JP2019132741A - Oxygen sensor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen sensor element having improved productivity and workability. SOLUTION: The oxygen sensor element is made of a ceramic sintered body and detects an oxygen concentration based on a current value when a voltage is applied. The ceramic sintered body has a composition formula LnBa2Cu3O7-δ (Ln is a rare earth element). In δ, a part of 0 to 1) is replaced with, for example, any element selected from the elements of the second genus of the periodic table and any element selected from the lanthanoid-based elements. To the composition represented by zCazBa2-zLazCu3O7-δ (0.25≤z≤1), xvol% (0 <x <30) of silver oxide (Ag2O) is added externally. [Selection diagram] Fig. 1

Description

  The present invention relates to a material composition of a gas (oxygen) sensor element using a ceramic sintered body.

There are demands for oxygen concentration detection in various gases, such as detection of oxygen concentration in exhaust gas of internal combustion engines, detection of oxygen concentration for boiler combustion management, etc., and it consists of various materials as detection elements for the oxygen concentration Oxygen sensors are known. For example, as a material composition of an oxygen sensor using a ceramic sintered body, an oxygen sensor using a composite ceramic in which LnBa ₂ Cu ₃ O _7-δ and Ln ₂ BaCuO ₅ (Ln is a rare earth element) is known. (Patent Document 1).

  The oxygen sensor using the ceramic sintered wire as described above is a hot spot type oxygen sensor using a hot spot phenomenon in which a part of the wire is heated red when a voltage is applied. Such an oxygen sensor can be reduced in size, weight, cost, and power consumption. However, the oxygen sensor element used for the oxygen sensor has a composition material that is easily hydroxylated and carbonated. At the time of detecting the oxygen concentration, there has been a problem that the sensor element deteriorates due to surrounding gas components such as water vapor and carbon dioxide gas, resulting in poor durability.

In view of the problem that it is difficult to put the sensor element having improved durability into practical use, the present inventors have, for example, an existing composition formula LnBa ₂ Cu ₃ O _7-δ (Ln is a rare earth element). An oxygen sensor element having a composition in which a part of δ, 0 to 1) is replaced with calcium (Ca) and lanthanum (La) has been proposed.

JP 2007-85816 A (Patent No. 4714867)

As described above, the oxygen sensor element obtained by substituting a part of the existing composition LnBa ₂ Cu ₃ O _7-δ with Ca and La is improved in moisture resistance, but Ca is easily segregated. Therefore, in the manufacturing process of the oxygen sensor element, it is necessary to repeat a cycle of calcining the raw material mixture and crushing the calcined material with a ball mill or the like.

  Thus, in the manufacturing process of the oxygen sensor element, repeating the calcination → pulverization cycle to align the grains (size adjustment) causes a problem that the productivity of the oxygen sensor element decreases due to an increase in the number of processes. Arise.

  This invention is made | formed in view of the subject mentioned above, The place made into the objective is providing the oxygen sensor element which improved productivity with durability.

The following configuration is provided as means for achieving the above object and solving the above-described problems. That is, the present invention is an oxygen sensor element that is made of a ceramic sintered body and detects an oxygen concentration based on a current value when a voltage is applied, and the ceramic sintered body has a composition formula LnBa ₂ Cu ₃ O _7. Silver (Ag) is mixed with the first composition represented by _-δ (Ln is a rare earth element and δ is 0 to 1). For example, as the silver (Ag), that obtained by adding the silver oxide (Ag ₂ O) xVOL% corresponds with an outer hook silver oxide (Ag ₂ O) of (0 <x <30) or silver (Ag) Features.

