US3913057A - Oxygen ion transport type thermistors - Google Patents

Oxygen ion transport type thermistors Download PDF

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Publication number
US3913057A
US3913057A US479472A US47947274A US3913057A US 3913057 A US3913057 A US 3913057A US 479472 A US479472 A US 479472A US 47947274 A US47947274 A US 47947274A US 3913057 A US3913057 A US 3913057A
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Prior art keywords
oxygen ion
percent
porosity
ion transport
transport type
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Expired - Lifetime
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US479472A
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English (en)
Inventor
Yoshiro Ushida
Shinji Nishio
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Niterra Co Ltd
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NGK Spark Plug Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/04—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having negative temperature coefficient
    • H01C7/042—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having negative temperature coefficient mainly consisting of inorganic non-metallic substances
    • H01C7/043—Oxides or oxidic compounds

Definitions

  • OXYGEN ION TRANSPORT TYPE THERNHSTORS Inventors: Yoshiro Ushida, Toyoake; Shinji Nishio, Komaki, both of Japan Assignee: NGK Spark Plug Co., Ltd., Nagoya, Japan Filed: June 14, 1974 Appl. No.: 479,472
  • the present invention relates to thermistors.
  • Oxygen ion transport type sintered oxide solid solutions having a stable crystal structure until a high temperature zone consisting of 50-95 mol percent of an oxide of tetravalent metals such as ZrO CeO l-ifO and ThO and 5-5O mol percent of oxide(s) of divalent alkaline earth metals and/or trivalent rare earth metals, such as CaO, MgO, SrO, La O Y O Yb O SC O Gd O and Nd O decrease rapidly the electrical resistance at a temperature'of 400-l ,200C and have excellent properties as a high temperature resistor of a thermistor.
  • Such a solid solution is generally composed of polycrystalline fluorite structures, which have oxygen vacancies to preserve lattice neutrality.
  • these oxide sintered bodies have been used for parts for measuring or controlling temperature of a high temperature furnace and an apparatus for purifying an exhaust gas of an internal combustion engine.
  • Such ceramic resistors are referred to as oxygen transport type thermistors, because the electrical conductivity is shown to be due to the transport of oxygen ion of the oxide in the solid solution constituting the resistor.
  • the electrodes of such oxygen ion transport type thermistors are provided by coating a platinum paste on both parallel main surfaces of the ceramic resistor fired in a disc form and arranging platinum wires to form lead wires thereon and bonding said wires to the resistors with the above described platinum paste and firing said paste at a temperature of l ,0OO1,500C, but the adhesion at the portions where the lead wires get out of the ceramic resistor, is weak and further the working steps are many and troublesome.
  • the adhesion at the bonded portions of the lead wires is degraded with the raising of the temperature owing to softening of vitreous components in the platinum paste at a high temperature. Accordingly, it is impossible at a high temperature, for example, higher than l,0()C to increase the bonding strength of the lead wires even by such oxidation resistant metal paste. Furthermore, the above described coated metal paste requires a moderate vapor permeability in order to make smooth the receiving and supply of oxygen ion in the atmosphere to be converted into electricity at the contact portion of the electrodes with the resistor, so that a thick coating exceeding a certain degree cannot be effected. Accordingly, the adhesion cannot be essentially improved.
  • the oxygen ion transport type thermistors according to the present invention which aim to obviate the above described drawbacks, are characterized in that as shown in FIG. 1, a molding is effected in such a manner that two fine metal wires 2, 2 composed of metals having a higher oxidation resistance, such as platinum or platinum-rhodium alloy are embedded in a resistor matrix leaving a space in parallel and the molded assembly is fired at an adequate temperature to form electrodes and lead wires which are embedded and held in a ceramic resistor 1 of the thermistor and that the porosity of the above described ceramic resistor 1 is made to be 755 percent, preferably l-35 percent, more particularly 25 percent.
  • a molding is effected in such a manner that two fine metal wires 2, 2 composed of metals having a higher oxidation resistance, such as platinum or platinum-rhodium alloy are embedded in a resistor matrix leaving a space in parallel and the molded assembly is fired at an adequate temperature to form electrodes and lead wires which are embedded
  • the conventional oxygen ion transport type thermistor in which the electrodes are provided on the surfaces 2 of the ceramic resistor, are very tightly sintered and the porosity is usually less than 2 percent.
  • the reason why the lower limit of the porosity of the ceramic resistor of the thermistor according to the present invention is defined to be 7 percent is as follows.
  • the oxygen ion transport type thermistor is supplied with a given direct current voltage of about 12V usually used between the electrodes, the oxygen molecule is absorbed from the atmosphere near the cathode in order that the oxygen ion 0 which transports in the ceramic resistor and is concerned in the electric transmission mechanism, is supplied at the cathode side as /2O +2e 0 and said oxygen molecule is discharged into the atmosphere near the anode in order that the above described oxygen ion is taken out at the anode side as 0 /2O +2e.
