JP3979901B2 - Carbon dioxide sensor - Google Patents

Description

【００５９】
【表２】

【００６０】
本発明の炭酸ガスセンサＸは、放置前後でセンサ出力の変化がほとんど見られず極めて安定していることが判明した。これに対し、従来の炭酸ガスセンサＸ’は放置後の出力は放置前の出力に比べて１〜２割程度低下することが判明した。つまり、従来の炭酸ガスセンサＸ’は高温に晒すことによりセンサ特性が劣化したものと考えられる。そのため、高温における使用には適さない。
【００６１】
これより、本発明の炭酸ガスセンサＸは、高温の影響を受けにくい安定したセンサであるものと認められた。そのため、工場等の設備において、高温である排煙中等においても実装可能となる。
【００６２】
尚、本発明は上記実施形態に限定されるものではなく、同様の作用効果を奏するものであれば、各部構成を適宜変更することが可能である。
【図面の簡単な説明】
【図１】本発明の炭酸ガスセンサの断面図
【図２】本発明の炭酸ガスセンサを用いて種々の濃度の炭酸ガスを被検知ガスとして測定した際のそれぞれの炭酸ガス測定時のセンサ出力（起電力）の結果を示した図
【図３】本発明の炭酸ガスセンサを用いて種々の濃度の炭酸ガスを被検知ガスとして連続して測定した際のセンサ出力（起電力）の経時変動結果を示した図
【図４】本発明の炭酸ガスセンサを１０００℃に１０００時間放置した前後における起電力の変化を示した図
【図５】従来の炭酸ガスセンサを１０００℃に１０００時間放置した前後における起電力の変化を示した図
【符号の説明】
１ カチオン伝導性固体電解質
２ 酸化物イオン伝導性固体電解質
３ 検出極
Ｘ 固体電解質型炭酸ガスセンサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a carbon dioxide gas sensor using a solid electrolyte.
[0002]
[Prior art]
Up to now, as a carbon dioxide gas sensor using a solid electrolyte, a sensor in which a cation conductor having an alkali metal ion that is a monovalent cation as a main conductive ion species and an alkali metal carbonate are combined has been widely developed. However, the sensor using the carbonate of the above had a problem in stability in an atmosphere where water vapor was present.
[0003]
In order to overcome such a problem, means for mixing various oxides and metals with an alkali metal carbonate serving as a detection electrode has been reported, but none of them has achieved a significant improvement in stability.
[0004]
Japanese Patent Laid-Open No. 9-257747 discloses an invention in which an alkaline earth metal carbonate having higher water resistance than an alkali metal carbonate is used as a detection electrode. A simple substance cannot detect carbon dioxide with high accuracy, and carbon dioxide can be detected by mixing various oxides as a decomposition catalyst.
[0005]
In the solid electrolyte carbon dioxide sensor, an equilibrium reaction involving the concentration of carbon dioxide contained in the measurement atmosphere occurs at the detection electrode. For this equilibrium reaction, a very small amount of decomposition of the detection electrode is necessary. However, since the solid electrolyte carbon dioxide sensor uses a decomposition catalyst, the alkaline earth metal carbonate continues to be decomposed, and the detection electrode itself Change. For this reason, it is easily predicted that carbon dioxide gas cannot be detected, which is a major obstacle to the practical use of a carbon dioxide gas sensor.
[0006]
Japanese Laid-Open Patent Publication No. 11-153576 has reported that a compound containing a rare earth carbonate is used as a detection electrode. However, the rare earth carbonate alone can be used to detect carbon dioxide gas. The conductivity is insufficient, and when an additive such as a metal is mixed in order to improve electrical conductivity, decomposition occurs and the characteristics are remarkably deteriorated.
[0007]
In addition, when a solid electrolyte containing alkali metal ions as the main conductive ion species is used for the sensor, once the sensor has cracked, the conductive ion species are carbonated by carbon dioxide in the measurement atmosphere, making detection impossible in principle. It also has the problem of becoming.
[0008]
Thus, in order to develop a solid electrolyte carbon dioxide sensor that can be put to practical use, it is necessary to greatly improve the characteristics of both the solid electrolyte and the detection electrode. Therefore, in order to overcome the problems of solid electrolytes among the constituent materials of carbon dioxide gas sensors, sensors using a cation conductive solid electrolyte and an oxide ion conductive solid electrolyte whose main conductive ion species are divalent or higher have been developed. It was.
