CN110006980B - Gas sensor element and gas sensor - Google Patents

Gas sensor element and gas sensor Download PDF

Info

Publication number
CN110006980B
CN110006980B CN201811510214.8A CN201811510214A CN110006980B CN 110006980 B CN110006980 B CN 110006980B CN 201811510214 A CN201811510214 A CN 201811510214A CN 110006980 B CN110006980 B CN 110006980B
Authority
CN
China
Prior art keywords
gas sensor
layer
electrode
sensor element
perovskite
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201811510214.8A
Other languages
Chinese (zh)
Other versions
CN110006980A (en
Inventor
佐佐木寿
山际胜也
大塚茂弘
小塚久司
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Niterra Co Ltd
Original Assignee
NGK Spark Plug Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NGK Spark Plug Co Ltd filed Critical NGK Spark Plug Co Ltd
Publication of CN110006980A publication Critical patent/CN110006980A/en
Application granted granted Critical
Publication of CN110006980B publication Critical patent/CN110006980B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/4071—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/4073—Composition or fabrication of the solid electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Molecular Biology (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Measuring Oxygen Concentration In Cells (AREA)

Abstract

The invention provides a gas sensor element and a gas sensor capable of detecting gas even in a low-temperature environment. In the gas sensor element, at least one of the pair of electrodes has a structure in which an intermediate layer and an electrode layer are stacked. The electrode layer contains a perovskite-type oxide having a perovskite-type crystal structure and containing an La element and an Fe element, and a rare-earth-added cerium oxide. The intermediate layer has a structure in which a 1 st layer formed of (La-Zr-Ln '-Ce-O) and a 2 nd layer formed of (La-Zr-Ln' -Ce-Fe-O) are laminated. In the gas sensor element, when a cross section is observed using an inner lens secondary electron detector of a scanning electron microscope, the coverage of the 2 nd layer with the 1 st layer is 90% or less.