  • both the electrodes are provided by embedding the fine metal wires in the ceramic resistor, so that the contact area of the electrodes to the resistor is small and consequently if the porosity in the resistor is less than 7 percent, the diffusion movement of the oxygen molecule which is effected through pores in the resistor between air in the pores near the electrodes and the ambient atmosphere, becomes not free and particularly when the oxygen to be supplied at the cathode side is deficient, the oxygen ion in the crystal structure of the sintered body of oxides is used for the electric transmission after the electric current flows for a given time under a high temperature condition and the oxides are reduced and blackened and the resistor becomes a semiconductor having a very small resistance and loses the normal function.
  • the porosity in order to prevent such a fact and to ensure the stable circulation mechanism of oxygen during use for a long time, the porosity must be not less than 7 percent.
  • the above described upper limit of the porosity is defined for on the following reason.
  • the porosity is more than 55 percent, the variation of the electric resistance with the lapse of time in the ceramic resistor not only becomes larger but also the mechanical strength lowers and the electrodes are readily removed and cracks and breaks are apt to be caused.
  • the porosity is too large, the contact resistance between the electrodes and the resistor is large and further the adhesion is gradually lowered owing to the ion conversion at the electrode portions.
  • FIG. 1A is a plan view of the oxygen ion transport type thermistor according to the present invention.
  • FIG. 1B is a side view of said thermistor.
  • the adhesion produce oxygen ion transport type disc-shaped therm- (pulling strength) of the platinum electrodes is insuffiistors having different porosities as shown in the atcient and there is problem in practical use.
  • the test retached drawing which have an outer diameter of about sults are shown in the following Tables 1-3 showing 3.8 mm and a thickness of about 1.4 mm and in which data from the. Process for testing the tension strength a pair of platinum wires 2, 2 are embedded and fixed in 10 of the electrodes. parallel at the center line of the thickness direction at a The two electrode wires are separately secured with spacing of about 2 mm.
  • the resulting thermistor was clips at a distance of 3 mm'from the ends of the ceramic applied with DC12V at 800C between the two platiresistor and pulled in such a direction that the two elecnum electrodes for 1,000 hours.
  • This test showed that trode wires are diverged, through a spring system tenin the thermistors having the porosity of less than 7 per- 15 sion gauge fixed between the two clips and the strength cent, the vicinity of the electrodes became grey or when the electrode wires are removed from the above black and the run away phenomenon occurred, while described resistor, is determined and is shown by an avthe thermistors having the porosity of 7-55 percent acerage value of 10 samples.
  • EXAMPLE 2 EXAMPLES 3 AND 4 70 mol percent of a mixture of 12 mol percent of CaO and 88 mol percent of ZrO was added with mol percent of spinel composed of MgO and A1 0,; as a resistance controlling agent. The resulting mixture was calcined at 1,350C for 2 hours and then added with 4 percent by weight of an emulsion consisting of equal weight amounts of stearic acid and water and pulverized in a wet process in a trommel for 20 hours. The pulverized mixture was treated in the same manner as described in Example 1 except that the heating temperature lower than 1,700C to produce the oxygen ion transport type thermistors. DC 12V was applied to each of the thermistors at 800C. The obtained results are shown in the following Table 4. As seen from this table, the thermistor having a porosity of 5 percent obtained by sintering at a temperature of 1,670C showed run away after 100 hours and was not able to be practically used.
  • Table 4 A mixture of 90 mol percent of ZrO and 10 mol percent of Y O and a mixture of 90 mol percent of ThO and 10 mol percent of Y O were calcined at 1,400C for 2 hours respectively. Then each of the mixtures was added with 3.2 percent by weight of an emulsion consisting of equal weight amounts of stearic acid and water. The resulting mixture was pulverized in a wet process in a trommel for 8 hours.
  • the pulverized mixture was treated in the same manner as described in Examples 1 and 2 at various temperatures as shown in the following Tables 5 and 6 by using 0.4 mm alloy wires having and consisting of 70 percent of platinum and 30 percent of rhodium as a pair of electrodes to produce oxygen ion transport type thermistors.
  • An oxygen ion transport type thermistor comprising an oxygen ion 'type solid solution consisting of 5 O9 5 mol percent of at least one metal oxide selected from the group consisting of ZrO CeO HfO and ThO and 5-50 mol'percent of at least one metal oxide selected from the group consisting of CaO, MgO, SrO, La O 1 0 Yb O S0 0 Gd O ancl Nd O and two metal lead wires are embedded in said solution and held in an adequately spaced parallel relationship to each other and lying substantially in the center line in the thickness direction of said solution and that the porosity of said oxygen ion transport type solid solution is 7 percent.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Thermistors And Varistors (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
US479472A 1973-06-21 1974-06-14 Oxygen ion transport type thermistors Expired - Lifetime US3913057A (en)

