S / cm. Absent.

  Furthermore, proton conducting oxides with 0.4 <a <0.8 and 0.3 <x <0.6 are more desirable because they have higher proton conductivity at 500 ° C. Further, a proton conductive oxide satisfying 0.4 <a <0.8 and 0.4 <x <0.6 is more desirable because it has high proton conductivity even at 100 ° C.

  A is a divalent element, B is a tetravalent element, and B 'is a trivalent element. O is divalent. Therefore, when the electrical neutral condition is satisfied, it is considered that the sum of the value of the deficiency of A and the half of the substitution amount of B ′ becomes the oxygen deficiency. That is, since the amount of deficiency of A is 1-a, the amount of substitution of B ′ is x, and the amount of oxygen deficiency is δ per unit cell of the crystal, the electrical neutral condition is satisfied by the ions of these elements. Assuming that, δ = (1−a) + x / 2 holds. Therefore, when 0.4 <a <0.9 and 0.2 <x <0.6, 0.2 <δ <0.9 is satisfied.

  By adjusting the value a indicating the composition ratio of the element A and the value x indicating the composition ratio of the element B ′ so as to be within the above ranges, the composition and crystal structure are substantially uniform. A single crystal or polycrystalline perovskite structure composed of a (homogeneous) single phase is realized. Here, “consisting of a single phase having a substantially uniform composition and crystal structure” means that the proton conductor does not contain a heterogeneous phase having a composition outside the above range. Note that the proton conductor used in the hydrogen sensor according to the embodiment of the present disclosure may contain a small amount of inevitable impurities. Moreover, when manufacturing the proton conductor used for the hydrogen sensor by embodiment of this indication by sintering, compounds and elements, such as a sintering aid, may be included in part. In addition, impurities may be added unintentionally in the course of the manufacturing process, or intentionally to obtain some effect. The important point is that the elements A, B, B ′, and O are within the above-described range, and they constitute a perovskite crystal structure. Therefore, the inclusion of impurities mixed in during the production can be allowed.

(Production method)
The proton conductive oxide can be formed by a film forming method such as a sputtering method, a plasma laser deposition method (PLD method), or a chemical vapor deposition method (CVD method). The method for forming the film is not particularly limited.

(Other)
The proton conductive oxide is also referred to as a proton conductor. An example of the shape of the proton conducting oxide is a membrane. The proton conductive oxide only needs to function as a proton conductive solid electrolyte and does not have to be a continuous film.

Further, the substrate on which the proton conductive oxide film is formed may not be flat. Leakage of reactants supplied to the perovskite proton conductive oxide from the viewpoint of avoiding direct reaction of reactants such as hydrogen and oxygen without going through the perovskite proton conductive oxide as a solid electrolyte It is desirable that there is no. Therefore, a thin film of a perovskite proton conductive oxide is formed on a base material made of magnesium oxide (MgO), strontium titanate (SrTiO ₃ ), silicon (Si) or the like having a smooth plane. Thereafter, it is more desirable to remove a part or the whole of the base material by etching or the like to obtain a proton conductive solid electrolyte. The material and shape of the substrate are not particularly limited.

The crystal structure of the proton conductive oxide may be single crystal or polycrystal. Crystal structure oriented by controlling the orientation of crystal growth on a magnesium (MgO) or strontium titanate (SrTiO ₃ ) substrate and a silicon (Si) substrate on which a buffer layer with a controlled lattice constant is formed The proton conductive oxide having a is desirable because it has higher proton conductivity. In addition, a proton conductive oxide having a single crystal structure epitaxially grown on a substrate is desirable because it has higher proton conductivity. Note that the crystal structure of a single crystal can be obtained by controlling the film formation conditions such as the plane orientation of the substrate, temperature, pressure, and atmosphere, but the thin film formation conditions and the thin film crystal system are not particularly limited.

  Hereinafter, the proton conductive oxide will be specifically described with reference to examples.

Example 1
The base material (10 mm × 10 mm, thickness 0.5 mm) was set on a substrate holder having a heating mechanism inside the vacuum chamber, and the inside of the vacuum chamber was evacuated to a degree of vacuum of about 10 ⁻³ Pa. The material of the base material was magnesium oxide (MgO) single crystal.

