JPH0756479B2 - Insertable sensor probe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an insertion type sensor used for measuring the concentration of hydrogen or water vapor in high temperature exhaust gas discharged from a boiler, a sintering furnace, an automobile or the like. The present invention relates to a probe, and more particularly, to an insertion type sensor probe that uses a solid reference material as a reference for galvanic electromotive force.

[Prior Art] Measuring the concentration of hydrogen and water vapor in high temperature exhaust gas is
It is indispensable for accurately obtaining the combustion efficiency of boilers, combustion furnaces, automobile engines, etc. Therefore, there is a demand for the development of a highly reliable hydrogen and water vapor concentration measuring device that operates stably in high-temperature exhaust gas.

Therefore, conventionally, there has been proposed a hydrogen or water vapor sensor which uses a proton conductive solid electrolyte made of a perovskite type oxide such as strontium oxide and cerium oxide (SrCeO ₃ ) as a sensor element (JP-A-58-5).
0458,60-263853,61-2064,61-3054,61-14566).
This solid electrolyte has proton conductivity at a temperature of 400 ° C. or higher, and a sensor element made of this solid electrolyte is formed in a closed type at one end, and a porous inner surface electrode and outer surface electrode are covered on the inner surface and outer surface, respectively. It is configured to wear. A reference gas that serves as a reference for galvanic electromotive force, that is, a gas containing hydrogen or water vapor at a predetermined concentration is enclosed in the sensor element.

When a sensor probe for measuring the concentration of hydrogen or water vapor using this perovskite-type proton conductive solid electrolyte is inserted into the gas to be measured, the inner surface becomes different due to the difference in hydrogen or water vapor concentration between the reference gas and the gas to be measured. An electromotive force is generated between the electrode and the outer surface electrode. Then, by detecting this electromotive force, the concentration of hydrogen or water vapor in the gas to be measured can be measured.

However, since the above-mentioned conventional technique uses a gas containing a predetermined concentration of hydrogen or water vapor as a reference substance,
There are the following problems.

When the solid electrolyte, the gas introduction pipe, or the like is damaged, the reference gas leaks into the measurement atmosphere, and the measurement becomes impossible or a measurement error occurs. Further, in this case, the leaked reference gas pollutes the measurement atmosphere.

In order to supply the reference gas to the probe for circulation,
A gas circulator or the like is required, and a compact device cannot be obtained.

Therefore, the present inventors have developed a solid reference material that exhibits a stable hydrogen activity at high temperatures, and have proposed using this solid reference material for a hydrogen or water vapor sensor (Japanese Patent Laid-Open No. 63-269053).

[Problems to be Solved by the Invention] However, particularly in the case of an insertion-type hydrogen or water vapor sensor that is installed by being inserted in a measurement atmosphere, the sensor itself is exposed to high temperatures, so that the solid reference substance and the measurement atmosphere It is difficult to completely seal the space. Therefore, the insertion type hydrogen or water vapor sensor using this solid reference material has not been put to practical use.

The present invention has been made in view of such problems,
In the insertion type hydrogen or water vapor sensor used at high temperature, the solid reference substance can be sufficiently sealed from the measurement atmosphere, and this solid reference substance can be used practically even at high temperature. An object of the present invention is to provide an insertable sensor probe that can eliminate the drawbacks of the sensor using the.

[Means for Solving the Problems] An insertion type sensor probe according to the present invention is a sensor element of one-end closed type formed of a perovskite type proton conductive solid electrolyte, and a galvanic electromotive force reference filled in the sensor element. A solid reference material, a reference electrode formed on the inner surface of the sensor element in contact with the solid reference material, and a measurement electrode formed on the outer surface of the sensor element,
A ceramic holder, one end of which is closed to fit and hold the sensor element at the other end side, and at least the space between the inner surface of the ceramic holder and the outer surface of the sensor element is hermetically sealed to seal the both. Having a solid reference material and a sealing material for isolating the reference electrode from the measurement atmosphere,
The sealing material has a softening temperature equal to or lower than a predetermined operating temperature of the sensor, has a pour point equal to or higher than the operating temperature, is in a powder form before the sensor is used, and is heated by a measurement atmosphere when the sensor is used. Is fused to the other end of the sensor element to hermetically seal the solid reference material and the reference electrode from the measurement atmosphere.