[0009]
In the sensor, the problem of the solid electrolyte could be overcome, but the problem of the detection electrode has not been completely overcome.
[0010]
Thus, although carbon dioxide gas sensors using various solid electrolytes have been proposed, none of the sensors has removed the influence of coexisting miscellaneous gases such as water vapor, which is the biggest problem, and monovalent alkali as a solid electrolyte. In the solid electrolyte having metal ions as the main conductive ion species, as described above, a large defect remains regardless of the presence or absence of water vapor.
[0011]
However, in Japanese Patent Application Laid-Open No. 2002-116175, the solid electrolyte also functions as a solid electrolyte having a divalent or higher cation having a poor reactivity with carbon dioxide and other gases in the atmosphere as the main conductive ion species, and an oxygen permeable membrane. It has been found that carbon dioxide gas detection according to the principle can be realized by superimposing an oxide ion conductor using oxide ions as a conductive species.
Also, by using a compound containing a solid solution in which a part of the rare earth element in the rare earth carbonate is replaced with an alkaline earth metal element as the detection electrode, the sensor electrode is left not in operation, that is, at room temperature. It has been found that a sensor that eliminates the influence of dew condensation that is a concern in a wet state can be realized.
[0012]
Such a carbon dioxide gas sensor can detect only carbon dioxide gas without being affected at all by miscellaneous gases such as water vapor.
[0013]
[Problems to be solved by the invention]
Carbon dioxide gas is one of the gases present in the exhaust gas discharged from the flue gas of factories and the like, and is considered to be a causative substance of global warming. In recent years, the emission regulations have become more stringent. For this reason, carbon dioxide released from the flue gas of factories and the like into the atmosphere is to be suppressed, and when carbon dioxide leaks occur in facilities such as factories, the leak location should be identified quickly to prevent further leaks. is important.
[0014]
This can be achieved, for example, by disposing carbon dioxide sensors at various locations in the facility or in flue gas and always detecting the carbon dioxide concentration in the air.
[0015]
However, the carbon dioxide gas in the flue gas is usually at a high temperature reaching about 500 to 600 ° C. Furthermore, the temperature of the heat source in the boiler is a high temperature reaching 900 to 1800 ° C. For this reason, the carbon dioxide sensor in the flue gas is required to have durability against a high temperature of about 600 ° C to about 1000 ° C. Since the conventional carbon dioxide sensor described above does not have durability at such a high temperature, it is difficult to obtain a stable output. For this reason, there has been a problem that carbon dioxide gas cannot be detected by mounting a conventional carbon dioxide sensor in the flue gas.
[0016]
For this reason, it is difficult to always detect the concentration of carbon dioxide in the air, and there is a disadvantage that it is difficult to control the amount of carbon dioxide released from the smoke of a factory or the like into the atmosphere.
[0017]
Accordingly, an object of the present invention is to provide a carbon dioxide gas sensor having excellent heat resistance and capable of being detected even in a high temperature environment such as during flue gas.
[0018]
[Means for Solving the Problems]
[Configuration 1]
In order to achieve this object, the characteristic configuration of the present invention includes a cation conductive solid electrolyte having a divalent or higher cation as a main conductive species, an oxide ion conductive solid electrolyte having an oxide ion as a conductive species, and a rare earth. The solid electrolyte type carbon dioxide gas sensor is provided with a detection electrode that is a compound containing a solid solution in which carbonate is dissolved in oxysulfate , and the function and effect thereof are as follows.
[0019]
[Function 1]
That is, in a solid electrolyte carbon dioxide sensor, a cation conductive solid electrolyte having a divalent or higher cation as a main conductive species, an oxide ion conductive solid electrolyte having an oxide ion as a conductive species, and a rare earth oxysulfate with carbonic acid. When a structure including a detection electrode, which is a compound containing a solid solution in which a salt is dissolved, as shown in the examples described later and FIG. 2, it is obtained when carbon dioxide gas having various concentrations is measured as a gas to be detected. From the measurement result of the sensor output (electromotive force) obtained, a good 1: 1 relationship is recognized between the sensor output and the logarithm of the carbon dioxide concentration, so that the carbon dioxide concentration can be accurately determined from the sensor output. At the same time, as shown in FIG. 3 (response waveform test), the sensor can detect carbon dioxide gas stably even under high temperature conditions.
[0020]
The rare earth oxysulfate itself has a heat resistance of 1000 ° C. or more and is excellent in stability. Therefore, if the detection electrode contains a rare earth oxysulfate, it is stable even in both oxidizing and reducing atmospheres. That is, by dissolving the carbonate in such a detection electrode, it is possible to obtain a detection electrode that has reactivity with carbon dioxide and is excellent in stability and heat resistance.
[0021]
FIG. 3 shows the results of temporal variation of the sensor output (electromotive force) when measuring carbon dioxide of various concentrations at 500 ° C. According to this, it is defined as 90% of the total output change. The response speed is within a few minutes and the reproducibility of the response is recognized as continuous. Therefore, the carbon dioxide sensor of the present invention is recognized as a sensor that can stably detect carbon dioxide of various concentrations under a high temperature condition of 500 ° C.
[0022]
Furthermore, in the high-temperature durability test described later, the carbon dioxide gas sensor of the present invention is evaluated by evaluating the sensitivity characteristic by measuring the carbon dioxide gas concentration before and after leaving it at 1000 ° C. for 1000 hours. Since no change in sensor output is observed before and after standing, it is recognized that the sensor output is extremely stable even under a high temperature condition of 1000 ° C.
[0023]
As described above, since the carbon dioxide sensor of the present invention is a stable sensor that is not easily affected by high temperatures, it can be mounted in a facility such as a factory even during high-temperature smoke exhaust. Therefore, it is possible to quickly detect the leakage of carbon dioxide gas.
[0024]
[Configuration 2]
In order to achieve this object, the characteristic configuration of the present invention is that, in the above-described configuration 1, the oxide ion conductive solid electrolyte is made of stabilized zirconia, and the effects thereof are as follows.
[0025]
[Operation effect 2]
Stabilized zirconia has excellent mechanical strength in addition to high oxide ion conductivity and high chemical stability. Therefore, when the oxide ion conductive solid electrolyte is stabilized zirconia, the solid electrolyte excellent in ion conductivity, ion transport number, stability to various atmospheres and compactness can be obtained.
[0026]
[Configuration 3]
In order to achieve this object, the characteristic configuration of the present invention is that, in the above configuration 1 or 2, the cation conductive solid electrolyte is mainly composed of trivalent aluminum ions, and the function and effect thereof are as follows. It is.
[0027]
[Operation effect 3]
That is, when the cation-conducting solid electrolyte is mainly composed of trivalent aluminum ions, the raw materials are inexpensive, the reactivity with other substances is low, and the trivalent aluminum ions have a small ionic radius. Therefore, since ionic conduction is easy, it can be set as the solid electrolyte excellent in practicality and stability.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
A carbon dioxide gas sensor sectional view of the present invention is illustrated in FIG. 1, and details of the sensor configuration will be described below.
[0029]
Various candidate materials, such as solid electrolytes and semiconductors, have been proposed as components for carbon dioxide sensors. Among these, carbon dioxide sensors using solid electrolytes have quick response and high carbon dioxide selectivity. Has the advantage. Therefore, the carbon dioxide sensor X of the present invention uses a cation conductive solid electrolyte 1 having a divalent or higher cation as a main conductive species, and an oxide ion conductive solid electrolyte 2 having an oxide ion as a conductive species. A solid electrolyte type sensor comprising a detection electrode 3 having heat resistance.
[0030]
As the cation conductive solid electrolyte 1, any known solid electrolyte can be used without any limitation as long as the solid electrolyte has a divalent or higher cation as a main conductive ion species. Among these solid electrolytes, from the viewpoint of practicality and stability, it is particularly preferable that the main conductive species is trivalent aluminum ions.
[0031]
As the oxide ion conductive solid electrolyte 2, any known solid electrolyte may be used without any limitation as long as the oxide ion is the conductive ion species as the solid electrolyte having oxide ions as the main conductive ion species. However, it is desirable to use stabilized zirconia and a compound containing the same from the viewpoints of ion conductivity, ion transport number, stability to various atmospheres, compactness, and the like.
[0032]
The detection electrode 3 can be used as long as it is a compound containing a solid solution obtained by dissolving a carbonate in a rare earth oxysulfate (Ln ₂ O ₂ SO ₄ ).
The carbon dioxide sensor X is required to have high stability in various environments where the sensor is installed. Furthermore, since the substance used for the detection electrode needs to cause an equilibrium reaction with carbon dioxide in the atmosphere, it needs to contain carbonate ions. Therefore, the carbon dioxide sensor X of the present invention is an oxysulfate detection electrode in which carbonate ions (carbonates) are contained in a rare earth oxysulfate having excellent heat resistance.
[0033]
Two kinds of solid electrolytes of the cation conductive solid electrolyte 1 and the oxide ion conductive solid electrolyte 2 are overlapped, and an inorganic adhesive 4 is applied to the side surface to fix them. The detection electrode 3 and the wire mesh electrode 5 are fixed to the surface of the cation conductive solid electrolyte 1 side, and the wire mesh electrode 6 is fixed to the surface of the oxide ion conductive solid electrolyte 2 side. Lead wires 7 are connected to both ends of the wire mesh electrodes 5 and 6.
[0034]
With such a configuration, the carbon dioxide sensor of the present invention has sensor performance that makes it possible to stably detect carbon dioxide in a carbon dioxide leakage atmosphere. Hereinafter, the present invention will be described in more detail using examples.
[0035]
【Example】
(Al _0.2 Zr _0.8 ) _{2 0/19} Nb (PO ₄ ) ₃ , oxide ion having oxide ion as conductive species as cation conductive solid electrolyte 1 having trivalent aluminum ion as the main conductive species Stabilized zirconia as the conductive solid electrolyte 2 and oxysulfate detection electrode (La _0.7 Li _0.3 ) in which lithium carbonate (Li ₂ CO ₃ ) is dissolved in rare earth oxysulfate (La ₂ O ₂ SO ₄ ) as the detection electrode 3. ) A carbon dioxide sensor with ₂ O _1.4 SO ₄ was produced.
[0036]
The cation conductive solid electrolyte 1 is produced as follows.
That is, aluminum hydroxide Al (OH) ₃ , zirconium nitrate dihydrate ZrO (NO ₃ ) ₂ .2H ₂ O, niobium oxide Nb ₂ O ₅ , and diammonium hydrogen phosphate (NH ₄ ) ₂ HPO ₄ Each was weighed at a molar ratio of 8: 32: 19: 114, mixed in a mortar, and calcined at 1000 ° C. for 12 hours. The calcined powder was formed into a disk shape and baked at 1200 ° C. for 12 hours in an electric furnace. The fired powder was again pulverized and mixed in a mortar, then formed into a disk shape and sintered in an electric furnace at 1300 ° C. for 12 hours. Thus, (Al _0.2 Zr _0.8 ) _20/19 Nb (PO ₄ ) ₃ was obtained as the cation conductive solid electrolyte 1.
[0037]
The stabilized zirconia as the oxide ion conductive solid electrolyte 2 is obtained by weighing zirconium oxide (ZrO ₂ ) and yttrium oxide (Y ₂ O ₃ ) in a ratio of 9: 1, mixing them in a mortar, It was obtained by firing at 1600 ° C. for 6 hours, pulverizing and mixing the fired powder again in a mortar, forming into a disk shape, and further firing twice at 1600 ° C. for 6 hours in an electric furnace.
[0038]
The oxysulfate detection electrode 3 is obtained by dissolving lithium carbonate (Li ₂ CO ₃ ) in La ₂ O ₂ SO ₄ which is a rare earth oxysulfate. La ₂ O ₂ SO ₄ is obtained by baking La ₂ S ₃ at 1000 ° C. for 12 hours. Then, after rare earth oxysulfate (La ₂ O ₂ SO ₄ ) and lithium carbonate (Li ₂ CO ₃ ) were weighed to a molar ratio of La: Li = 7: 3 and mixed for 12 hours by a ball mill, by baking for 12 hours in an electric furnace at 1000 ° C., a oxysulfate detection electrode _{3 (La 0.7 Li 0.3) 2} O 1 .4 SO 4 were obtained.
[0039]
And as above-mentioned, after superposing | stacking two types of solid electrolytes, the said cation conductive solid electrolyte 1 and the said oxide ion conductive solid electrolyte 2, the inorganic adhesive 4 is apply | coated to a side surface and both are fixed. The detection electrode 3 and a wire mesh electrode (gold) 5 were fixed to the surface of the cation conductive solid electrolyte 1 side, and a wire mesh electrode (platinum) 6 was fixed to the surface of the oxide ion conductive solid electrolyte 2 side. For the lead wire 7, gold was used on the cation conductive solid electrolyte 1 side, and platinum was used on the oxide ion conductive solid electrolyte 2 side.
[0040]
The carbon dioxide sensor X according to the present invention includes a chemical compound 1 at the oxysulfate detection electrode 3, chemical compound 2 at the ionic conductor interface between the oxysulfate detection electrode 3 and the cation conductive solid electrolyte 1, and the cation conductive solid. The reaction of Chemical Formula 3 occurs at the ion conductor interface between the electrolyte 1 and the oxide ion conductive solid electrolyte 2, and Chemical Formula 4 occurs at the oxide ion conductive solid electrolyte 2.
[0041]
[Chemical 1]
Li ₂ CO ₃ → 2Li ⁺ + CO ₂ + 1 / 2O ₂ ^I + 2e ⁻
[0042]
[Chemical 2]
_{^{2Li + + 19/6 (Al 0.2 Zr}} 0.8) 20/19 Nb (PO 4) 3 →
2 / 3Al ³⁺ + 19/6 (Li _0.6 Zr _0.8 ) _20/19 Nb (PO ₄ ) ₃
[0043]
[Chemical 3]
2 / 3Al ³⁺ + O ^2- → 1 / 3Al ₂ O ₃
[0044]
[Formula 4]
^{_{1 / 2O 2 II + 2e -}} → O 2 -
[0045]
The overall reaction of the carbon dioxide sensor is as shown in Chemical formula 5.
[0046]
[Chemical formula 5]
Li ₂ CO ₃ + 19/6 (Al _0.2 Zr _0.8 ) _20/19 Nb (PO ₄ ) ₃ →
CO ₂ + 19/6 (Li _0.6 Zr _0.8 ) _20/19 Nb (PO ₄ ) ₃ + 1/3 Al ₂ O ₃
[0047]
From this, the following Nernst equation is obtained.
[0048]
[Expression 1]
E = E ₀ ′ (constant) − (R / nF) Tln {(PCO ₂ ) · (a (Li _0.6 Zr _0.8 ) _20/19 Nb (PO ₄ ) ₃ ) ^19/6 · (aAl ₂ O ₃ ) ^{1 / 3} · (aLi ₂ CO ₃ ) ⁻¹ · (a (Al _0.2 Zr _0.8 ) _20/19 Nb (PO ₄ ) ₃ ) ^-19/6 } (n = 2.00)
[0049]
Here, (Al _0.2 Zr _0.8 ) _20/19 Nb (PO ₄ ) ₃ , Al ₂ O ₃ , Li ₂ CO ₃ and (Li _0.6 Zr _0.8 ) _20/19 Nb (PO ₄ ) ₃ are solid, Equation 1 is simplified as follows.
[0050]
[Expression 2]
E = E ₀ ″ (constant) − (R / nF) Tln (PCO ₂ ) (n = 2.00)
[0051]
In FIG. 2, the measurement result of the sensor output (electromotive force) obtained when the carbon dioxide sensor of the present invention was used to measure carbon dioxide of various concentrations as the gas to be detected is shown.
[0052]
As a result, a good 1: 1 relationship was recognized between the sensor output and the logarithm of the carbon dioxide concentration. Therefore, it has been found that the carbon dioxide gas concentration is accurately determined from the sensor output.
[0053]
At this time, n = 2.02 was calculated from the slope of the graph of FIG. This value substantially coincides with n = 2.00 (shown by a solid line in FIG. 2), which is the theoretical value in the above formula 2.
[0054]
(Response waveform test)
FIG. 3 shows the temporal variation results of the sensor output (electromotive force) when measuring carbon dioxide (CO ₂ ) of various concentrations using the carbon dioxide sensor X of the present invention as a gas to be detected. The carbon dioxide concentration was adjusted by adding oxygen gas and nitrogen gas to 1000 ppm, 1%, 10% carbon dioxide. At this time, the oxygen concentration was adjusted so as to be finally 20 vol%. The detected gas supply rate to the carbon dioxide sensor was 100 mL / min, and the measurement temperature was 500 ° C. FIG. 3 (a) shows the sensor output results obtained when 1000 to 5000 ppm of carbon dioxide gas was continuously supplied and FIG. 3 (b) was continuously supplied with 1 to 5% carbon dioxide gas.
[0055]
From the results of FIGS. 3 (a) and 3 (b), it was confirmed that the response speed defined as 90% of the total output change was within several minutes, and the reproducibility of the response was continuous. From this, it was recognized that the carbon dioxide gas sensor X of the present invention is a sensor capable of stably detecting various concentrations of carbon dioxide gas under a high temperature condition of 500 ° C.
[0056]
(High temperature durability test)
Furthermore, the carbon dioxide sensor X of the present invention and the conventional carbon dioxide sensor X ′ were exposed to high temperature conditions, and their high temperature durability was compared.
The carbon dioxide sensor X of the present invention was the same as that used in the heat resistance test. The conventional carbon dioxide sensor X ′ uses Mg _0.7 (Zr _0.85 Nb _0.15 ) ₄ P ₆ O ₂₄ containing divalent Mg ²⁺ as a main conductive ion species as a cation conductive solid electrolyte, and is oxidized. Stabilized zirconia was used as a solid electrolyte whose main ion was a conductive ion, and a solid solution of neodymium carbonate and lithium carbonate was used as a detection electrode.
[0057]
These carbon dioxide sensors X and X ′ were left at 1000 ° C. for 1000 hours, and the carbon dioxide concentration was measured before and after that to evaluate the sensitivity characteristics. The measurement results of the carbon dioxide sensor X of the present invention are shown in FIG. 4 and Table 1, and the measurement results of the conventional carbon dioxide sensor X ′ are shown in FIGS. The slope of the theoretical value is shown by a solid line in FIGS.
[0058]
[Table 1]

[0059]
[Table 2]

[0060]
The carbon dioxide sensor X of the present invention was found to be extremely stable with little change in sensor output before and after being left. On the other hand, it has been found that the output of the conventional carbon dioxide sensor X ′ after being left is lowered by about 10 to 20% compared with the output before being left. That is, it is considered that the sensor characteristics of the conventional carbon dioxide sensor X ′ are deteriorated by exposure to a high temperature. Therefore, it is not suitable for use at high temperatures.
[0061]
From this, it was recognized that the carbon dioxide gas sensor X of the present invention is a stable sensor that is not easily affected by high temperatures. For this reason, it can be mounted in a facility such as a factory even during high-temperature smoke exhaust.
[0062]
In addition, this invention is not limited to the said embodiment, As long as there exists the same effect, the structure of each part can be changed suitably.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a carbon dioxide sensor of the present invention. FIG. 2 shows sensor outputs (starts) when measuring carbon dioxide of various concentrations using the carbon dioxide sensor of the present invention as a gas to be detected. Fig. 3 shows the results of fluctuations in sensor output (electromotive force) over time when carbon dioxide of various concentrations is continuously measured as a gas to be detected using the carbon dioxide sensor of the present invention. FIG. 4 is a graph showing changes in electromotive force before and after leaving the carbon dioxide sensor of the present invention at 1000 ° C. for 1000 hours. FIG. 5 is a graph of electromotive force before and after leaving a conventional carbon dioxide sensor at 1000 ° C. for 1000 hours. Diagram showing changes 【Explanation of symbols】
DESCRIPTION OF SYMBOLS 1 Cation conductive solid electrolyte 2 Oxide ion conductive solid electrolyte 3 Detection pole X Solid electrolyte type carbon dioxide sensor

Claims (3)

A cation conductive solid electrolyte having a divalent or higher cation as a main conductive species, an oxide ion conductive solid electrolyte having an oxide ion as a conductive species, and a solid solution in which a carbonate is dissolved in a rare earth oxysulfate. A solid oxide carbon dioxide sensor having a detection electrode which is a compound .   The solid oxide carbon dioxide sensor according to claim 1, wherein the oxide ion conductive solid electrolyte is made of stabilized zirconia. The cationically conductive solid electrolyte, the solid electrolyte type carbon dioxide gas sensor according to trivalent aluminum ion to claim 1 or 2 as a main conductive species.

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