  After evacuation, the substrate was heated to 650 ° C to 750 ° C. Oxygen gas (flow rate of 2 sccm) and argon gas (flow rate of 8 sccm) were introduced, and the pressure in the vacuum chamber was adjusted to about 1 Pa.

  A proton conductive oxide film was formed by sputtering using a sintered compact target having an element ratio of Ba: Zr: Y = 7: 7: 3.

  The structure, composition ratio, and proton conductivity of the deposited proton conductive oxide were evaluated. Table 1 shows the results. Hereinafter, each evaluation method and the result are shown. In Table 1, Examples 2 to 13 and Comparative Examples 1 to 5 described later are also described.

  Using a Cu target, the X-ray diffraction of the deposited proton conductive oxide was measured. As shown in Table 1, the proton conductive oxide of Example 1 was confirmed to have a perovskite crystal structure and a single crystal.

The composition ratio of the deposited proton-conductive oxide was examined using ion-coupled plasma spectroscopy (ICP: Inductively Coupled Plasma). As shown in Table 1, in the proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ) of Example 1, the element of A is barium (Ba), and the value of a is 0. 73. Further, the element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.31 (Zr: 0.69, Y: 0.31).

In FIG. 2, the measurement result of the proton conductivity of the proton-conductive oxide in Example 1 is shown. An electrode was formed on the proton conductive oxide using a silver paste. The proton conductivity was measured using an impedance method in an argon (Ar) gas mixed with 5% hydrogen (H ₂ ) and under a temperature range of 100 ° C. to 600 ° C.

  As shown in Table 1, the proton conductivity of Example 1 at 100 ° C. was 0.36 S / cm, and the proton conductivity at 500 ° C. was 0.71 S / cm.

(Example 2)
An experiment was performed in the same manner as in Example 1 except that the film was formed using a sintered body target having an element ratio of Ba: Zr: Y = 1: 1: 1. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, the proton conductive oxide of Example 2 was confirmed to have a perovskite crystal structure and a single crystal. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the element of A is barium (Ba), and the value of a is 0.48. It was. Moreover, the element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.48 (Zr: 0.52, Y: 0.48). As shown in Table 1, the proton conductivity of Example 2 at 100 ° C. was 0.42 S / cm, and the proton conductivity at 500 ° C. was 0.79 S / cm.

(Example 3)
The experiment was performed in the same manner as in Example 1 except that the film was formed using a sintered body target having an element ratio of Ba: Zr: Y = 9: 4: 6. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, it was confirmed that the proton conductive oxide of Example 3 had a perovskite crystal structure and was polycrystalline. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the element A is barium (Ba), and the value of a is 0.89. It was. Further, the element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.58 (Zr: 0.42, Y: 0.58). As shown in Table 1, the proton conductivity of Example 3 at 100 ° C. was 0.14 S / cm, and the proton conductivity at 500 ° C. was 0.55 S / cm.

Example 4
The experiment was performed in the same manner as in Example 1 except that the film was formed using a sintered body target having an element ratio of Ba: Zr: In = 5: 8: 2. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, the proton conductive oxide of Example 4 was confirmed to have a perovskite crystal structure and a single crystal. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the element of A is barium (Ba), and the value of a is 0.44. It was. The element of B was zirconium (Zr), the element of B ′ was indium (In), and the value of x was 0.22 (Zr: 0.78, In: 0.22). As shown in Table 1, the proton conductivity of Example 4 at 100 ° C. was 0.32 S / cm, and the proton conductivity at 500 ° C. was 0.57 S / cm.

(Example 5)
An experiment was performed in the same manner as in Example 1 except that the film was formed using a sintered body target having an element ratio of Ba: Zr: Y = 8: 6: 4. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, the proton conductive oxide of Example 5 was confirmed to have a perovskite crystal structure and a single crystal. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the element A is barium (Ba), and the value of a is 0.71. It was. Further, the element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.41 (Zr: 0.59, Y: 0.41). As shown in Table 1, the proton conductivity of Example 5 at 100 ° C. was 0.39 S / cm, and the proton conductivity at 500 ° C. was 0.79 S / cm.