[Operation] In the present invention, the solid reference substance filled in the sensor element of the one-end closed type, together with the reference electrode in the sensor element, is formed by the seal portion formed at the other end of the sensor element as follows. It is hermetically sealed from the measurement atmosphere outside the sensor element.

That is, in the sensor probe according to the present invention, the other end of the sensor element is closed by a sealing material, and the sealing material has a softening point below a predetermined working temperature of the sensor and a pour point above the working temperature. . Therefore, when this sensor probe is inserted into an atmosphere in which hydrogen or water vapor concentration is measured, the sensor probe itself is heated from the measurement atmosphere, and the temperature of the sealing material rises. Then, in the process of this temperature rise, the sealing material exceeds the softening temperature and is fused to the other end of the sensor element. As a result, the solid reference substance and the reference electrode are hermetically sealed from the measurement atmosphere by the seal portion formed by softening the seal material.

In the present invention, when the sensor probe is inserted into the measurement atmosphere, the sealing material softens and fuses to the sensor element, so the sealing portion formed by softening the sealing material heats the sensor element to a predetermined operating temperature. It is brought into close contact with the other end of the sensor element in a state of being thermally expanded. Therefore, this seal portion is in close contact with the other end portion of the sensor element to hermetically seal the solid reference substance and the reference electrode from the measurement atmosphere when the sensor probe is used. Unlike the case where the probe is heated to the operating temperature at the time of measurement, its sealing property is extremely excellent.

As the sealing material, there is, for example, one whose composition after softening is dense glass. This dense glass seal portion has excellent heat resistance at the sensor operating temperature, has sufficient strength without fluidization, and can form a dense seal portion.

Further, this dense glass sealing material has no reactivity with the solid electrolyte that constitutes the sensor element, and has excellent wettability with the solid electrolyte and has good bondability.

The proton conductive solid electrolyte is Ca, Sr and B.
at least one element selected from the group consisting of a
As a component, at least one element selected from the group consisting of Ce, Zr, Ti and Hf is used as a B component, and Yb, Y, Sc, Zn, Nd, Mg, I
When M component is at least one element selected from the group consisting of n, Sm, Dy, Eu, Ho, Gd, Tm, Ca and La, the general formula
It is a perovskite complex oxide represented by AB _1-X M _X O _3-Y . However, both X and Y are numerical values in the range of 0 to 0.5.

Examples of such a perovskite type complex oxide include SrCe _0.95 Yb _0.05 O _3-Y , BaCe _0.9 Nd _0.1 O _3-Y and CaZr _0.9 In.
_0.1 O _3-Y etc.

EXAMPLES Examples of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a sensor probe according to a first comparative example of the present invention. The sensor element 1 has a tubular shape with one end closed, and a measuring electrode 3 and a reference electrode 4 are formed by depositing a porous material on the outer surface and the inner surface of approximately half of the closed end side. The measurement electrode 3 and the reference electrode 4 cover approximately half of the sensor element 1 on the closed end side. The sensor element 1 is filled with a solid reference material 2, and the solid reference material 2 is enclosed in the sensor element 1 so that a cylindrical shape is formed in approximately half of the open end side of the sensor element 1. The eggplant ceramic chip 5a is inserted.

A lead wire 8 connected to the reference electrode 4 is inserted through the center of the ceramic chip 5a, and the reference electrode 4 is electrically led out of the sensor element 1 by the lead wire 8. A metal paste 6 is interposed between the ceramic chip 5a and the inner surface of the sensor element 1. Then, at the open end of the sensor element 1, in order to hermetically seal between the inner surface of the sensor element 1 and the ceramic chip 5a and between the ceramic chip 5a and the lead wire 8, a powdery glass sealing material is provided. 7a is served.

The sensor element 1 is SrCe _0.95 Yb _0.05 O _3-Y , CaZr _0.9 In _0.1 O _3-Y ,
It is molded with a proton conductive solid electrolyte composed of a perovskite type complex oxide such as BaCe _0.95 Y _0.05 O _3-Y .

The reference electrode 4 and the measurement electrode 3 are formed by baking a porous material such as Pt, Ni or an oxide conductor.

Further, as the solid reference substance 2, for example, there is a mixture of Ni powder with a mixed salt of cerium sulfate and an alkali carbonate. The ceramic chip 5a acts as a plug for enclosing the solid reference substance 2 in the sensor element 1, and separates the glass seal material 7a and the solid reference substance 2 at a high temperature from each other in order to prevent them from fusing. Acts as.