Description

Gas sensor element and gas sensor
Technical Field
The present invention relates to a gas sensor element and a gas sensor having a solid electrolyte body and a pair of electrodes.
Background
As shown in patent document 1, a sensor having a gas sensor element whose electrical characteristics change in accordance with the concentration of a specific gas component in a measurement target gas is known.
For example, patent document 1 discloses a gas sensor element including: a solid electrolyte body having a bottomed cylindrical shape and a closed front end; an inner electrode formed on an inner surface of the solid electrolyte body; and an outer electrode formed at a distal end portion of an outer surface of the solid electrolyte body. Such a gas sensor is used to detect the concentration of a specific gas contained in exhaust gas discharged from an internal combustion engine, for example.
Patent documents 2 and 3 disclose various conductive oxides. These conductive oxides can be used as electrode materials of gas sensor elements. When the conductive oxides disclosed in patent documents 2 and 3 are used as the electrode material of the gas sensor element, an electrode having a sufficiently low resistance value can be obtained, and thus the gas detection accuracy of the gas sensor element can be improved. Further, by using the conductive oxides disclosed in patent documents 2 and 3 as the electrode material of the gas sensor element, an inexpensive gas sensor element can be obtained as compared with the case where only a noble metal is used as the electrode material.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2009-63330
Patent document 2: japanese patent No. 3417090
Patent document 3: international publication No. 2013/150779
Disclosure of Invention
Problems to be solved by the invention
However, depending on the application, a gas sensor may require gas detection in a low-temperature environment (for example, 300 ℃ or lower), and even when the gas sensor element is used, the activation of the electrode may be insufficient, and the gas may not be detected.
The present invention aims to provide a gas sensor element and a gas sensor capable of detecting a gas even in a low-temperature environment.
Means for solving the problems
One aspect of the present invention is a gas sensor element including: a solid electrolyte body containing ZrO having oxygen ion conductivity2(ii) a And a pair of electrodes disposed on the solid electrolyte body.
In the gas sensor element according to the present invention, at least one of the pair of electrodes has a structure in which at least an intermediate layer and an electrode layer are stacked in this order from a side closer to the solid electrolyte body. The electrode layer contains a rare earth-doped cerium oxide and a perovskite oxide having a perovskite crystal structure and containing an La element and an Fe element.
In the gas sensor element of the present invention, the intermediate layer has a structure in which at least the 1 st layer made of (La-Zr-Ln '-Ce-O) and the 2 nd layer made of (La-Zr-Ln' -Ce-Fe-O) are stacked in this order from the side closer to the solid electrolyte body. In addition, the rare earth elements other than the La element and the Ce element are Ln' elements.
In the gas sensor element of the present invention, when a cross section including the solid electrolyte body, the intermediate layer, and the electrode layer is observed using an inner lens secondary electron detector of a scanning electron microscope, the coverage of the 2 nd layer with the 1 st layer is 90% or less.
The gas sensor element of the present invention thus constituted has good low-temperature operability, and thus can detect a gas even in a low-temperature environment.
In one embodiment of the present invention, the rare earth element added to the rare earth-added cerium oxide may be Gd. Thus, the gas sensor element of the present invention can realize stable detection accuracy over a long period of time.
In one embodiment of the present invention, the perovskite oxide may not substantially contain an alkaline earth metal. Thus, the gas sensor element of the present invention can suppress the alkaline earth metal contained in the electrode layer and the ZrO contained in the solid electrolyte body2The reaction forms a reaction layer containing an alkaline earth metal between the electrode layer and the solid electrolyte body, and thus the reduction of low-temperature operability can be suppressed.
In one embodiment of the present invention, the perovskite-type oxide may be a (La-Ni-Fe-O) -based perovskite phase. The gas sensor element of the present invention thus constituted can reduce temperature-dependent characteristic variations by containing Ni element and Fe element.
Another aspect of the present invention is a gas sensor including the gas sensor element according to one aspect of the present invention and a holding member for holding the gas sensor element.
The gas sensor of the present invention thus constituted is a gas sensor including the gas sensor element according to one aspect of the present invention, and can obtain the same effects as those of the gas sensor element of the present invention.
Drawings
Fig. 1 is a view showing a state in which a gas sensor is cut in an axial direction.
Fig. 2 is a front view showing an external appearance of the gas sensor element.
Fig. 3 is a sectional view showing the structure of the gas sensor element.
Fig. 4 is a sectional view enlarging regions D1, D2 of fig. 3.
Fig. 5 is a graph showing a reflected electron image showing a cross section near the boundary between the element main body and the inner detection electrode portion and a Zr distribution.
Fig. 6 is a secondary electron image showing a cross section near the boundary between the element main body and the inner detection electrode section, which is acquired using the inner lens secondary electron detector.
Fig. 7 is a graph showing the results of linear analysis in the vicinity of the boundary between the element main body and the inner detection electrode portion.
Fig. 8 is a reflected electron image of example 4 and a secondary electron image obtained by an inner lens secondary electron detector.
Fig. 9 is a diagram showing a luminance distribution of pixels on a boundary line.
Fig. 10 is a graph showing the relationship between the addition rate of rare earth-doped cerium oxide, the internal resistance value, and the coverage rate.
Fig. 11 is a perspective view of a plate-type gas sensor element.
Fig. 12 is a schematic exploded perspective view of a plate-type gas sensor element.
Fig. 13 is a partially enlarged cross-sectional view of the front end side of the plate-type gas sensor element.
Fig. 14 is a partially enlarged cross-sectional view of a region of the plate-type gas sensor element where the reference electrode portion of the reference electrode is formed.
Description of the reference numerals
1 … gas sensor, 3 … gas sensor element, 21 … element body, 27 … outer electrode, 30 … inner electrode, 31 … intermediate layer, 31a … first layer 1, 31b … second layer 2, 32 … electrode layer, 100 … plate type gas sensor element, 104 … reference electrode, 104b … intermediate layer, 104c … electrode layer, 105 … solid electrolyte body, 106 … measurement electrode, 151 … first layer 1, 152 … second layer 2.
Detailed Description
(embodiment 1)
Embodiment 1 of the present invention is explained below based on the drawings.
The gas sensor 1 of the present embodiment is mounted on an exhaust pipe of a vehicle such as an automobile or a motorcycle, for example, and detects the oxygen concentration contained in the exhaust gas in the exhaust pipe.
As shown in fig. 1, the gas sensor 1 includes a gas sensor element 3, a spacer 5, a blocking member 7, a terminal metal case 9, and a lead wire 11. The gas sensor 1 further includes a metal shell 13, a protector 15, and an outer cylinder 16. The metal shell 13, the protector 15, and the outer cylinder 16 are disposed so as to cover the gas sensor element 3, the spacer 5, and the closing member 7. The outer cylinder 16 has an inner outer cylinder 17 and an outer cylinder 19.
The gas sensor 1 does not have a heater for heating the gas sensor element 3. That is, the gas sensor 1 detects the oxygen concentration by activating the gas sensor element 3 by the heat of the exhaust gas.
The gas sensor element 3 is formed using a solid electrolyte body having oxygen ion conductivity. As shown in fig. 2, the gas sensor element 3 has a bottomed cylindrical shape with a closed distal end portion 25, and the gas sensor element 3 has a cylindrical element body 21 extending in the direction of the axis O shown in fig. 1 (hereinafter, axial direction). An element flange portion 23 protruding outward in the radial direction in the circumferential direction is formed on the outer periphery of the element main body 21.
Zirconia (ZrO) was used as the solid electrolyte constituting the element body 212) Adding yttrium oxide (Y) as a stabilizer2O3) And the partially stabilized zirconia sintered body is obtained.
An outer electrode 27 is formed on the outer peripheral surface of the element main body 21 at the distal end portion 25 of the gas sensor element 3. The outer electrode 27 is formed by forming Pt or a Pt alloy in a porous manner.
An annular conductive portion 28 formed of Pt or the like is formed on the distal end side (i.e., the lower side in fig. 2) of the element flange portion 23.
A vertical conductive portion 29 formed of Pt or the like is formed on the outer peripheral surface of the element main body 21 so as to extend in the axial direction between the outer electrode 27 and the annular conductive portion 28. The vertical conductive portion 29 electrically connects the outer electrode 27 and the annular conductive portion 28.
As shown in fig. 1, an inner electrode 30 is formed on the inner peripheral surface of the gas sensor element 3. The detailed structure of the inner electrode 30 will be described later. In the tip portion 25 of the gas sensor element 3, the outer electrode 27 is exposed to the exhaust gas, and the inner electrode 30 is exposed to the reference gas, whereby an electromotive force corresponding to the oxygen concentration in the exhaust gas is generated, and the oxygen concentration in the exhaust gas is detected. In the present embodiment, the reference gas is atmospheric air.
The spacer 5 is a cylindrical member formed of an electrically insulating material (e.g., alumina). The spacer 5 is formed with a through hole 35 at its axial center into which the lead wire 11 is inserted. The spacer 5 is disposed so that a gap 18 is formed between the spacer and an inner outer tube 17 covering the outer circumferential side of the spacer.