(Example 6)
The base material is strontium titanate (SrTiO ₃ ) single crystal, and the film was formed using a sintered body target having an element ratio of Ba: Sr: Zr: Y = 3: 4: 7: 3. Except that, the experiment was performed in the same manner as in Example 1. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, it was confirmed that the proton conductive oxide of Example 6 had a perovskite crystal structure and was polycrystalline. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the elements of A were barium (Ba) and strontium (Sr). The ratio of barium (Ba) to strontium (Sr) was 0.22 for barium (Ba), 0.49 for strontium (Sr), and the value of a was 0.71. The element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.27 (Zr: 0.73, Y: 0.27). As shown in Table 1, the proton conductivity of Example 6 at 100 ° C. was 0.35 S / cm, and the proton conductivity at 500 ° C. was 0.66 S / cm.

(Example 7)
An experiment was performed in the same manner as in Example 6 except that a film was formed using a sintered compact target having an element ratio of Ba: Sr: Zr: Y = 1: 1: 2: 2. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, it was confirmed that the proton conductive oxide of Example 7 had a perovskite crystal structure and was polycrystalline. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the elements of A were barium (Ba) and strontium (Sr). The ratio of barium (Ba) to strontium (Sr) was 0.22 for barium (Ba), 0.25 for strontium (Sr), and the value of a was 0.47. Further, the element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.47 (Zr: 0.53, Y: 0.47). As shown in Table 1, the proton conductivity of Example 7 at 100 ° C. was 0.39 S / cm, and the proton conductivity at 500 ° C. was 0.71 S / cm.

(Example 8)
An experiment was performed in the same manner as in Example 6 except that the film was formed using a sintered body target having an element ratio of Ba: Sr: Zr: Y = 2: 7: 4: 6. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, it was confirmed that the proton conductive oxide of Example 8 had a perovskite crystal structure and was polycrystalline. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the elements of A were barium (Ba) and strontium (Sr). The ratio of barium (Ba) to strontium (Sr) was 0.20 for barium (Ba), 0.68 for strontium (Sr), and the value of a was 0.88. Further, the element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.58 (Zr: 0.42, Y: 0.58). As shown in Table 1, the proton conductivity of Example 8 at 100 ° C. was 0.15 S / cm, and the proton conductivity at 500 ° C. was 0.57 S / cm.

Example 9
An experiment was performed in the same manner as in Example 6 except that the film was formed using a sintered body target having an element ratio of Ba: Sr: Zr: In = 4: 1: 8: 2. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, the proton conductive oxide of Example 9 was confirmed to have a perovskite crystal structure and a single crystal. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the elements of A were barium (Ba) and strontium (Sr). The ratio of barium (Ba) to strontium (Sr) was 0.35 for barium (Ba) and 0.08 for strontium (Sr), and the value of a was 0.43. The element of B was zirconium (Zr), the element of B ′ was indium (In), and the value of x was 0.21 (Zr: 0.79, In: 0.21). As shown in Table 1, the proton conductivity of Example 9 at 100 ° C. was 0.29 S / cm, and the proton conductivity at 500 ° C. was 0.55 S / cm.

(Example 10)
An experiment was performed in the same manner as in Example 6 except that the film was formed using a sintered body target having an element ratio of Ba: Sr: Zr: Y = 5: 2: 6: 4. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, it was confirmed that the proton conductive oxide of Example 10 had a perovskite crystal structure and was a single crystal. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the elements of A were barium (Ba) and strontium (Sr). The ratio of barium (Ba) to strontium (Sr) was 0.48 for barium (Ba), 0.21 for strontium (Sr), and the value of a was 0.69. Further, the element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.39 (Zr: 0.61, Y: 0.39). As shown in Table 1, the proton conductivity of Example 10 at 100 ° C. was 0.35 S / cm, and the proton conductivity at 500 ° C. was 0.69 S / cm.