For example, the oxygen sensor element according to the present invention further includes any element selected from elements of Group 2 of the periodic table and a lanthanoid-based element selected from a part of the composition formula LnBa ₂ Cu ₃ O _7-δ. It is characterized in that silver oxide (Ag ₂ O) of xvol% (0 <x <30) is added as an outer coat to the second composition substituted with such an element. For example, the second composition is substituted with calcium (Ca) selected from the elements of Group 2 of the periodic table and lanthanum (La) selected from the lanthanoid elements, when representing the composition by the composition formula _{Ln 1-z Ca z Ba 2} -z La z Cu 3 O 7-δ, substitution amount z is characterized by a 0.25 ≦ z ≦ 1. Further, for example, characterized in that part of the composition formula _{Ln 1-z Ca z Ba 2} -z La z Cu 3 O 7-δ wherein the second composition represented by, and further substituted with strontium (Sr) And Furthermore, for example, the composition formula _{Ln 1-z Ca z Ba 2} -z La z Cu 3 O 7-δ wherein the second composition represented by a composition represented by the composition formula Ln ₂ BaCuO ₅ It is characterized by mixing.

Further, for example, the oxygen sensor element of the present invention further includes a _third element obtained by substituting a part of the composition formula LnBa ₂ Cu ₃ O _7-δ with any element selected from elements of Group 2 of the periodic table. The composition is characterized in that xvol% (0 <x <30) of silver oxide (Ag ₂ O) is added to the composition. For example, the third composition, the result is replaced with periodic table 2 genus strontium selected from elements (Sr), composition formula a third composition _{LnBa 2-y Sr y Cu 3} O 7 When represented by _-δ , the substitution amount y is 0 <y ≦ 1.5. For example, characterized by being substituted with a part of the composition formula _{LnBa 2-y Sr y Cu 3} O 7-δ wherein the third composition represented by further calcium (Ca) and lanthanum (La). Further, for example, the third composition represented by the composition formula _{LnBa 2-y Sr y Cu 3} O 7-δ, characterized in that a mixture of composition represented by the composition formula Ln ₂ BaCuO ₅ . For example, the bending strength of the ceramic sintered body is adjusted by the amount of silver oxide (Ag ₂ O) or silver (Ag) added. Further, for example, the ceramic sintered body is a linear sensor element.

  The oxygen sensor according to the present invention is characterized in that any one of the above oxygen sensor elements is an oxygen concentration detection element. For example, the oxygen sensor element is housed in a protective tube having vent holes at both ends.

  According to the present invention, not only the durability of the oxygen sensor element but also the productivity and workability can be improved.

X-ray diffraction (XRD) for a test sample (Example) in which silver oxide (Ag ₂ O) is added to a Ca, La-substituted composition and a test sample (Conventional example) to which no Ag ₂ O is added ) It is a figure showing a measurement result. Conventional, and is a view showing the measurement results of flexural strength for Example for changing the addition amount of Ag ₂ O. It is a flowchart which shows the manufacturing process of the oxygen sensor element which concerns on the example of this Embodiment, and the oxygen sensor using the oxygen sensor element in time series. 1 is an external perspective view of an oxygen sensor using an oxygen sensor element according to an embodiment of the present invention.

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. The oxygen sensor element according to the present embodiment is made of a ceramic sintered body, and is connected to a power source so that a current flows, whereby the central portion of the sintered body generates heat at a high temperature, and the heat generation location (called a hot spot). Is an oxygen concentration detection unit. Further, the oxygen sensor using the oxygen sensor element according to the present embodiment as an oxygen detector detects the oxygen concentration based on the current value flowing through the sintered body that is the sensor element.

<About oxygen sensor element>
The oxygen sensor element according to Embodiment 1 of the present invention as an oxygen concentration detector is a first composition represented by a composition formula LnBa ₂ Cu ₃ O _7-δ (hereinafter also referred to as a conventional composition). And a ceramic sintered body to which a predetermined amount of silver oxide (Ag ₂ O) described later is added.