The closing member 7 is a cylindrical sealing member formed of a material having electrical insulation (e.g., fluorine rubber). The closing member 7 has a projection 36 projecting radially outward at its rear end. The blocking member 7 has a wire insertion hole 37 at its axial center into which the wire 11 is inserted. The front end surface 95 of the blocking member 7 is in close contact with the rear end surface 97 of the spacer 5, and the lateral outer peripheral surface 98 of the blocking member 7 on the front end side of the protruding portion 36 is in close contact with the inner surface of the inner outer cylinder 17. That is, the closing member 7 closes the rear end side of the outer tube 16.
The wire protecting member 89 is supported with the flange portion 89b of the wire protecting member 89 interposed between the rearward end surface 99 of the blocking member 7 and the distal end surface 19a of the reduced diameter portion 19g of the outer cylinder 19.
The reduced diameter portion 19g extends radially inward on the rear end side of the blocking member 7, and a surface 19a of the reduced diameter portion 19g facing the distal end is formed as a surface facing the distal end side of the gas sensor 1. A lead wire insertion portion 19c for inserting the lead wire 11 and the lead wire protecting member 89 is formed in a central region of the reduced diameter portion 19 g.
The lead wire protecting member 89 is a cylindrical member having an inner diameter dimension capable of accommodating the lead wire 11, and is made of a material having flexibility, heat resistance, and insulation properties (for example, a glass tube, a resin tube, or the like). The wire protecting member 89 is installed to protect the wire 11 from flying objects (e.g., stones, water, etc.) from the outside.
The lead wire protecting member 89 has a plate-like flange portion 89b protruding outward in the axial direction perpendicular to the distal end portion 89 a. The flange portion 89b is not formed partially in the circumferential direction of the wire protecting member 89, but formed over the entire circumference.
The flange portion 89b of the wire protecting member 89 is sandwiched between the surface 19a of the reduced diameter portion 19g of the outer cylinder 19 facing the front end and the surface 99 of the closing member 7 facing the rear end.
The terminal metal case 9 is a cylindrical member formed of a conductive material to take out an output of the sensor to the outside. The terminal metal case 9 is disposed so as to be electrically connected to the lead wire 11 and electrically contacted to the inner electrode 30 of the gas sensor element 3. The terminal metal housing 9 has a flange portion 77 protruding outward in the radial direction (i.e., in a direction perpendicular to the axial direction) on the rear end side thereof. The flange portion 77 has plate-like flange pieces 75 at 3 positions in the circumferential direction (circular angular direction) at equal intervals.
The wire 11 has a core wire 65 and a covering portion 67 covering the outer periphery of the core wire 65.
The main body metal housing 13 is a cylindrical member formed of a metal material (e.g., iron or SUS 430). A step portion 39 is formed on the inner peripheral surface of the metal shell 13 so as to protrude radially inward. The step portion 39 is formed to support the element flange portion 23 of the gas sensor element 3.
A screw portion 41 for attaching the gas sensor 1 to the exhaust pipe is formed on the outer peripheral surface of the metal shell 13 on the distal end side. A hexagonal portion 43 is formed at the rear end side of the threaded portion 41 in the metal shell 13, and the hexagonal portion 43 engages with an attachment tool when the gas sensor 1 is attached to and detached from the exhaust pipe. Further, a cylindrical portion 45 is provided on the rear end side of the hexagonal portion 43 in the metal shell 13.
The protector 15 is a protection member made of a metal material (for example, SUS310S) and covering the tip side of the gas sensor element 3, and introduces the measurement target gas into the gas sensor element 3 through a plurality of gas flow holes formed therein. The rear end edge of the protector 15 is fixed by being sandwiched between the element flange portion 23 of the gas sensor element 3 and the stepped portion 39 of the metal case 13 via a gasket 88 made of a conductive material.
In the rear end side region of the element flange portion 23 in the gas sensor element 3, ceramic powder 47 formed of talc and a ceramic bush 49 formed of alumina are arranged between the main body metal case 13 and the gas sensor element 3 in a range from the front end side to the rear end side.
Further, inside the rear end portion 51 of the cylindrical portion 45 of the metal shell 13, there are disposed: a metal ring 53 formed of a metal material (e.g., SUS 430); and a front end portion 55 of the inner outer cylinder 17, which is formed of a metal material (for example, SUS 304L). The front end 55 of the inner outer cylinder 17 is formed in a shape expanding radially outward. That is, by pressing the rear end portion 51 of the cylindrical portion 45, the front end portion 55 of the inner outer cylinder 17 is sandwiched between the rear end portion 51 of the cylindrical portion 45 and the ceramic bush 49 via the metal ring 53, and the inner outer cylinder 17 is fixed to the metal shell 13.
Further, a cylindrical filter 57 formed of a resin material (e.g., PTFE) is disposed on the outer periphery of the inner outer cylinder 17, and an outer cylinder 19 formed of SUS304L, for example, is disposed on the outer periphery of the filter 57. The filter 57 is capable of ventilation but inhibiting the ingress of moisture.
The inner outer cylinder 17, the filter 57, and the outer cylinder 19 are integrally fixed by pressing the pressing portion 19b of the outer cylinder 19 from the outer peripheral side to the radially inner side. Then, by pressing the pressing portion 19h of the outer cylinder 19 from the outer peripheral side to the radially inner side, the inner outer cylinder 17 and the outer cylinder 19 are integrally fixed, and the lateral outer peripheral surface 98 of the closing member 7 is brought into close contact with the inner surface of the inner outer cylinder 17.
The inner outer cylinder 17 and the outer cylinder 19 have a vent hole 59 and a vent hole 61, respectively. That is, ventilation between the inside and the outside of the gas sensor 1 is enabled via the ventilation holes 59 and 61 and the filter 57.
As shown in fig. 3, the outer electrode 27 and the inner electrode 30 are disposed so as to sandwich the element body 21 at the distal end portion 25 of the gas sensor element 3. The element main body 21 and the pair of electrodes (i.e., the outer electrode 27 and the inner electrode 30) constitute an oxygen concentration cell, and generate an electromotive force corresponding to the oxygen concentration in the exhaust gas. That is, in the front end portion 25 of the gas sensor element 3, the outer electrode 27 is exposed to the exhaust gas, and the inner electrode 30 is exposed to the reference gas, so that the gas sensor element 3 can detect the oxygen concentration in the exhaust gas.
As described above, the outer electrode 27 is electrically connected to the annular conductive portion 28 via the vertical conductive portion 29. The annular conductive portion 28 is electrically connected to the metal shell 13 via a gasket 88 made of a conductive material and the protector 15. An electrode protection layer, not shown, for protecting outer electrode 27 may be formed so as to cover outer electrode 27. The shape and arrangement of the outer electrode 27 are merely examples, and various other shapes and arrangements may be adopted.
An inner electrode 30 is formed on the inner peripheral surface of the element body 21 of the gas sensor element 3. The inner electrode 30 is formed by forming a porous material containing a rare earth-doped cerium oxide, a perovskite, or the like. The inner electrode 30 has an inner detection electrode portion 30a and an inner conductive portion 30 b.
The inner detection electrode portion 30a is formed so as to cover the inner surface of the distal end portion 25 of the element main body 21. The inner conductive portion 30b is formed so as to abut on the inner detection electrode portion 30a and cover the entire upper surface of the inner detection electrode portion 30a, and the inner conductive portion 30b is electrically connected to the terminal metal case 9. The inner detection electrode portion 30a and the inner conductive portion 30b are formed to entirely cover the entire surface of the inner surface of the element main body 21.
That is, the element main body 21 of the gas sensor element 3 has the outer electrode 27 and the inner detection electrode portion 30a formed in the front end side region F1, and has the inner conductive portion 30b formed in the rear end side region F2. The distal end side region F1 of the element main body 21 corresponds to the distal end portion 25 of the element main body 21.
As shown in fig. 4, the inner detection electrode portion 30a has a structure in which an intermediate layer 31, an electrode layer 32, and a tip conductive layer 33a are laminated in this order from the side closer to the element main body 21.
The front end conductive layer 33a forms a conductive layer 33 together with a rear end conductive layer 33b described later. That is, the conductive layer 33 has a front end conductive layer 33a and a rear end conductive layer 33 b.
The intermediate layer 31 is formed by at least lanthanum (La) contained in the electrode layer 32 and zirconium oxide (ZrO) contained in the element main body 212) A layer formed by a reaction between them. In the present embodiment, the intermediate layer 31 is formed by lanthanum (La) and zirconium oxide (ZrO)2) A layer formed by the reaction between lanthanum (La) and zirconium oxide (ZrO) by a method such as printing2) The component obtained by the preliminary reaction is separately sandwiched (laminated) between the element main body 21 and the electrode layer 32.
The electrode layer 32 and the conductive layer 33 are configured to include a perovskite-type oxide having a perovskite-type crystal structure satisfying the following chemical formula (1) (hereinafter, also simply referred to as a "perovskite phase").
LaaFebNicOX···(1)
Here, a + b + c is 1, and 1.25. ltoreq. x.ltoreq.1.75. Preferably, the coefficients a, b, c satisfy the following relational expressions (2a), (2b), (2c), respectively.
0.375≤a≤0.535···(2a)
0.200≤b≤0.475···(2b)
0.025≤c≤0.350···(2c)
The perovskite oxide having the composition represented by the above relational expressions (2a) to (2c) has a conductivity of 250S/cm or more and a B constant of 600K or less at room temperature (e.g., 25 ℃), and has favorable characteristics such as a higher conductivity and a smaller B constant than those in the case where the above relational expressions (2a) to (2c) are not satisfied. In addition, the Pt electrode oxidizes when placed in an atmosphere at about 600 ℃ in the atmosphere, resulting in an increase in the interface resistance between the solid electrolyte body and the electrode. On the other hand, the perovskite oxide described above is less likely to cause such a temporal change.