(Example 11)
An experiment was performed in the same manner as in Example 1 except that the film was formed using a sintered body target having an element ratio of Ba: Zr: Y = 2: 2: 3. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, it was confirmed that the proton conductive oxide of Example 11 had a perovskite crystal structure and was a single crystal. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the element of A is barium (Ba), and the value of a is 0.41. It was. Further, the element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.58 (Zr: 0.42, Y: 0.58). As shown in Table 1, the proton conductivity of Example 11 at 100 ° C. was 0.45 S / cm, and the proton conductivity at 500 ° C. was 0.95 S / cm.

(Example 12)
An experiment was performed in the same manner as in Example 1 except that the film was formed using a sintered body target having an element ratio of Ba: Zr: Y = 9: 8: 2. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, the proton conductive oxide of Example 12 was confirmed to have a perovskite crystal structure and a single crystal. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the element of A is barium (Ba), and the value of a is 0.88. It was. The element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.21 (Zr: 0.79, Y: 0.21). As shown in Table 1, the proton conductivity of Example 12 at 100 ° C. was 0.12 S / cm, and the proton conductivity at 500 ° C. was 0.65 S / cm.

(Example 13)
An experiment was performed in the same manner as in Example 1 except that the film was formed using a sintered body target having an element ratio of Ba: Zr: Y = 3: 4: 1. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, it was confirmed that the proton conductive oxide of Example 13 had a perovskite type crystal structure and was a single crystal. As shown in Table 1, in this proton conductive oxide (A _a B _1-x B ′ _x O _3-δ ), the element of A is barium (Ba), and the value of a is 0.42. It was. Moreover, the element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.22 (Zr: 0.78, Y: 0.22). As shown in Table 1, the proton conductivity of Example 13 at 100 ° C. was 0.31 S / cm, and the proton conductivity at 500 ° C. was 0.54 S / cm.

(Comparative Example 1)
An experiment was performed in the same manner as in Example 1 except that the film was formed using a sintered body target having an element ratio of Ba: Zr: Y = 5: 4: 1. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, the proton conductive oxide of Comparative Example 1 was confirmed to have a perovskite crystal structure and a single crystal. As shown in Table 1, in this oxide (A _a B _1-x B ′ _x O _3-δ ), the element of A was barium (Ba), and the value of a was 0.98. The element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.19 (Zr: 0.81, Y: 0.19).

As shown in Table 1, the proton conductivity of Comparative Example 1 at 100 ° C. was 2.3 × 10 ⁻⁵ S / cm, and the proton conductivity at 500 ° C. was 0.039 S / cm.

(Comparative Example 2)
An experiment was performed in the same manner as in Example 1 except that the film was formed using a sintered body target having an element ratio of Ba: Zr: In = 7: 9: 1. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, the proton conductive oxide of Comparative Example 2 was confirmed to have a perovskite crystal structure and a single crystal. As shown in Table 1, in this oxide (A _a B _1-x B ′ _x O _3-δ ), the element of A was barium (Ba), and the value of a was 0.65. The element of B was zirconium (Zr), the element of B ′ was indium (In), and the value of x was 0.13 (Zr: 0.87, In: 0.13). As shown in Table 1, the proton conductivity of Comparative Example 2 at 100 ° C. was 0.01 S / cm, and the proton conductivity at 500 ° C. was 0.013 S / cm.

(Comparative Example 3)
The experiment was performed in the same manner as in Example 1 except that the film was formed using a sintered body target having an element ratio of Ba: Zr: Y = 4: 7: 3. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, the proton conductive oxide of Comparative Example 3 contained a polycrystalline perovskite crystal structure. Further, zirconium oxide (ZrO ₂ ) was detected as the impurity layer. As shown in Table 1, in this oxide (A _a B _1−x B ′ _x O _3−δ ), the element of A was barium (Ba), and the value of a was 0.35. The element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.32 (Zr: 0.68, Y: 0.32). As shown in Table 1, the proton conductivity of Comparative Example 3 at 100 ° C. is 3.2 × 10 ⁻⁶ S / cm, and the proton conductivity at 500 ° C. is 8.5 × 10 ⁻³ S / cm. Met.