Furthermore, the metal paste 6 is interposed between the ceramic chip 5a and the inner surface of the sensor element 1 in order to secure electrical conduction between the porous reference electrode 4 and the lead wire 8. The metal paste 6 contains Pt, Ni, or the like, has conductivity, and is applied to the peripheral surface of the ceramic chip 5a, and then the ceramic chip 5a is fitted into the sensor element 1 to provide a space between them. Intervened.

As the lead wire 8, an ordinary conductor wire such as a Pt wire or a Ni wire may be used.

The powdery glass sealing material 7a has, for example, a composition of ZnO · B ₂ O ₃ · SiO ₂ . The softening point and the pour point of the powdery glass sealing material 7a of this composition are 660 ° C and 724 ° C, respectively. Therefore, when powder glass having this composition is used, the operating temperature range of this sensor probe is 660 to 724 ° C. Further, the powder having this composition is heated to a temperature equal to or higher than the softening point to become a dense glass.

In the insertion type sensor probe configured as above, when the sensor element 1 formed of the solid electrolyte is inserted into the measurement atmosphere, the sensor element 1 is heated from the measurement atmosphere and the temperature rises, and Powder glass sealing material 7a that is placed on the other end and closes the other end
Heats up. Then, the powdery glass sealing material 7a is softened by exceeding its softening temperature in the temperature rising process, becomes a dense glass material, and is fused to the other end of the sensor element 1. As a result, a dense glassy seal portion is formed at the other end of the sensor element 1. Then, the solid reference substance 2 and the reference electrode 4 in the sensor element 1 are hermetically sealed from the external measurement atmosphere by this seal portion.

As described above, in the present sensor probe, the solid reference substance 2 and the reference electrode 4 are hermetically sealed by the seal portion (glass sealing material 7a) and housed in the sensor element 1. The reference electrode 4 is shielded from the measurement atmosphere so that the gas in the measurement atmosphere does not enter. Therefore, even if this sensor probe is inserted into the measurement atmosphere, the solid reference material 2 does not react with the gas in the measurement atmosphere to change its concentration.

The seal portion at the other end of the sensor element 1 is formed by softening the powdery glass sealing material 7a to become dense in the process of inserting the sensor probe into the measurement atmosphere and raising the temperature. Since this seal portion is in a state where the sensor element 1 is heated to the working temperature and expanded, the sensor element 1
Close to the other end of the. Therefore, unlike the case where the dense glass seal portion is provided at the other end of the sensor element 1 when the sensor element 1 is at room temperature, in the present sensor probe, the other end of the sensor element 1 is extremely airtight. Can be sealed with.

Thus, in the sensor probe inserted in the measurement atmosphere, the measurement is performed between the outer surface of the solid electrolyte which is in contact with the measurement atmosphere containing hydrogen or water vapor and the inner surface of the solid electrolyte which is in contact with the solid reference substance 2. Due to the difference between the hydrogen or water vapor concentration in the atmosphere and the reference concentration of the solid reference substance 2, protons move. A galvanic electromotive force is generated between the measurement electrode 3 and the reference electrode 4 due to the movement of the protons. By detecting this electromotive force via the lead wire 8 or the like, the hydrogen or water vapor concentration in the measurement atmosphere can be detected.

FIG. 2 is a sectional view showing a second comparative example of the present invention. This sensor probe is different from that shown in FIG. 1 only in the ceramic chip and the powder glass sealing material, and other configurations are the same, so the same components are designated by the same reference numerals and detailed description thereof will be omitted.

That is, the ceramic chip 5b is shorter than the ceramic chip 5a of FIG. 1, and the recess formed in the sensor element 1 on the open end side of the ceramic chip 5b is filled with the powder glass sealing material 7b. . As described above, since the powder glass sealing material 7b is packed inside the sensor element 1, when the powder glass sealing material 7b rises in temperature and softens when the sensor probe is inserted into the measurement atmosphere, it is obtained. The dense glass seal portion is embedded inside the sensor element 1 and attached to the inner surface thereof. Therefore, compared with the case of FIG. 1 in which the glass sealing material is attached to the outer surface of the sensor element 1, the glass sealing material 7b in the sensor probe of FIG. It can be further closely attached to the above.