Instead of satisfying the relational expressions (2a), (2b), and (2c), the coefficients a, b, and c may satisfy the relational expressions (3a), (3b), and (3c), respectively. In this case, the conductivity can be further increased, and the B constant can be further decreased.
0.459≤a≤0.535···(3a)
0.200≤b≤0.375···(3b)
0.125≤c≤0.300···(3c)
In the case where the oxides having the above-described compositions are each formed of a perovskite phase, the coefficient x of O in the above-described chemical formula (1) is theoretically 1.5. However, since oxygen may deviate from the stoichiometric composition, the range of the coefficient x is typically limited to 1.25. ltoreq. x.ltoreq.1.75.
The electrode layer 32 is formed to contain the perovskite phase and rare-earth-doped cerium oxide. The content ratio of the rare earth element RE in the rare earth-added cerium oxide can be, for example, 5 mol% or more and 40 mol% or less in terms of the molar fraction { RE/(Ce + RE) } of cerium and the rare earth element RE other than cerium. Such rare earth-added cerium oxide is an insulator at low temperatures (i.e., room temperature) and a solid electrolyte having oxygen ion conductivity at high temperatures (i.e., the use temperature of the gas sensor 1).
The perovskite phase of the electrode layer 32 contains substantially no alkaline earth metal. Here, "substantially not contained" means a degree that cannot be detected by energy dispersive X-ray spectrometry.
Such an electrode layer 32 has both properties of ion conductivity and electron conductivity at high temperatures (i.e., when the gas sensor 1 is used), and thus exhibits a sufficiently low interface resistance value.
The conductive layer 33 is formed to contain the above-described perovskite phase as a main component and does not contain cerium oxide to which a rare earth is added.
The inner conductive part 30b has a multilayer structure including a rear end conductive layer 33b and an intermediate layer 34. The intermediate layer 34 is disposed closer to the element main body 21 than the rear end conductive layer 33 b.
The rear end conductive layer 33b is formed of the same composition as the front end conductive layer 33a of the inner detection electrode section 30 a. However, the content ratio of the perovskite phase in the front end conductive layer 33a constituting the inner detection electrode portion 30a may be the same as the content ratio of the perovskite phase in the rear end conductive layer 33b constituting the inner conductive portion 30b, or may be higher than the content ratio of the perovskite phase in the rear end conductive layer 33 b.
The intermediate layer 34 is formed of lanthanum (La) contained in the rear end conductive layer 33b and ZrO contained in the element body 21 when the inner conductive portion 30b is fired2A layer formed by the reaction. In addition, lanthanum (La) and zirconium oxide (ZrO) may be provided for the intermediate layer 342) The components obtained by the preliminary reaction are separately stacked on the element body 21.
Next, a method for manufacturing the gas sensor element 3 will be described.
In step 1, an unsintered compact is produced. Specifically, first, as a powder of a solid electrolyte body as a material of the element main body 21, a powder of opposite-direction zirconia (ZrO) was prepared2) Adding 5 mol% of yttrium oxide (Y) as a stabilizer2O3) The resulting powder (hereinafter also referred to as 5YSZ) was further added with alumina powder. When the total material powder of the element main body 21 is 100 mass%, the content of 5YSZ is 99.6 mass%, and the content of alumina powder is 0.4 mass%. After the powder was pressed, it was cut into a cylindrical shape to obtain an unsintered compact.
Next, in step 2, a paste of the electrode layer 32 and a paste of the conductive layer 33 are prepared.
In the preparation of the paste of the electrode layer 32, first, the raw material powder of the perovskite phase is weighedThen, the raw material powder mixture is adjusted by wet mixing and drying, and calcined at 700 to 1300 ℃ for 1 to 5 hours to prepare calcined powder. The calcined powder is pulverized by a wet ball mill or the like to be prepared into a predetermined particle size. In this case, as the raw material powder of the perovskite phase, for example, La (OH) can be used3Or La2O3、Fe2O3And NiO. Next, a raw material powder of rare earth-doped cerium oxide is weighed, wet-mixed and dried to adjust a raw material powder mixture, and the raw material powder mixture is calcined at 1000 to 1600 ℃ for 1 to 5 hours in an atmospheric environment to prepare a calcined powder. The calcined powder is pulverized by a wet ball mill or the like to prepare a predetermined particle size. As the raw material powder of rare earth-added cerium oxide, CeO is excluded2In addition, Gd can be used2O3、Sm2O3、Y2O3And the like. The two calcined powders prepared to have a predetermined particle size are mixed by a wet ball mill or the like, and dissolved in a solvent such as terpineol or butyl carbitol together with a binder such as ethyl cellulose to prepare a paste.
In the preparation of the paste of the conductive layer 33, for example, a raw material powder of the perovskite phase is weighed, wet-mixed and dried to prepare a raw material powder mixture, and the raw material powder mixture is calcined at 700 to 1300 ℃ for 1 to 5 hours to prepare a calcined powder. The calcined powder is mixed and pulverized by a wet ball mill or the like to prepare a powder having a predetermined particle size. In this case, as the raw material powder of the perovskite phase, for example, La (OH) can be used3Or La2O3、Fe2O3And NiO. Then, a paste is prepared by dissolving a powder obtained by adding 30 vol% of carbon to the calcined powder and a binder such as ethyl cellulose in a solvent such as terpineol or butyl carbitol.
Next, in step 3, the respective pastes are applied to the portions of the green compact where the outer electrodes 27, the inner detection electrode portions 30a, and the inner conductive portions 30b are formed.
First, a paste of a noble metal such as Pt paste is applied to the formation portion of the outer electrode 27. Next, the paste of the electrode layer 32 is applied to the portion where the electrode layer 32 is formed. The paste of the conductive layer 33 is applied so as to cover the entire surface of the inner surface of the element main body 21.
In the next 4 th step, the green compact coated with each paste is dried and then fired at a predetermined firing temperature. The firing temperature is, for example, 1250 ℃ or higher and 1450 ℃ or lower, preferably 1350 ± 50 ℃. In this firing step, the intermediate layer 31 is formed between the electrode layer 32 of the inner detection electrode section 30a and the element main body 21, and the intermediate layer 34 is formed between the rear end conductive layer 33b of the inner conductive section 30b and the element main body 21.
By performing the above steps, the gas sensor element 3 can be manufactured.
Fig. 5 is a reflected electron image obtained by imaging a cross section near the boundary between the element main body 21 and the inner detection electrode section 30a with a scanning electron microscope (hereinafter referred to as SEM). SEM is short for Scanning Electron Microscope.
As shown in fig. 5, an intermediate layer 31, an electrode layer 32, and a conductive layer 33 are laminated in this order from the side closer to the solid electrolyte body of the element main body 21 in the vicinity of the boundary between the element main body 21 and the inner detection electrode portion 30 a. Further, the concentration of zirconium (Zr) element increases as going from the inner detection electrode portion 30a toward the element main body 21. The boundary line BL between the intermediate layer 31 and the electrode layer 32 is a portion where the concentration of the Zr element is 5% of the maximum value of the concentration of the Zr element.
Fig. 6 is a secondary electron image obtained by taking the same cross section as that of fig. 5 by SEM. The secondary electron image is captured by an inner lens secondary electron detector provided inside an objective lens of the SEM. The secondary electron image obtained by using the inner lens detector shows a sensitive contrast against a slight composition difference (or potential difference) in the surface irradiated with the electron beam.
As shown in fig. 6, the intermediate layer 31 is formed by stacking the 1 st layer 31a and the 2 nd layer 31b in this order from the side closer to the solid electrolyte body of the element main body 21.
The 1 st layer 31a is a layer formed of an oxide containing a rare earth element (hereinafter referred to as Ln 'element) other than La element, Zr element, La element and Ce element (hereinafter referred to as (La-Zr-Ln' -Ce-O)).
The 2 nd layer 31b is a layer formed of an oxide containing La element, Zr element, Ln 'element, Ce element, and Fe element (hereinafter referred to as (La-Zr-Ln' -Ce-Fe-O)). Similarly to fig. 5, the boundary line BL between the intermediate layer 31 and the electrode layer 32 in fig. 6 is a portion where the concentration of the Zr element is 5% of the maximum value of the concentration of the Zr element.
An image PG1 of fig. 7 is a reflected electron image obtained by using a cross section near the boundary between the SEM imaging element main body 21 and the inner detection electrode section 30 a. The measurement line ML set in the image PG1 represents the measurement position of the EDS composition analysis. EDS is short for Energy Dispersive X-ray Spectroscopy.
Image PG2 of fig. 7 is an image obtained by cutting out the region around measurement line ML in image PG1 and then rotating the image by 90 ° to the right. In addition, the rectangular region RR set in image PG2 is replaced with a secondary electron image. In the region RR, the 1 st layer 31a and the 2 nd layer 31b are displayed so as to be distinguishable from each other.
The graph GR1 of fig. 7 represents the distribution of Fe elements measured by EDS composition analysis on the measurement line ML. The graph GR2 of fig. 7 represents the distribution of Zr element measured by EDS composition analysis on the measurement line ML.
As shown by the indicating circle C1 of the graph GR1, almost no Fe element exists within the 1 st layer 31 a. As shown by the indication circle C2 of the graph GR1, in the 2 nd layer 31b, Fe elements are present much more than in the 1 st layer 31 a. In addition, the Ni element may be present in this region as in the Fe element.
As shown in the graph GR2, the boundary line BL between the intermediate layer 31 and the electrode layer 32 is a portion where the concentration of the Zr element is 5% with respect to the maximum value of the concentration of the Zr element.