(Comparative Example 4)
Example 1 except that the material of the base material was strontium titanate (SrTiO ₃ ) single crystal and the film was formed using a sintered body target having an element ratio of Sr: Zr: Y = 8: 3: 7. The experiment was conducted in the same manner as above. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, the proton conductive oxide of Comparative Example 4 contained a polycrystalline perovskite crystal structure. Further, barium carbonate (BaCO ₃ ) and yttrium oxide (Y ₂ O ₃ ) were also detected as impurity layers. As shown in Table 1, in this oxide (A _a B _1-x B ′ _x O _3-δ ), the element of A was strontium (Sr), and the value of a was 0.78. Further, the element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.68 (Zr: 0.32, Y: 0.68).

As shown in Table 1, the proton conductivity of Comparative Example 4 at 100 ° C. is 6.5 × 10 ⁻⁶ S / cm, and the proton conductivity at 500 ° C. is 9.4 × 10 ⁻³ S / cm. Met.

(Comparative Example 5)
The experiment was performed in the same manner as in Comparative Example 4 except that the film was formed using a sintered body target having an element ratio of Sr: Zr: Y = 5: 3: 2. Table 1 shows the structure, composition ratio, and proton conductivity of the deposited proton conductive oxide.

As shown in Table 1, it was confirmed that the proton conductive oxide of Comparative Example 5 had a perovskite crystal structure and was polycrystalline. As shown in Table 1, in this oxide (A _a B _1-x B ′ _x O _3-δ ), the element of A was strontium (Sr), and the value of a was 1.01. The element of B was zirconium (Zr), the element of B ′ was yttrium (Y), and the value of x was 0.45 (Zr: 0.55, Y: 0.45).

As shown in Table 1, the proton conductivity of Comparative Example 5 at 100 ° C. is 4.3 × 10 ⁻⁶ S / cm, and the proton conductivity at 500 ° C. is 8.6 × 10 ⁻³ / cm. there were.

  As shown in Table 1, it can be seen that the proton conductive oxides of Examples 1 to 13 have higher proton conductivity than Comparative Examples 1 to 5. The proton conductive oxides of Examples 1 to 13 satisfy the condition of 0.4 <a <0.9 and 0.2 <x <0.6.

  It is known that it has a manufacturing error of at least about 5%. From the values of a and x in Examples 1 to 13, 0.4 <a <0.9 and 0.2 <x <0. The proton conductive oxide satisfying 6 has high proton conductivity.

More specifically, the proton conductor oxides of Example 3, Example 9, Example 11, and Example 12 have x = 0.21, x = 0.58, and a = −0.054x + 0.441. , And a = −0.027x + 0.886. That is, in these examples, the composition ratios x and a satisfy the following relationship.
0.21 ≦ x ≦ 0.58,
a ≧ −0.054x + 0.441, and a ≦ −0.027x + 0.886

In addition, the proton conductive oxides of Examples 1 to 13 show activation energy lower than 0.1 eV at 100 ° C. and 500 ° C. The ˜5 oxide had an activation energy higher than 0.1 eV. That is, when the composition ratio satisfies the above-described conditions (Example), the proton conductive oxide maintains a high proton conductivity of 10 ⁻¹ S / cm or more even in a temperature range of 100 ° C. or more and 500 ° C. or less. To do. As shown in the examples, the activation energy of proton conductivity can be reduced to 0.1 eV or less by adjusting the values of a and x to be within the above-described range. The accompanying decrease in proton conductivity can be suppressed. Furthermore, the proton conductive oxide satisfying the condition of 0.4 <a <0.9 and 0.2 <x <0.6 has an activation energy of proton conductivity of 0.1 eV or less. The proton conductivity is higher than that of the oxide of Comparative Example 2.

In addition, it has been found from the experiments of the present inventors that the production is easy when (1-a) indicating the deficiency of the element A is close to the composition ratio x of the element B ′. For this reason, it is practically useful if the following relationship is established.
0.5 <(1-a) / x <2.5

  As is clear from Table 1, when 0.4 <a <0.6 and 0.4 <x <0.6, a relatively high proton conductivity is realized, and 0.4 When <a <0.5 and 0.4 <x <0.6, the highest proton conductivity is realized.