Next, examples of the present invention will be described. FIG. 3 is a sectional view showing a sensor probe according to an embodiment of the present invention.
In FIG. 3, the same parts as those in FIG. 1 or 2 are designated by the same reference numerals, and detailed description thereof will be omitted. A solid reference substance 2 is filled inside the sensor element 1, and a relatively short ceramic chip 5c is provided on the open end side of the sensor element 1 so that the solid reference substance 2 is enclosed in the sensor element 1. Has been inserted. A recess filled with the glass sealing material 7c is formed in a portion closer to the open end of the sensor element 1 than the ceramic chip 5c, as in the embodiment shown in FIG.

A lead wire 8 connected to the reference electrode 4 is inserted through the center of the ceramic chip 5c, and the reference electrode 4 is electrically led out of the sensor element 1 by the lead wire 8. A metal paste 6 is interposed between the ceramic chip 5c and the inner surface of the sensor element 1.

Then, the ceramic holder 9 is fitted in approximately half of the open side of the sensor element 1. This ceramic holder 9
Has a tubular shape whose inner diameter is larger than the outer diameter of the sensor element 1 and which is closed at one end, and is externally fitted to the sensor element 1 with the open end of the sensor element 1 in contact with the inner end surface of the ceramic holder 9. . The ceramic holder 9 has a conical surface on which the edge of the sensor element 1 fitted inside contacts. A hole for inserting the lead wire 8 extends from the apex of the cone to the outer surface of the ceramic holder 9. The ceramic holder 9 is made of ceramic such as alumina or mullite.

The area between the inner peripheral surface of the ceramic holder 9 and the outer surface of the sensor element 1, and the portion of the sensor element 1 on the open end side of the ceramic chip 5c and the ceramic holder 9
A paste-like glass sealing material 7c is filled in the area surrounded by the inner surface of the glass sealing material 7c. The inner surface of the ceramic holder 9 is slightly expanded at the open end side, and a large amount of paste glass sealing material is applied to this part. Further, the paste-like glass sealing material is also applied in the center hole of the ceramic holder 9 through which the lead wire 8 is inserted.

The pasty glass sealing material 7c is, for example, PbO / B.
A dense glass having a composition of aO · B ₂ O ₃ may be used. The glass sealant having this composition has a softening point of 693 ° C and a pour point of 780 ° C. Therefore, the sensor probe using the glass sealing material of this composition is used in the temperature range of 693 to 780 ° C.

In the insertion type sensor probe configured in this way, when it is inserted into the measurement atmosphere, the paste-like glass sealing material 7c exceeds its softening point in the process of temperature rise, becomes a dense glass, and the sensor It is fused to the inner surfaces of the element 1 and the ceramic holder 9. As a result, similarly to the first and second embodiments, a seal portion that hermetically seals the open end side of the sensor element 1 is formed.

In this embodiment, since the paste-like glass sealing material 7c is packed in the area surrounded by the inside of the ceramic holder 9 including the inside of the sensor element 1, the glass sealing material 7c is formed.
7c is attached to the outer surface of the sensor element 1 as well as the inner surface thereof. Therefore, the sealing portion obtained by softening the glass sealing material 7c can seal the portion on the open end side of the sensor element 1 with extremely high airtightness.

Next, the results of actually measuring the concentrations of hydrogen and water vapor using the sensor probe according to the present embodiment described above will be described.

Measurement of Hydrogen Concentration A sensor probe having the structure shown in FIG. 2 was used. The sensor element 1 of this sensor probe is formed of a perovskite type proton conductive solid electrolyte having a composition of SrCe _0.95 Yb _0.05 O _3-Y . The outer diameter of this sensor element 1 is 4m.
m, inner diameter 2.5 mm, length 20 mm. This sensor element 1
Platinum porous electrodes on the inner and outer surfaces (4 reference electrodes, 3 measurement electrodes)
After baking at 900 ° C., the solid reference substance 2 adjusted to a predetermined composition was filled in the sensor element 1 in a length of 10 mm. Then, a platinum paste 6 was applied to a mullite chip (ceramic chip 5b) through which a Pt wire having a wire diameter of 0.2 mm was passed and inserted into the sensor element 1. The mullite chip has a diameter of 2 mm and a length of 7 mm. Next, the composition is ZnO ・ B ₂ O ₃・ S.
The powdery glass sealing material 7b of iO ₂ was filled in the sensor element 1. This glass sealing material 7b has a softening point of 660 ° C and a pour point of 7
24 ° C.