Furthermore, as described in Japanese Patent Application No. 2018-15922 filed by the applicant of the present application, the oxygen sensor element according to Embodiment 2 of the present invention is partially converted from an element belonging to Group 2 of the periodic table, that is, beryllium (Be ), Magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra) and lanthanoid elements, ie, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium Substitution with an element selected from (Tm), ytterbium (Yb), and lutetium (Lu) The second composition, a ceramic sintered body obtained by adding a predetermined amount of silver oxide to be described later (Ag ₂ O).

In Japanese Patent Application No. 2018-15922, as the second composition, calcium (Ca) in which a part of the conventional composition is selected from elements of Group 2 of the periodic table, and lanthanum (La) selected from lanthanoid elements. a composition obtained by substitution, when expressed by the composition formula _{Ln 1-z Ca z Ba 2} -z La z Cu 3 O 7-δ, the effect substitution amount z is 0.25 ≦ z ≦ 1 Illustrated.

In addition, as described in Japanese Patent Application No. 2018-15923 filed by the applicant of the present application, the oxygen sensor element according to Embodiment 3 of the present invention is a part of the periodic table belonging to the _{second group} of the periodic composition LnBa ₂ Cu ₃ O _7-δ. A third element that is substituted with any one element selected from beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra) It consists of a ceramic sintered body obtained by adding a predetermined amount of silver oxide (Ag ₂ O) described later to the composition.

In Japanese Patent Application No. 2018-15923, the third composition is a composition obtained by substituting a part of the conventional composition with strontium (Sr) selected from the elements of Group 2 of the periodic table, and the composition formula LnBa ₂ when expressed in _{-y Sr y Cu 3 O 7-} δ, the substitution amount y illustrates the effect that 0 <y ≦ 1.5.

  In each of the above composition formulas, Ln is a rare earth element (for example, Sc (scandium), Y (yttrium), La (lanthanum), Nd (neodymium), Sm (samarium), Eu (europium), Gd (gadolinium), Dy. (Dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium) and the like, and δ represents an oxygen defect (0 to 1).

In the following description, some conventional compositions LnBa ₂ Cu ₃ O _7-δ was replaced with calcium (Ca) and lanthanum (La), composition formula _{Ln 1-z Ca z Ba 2} -z La z Cu 3 O 7 An oxygen sensor element manufactured from a ceramic sintered body obtained by adding a predetermined amount of silver oxide (Ag ₂ O) to a composition represented by _−δ (0.25 ≦ z ≦ 1) will be described as an example. To do.

FIG. 1 shows a test sample (also simply referred to as “Example”) produced by using a composition material obtained by adding silver oxide (Ag ₂ O) to a composition obtained by replacing a part of the conventional composition with Ca and La. X-ray diffraction (XRD) and a test sample in which silver oxide (Ag ₂ O) is not added to a material obtained by substituting a part of the conventional composition with Ca and La (also simply referred to as “conventional example”) The measurement results are shown.

Here, Y (yttrium) is used as a rare earth element which is an oxygen sensor element material, and yttrium oxide (Y ₂ O ₃ ), calcium carbonate (CaCO ₃ ), barium carbonate (BaCO ₃ ), lanthanum oxide (La ₂ O _3). ) And copper oxide (CuO) are mixed at a ratio of 5: 10: 30: 5: 60, and the composition material represented by the composition formula Y _0.5 Ca _0.5 Ba _1.5 La _0.5 Cu ₃ O _7-δ is added to the outside. samples spiked with 1 vol% of silver oxide (Ag ₂ O) in multiplied (example 1), sample (example 2) supplemented with 10 vol% of silver oxide in outer percentage (Ag ₂ O), 30 vol% in outer percentage A sample to which silver oxide (Ag ₂ O) was added (Example 3) and a sample to which no silver oxide (Ag ₂ O) was added (conventional example) were prepared.

  Each sample shown in FIG. 1 was prepared by calcining the pulverized raw material at 900 ° C. for 5 hours and then firing at 920 ° C. for 10 hours. FIG. 1 shows the X-ray diffraction (XRD) measurement results when the calcining → grinding cycle is performed once for the mixed material for producing the oxygen sensor element.

From FIG. 1, the peak does not appear in the conventional example in which silver oxide (Ag ₂ O) is not added, whereas the amount of addition increases in Examples 1 to 3 in which silver oxide (Ag ₂ O) is added. It can be seen that the peak of the composition (oxygen sensor element) represented by the composition formula Y _0.5 Ca _0.5 Ba _1.5 La _0.5 Cu ₃ O _7-δ (ICDD: 48-0234) increases. This is considered to mean that the added Ag ₂ O acts as a catalyst to improve the reactivity, thereby making it easy to obtain a target composition as an oxygen sensor element.

  Next, the mechanical strength of the oxygen sensor element according to this embodiment will be described. FIG. 2 shows the results of measuring the bending strength of samples (conventional example and Examples 1 to 3 described above) produced using the oxygen sensor element material according to the present embodiment.

  Here, a three-point bending test was performed according to JIS R 1601, which defines the bending strength of fine ceramics at room temperature (5-35 ° C.). That is, for each sample as a test piece, the cross-sectional shape was a rectangular prism, a standard test piece having a prescribed size was prepared, and the bending strength was measured.

From FIG. 2, the oxygen sensor element according to the example has a tendency that the bending strength increases as the added amount of Ag ₂ O increases. Further, since there was a difference in machinability when cutting the oxygen sensor elements according to the respective examples having different Ag ₂ O addition amounts into outer dimensions (sizes) to be described later, the bending due to the addition of Ag ₂ O was also observed. It was found that the mechanical strength is improved by increasing the strength.

In addition, in FIG. 2, the oxygen sensor element according to the example to which silver oxide (Ag ₂ O) is added has a bending strength even when compared with the sample according to the conventional example in which the addition amount of Ag ₂ O is 0 vol%. It can be seen that is improved. Accordingly, the bending strength, workability, etc. of the ceramic sintered body (oxygen sensor element) can be adjusted by the addition amount of Ag ₂ O. This is advantageous for meeting the demand for reducing power consumption by reducing the size of the oxygen sensor element.

From the tendency of the bending strength to increase as shown in FIG. 2, even when the addition amount of Ag ₂ O exceeds 30 vol%, the same bending strength is expected to increase, and the Ag strength increases as the addition amount of Ag ₂ O increases. Presumed to approach. On the other hand, from the viewpoint of sensor characteristics, if the added amount of Ag ₂ O exceeds 30 vol%, a conductive path of the Ag portion is generated in the sensor element, which may be an incentive to lower the sensor characteristics.

Therefore, in the oxygen sensor element according to the present embodiment, the addition amount x of silver oxide (Ag ₂ O) for obtaining desired reactivity or the like is 0 vol% < x <30 vol%.

  Although illustration is omitted here, for the oxygen sensor element according to the present embodiment, from the results of external observation and XRD measurement of each sample when left in a 40 ° C., 93% RH environment for a predetermined time, Similar to the test sample disclosed in Japanese Patent Application No. 2018-15923, there was no phenomenon in which calcium carbonate, barium carbonate or the like was generated on the surface of the sensor element and the color turned white, and no deterioration of the sensor element was observed.

  Further, when the oxygen responsiveness was evaluated based on the rising and falling characteristics of the current change at each change point when the oxygen atmosphere (oxygen concentration) with respect to the oxygen sensor element was changed periodically, the present embodiment It was also confirmed that the oxygen sensor element according to the example was not different from the test sample disclosed in Japanese Patent Application No. 2018-15923 regarding oxygen responsiveness.

Accordingly, the oxygen sensor element according to the present embodiment in which Ag ₂ O is added to a composition material in which a part of the conventional composition LnBa ₂ Cu ₃ O _7-δ is replaced with Ca and La is also subjected to a heat treatment test, etc. It was found that there was no change in appearance, no deterioration in durability such as moisture resistance, and no change in sensor characteristics such as oxygen responsiveness. In addition, the catalytic effect of Ag ₂ O in such a composition material was confirmed.

  Next, an oxygen sensor element according to this embodiment and an oxygen sensor manufacturing method using the same will be described. FIG. 3 is a flowchart showing the oxygen sensor element according to the present embodiment and the manufacturing process of the oxygen sensor using the oxygen sensor element in time series.

In step S1 of FIG. 3, the raw materials of the oxygen sensor element are weighed and mixed. Here, as the material of the oxygen sensor element, for example, Y ₂ O ₃ , La ₂ O ₃ , BaCO ₃ , CaCO ₃ , CuO, Ag ₂ O are weighed so as to have a predetermined composition using an electronic balance or the like. , Mix.

In addition, although yttrium (Y) is illustrated here as Ln (rare earth element) of the oxygen sensor element material, it may be another single rare earth element or a plurality of rare earth elements may be mixed. Any rare earth element can be used. This mixture may be further added Ln ₂ BaCuO _5. Ag ₂ O can be replaced by Ag. Further, instead of the Ag ₂ O, for example, Ag ₂ O _3, AgO, silver carbonate (Ag ₂ CO _3), can be used silver hydroxide (AgOH).

  In step S2, the oxygen sensor element raw material weighed and mixed in step S1 is pulverized by a ball mill device. The pulverization can also be performed by a solid phase method such as a bead mill using a pulverization medium as a bead, or a liquid phase method.

  In subsequent step S3, the pulverized material (raw material powder) is heat-treated (calcined) in the atmosphere at 900 ° C. for 5 hours. The reactivity and particle size are adjusted by calcining. The calcination temperature may be 880 to 970 ° C, but 900 ° C to 935 ° C is more preferable.

  Next, the process proceeds to a granulation step. Specifically, granulated powder is produced in step S4. Here, a granulated powder is produced by adding an aqueous solution of a binder resin (for example, polyvinyl alcohol (PVA)) to the calcined mixture.

  In subsequent step S5, the granulated powder is molded by applying a pressing pressure, for example, by a uniaxial pressing method, and for example, a plate-like member (press-molded body) having a thickness of 300 μm is produced. Molding can also be performed by an isostatic pressing method, a hot pressing method, a doctor blade method, a printing method, or a thin film method.

  In step S6, dicing is performed. In dicing, the formed plate-shaped member is cut in accordance with a predetermined product size and shape (for example, a linear body shape of 0.3 × 0.3 × 7 mm). Since the oxygen sensor element is more excellent in power saving as the size diameter is smaller, the product size may be other than the above.

  In step S7, the above-described oxygen sensor element after dicing is debindered, and the oxygen sensor element is baked in the atmosphere, for example, at 920 ° C. for 10 hours. In addition, although 900-1000 degreeC is possible as baking temperature, since optimal temperature changes with compositions, you may change baking temperature with a composition. Thereafter, an annealing treatment may be performed.

  In subsequent step S8, silver (Ag) is dip coated on both ends of the oxygen sensor element and dried at 150 ° C. for 10 minutes to form electrodes. In step S9, a silver (Ag) wire of φ0.1 mm, for example, is attached to the electrode formed in step S8 by a bonding method such as wire bonding, and dried at 150 ° C. for 10 minutes. The terminal electrode thus formed is baked at step S10, for example, at 670 ° C. for 20 minutes.

  The electrode and wire material may be a material other than silver (Ag), for example, gold (Au), platinum (Pt), nickel (Ni), tin (Sn), copper (Cu), resin electrode, etc. Good. In addition, a film forming method such as a printing method or sputtering may be used for dipping the electrode. Furthermore, as a final step in FIG. 3, the electrical characteristics of the oxygen sensor element manufactured through the above steps may be evaluated by, for example, a four-terminal method.

<About the oxygen sensor>
In the oxygen sensor using the oxygen sensor element according to the present embodiment, the heat generation point (hot spot) at the center of the oxygen sensor element serves as the oxygen concentration detection unit. For example, the oxygen sensor 1 shown in FIG. 4 has a structure in which the oxygen sensor element 5 is housed in a cylindrical glass tube 4 made of heat-resistant glass that functions as a protective member for the oxygen sensor element. In order to make the oxygen sensor 1 electrically connect to the outside, both ends of the glass tube 4 are fitted with metal conductive caps (caps) 2a and 2b made of, for example, copper (Cu).

  Silver (Ag) wires attached to both ends of the oxygen sensor element 5 are electrically connected to the conductive caps 2a and 2b by lead-free solder, so that the oxygen sensor element 5 does not contact the glass tube 4. Are arranged such that the longitudinal direction of the glass tube 4 is the axial direction of the glass tube 4. Further, the gas (oxygen) to be measured smoothly flows into the glass tube 4 from the vent holes 3a and 3b provided on the end face sides of the conductive caps 2a and 2b, respectively, and the oxygen sensor element 5 is exposed to the gas. Therefore, the oxygen concentration in the atmosphere can be measured accurately.

  The outer dimensions (size) of the oxygen sensor 1 are, for example, a glass tube diameter of 5.2 mm, a length of 20 mm, and a vent hole diameter of 2.5 mm. The dimensions described above (0.3 × 0.3 × 7 mm) ) Oxygen sensor element can be exchanged through the vent of the glass tube.

  The protective member of the oxygen sensor element 5 may be, for example, a ceramic case, a resin case, or the like other than the glass tube. Further, for the connection between the silver (Ag) wire attached to the oxygen sensor element 5 and the conductive caps 2a and 2b, a joining method such as leaded solder, welding, caulking or the like may be used.

  Although not shown, the oxygen sensor using the oxygen sensor element according to the present embodiment, when a predetermined voltage is applied to the oxygen sensor from the power source, the oxygen sensor element has a current corresponding to the surrounding oxygen concentration. Therefore, the oxygen concentration of the atmosphere to be measured is measured based on the value obtained by measuring the current with an ammeter.

As described above, the oxygen sensor element according to the present embodiment includes a composition of a conventional composition represented by the composition formula LnBa ₂ Cu ₃ O _7-δ (Ln is a rare earth element) with a predetermined amount of silver oxide ( It consists of a composition material to which Ag ₂ O) is added. Further, the oxygen sensor element according to the present embodiment has a predetermined amount of a composition obtained by substituting a part of the conventional composition LnBa ₂ Cu ₃ O _7-δ with an element selected from the elements of Group 2 of the periodic table. It consists of a composition material added with silver oxide (Ag ₂ O).

Furthermore, the oxygen sensor element according to the present embodiment is a composition in which a part of the conventional composition is replaced with an element selected from the elements of Group 2 of the periodic table and an element selected from the lanthanoid elements. And a composition material in which a predetermined amount of silver oxide (Ag ₂ O) is added.

In such a composition material, the added silver oxide (Ag ₂ O) acts as a catalyst to improve the reactivity, and the addition of Ag ₂ O can increase the bending strength and improve the mechanical strength of the oxygen sensor element. . In addition, the addition of Ag ₂ O suppresses the segregation of Ca in the manufacturing process of the oxygen sensor element and eliminates the need to repeat the calcination → pulverization cycle, thereby improving productivity.

  Therefore, it is possible to provide a highly durable oxygen sensor element with improved heat resistance and moisture resistance without impairing the sensor characteristics, and improve the mechanical strength of the sensor element. When making (dicing), processing such as cutting and cutting becomes easy.

In the above-described embodiment, an example in which Ag ₂ O is added to a composition obtained by substituting a part of the conventional composition with Ca and La is given, but selected from other elements of the second group of the periodic table other than Ca. Even if Ag ₂ O is added to a composition substituted with any of the above elements and any element selected from other elements of the lanthanoid series other than La, the same effect as the composition substituted with Ca and La Can be assumed to be played.

Similarly, the example in which part of the addition of Ag ₂ O in composition Sr substitution of the conventional composition, Ag ₂ in composition obtained by replacing an element selected from the elements of the periodic table second genus other than Sr O Even if added, it can be assumed that the same effect as the Sr-substituted composition is produced.

DESCRIPTION OF SYMBOLS 1 Oxygen sensor 2a, 2b Conductive cap 3a, 3b Vent hole 4 Glass tube 5 Oxygen sensor element

Claims (12)

An oxygen sensor element comprising a ceramic sintered body and detecting an oxygen concentration based on a current value when a voltage is applied,
In the ceramic sintered body, silver (Ag) is mixed with a first composition represented by a composition formula LnBa ₂ Cu ₃ O _7-δ (Ln is a rare earth element, δ is 0 to 1). An oxygen sensor element. The silver (Ag) is characterized by adding silver oxide (Ag ₂ O) or silver (Ag) corresponding to silver oxide (Ag ₂ O) and having xvol% (0 <x <30) as an outer shell. The oxygen sensor element according to claim 1. Further, a part of the composition formula LnBa ₂ Cu ₃ O _7-δ is substituted with any element selected from elements of Group 2 of the periodic table and any element selected from elements of the lanthanoid series. 2. The oxygen sensor element according to claim 1, wherein xvol% (0 <x <30) of silver oxide (Ag ₂ O) is added to the composition of No. 2 as an outer coating. The second composition is formed by substituting calcium (Ca) selected from the elements of Group 2 of the periodic table with lanthanum (La) selected from the lanthanoid elements, and the second composition. when the expressed by the composition formula _{Ln 1-z Ca z Ba 2} -z La z Cu 3 O 7-δ, according to claim 3, wherein the substitution amount z is 0.25 ≦ z ≦ 1 Oxygen sensor element. Claims, characterized in that part of the composition formula _{Ln 1-z Ca z Ba 2} -z La z Cu 3 O 7-δ wherein the second composition represented by, and further substituted with strontium (Sr) 5. The oxygen sensor element according to 4. The composition formula _{Ln 1-z Ca z Ba 2} -z La z Cu 3 O 7-δ wherein the second composition represented by, characterized in that a mixture of composition represented by the composition formula Ln ₂ BaCuO ₅ The oxygen sensor element according to claim 4 or 5. Furthermore, the third composition obtained by substituting a part of the composition formula LnBa ₂ Cu ₃ O _7-δ with any element selected from the group 2 elements of the periodic table is xvol% ( The oxygen sensor element according to claim 1, wherein silver oxide (Ag ₂ O) of 0 <x <30 is added. Said third composition comprises replaced by the periodic table 2 genus strontium selected from elements (Sr), composition formula a third composition _{LnBa 2-y Sr y Cu 3} O 7-δ The oxygen sensor element according to claim 7, wherein the substitution amount y is 0 <y ≦ 1.5. Formula LnBa _2-y Sr y Cu ₃ a portion of the O _7-[delta] wherein the third composition represented by the claims, characterized in that further substituted with calcium (Ca) and lanthanum (La) 8 The oxygen sensor element according to 1. The composition formula _{LnBa 2-y Sr y Cu 3} O 7-δ wherein the third composition represented by the claims 8, characterized in that a mixture of composition represented by the composition formula Ln ₂ BaCuO ₅ or 9. The oxygen sensor element according to 9. 11. The oxygen sensor element according to claim 1, wherein a bending strength of the ceramic sintered body is adjusted by an addition amount of the silver oxide (Ag ₂ O) or silver (Ag). . The oxygen sensor element according to claim 1, wherein the ceramic sintered body is a linear sensor element.