  Furthermore, the proton conducting oxides of Examples 1, 2, 5, 7, 10, and 11 are more desirable because they have higher proton conduction at 500 ° C. In the proton conductive oxides of Examples 1, 2, 5, 7, 10, and 11, the manufacturing error of at least about 5% is considered, and 0.4 <a <0.8 and 0.3 < The condition x <0.6 is satisfied. More specifically, the proton conducting oxides of Examples 1, 2, 5, 7, 10, and 11 have 0.41 <a <0.73 and 0.31 <x <0.58. Satisfy the condition of adding a manufacturing error to the numerical range.

  Furthermore, the proton conductive oxides of Examples 2, 5, 7, and 11 are more desirable because they have high proton conductivity at 100 ° C. In the proton conductive oxides of Examples 2, 5, 7, and 11, in consideration of a manufacturing error of at least about 5%, 0.4 <a <0.8 and 0.4 <x <0. Condition 6 is satisfied. More specifically, the proton conducting oxides of Examples 2, 5, 7, and 11 have a numerical range of 0.41 <a <0.71 and 0.41 <x <0.58. To satisfy the conditions with manufacturing errors added.

(Embodiment of hydrogen sensor)
Hereinafter, the configuration and operation of the hydrogen sensor according to the embodiment of the present disclosure will be described with reference to FIG. 3.

  A hydrogen sensor 100 shown in FIG. 3 includes a proton conductor 101, and a detection electrode 102 and a reference electrode 103 disposed in contact with the proton conductor 101. As the proton conductor 101, the above-described proton conductor described with reference to the embodiment can be used. The proton conductor 101 has high proton conductivity even in a temperature range of 100 ° C. or more and 500 ° C. or less. Therefore, the hydrogen sensor 100 can detect hydrogen gas with high sensitivity in a temperature range of 100 ° C. or more and 500 ° C. or less. In addition, as described above, since the activation energy of proton conductivity is smaller than that of a conventional proton conductor, hydrogen gas can be detected even at a temperature of 100 ° C. or lower. Further, unlike a hydrogen sensor provided with a proton conductive solid polymer membrane, the hydrogen sensor 100 can detect hydrogen in a gas to be detected that is not actively humidified.

  As illustrated in FIG. 3, the detection electrode 102 and the reference electrode 103 are typically arranged so as to sandwich the proton conductor 101. In the illustrated example, the detection electrode 102 is disposed on one main surface of the proton conductor 101, and the reference electrode 103 is disposed on the main surface of the proton conductor 101 on which the detection electrode 102 is not disposed. Has been placed. The arrangement of the proton conductor 101, the detection electrode 102, and the reference electrode 103 is not limited to the example in FIG. 3, and various arrangements can be adopted. For example, the detection electrode 102 and the reference electrode 103 may be disposed on the same main surface of the proton conductor 101. In this case, a heating heater or the like may be provided on the main surface where the detection electrode 102 and the reference electrode 103 are not provided.

  A voltmeter 104 is connected to the detection electrode 102 and the reference electrode 103 of the hydrogen sensor 100.

  The detection electrode 102 has a structure that allows hydrogen gas to pass therethrough. In addition, it has a catalytic action of oxidizing protons to generate protons. Specifically, the detection electrode 102 includes titanium (Ti), zirconium (Zr), tantalum (Ta), zinc (Zn), chromium (Cr), iron (Fe), cobalt (Co), aluminum (Al), A metal or alloy having at least one selected from the group consisting of nickel (Ni), tin (Sn), and vanadium (V) may be included.

  Further, in order to obtain a porous structure that allows hydrogen gas to pass therethrough, the detection electrode 102 may include a metal or an alloy obtained by reducing the above-described metal oxide. In this case, in the detection electrode 102, the above-described metal oxide may not be reduced and may remain as an oxide. That is, the detection electrode 102 includes titanium (Ti), zirconium (Zr), tantalum (Ta), zinc (Zn), chromium (Cr), iron (Fe), cobalt (Co), aluminum (Al), nickel (Ni ), Tin (Sn), and vanadium (V), the oxide may include at least one selected from the group consisting of vanadium (V). In this case, the detection electrode 102 has electronic conductivity as a whole.