Next, as shown in FIG. 4, a part of this sensor probe is inserted into the alumina insertion tube 10 so that the portion of the measuring electrode 3 is exposed to the outside by the inorganic adhesive 12 to the insertion tube 10. Fixed The insertion tube 10 has a platinum paste baked on the outer surface thereof so that the outer surface measurement electrode 3 of the sensor probe 3
The print lead wiring 11 electrically connected to the is formed. Also, the outer diameter of the insertion tube 10 is 6.5 mm, the inner diameter is 4.5 mm,
The length is 300 mm. Then, this sensor probe was inserted and installed in the furnace core tube 22 of the tubular furnace 21 shown in FIG. 6 with the sensor element 1 centered. In this tubular furnace 21, the hydrogen gas and the nitrogen gas supplied from the hydrogen gas cylinder 24 and the nitrogen gas cylinder 25 are once collected in the gas mixer 23, and after being mixed in the gas mixer 23 to a predetermined blending amount, Piping
It is adapted to be introduced into the furnace core tube 22 via 29.
A thermocouple 26 is inserted in the furnace core tube 22, and the output of the thermocouple 26 is input to the analyzing recorder 27 and recorded. As a result, the sensor element 1 in the furnace core tube 22
The temperature in the vicinity of is measured and recorded. Furthermore, the furnace core tube 22
The gas inside is taken out from the lower end of the furnace core tube 22 and supplied to the gas chromatograph analyzer 28.

Using the device configured as described above, the relationship between the hydrogen partial pressure and the electromotive force in the sensor probe was determined. However, the ambient temperature in the furnace core tube 22 heated by the tubular furnace 21 is 700 ° C.
The amount of hydrogen was changed by the gas mixer 23 within the range of 0.1 to 100%.

The results are shown in FIG. The horizontal axis of FIG. 7 is the hydrogen partial pressure measured by the gas chromatograph analyzer 28, and the vertical axis is the galvanic electromotive force generated between the measurement electrode 3 and the reference electrode 4 of the sensor probe. However, the horizontal axis of FIG. 7 is a logarithmic scale. The ambient temperature is 700 ° C as described above,
The ambient temperature was adjusted to a constant value by detecting the ambient temperature with the thermocouple 26 and feeding back the detection result to the control of the drive power of the tubular furnace 21.

As is clear from FIG. 7, there is a proportional relationship with good linearity between the logarithm of the hydrogen partial pressure and the electromotive force. Therefore, as shown in FIG. 7, the relationship between the known hydrogen partial pressure at a specific atmospheric temperature and the electromotive force is obtained in advance, and this is used as a calibration line to measure from the measured value of the electromotive force. An unknown amount of hydrogen in the atmosphere can be measured.

Measurement of Water Vapor Concentration Next, the result of measuring the water vapor concentration using the sensor probe shown in FIG. 3 will be described. The sensor element 1 of this sensor probe is formed of a perovskite type proton conductive solid electrolyte having a composition of SrCe _0.95 Yb _0.05 O _3-Y . The sensor element 1 has an outer diameter of 4 mm, an inner diameter of 2.5 mm and a length of 20 mm. 900 platinum electrodes (reference electrode 4, measurement electrode 3) are provided on the inner and outer surfaces of the sensor element 1.
After baking at 0 ° C., the solid reference substance 2 adjusted to a predetermined composition was filled in the sensor element 1 in a length of 10 mm. Then, a platinum paste 6 was applied to a mullite chip (ceramic chip 5c) through which a Pt wire having a wire diameter of 0.2 mm was passed and inserted into the sensor element 1. The diameter of this mullite chip is 2mm,
The length is 10 mm. Next, a paste glass sealing material having a composition of PbO / BaO / B ₂ O ₃ is applied to the inside of the ceramic holder 9 made of alumina, and then the sensor element 1 is attached to the ceramic holder 9
The sensor probe was assembled by inserting it inside. The glass sealant having this composition has a softening point of 693 ° C and a pour point of 780 ° C.

As shown in FIG. 5, this sensor probe was fixed to one end of an alumina insertion tube 10 with an inorganic adhesive 12. A print lead wire 11 electrically connected to the outer surface measurement electrode 3 of the sensor probe is formed by baking platinum paste on the outer surface of the insertion tube 10. Also,
The insertion tube 10 has an outer diameter of 6.5 mm, an inner diameter of 4.5 mm, and a length of 300 mm.

Then, this sensor probe was attached to the device shown in FIG. 8 to measure the water vapor concentration. This apparatus is adapted to supply steam into the furnace core tube 22 from its head through a pipe 34. A constant temperature medium 31 having a temperature near the boiling point of water is stored in the constant temperature tank 30, and a buffler 32 is immersed in the constant temperature medium 31. And this buffler 32
Water is stored inside, and by introducing compressed air from the air pump 33 into the baffler 32, the steam generated in the buffler 32 is sent out to the pipe 34, and this steam is introduced into the furnace core tube 22 via the pipe 34. It is supposed to be supplied. The amount of water vapor was defined by the temperature in the constant temperature bath 30.

The amount of water vapor was measured using the apparatus configured as described above. However, the ambient temperature is 700 ℃, and the amount of water vapor is 4.6 to 150T.
orr. As a result, as shown in FIG. 9, in the measurement result of the amount of water vapor, a relationship with excellent linearity was obtained between the water vapor partial pressure P _H20 and the electromotive force. Therefore, also with respect to this water vapor, by previously obtaining the relationship between the water vapor amount and the electromotive force at a specific temperature, the water vapor amount in the measurement atmosphere of unknown water vapor concentration can be measured based on this.

[Effects of the Invention] According to the present invention, the reference electrode and the solid reference substance can be reliably sealed from the measurement atmosphere even at a high temperature. Therefore, the sensor using the solid reference substance should be used for the measurement of hydrogen or water vapor. Therefore, unlike the conventional sensor using a reference gas as a reference substance, a device for circulating the reference gas is not required, and a small and highly reliable insertion type sensor probe can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a sensor probe according to a first comparative example of the present invention, FIG. 2 is a sectional view showing a sensor probe according to a second comparative example of the present invention, and FIG. FIG. 4 is a sectional view showing a sensor probe according to the embodiment of the present invention, FIG. 4 is a side view showing a detection member having the sensor probe shown in FIG. 2 incorporated therein, and FIG. 5 is a detection having the sensor probe shown in FIG. 3 incorporated therein. A side view showing members, FIG. 6 is a schematic view showing a hydrogen concentration analyzer, FIG. 7 is a graph showing results of the hydrogen concentration analysis, FIG. 8 is a schematic view showing a water vapor concentration analyzer, FIG. FIG. 4 is a graph showing the results of the water vapor concentration analysis. 1; sensor element, 2; solid reference material, 3; measuring electrode, 4; reference electrode,
5a, 5b, 5c; Ceramic chip, 7a, 7b, 7c; Glass sealing material, 9; Ceramic holder

Claims (4)

[Claims] 1. A sensor element of one-end closed type formed of a perovskite type proton conductive solid electrolyte, a solid reference substance filled in the sensor element and serving as a reference of galvanic electromotive force, and an inner surface of the sensor element. A reference electrode formed in contact with the solid reference material, a measurement electrode formed on the outer surface of the sensor element, and a ceramic holder for closing the one end and fittingly holding the sensor element at the other end side. And a sealing material which is at least filled between the inner surface of the ceramic holder and the outer surface of the sensor element and hermetically seals both of them to isolate the solid reference material and the reference electrode from the measurement atmosphere, The sealing material has a softening temperature equal to or lower than a predetermined use temperature of the sensor, has a pour point equal to or higher than the use temperature, and has a powder form before the sensor is used,
An insertable sensor probe, wherein the solid reference substance and the reference electrode are hermetically sealed from the measurement atmosphere by being fused to the other end of the sensor element by being heated by the measurement atmosphere when the sensor is used. 2. The perovskite-type proton conductive solid electrolyte is a composite oxide of strontium and cerium,
The insertion type sensor probe according to claim 1, wherein the main component is any one selected from the group consisting of a complex oxide of barium and cerium and a complex oxide of calcium and zirconium. 3. The perovskite-type proton-conductive solid electrolyte contains at least one element selected from the group consisting of indium, scandium, ytterbium, magnesium, bismuth, aluminum, gallium, yttrium and neodymium. The insertable sensor probe according to claim 2. 4. The insertion type sensor probe according to claim 1, wherein the sealing material has a composition that becomes a dense glass at a temperature equal to or higher than the softening temperature.