Next, the test results of the evaluation test performed to evaluate the low-temperature operability of the gas sensor element 3 will be described.
The low-temperature workability is an index indicating that gas can be detected even in a low-temperature environment (for example, 300 ℃ or lower). The higher the internal resistance value between the outer electrode and the inner electrode is, the worse the low-temperature operability of the gas sensor element 3 is. In other words, the lower the internal resistance value between the outer electrode and the inner electrode, the more excellent the low-temperature operability of the gas sensor element 3.
In this evaluation test, the low-temperature workability of the gas sensor element was evaluated by changing the ratio of the 2 nd layer 31b to the 1 st layer 31a (hereinafter referred to as the coverage ratio). The coverage can be controlled by adjusting the addition rate of the rare earth-added cerium oxide in the preparation of the paste for the electrode layer 32, or by the value of the firing temperature of the green compact to be the element body in the state of the paste to be the electrode being applied. Specifically, it shows a tendency that the coverage is decreased by increasing the addition rate of the rare earth-added cerium oxide, or the coverage is decreased by decreasing the value of the firing temperature of the green compact.
In the test of low-temperature operability, the internal resistance value between the outer electrode 27 and the inner electrode 30 of the gas sensor element was measured, and the low-temperature operability of the gas sensor element was evaluated based on the internal resistance value.
In this test, the gas sensor element was mounted on a known combustion measuring device in a state where the gas sensor element was assembled to the gas sensor, and the internal resistance value of the gas sensor element was measured by a combustion measuring method. Specifically, sensor outputs having an element temperature of 300 ℃ and an air-fuel ratio λ of 0.9 (i.e., rich) are detected when the input impedances are 1M Ω and 100K Ω, respectively, and the internal resistance value of the gas sensor element is calculated based on the difference in the outputs.
In this test, a gas sensor element having an internal resistance value of less than 200K Ω was determined to have good low-temperature operability, and a gas sensor element having an internal resistance value of 200K Ω or more was determined to have poor low-temperature operability.
As the gas sensor elements of examples 1 to 7 and comparative examples, gas sensor elements having coverage ratios of the numerical values shown in table 1 were used. In examples 1 to 7 and comparative examples, the perovskite phase of the electrode layer 32 was LaFe0.5Ni0.5O3The rare earth-added cerium oxide of the electrode layer 32 is Ce0.8Ln’0.2O1.9。
As shown in table 1, the coverage was changed in the range of 0% to 100% by changing the addition rate of the rare earth-added cerium oxide in the range of 10% to 65% by volume. The rare earth element (i.e., Ln' element) added to the rare earth-doped ceria was gadolinium (Gd) element in comparative examples and examples 1, 2, 4 to 7, and samarium (Sm) element in example 3. The values of the firing temperatures in the production of the gas sensor elements of examples 1 to 7 and comparative example were constant.
[ TABLE 1 ]
Figure BDA0001900543180000141
In the comparative examples and examples 1 to 7, the coverage was measured using the secondary electron image obtained by imaging the vicinity of the boundary line BL between the intermediate layer 31 and the electrode layer 32. In this test, the magnification of SEM was set to 1 ten thousand times, and secondary electron images at 5 viewing angles were obtained for comparative examples and examples 1 to 7.
Fig. 8 shows a reflected electron image obtained by imaging the vicinity of the boundary line BL between the intermediate layer 31 and the electrode layer 32 in example 4 and a secondary electron image obtained by an inner lens secondary electron detector.
As shown in the secondary electron image of fig. 8, there are portions having different contrasts between the self-boundary line BL and the surface of the solid electrolyte body of the element main body 21. In the portion having different contrast, the portion on the electrode layer 32 side is the 2 nd layer 31b, and the portion on the element main body 21 side is the 1 st layer 31 a. In this test, the coverage is defined as a ratio indicating a contrast of a portion on the boundary line BL on the electrode layer 32 side with respect to the entire length of the boundary line BL of the secondary electron image.
The portions with different contrasts are set by the following method.
First, a luminance distribution is created in a range between the boundary line BL and the surface of the solid electrolyte body of the element main body 21. As shown in fig. 9, the peak PK1 including the luminance on the electrode layer 32 side and the peak PK2 including the luminance on the element main body 21 side were detected in the luminance distribution. The average value of the luminance value L1 of the peak PK1 and the luminance value L2 of the peak PK2 was set as the luminance determination value JC. Then, for each pixel on the boundary line BL, a portion indicating the contrast on the electrode layer 32 side is set when the luminance is equal to or higher than the luminance determination value JC, and a portion indicating the contrast on the element main body 21 side is set when the luminance is lower than the luminance determination value JC.
In comparative examples and examples 1 to 7, after the coverage was measured using 5 secondary electron images at the viewing angles, the average of the measured coverage at the 5 viewing angles was calculated, and the average was set as the final coverage.
In this test, as shown in table 1, as the measurement results of the internal resistance, the internal resistance value was "x" when it was 200K Ω or more, Δ when it was 100K Ω to 200K Ω, o when it was 50K Ω to 100K Ω, and ∈ when it was 50K Ω or less. The determination result is "NG" when the internal resistance value is 200K Ω or more, and is "OK" when the internal resistance value is less than 200K Ω.
As shown in fig. 10, in this test, the internal resistance value exceeded 200K Ω when the coverage was 100%. When the coverage is 89%, the internal resistance value is in the range of 100K Ω to 200K Ω. When the coverage is 47% to 63%, the internal resistance value is in the range of 50K Ω to 100K Ω. When the coverage is 0% to 16%, the internal resistance value is 50K Ω or less.
The gas sensor element 3 configured as described above includes: element body 21, bag thereofContaining ZrO having oxygen ion conductivity2(ii) a And an outer electrode 27 and an inner electrode 30, the outer electrode 27 and the inner electrode 30 being disposed on the element main body 21.
In the gas sensor element 3, the inner electrode 30 has a structure in which at least an intermediate layer 31 and an electrode layer 32 are laminated in this order from the side closer to the element main body 21. The electrode layer 32 contains a rare earth-doped cerium oxide and a perovskite-type oxide having a perovskite-type crystal structure and containing La element and Fe element.
And in the gas sensor element 3, the intermediate layer 31 has a configuration in which at least a 1 st layer 31a formed of (La-Zr-Ln '-Ce-O) and a 2 nd layer 31b formed of (La-Zr-Ln' -Ce-Fe-O) are laminated in this order from the side closer to the element main body 21.
In the gas sensor element 3, when a cross section including the element body 21, the intermediate layer 31, and the electrode layer 32 is observed using an inner lens secondary electron detector of a scanning electron microscope, the coverage of the 1 st layer 31a with the 2 nd layer 31b is 90% or less. As can be understood from the above test results, the coverage of 90% or less in the present invention includes a coverage of 0%.
The gas sensor element 3 thus configured has good low-temperature operability, and thus can detect gas even in a low-temperature environment.
In the gas sensor element 3, the rare earth element added to the rare earth-added cerium oxide is Gd element. This enables the gas sensor element 3 to achieve stable detection accuracy over a long period of time.
The perovskite oxide of the electrode layer 32 does not substantially contain an alkaline earth metal. Thereby, the gas sensor element 3 can suppress the alkaline earth metal contained in the electrode layer 32 and the ZrO contained in the element main body 212By the reaction, a reaction layer containing an alkaline earth metal is formed between the electrode layer 32 and the element main body 21, and a decrease in low-temperature operability can be suppressed.
The perovskite oxide of the electrode layer 32 is a (La-Ni-Fe-O) perovskite phase. The gas sensor element 3 configured as described above can reduce the temperature-dependent characteristic variation by containing the Ni element and the Fe element.
In the embodiment described above, the element main body 21 corresponds to a solid electrolyte body, the outer electrode 27 and the inner electrode 30 correspond to a pair of electrodes, and the main body metal case 13 corresponds to a holding member.
(embodiment 2)
Embodiment 2 of the present invention will be described below with reference to the drawings.
As shown in fig. 11, the plate-type gas sensor element 100 of the present embodiment includes an element main body 101 and a porous protection layer 120.
As shown in fig. 12, the element main body 101 has an oxygen concentration detection unit 130, a reinforcing protective layer 111, an atmosphere introducing layer 107, and a lower surface layer 103. In fig. 12, the porous protection layer 120 is not shown.
The oxygen concentration detection unit 130 has a reference electrode 104, a solid electrolyte body 105, and a measurement electrode 106. The reference electrode 104 and the measurement electrode 106 are disposed so as to sandwich the solid electrolyte body 105.
The reference electrode 104 includes a reference electrode portion 104a and a reference conductive portion 104L. As shown in fig. 14, the reference electrode portion 104a has a multilayer structure in which an intermediate layer 104b, an electrode layer 104c, and a conductive layer 104d are laminated in this order from the side closer to the solid electrolyte body 105.
The intermediate layer 104b is formed by stacking the 1 st layer 151 and the 2 nd layer 152 in this order from the side closer to the solid electrolyte body 105.
As shown in fig. 12, the reference conductive portion 104L is formed to extend from the reference electrode portion 104a in the longitudinal direction of the solid electrolyte body 105.
The measurement electrode 106 has a measurement electrode portion 106a and a detection conductive portion 106L. The detection conductive section 106L is formed to extend from the measurement electrode section 106a in the longitudinal direction of the solid electrolyte body 105.