  The detection electrode 102 includes titanium (Ti), zirconium (Zr), tantalum (Ta), zinc (Zn), chromium (Cr), iron (Fe), cobalt (Co), aluminum (Al), nickel (Ni ), Tin (Sn), vanadium (V) and at least one selected from the group consisting of boron (B), carbon (C), and nitrogen (N), and electron conduction An intermetallic compound may be included.

  The detection electrode 102 can be formed by a film forming method such as sputtering, PLD, or CVD. The detection electrode 102 may be formed by screen-printing ink in which powder of the above material is dispersed in a solvent and then drying and solidifying by heating, vacuum treatment, or the like. The method for forming the detection electrode 102 is not particularly limited.

  The reference electrode 103 contains a metal having a smaller ionization tendency than hydrogen. Specifically, a metal or alloy having at least one selected from the group consisting of copper (Cu), iridium (Ir), platinum (Pt), and gold (Au) may be included.

  The reference electrode 103 includes at least one selected from the group consisting of copper (Cu), iridium (Ir), platinum (Pt), and gold (Au), boron (B), carbon (C), and nitrogen (N). And at least one selected from the group consisting of, and may contain an electron conductive intermetallic compound.

  The reference electrode 103 can be formed by a film formation method such as sputtering, PLD, or CVD. The reference electrode 103 may be formed by screen-printing ink in which powder of the above material is dispersed in a solvent and then drying and solidifying by heating, vacuum treatment, or the like. A method for forming the reference electrode 103 is not particularly limited.

  As shown in FIG. 3, in this embodiment, the hydrogen sensor 100 further includes a case 111, and the proton conductor 101 divides the space inside the case 111 into a detection space 109 and a reference space 112 in the case 111. It is divided. The detection electrode 102 is exposed in the detection space 109. The case 111 is provided with an inlet 105 for introducing the gas to be detected into the detection space 109 and an outlet 106 for discharging the gas from the detection space 109. In the reference space 112, the reference electrode 103 is exposed. The reference space 112 is sealed and filled with a gas not containing hydrogen. The reference space 112 is provided so that the electromotive force generated in the reference electrode 103 does not change depending on the measurement environment. In the case where fluctuations in electromotive force generated in the reference electrode 103 do not greatly affect the measurement, such as the measurement environment does not change significantly, the reference space 112 may not be provided, and the reference electrode 103 is exposed to the atmosphere. May be.

In the hydrogen sensor 100, a detection gas containing hydrogen gas is introduced from the inlet 105, the detection gas 109 is filled with the detection gas, and excess detection gas is discharged from the outlet 106. The light passes through the detection electrode 102 and reaches the interface between the proton conductor 101 and the detection electrode 102. This interface is a three-phase interface. According to the following formula, hydrogen in the gas to be detected is oxidized and protons are generated.
H ₂ → 2H ⁺ + 2e ⁻

  The generated protons diffuse through the proton conductor 101. Further, the generated electrons are conducted through the detection electrode 102 and an electromotive force is generated.

  This electromotive force is detected by the voltmeter 104 as a potential difference with the reference electrode 103 as a reference. Since the amount of proton generation changes according to the concentration of hydrogen gas in the detection gas, the electromotive force generated at the detection electrode 102 changes according to the concentration of hydrogen gas in the detection gas. Therefore, the concentration of hydrogen gas in the gas to be detected can be measured by the voltage detected by the voltmeter 104. For example, by using a calibration gas having a known hydrogen concentration, measuring the voltage with the voltmeter 104 and creating a calibration curve, the hydrogen concentration in the gas to be detected containing hydrogen at an arbitrary concentration can be obtained. Can be measured.

  As described above, according to the embodiment of the present disclosure, the proton conductor 101 has high proton conductivity even in a temperature range of 100 ° C. or more and 500 ° C. or less. Therefore, the hydrogen sensor 100 generates a larger electromotive force in the temperature range of 100 ° C. or more and 500 ° C. or less, and can detect hydrogen gas with high sensitivity. Further, even if the gas to be detected is not humidified, it is possible to detect hydrogen in the gas to be detected with high accuracy.