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JP7049373A JPS5439920B2 (enrdf_load_stackoverflow) 1973-06-21 1973-06-21

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US3913057A true US3913057A (en) 1975-10-14

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US (1) US3913057A (enrdf_load_stackoverflow)
JP (1) JPS5439920B2 (enrdf_load_stackoverflow)
DE (1) DE2429866C3 (enrdf_load_stackoverflow)
FR (1) FR2234639B1 (enrdf_load_stackoverflow)
GB (1) GB1476374A (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4010121A (en) * 1975-04-28 1977-03-01 Siemens Aktiengesellschaft High temperature hot conductors
US4010118A (en) * 1975-04-28 1977-03-01 Siemens Aktiengesellschaft High temperature hot conductors
US4010119A (en) * 1975-04-28 1977-03-01 Siemens Aktiengesellschaft High temperature hot conductors
US4308178A (en) * 1979-09-17 1981-12-29 North American Philips Consumer Electronics Corp. Thermionic cathode emitter coating
US4324702A (en) * 1979-11-02 1982-04-13 Matsushita Electric Industrial Co., Ltd. Oxide thermistor compositions

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2913279C2 (de) * 1979-04-03 1983-03-17 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Elektrischer Widerstands-Temperaturfühler
WO1986003051A1 (en) * 1984-11-08 1986-05-22 Mtsushita Electric Industrial Co., Ltd. Oxide semiconductor for thermistor and a method of producing the same
US4677415A (en) * 1985-05-08 1987-06-30 Motorola, Inc. Ceramic humidity sensor
US4743881A (en) * 1985-05-08 1988-05-10 Motorola, Inc. Ceramic temperature sensor
US4647895A (en) * 1985-05-08 1987-03-03 Motorola, Inc. Ceramic temperature sensor
DE3733193C1 (de) * 1987-10-01 1988-11-24 Bosch Gmbh Robert NTC-Temperaturfuehler sowie Verfahren zur Herstellung von NTC-Temperaturfuehlerelementen
GB2236750B (en) * 1989-09-08 1993-11-17 United Technologies Corp Ceramic material and insulating coating made thereof
JPH04357165A (ja) * 1991-05-29 1992-12-10 Ngk Insulators Ltd ジルコニア磁器およびこれを用いた電気化学的素子
DE19621934A1 (de) * 1996-05-31 1997-12-04 Philips Patentverwaltung Seltenerdmetallhaltiger Hochtemperatur-Thermistor

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2976505A (en) * 1958-02-24 1961-03-21 Westinghouse Electric Corp Thermistors
US2985700A (en) * 1959-06-10 1961-05-23 Westinghouse Electric Corp Titanate thermoelectric materials
US3044968A (en) * 1958-05-13 1962-07-17 Westinghouse Electric Corp Positive temperature coefficient thermistor materials
US3377561A (en) * 1965-07-13 1968-04-09 Bell Telephone Labor Inc Positive temperature coefficient titanate thermistor
US3786390A (en) * 1971-08-09 1974-01-15 Jenaer Glaswerk Schott & Gen Temperature measuring resistance

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2976505A (en) * 1958-02-24 1961-03-21 Westinghouse Electric Corp Thermistors
US3044968A (en) * 1958-05-13 1962-07-17 Westinghouse Electric Corp Positive temperature coefficient thermistor materials
US2985700A (en) * 1959-06-10 1961-05-23 Westinghouse Electric Corp Titanate thermoelectric materials
US3377561A (en) * 1965-07-13 1968-04-09 Bell Telephone Labor Inc Positive temperature coefficient titanate thermistor
US3786390A (en) * 1971-08-09 1974-01-15 Jenaer Glaswerk Schott & Gen Temperature measuring resistance

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4010121A (en) * 1975-04-28 1977-03-01 Siemens Aktiengesellschaft High temperature hot conductors
US4010118A (en) * 1975-04-28 1977-03-01 Siemens Aktiengesellschaft High temperature hot conductors
US4010119A (en) * 1975-04-28 1977-03-01 Siemens Aktiengesellschaft High temperature hot conductors
US4308178A (en) * 1979-09-17 1981-12-29 North American Philips Consumer Electronics Corp. Thermionic cathode emitter coating
US4324702A (en) * 1979-11-02 1982-04-13 Matsushita Electric Industrial Co., Ltd. Oxide thermistor compositions

Also Published As

Publication number Publication date
DE2429866A1 (de) 1975-01-16
FR2234639A1 (enrdf_load_stackoverflow) 1975-01-17
JPS5018961A (enrdf_load_stackoverflow) 1975-02-27
GB1476374A (en) 1977-06-10
FR2234639B1 (enrdf_load_stackoverflow) 1980-03-14
DE2429866B2 (de) 1980-04-03
DE2429866C3 (de) 1980-11-27
JPS5439920B2 (enrdf_load_stackoverflow) 1979-11-30

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