The reinforcing protective layer 111 has a reinforcing portion 112 and an electrode protecting portion 113 a.
The reinforcing portion 112 is a plate-shaped member for protecting the solid electrolyte body 105 by sandwiching the detection conductive portion 106L between the reinforcing portion and the solid electrolyte body 105. The reinforcing portion 112 is formed of the same material as the solid electrolyte body 105, and the reinforcing portion 112 has a protection portion arrangement space 112a penetrating in the thickness direction of the plate.
The electrode protection portion 113a is formed of a porous material, and the electrode protection portion 113a is disposed in the protection portion disposition space 112 a. The electrode protection portion 113a protects the measurement electrode portion 106a so as to sandwich the measurement electrode portion 106a between the electrode protection portion and the solid electrolyte body 105.
The plate-type gas sensor element 100 of the present embodiment is a so-called oxygen concentration electromotive force type gas sensor, and can detect the oxygen concentration using the value of electromotive force generated between the electrodes of the oxygen concentration detection cell 130.
The lower surface layer 103 and the atmosphere inlet layer 107 are laminated on the reference electrode 104 in such a manner that the reference electrode 104 is sandwiched between the lower surface layer 103 and the atmosphere inlet layer 107 and the solid electrolyte body 105. The atmospheric air inlet layer 107 has a substantially U-letter shape with an open rear end. The internal space surrounded by the solid electrolyte body 105, the atmosphere introduction hole layer 107, and the lower surface layer 103 is an atmosphere introduction hole 107 h. The reference electrode 104 is disposed so as to be exposed to the atmosphere introduced into the atmosphere introduction hole 107 h.
Thus, the element body 101 is a laminated body in which the lower surface layer 103, the atmosphere introducing layer 107, the reference electrode 104, the solid electrolyte body 105, the measurement electrode 106, and the reinforcing protective layer 111 are laminated. The element body 101 is formed in a plate shape.
The end of the reference conductive portion 104L is electrically connected to the detection element-side pad 121 on the solid electrolyte body 105 via a conductor formed in the through hole 105a provided in the solid electrolyte body 105. The reinforcing protective layer 111 is configured to be formed shorter in the axial direction (i.e., the left-right direction in fig. 12) than the solid electrolyte body 105 and to expose the end of the detection conductive portion 106L. The ends of the detection element-side pad 121 and the detection conductive portion 106L are exposed to the outside from the rear end of the reinforcing protective layer 111, and are electrically connected to an external terminal, not shown, for external circuit connection.
As shown in fig. 11, the porous protection layer 120 is provided so as to cover the entire circumference of the front end side of the element main body 101.
As shown in fig. 13, the porous protection layer 120 is formed to extend toward the rear end side along the axial direction (i.e., the left-right direction in fig. 13) while including the front end surface of the element main body 101.
The porous protection layer 120 is formed so as to cover, in the axial direction, a region including at least the reference electrode portion 104a and the measurement electrode portion 106a in the element main body 101.
The plate-type gas sensor element 100 may be exposed to toxic substances such as silicon element and phosphorus element contained in the exhaust gas, or may have water droplets adhered thereto. Here, by covering the outer surface of the plate-type gas sensor element 100 with the porous protection layer 120, it is possible to suppress the plate-type gas sensor element 100 from being stuck with a poisoning substance and to suppress water droplets from directly contacting the plate-type gas sensor element 100.
Next, the composition of the solid electrolyte, the measurement electrode, the reference electrode, and the like will be described.
The solid electrolyte body 105 is composed of zirconia (ZrO) in the same manner as the element main body 21 of embodiment 12) Adding yttrium oxide (Y) as a stabilizer2O3) And the partially stabilized zirconia sintered body is formed.
The measuring electrode 106 contains Pt as a main component and contains monoclinic zirconia. The measurement electrode 106 may also contain a ceramic composition.
The "main component" is a component exceeding 50 mass% of the total components constituting the target site (i.e., the solid electrolyte body 105, the measurement electrode 106, and the like).
The 1 st layer 151 in the reference electrode portion 104a of the reference electrode 104 is a layer formed of (La-Zr-Ln' -Ce-O). The 2 nd layer 152 is a layer formed of (La-Zr-Ln' -Ce-Fe-O). Similarly to the gas sensor element 3 according to embodiment 1, the coverage of the 1 st layer 151 with the 2 nd layer 152 is 90% or less (including 0%).
The electrode layer 104c is configured to include a perovskite phase and a rare-earth-doped cerium oxide. Similarly to the electrode layer 32 of embodiment 1, the perovskite phase included in the electrode layer 104c has a perovskite-type oxide crystal structure satisfying the conditions of the above formulas (1), (2a), (2b), and (2c), and the perovskite phase included in the electrode layer 104c is a crystal phase containing La. Such an electrode layer 104c has both ion conductivity and electron conductivity at high temperature (that is, when the plate-type gas sensor element 100 is used), and therefore exhibits a sufficiently low interface resistance value.
Similarly to the conductive layer 33 of embodiment 1, the conductive layer 104d has a structure containing, as a main component, a perovskite phase having a perovskite-type oxide crystal structure satisfying the conditions of the above formulas (1), (2a), (2b), and (2 c). The conductive layer 104d of the present embodiment does not contain rare-earth-doped cerium oxide.
The reference conductive portion 104L is formed of the same material as the conductive layer 104 d.
At least a portion of the porous protection layer 120 covering the measurement electrode 106 is made of spinel (MgAl)2O4) And titanium dioxide (TiO)2) Formed and carrying precious metals (at least 1 of Pt, Pd, Rh). The precious metal functions as a catalyst for promoting combustion of unburned gas components contained in the exhaust gas. In addition, the portion of the porous protection layer 120 that covers at least the measurement electrode 106 is a portion that overlaps the measurement electrode 106 in the stacking direction of the element main body 101.
The plate-type gas sensor element 100 thus configured has: a solid electrolyte body 105 containing ZrO having oxygen ion conductivity2(ii) a And a reference electrode 104 and a measurement electrode 106, the reference electrode 104 and the measurement electrode 106 being disposed on the solid electrolyte body 105.
In the plate-type gas sensor element 100, the reference electrode 104 has a structure in which at least the intermediate layer 104b and the electrode layer 104c are stacked in this order from the side closer to the solid electrolyte body 105. The electrode layer 104c contains a rare earth-doped cerium oxide and a perovskite-type oxide having a perovskite-type crystal structure and containing La element and Fe element.
And in the plate-type gas sensor element 100, the intermediate layer 104b has a structure in which at least the 1 st layer 151 formed of (La-Zr-Ln '-Ce-O) and the 2 nd layer 152 formed of (La-Zr-Ln' -Ce-Fe-O) are laminated in this order from the side closer to the solid electrolyte body 105.
In the plate-type gas sensor element 100, when a cross section including the solid electrolyte body 105, the intermediate layer 104b, and the electrode layer 104c is observed using an inner lens secondary electron detector of a scanning electron microscope, the coverage of the 1 st layer 151 with the 2 nd layer 152 is 90% or less.
The plate-type gas sensor element 100 thus configured can obtain the same effects as the gas sensor element 3 of embodiment 1.
In the embodiment described above, the plate-type gas sensor element 100 corresponds to a gas sensor element, the solid electrolyte body 105 corresponds to a solid electrolyte body, and the reference electrode 104 and the measurement electrode 106 correspond to a pair of electrodes.
While the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be implemented by various modifications.
For example, in embodiment 1 described above, a gas sensor element in which the inner electrode has a multilayer structure in which an intermediate layer, an electrode layer, and a conductive layer are laminated has been described, but the present invention is not limited to this. That is, the outer electrode may be the gas sensor element having the multilayer structure, or the inner electrode and the outer electrode may be the gas sensor element having the multilayer structure. Similarly, in embodiment 2, the description has been given of the plate-type gas sensor element in which the reference electrode has a multilayer structure in which an intermediate layer, an electrode layer, and a conductive layer are laminated, but the invention is not limited to this. That is, the measurement electrode may be the plate-type gas sensor element having the multilayer structure, or the reference electrode and the measurement electrode may be the plate-type gas sensor element having the multilayer structure.
In the above embodiment, the gas sensor element having the perovskite phase as a main component and having the conductive layer containing no rare earth-doped cerium oxide has been described, but the present invention is not limited thereto. For example, the conductive layer may contain rare-earth-doped cerium oxide, and such a conductive layer can reduce the internal resistance value between the outer electrode and the inner electrode when the gas sensor element is used. In addition, although the case where the conductive layer covers the entire upper surface of the electrode layer has been described, at least a part of the upper surface of the electrode layer may be covered.
In the above embodiments, the functions of one component may be shared among a plurality of components, or the functions of a plurality of components may be exhibited by one component. Moreover, a part of the structure of each of the above embodiments may be omitted. In addition, at least a part of the structures of the above embodiments may be added or replaced to other structures of the above embodiments. All the aspects included in the technical idea defined by the characters described in the claims are embodiments of the present invention.