  In this embodiment, the reference electrode 103 is sealed in the reference space 112 and is in contact with the reference gas. However, the hydrogen sensor may have a structure in which the reference electrode 103 is not in contact with the gas to be detected. Specifically, as shown in FIG. 4, the surface of the reference electrode 103 may be covered with a coating 113 made of a material that does not transmit the gas to be detected. In this case, the hydrogen sensor 120 shown in FIG. 4 can measure the concentration of hydrogen gas in the gas to be detected even if it is disposed so as to be exposed to the gas to be detected.

  In the present embodiment, the hydrogen sensors 100 and 120 have been described as measuring the concentration of the hydrogen gas in the gas to be detected. However, the hydrogen sensors 100 and 120 may detect the hydrogen gas dissolved in the liquid. Is possible.

  The hydrogen sensor according to the embodiment of the present disclosure can measure the concentration of hydrogen gas in a gas or liquid in various industrial fields and applications.

100, 120 Hydrogen sensor 101 Proton conductor 102 Detection electrode 103 Reference electrode 104 Voltmeter 105 Inlet 106 Outlet 109 Detection space 111 Case 112 Reference space 113 Coating

Claims (16)

A proton conductor having a perovskite crystal structure represented by _a composition formula A _a B _1-x B ′ _x O _3-δ ;
A sensing electrode that is disposed in contact with the proton conductor, has a catalytic action to transmit hydrogen gas, oxidize hydrogen, and generate protons;
A reference electrode disposed in contact with the proton conductor;
With
A is at least one selected from alkaline earth metals,
B is a tetravalent group 4 transition metal or Ce;
B ′ is a trivalent group 3 or group 13 element;
Hydrogen sensor satisfying 0.4 <a <0.9 and 0.2 <x <0.6. A is at least one selected from Ba and Sr;
B is Zr;
B ′ is Y or In.
The hydrogen sensor according to claim 1. The value of a is 0.4 <a <0.8,
The value of x is 0.3 <x <0.6,
The hydrogen sensor according to claim 1 or 2. The value of a is 0.4 <a <0.8,
The value of x is 0.4 <x <0.6,
The hydrogen sensor according to claim 1 or 2. The value of a is 0.4 <a <0.6,
The value of x is 0.4 <x <0.6,
The hydrogen sensor according to claim 1 or 2. The value of a is 0.4 <a <0.5,
The value of x is 0.4 <x <0.6,
The hydrogen sensor according to claim 1 or 2. Activation energy of proton conduction of the proton conductor in a temperature range of 100 ° C. or more and 500 ° C. or less is 0.1 eV or less.
The hydrogen sensor according to claim 1. 0.21 ≦ x ≦ 0.58,
a ≧ −0.054x + 0.441, and a ≦ −0.027x + 0.886
Is established,
The hydrogen sensor according to claim 1 or 2. The proton conductor is composed of a single phase having a substantially uniform composition and crystal structure.
The hydrogen sensor according to claim 1. The detection electrode includes a metal or alloy having at least one selected from the group consisting of Ti, Zr, Ta, Zn, Cr, Fe, Co, Al, Ni, Sn, and V.
The hydrogen sensor according to claim 1. The detection electrode includes an oxide having at least one selected from the group consisting of Ti, Zr, Ta, Zn, Cr, Fe, Co, Al, Ni, Sn, and V.
The hydrogen sensor according to claim 1. The detection electrode is
At least one selected from the group consisting of Ti, Zr, Ta, Zn, Cr, Fe, Co, Al, Ni, Sn and V;
An intermetallic compound having at least one selected from the group consisting of B, C and N,
The hydrogen sensor according to claim 1. The reference electrode has a structure that does not transmit hydrogen gas.
The hydrogen sensor according to claim 1. The reference electrode includes a metal having a lower ionization tendency than hydrogen or an alloy including a metal having a lower ionization tendency than hydrogen.
The hydrogen sensor according to claim 1. The reference electrode includes a metal or alloy having at least one selected from the group consisting of Cu, Ir, Pt and Au.
The hydrogen sensor according to claim 1. The reference electrode is
At least one selected from the group consisting of Cu, Ir, Pt and Au;
Including at least one intermetallic compound selected from the group consisting of B, C and N,
The hydrogen sensor according to claim 1.

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