Claims (6)

1. A gas sensor element having: a solid electrolyte body containing ZrO having oxygen ion conductivity2(ii) a And a pair of electrodes disposed on the solid electrolyte body, wherein the gas sensor element,
at least one of the pair of electrodes has a configuration in which at least an intermediate layer and an electrode layer are laminated in this order from a side closer to the solid electrolyte body,
the electrode layer contains a perovskite-type oxide having a perovskite-type crystal structure and containing an La element and an Fe element, and a rare earth-added cerium oxide,
a rare earth element other than La and Ce as an Ln ' element, wherein the intermediate layer has a structure in which at least a 1 st layer made of (La-Zr-Ln ' -Ce-O) and a 2 nd layer made of (La-Zr-Ln ' -Ce-Fe-O) are stacked in this order from a side closer to the solid electrolyte body,
when a cross section including the solid electrolyte body, the intermediate layer, and the electrode layer is observed using an inner lens secondary electron detector of a scanning electron microscope, the coverage of the 2 nd layer with respect to the 1 st layer is 90% or less.
2. The gas sensor element according to claim 1,
the rare earth element added to the rare earth-added cerium oxide is Gd element.
3. The gas sensor element according to claim 1 or 2,
the perovskite-type oxide contains substantially no alkaline earth metal.
4. The gas sensor element according to claim 1 or 2,
the perovskite-type oxide is a (La-Ni-Fe-O) perovskite-type oxide.
5. The gas sensor element according to claim 3,
the perovskite-type oxide is a (La-Ni-Fe-O) perovskite-type oxide.
6. A gas sensor, wherein,
the gas sensor includes: the gas sensor element according to any one of claims 1 to 5; and a holding member that holds the gas sensor element.
CN201811510214.8A 2017-12-12 2018-12-11 Gas sensor element and gas sensor Active CN110006980B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2017237610A JP6904896B2 (en) 2017-12-12 2017-12-12 Gas sensor element and gas sensor
JP2017-237610 2017-12-12

Publications (2)

Publication Number Publication Date
CN110006980A CN110006980A (en) 2019-07-12
CN110006980B true CN110006980B (en) 2022-07-08

Family

ID=67062420

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201811510214.8A Active CN110006980B (en) 2017-12-12 2018-12-11 Gas sensor element and gas sensor

Country Status (2)

Country Link
JP (1) JP6904896B2 (en)
CN (1) CN110006980B (en)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003149195A (en) * 2001-11-19 2003-05-21 Matsushita Electric Ind Co Ltd Gas sensor
CN103187581A (en) * 2011-12-29 2013-07-03 Toto株式会社 Solid oxide fuel battery cell
JP2015053235A (en) * 2013-09-09 2015-03-19 株式会社ノリタケカンパニーリミテド Electrochemical reactor cell
CN105606651A (en) * 2014-11-17 2016-05-25 一般财团法人日本精细陶瓷中心 Nitrogen oxide responsive element and method for producing same
CN106353365A (en) * 2015-07-13 2017-01-25 日本特殊陶业株式会社 Gas sensor element and gas sensor
CN107001145A (en) * 2014-12-15 2017-08-01 日本特殊陶业株式会社 Electroconductive oxide sintered body, conductive component, gas sensor, the manufacture method of piezoelectric element and piezoelectric element
JP2017198659A (en) * 2016-04-20 2017-11-02 日本特殊陶業株式会社 Gas sensor element and gas sensor

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6523878B2 (en) * 2015-08-31 2019-06-05 日本特殊陶業株式会社 Gas sensor controller
JP6577408B2 (en) * 2016-04-20 2019-09-18 日本特殊陶業株式会社 Gas sensor element and gas sensor

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003149195A (en) * 2001-11-19 2003-05-21 Matsushita Electric Ind Co Ltd Gas sensor
CN103187581A (en) * 2011-12-29 2013-07-03 Toto株式会社 Solid oxide fuel battery cell
JP2015053235A (en) * 2013-09-09 2015-03-19 株式会社ノリタケカンパニーリミテド Electrochemical reactor cell
CN105606651A (en) * 2014-11-17 2016-05-25 一般财团法人日本精细陶瓷中心 Nitrogen oxide responsive element and method for producing same
CN107001145A (en) * 2014-12-15 2017-08-01 日本特殊陶业株式会社 Electroconductive oxide sintered body, conductive component, gas sensor, the manufacture method of piezoelectric element and piezoelectric element
CN106353365A (en) * 2015-07-13 2017-01-25 日本特殊陶业株式会社 Gas sensor element and gas sensor
JP2017198659A (en) * 2016-04-20 2017-11-02 日本特殊陶業株式会社 Gas sensor element and gas sensor

Also Published As

Publication number Publication date
JP2019105504A (en) 2019-06-27
JP6904896B2 (en) 2021-07-21
CN110006980A (en) 2019-07-12

Similar Documents

Publication Publication Date Title
CN106353365B (en) Gas sensor element and gas sensor
JP6577408B2 (en) Gas sensor element and gas sensor
US7633371B2 (en) Thermistor element, thermistor element production method and thermistor temperature sensor
US20120043511A1 (en) Conductive sintered oxide, thermistor element including the same, and temperature sensor including the same
CN110274942A (en) Sensor element and gas sensor
CN110006980B (en) Gas sensor element and gas sensor
JP6718385B2 (en) Gas sensor element and gas sensor
US10302589B2 (en) Gas sensor, electrically conductive oxide sintered body, and wiring board
CN110006981B (en) Gas sensor element and gas sensor
JP6804994B2 (en) Gas sensor element and gas sensor
WO2019087735A1 (en) Solid electrolyte, method for producing same and gas sensor
JP7009262B2 (en) Gas sensor element and gas sensor
JP6718386B2 (en) Gas sensor element and gas sensor
JP6917923B2 (en) Gas sensor element and gas sensor
JP6966356B2 (en) Gas sensor element and gas sensor
US20210055254A1 (en) Sensor element and gas sensor
JP2019027993A (en) Gas sensor element and gas sensor
JP6804995B2 (en) Gas sensor element and gas sensor
JP6822854B2 (en) Gas sensor element and gas sensor
CN111656176B (en) Gas sensor element and gas sensor
CN111372905A (en) Solid electrolyte, method for producing same, and gas sensor
WO2019130849A1 (en) Gas sensor element, and gas sensor
JP2018112483A (en) Gas sensor element and gas sensor

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant