US3926858A - Moisture sensitive element - Google Patents

Moisture sensitive element Download PDF

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Publication number
US3926858A
US3926858A US487533A US48753374A US3926858A US 3926858 A US3926858 A US 3926858A US 487533 A US487533 A US 487533A US 48753374 A US48753374 A US 48753374A US 3926858 A US3926858 A US 3926858A
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United States
Prior art keywords
mol
sensitive element
moisture sensitive
oxide
metal oxide
Prior art date
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Expired - Lifetime
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US487533A
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English (en)
Inventor
Noboru Ichinose
Yuhji Yokomizo
Masaki Katsura
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Toshiba Corp
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Tokyo Shibaura Electric Co Ltd
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Priority claimed from JP7847673A external-priority patent/JPS5316915B2/ja
Priority claimed from JP7847773A external-priority patent/JPS5316916B2/ja
Priority claimed from JP7847873A external-priority patent/JPS5316917B2/ja
Priority claimed from JP10545673A external-priority patent/JPS5318278B2/ja
Priority claimed from JP48105455A external-priority patent/JPS5243487B2/ja
Application filed by Tokyo Shibaura Electric Co Ltd filed Critical Tokyo Shibaura Electric Co Ltd
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Publication of US3926858A publication Critical patent/US3926858A/en
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    • 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
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/121—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid for determining moisture content, e.g. humidity, of the fluid

Definitions

  • a moisture sensitive element formed of an oxide com- 1973 Japan 48'78478 plex semiconductor comprising 89.9 to 20 mol% of Sept r r 48405455 ZnO, 0.1 to 20 mol% of c1 0 and 10 to 60 mol% of Sept 1973 Japan 48405456 at least one member selected from oxides of certain h l t- 521 US. (:1. 252/517; 252/518; 252/519; :3 Ofmono tetra penta and em me 252/520; 252/521 [51] Int. Cl. HOIB l/Ofl 8 Claims, 37 Drawing Figures LLI O I I 41 0 5 1o 15 2 FIG.
  • FIG. 21 RELATIVE HUMIDlTYI o
  • This invention relates to a moisture sensitive element which detects the variation of humidity with electric resistivity. and more particularly to an element formed of an oxide complex semiconductor.
  • a prior art moisture sensitive element comprises a fine powder of a metal oxide such as Fe O Fe O A1 0,, and Cr O which is coated on an inorganic insulating substrate.
  • This sensitive element is based on excellent hygroscopicity which the metal oxide generally has.
  • the coated powder of the metal oxide exhibits significant variation in electric resistivity in response to the variation in ambient humidity.
  • a moisture sensitive element utilizing metal oxide film is known. This element has small weight and size, and promptly responds to humidity changes. In addition it satisfactorily functions over a wide range of temperatures, from a low to a high temperature.
  • the element using powdery metal oxide is physically, chemically, and thermally stable
  • the coated layer of powdery metal oxide generally has high resistivity and therefore the element hardly detects electrically the changes of humidity with accuracy when such changes are small.
  • its reproducibility of the measured value and aging property are not satisfactory.
  • the element based on metal oxide film sometimes fails to measure the humidity accurately, and is inferior in sensitivity due to the unstability and nonhomogeneity of the film.
  • the element can hardly be mass produced.
  • oxide semiconductors which are prepared essentially from metal oxides may be used in a moisture sensitive element since the oxide semiconductor has lower resistivity than raw metal oxide and is therefore assumed to show great changes in resistivity due to the absorption and release of moisture.
  • oxide semiconductors have, as they are called thermistors (i.e., thermally sensitive resistors), a great negative temperature coefficient of resistivity and their resistivities are much affected by only a little change of temperature. The utilization of the oxide semiconductor has therefore been neglected in measurement of humidity accompanied with variation of temperature.
  • Another object of the invention is to provide a moisture sensitive element formed of an oxide complex semiconductor.
  • a moisture sensitive element formed of an oxide complex semiconductor comprising 89.9 to 20 mol% of ZnO, 0.1 to 20 mol% of Cr O- and 10 to 60 mol% of at least one of the third metal oxides selected from the group consisting of Li O, Na O, K 0, Rb. O, Cu O. BaO. SrO, CaO, PbO, MnO, NiO, CoO, MgO, CdO, CuO, FeO, BeO, TiO.
  • FIG. I shows the content of Cr O and the resistivity of ZnO-Me OCr O;, system in which the molar ratio of Me- O to ZnO is rendered constant:
  • FIG. 2 shows the content of Cr O and the resistivity of ZnO-Me O-Cr O system in which the molar ratio of Me O to ZnO is rendered constant;
  • FIG. 3 shows the content of Cr O and the resistivity of ZnO-Me""O -Cr O system in which the molar ratio of Me O to ZnO is rendered constant;
  • FIG. 4 shows the content of Cr- ,O and the resistivity of ZnO-Me O -Cr O system in which the molar ratio of Me- O to ZnO is rendered constant;
  • FIG. 5 shows the content of Cr O and the resistivity of ZnO-Me Q -Cr O system in which the molar ratio of Me O to ZnO is rendered constant;
  • FIG. 6 shows a plan view of a humidity measuring device using a moisture sensitive element according to this invention
  • FIG. 7 shows the relationship between the humidity and the resistivity of a prior art moisture sensitive element at a constant temperature
  • FIGS. 8 to 22 show the relationship between the humidity and the resistivity of the moisture sensitive elements according to this invention at a constant temperature
  • FIGS. 23 to 37 show the relationship between the temperature and the resistivity of the moisture sensitive elements according to this invention at a constant humidity.
  • This invention is based on the discovery that even an oxide semiconductor, though classified as a thermistor, turns out a moisture sensitive element having a low resistivity and a small temperature coefficient of resistivity if its composition ratio is defined as above. Such an element exhibits a resistivity greatly changing with the humidity variation and being little affected by ambient temperature.
  • the oxide semiconductor forming a moisture sensitive element of the invention contains, in addition to ZnO and Cr O at least one oxide of certain mono-, di-, tetra-, pentaand hexavalent metals (the oxide being hereinafter referred to as the third metal oxide).
  • the oxide (Me. ,O) of monovalent metals of the third metal oxide is selected from Li. ,O, Na O, K 0, Rb O and Cu O, that (Me O) of divalent metals from BaO, SrO, CaO, PbO, MnO, NiO, CoO, MgO, CdO, CuO.
  • the content of ZnO is 89.9 to 20 mol%, preferably to 30 mol%, that of Cr O .O.l to 20 mol%, preferably 5 to 20 mol%, and that of the third metal oxide 10 to 60 mol%, preferably 15 to 50 mol%.
  • the resultant element has a resistivity as large as M9, and is a poor moisture sensitive element. This is true also when the content of ZnO is less than 20 mol% and/or when that of the third metal oxide exceeds 60 mol%.
  • FIG. 1 indicates the resistivity characteristics of the semiconductor containing the third metal oxide Me o, in which curves a, b and represent the resistivity characteristics in the case where Me are Li, K and Cu. respectively.
  • FIG. 2 indicates the resistivity characteristics of the semiconductor containing the third metal oxide Me o, in which curves d, e and f represent the resistivity characteristics in the case where Me are Sr, Ni and Co, respectively.
  • FIG. 3 shows the resistivity characteristics of the semiconductor containing the third metal oxide Me O in which curves g, h and 1' represent the resistivity characteristics in the case where Me are Ti, Sn and Ce, respectively.
  • FIG. 4 shows the resistivity characteristics of the semiconductor containing the third metal oxide Me O in which curves j, k and I represent the resistivity characteristics in the case where Me" are Ta, Sb and V, respectively.
  • FIG. 5 indicates the resistivity characteristics of the semiconductor containing the third metal oxide Me O;, in which curves m, n and 0 represent the resistivity characteristics in the case where Me are W. Mo and Te, respectively.
  • a content of Cr O more than 20 mol% causes the resultant semiconductor to have a resistivity of over 100 MO and to become an unsuitable moisture sensitive element. All the above being considered, it is apparent that the upper limit of ZnO content is 89.9 mol%. Particularly, a mixture of 60 mol% of ZnO, mol% of Cr O and 30 mol% of the third metal oxide can make a highly desirable moisture sensitive element.
  • the moisture sensitive element of this invention may be prepared in the following manner.
  • Raw metal oxides accurately weighed out in prescribed amounts are mixed together in a ball mill and presintered at a relatively low temperature, for example, at 600 to 900C.
  • the presintered mass is pulverized into powder.
  • the raw materials used may be metal compounds such as a hydroxide, carbonate and oxalate which can be converted to the oxide upon heating.
  • the powder thus obtained is mixed with a binder such as polyvinyl alcohol, and the mixture is shaped, under a pressure of about I00 to 1,000 kg/cm into, for example, a plate having a width of 10 mm, a length of mm and a thickness of l mm.
  • the plate is sintered at about 1,000 to 1,300C generally in air. During sintering, it is kept at a maximum temperature for l to 5 hours.
  • the moisture sensitive element prepared as above is constructed in, for example, a humidity measuring device as shown in FIG. 6.
  • numeral 1 denotes the moisture sensitive element of the invention
  • numerals 2 and 3 electrodes made of material such as a high-temperature baking silver paint which well adheres to and has a little contact resistance with the element 1.
  • the moisture sensitive element of the invention though unexpectedly composed of the oxide semiconductor, has its resistivity hardly changed with temperature. Further, it exhibits such an excellent aging property that its resistivity varied within only several percents even it has been used for a long period of time. Its resistivity variation accompanying with its aging is negligibly small as mentioned above. The element is therefore practically satisfactory. Furthermore. it responds to humidity variation far morequickly than a prior art element. Its sensitivity or responding speed is such that it responds in about 10 seconds to O-to-l00 percent humidity change, and in 2 seconds after a humidity change of 3:20 percent. A prior art element responds in about 40 seconds and in 5 to 7 seconds to O-to-lOO percent and 'i20 percent humidity changes, respectively. With respect to the element of the invention no or little difference occurs between the plotted value of resistivity measured by a decreasing humidity and that measured conversely by increasing humidity. In addition the element of the invention can be manufactured economically since the raw materials used are obtained cheeply.
  • the moisture sensitive element of the invention shows such an excellent characteristic as described above.
  • the element becomes electrically conductive just as a semiconductor becomes, as is well known, when it adsorbs a gas.
  • Electrodes To the plate was ordinarily baked silver electrodes, forming a humidity measuring device. Either an elemental Ag or Ag- O may be used as a starting material for the silver electrodes. Since the sintered mass is stable to temperature, the electrode could be baked over a wide temperature range of, for example, 400 to 800C.
  • Table 1 shows the results with respect to samples containing the third metal oxide Me O
  • Table 2 the results with respect to samples containing the third metal oxide Me o
  • Table 3 the results with respect to samples containing the third metal oxide Me O
  • Table 4 the results with respect to samples containing the third metal oxide Me O
  • Table 5 the results with respect to samples containing the third metal oxide Me O
  • Table 6 the results with respect to samples containing a mixture of the third metal oxides Me O, Me O, Me O- MeflO and Me o
  • FIG. 7 the resistivity-humidity characteristics of a prior art element formed of a sintered mixture of silicon and a metal oxide are indicated in FIG. 7.
  • This figure reveals that appreciable difference occurs between resistivity measured by a decreasing humidity and that measured conversely by increasing humidity.
  • the moisture sensitive element of the invention gives rise to, as is apparent from FIGS. 8 to 22. no or only a little of such a difference, indicating that it reproduces the measured value much more highly than the prior art element.
  • FIGS. 23 to 37 show the resistivity characteristics of the samples of Examples 3. l5. 25.39.50.616, 74. 91. 102. 111, 116. l26. 132, I37 and 147. respectively.
  • These figures clearly show that the moisture sensitive element of the invention. though comprised of the oxide semiconductor. indicates a resistivity which changes little with temperature varia- Table 1 Zn() Cr Q, Me '0 R27, R- .,-,1 (1"; RH 1/ (mol'lr) (mol?) lmol z) ((V'PRH) R.
  • a moisture sensitive element formed of an oxide complex semiconductor comprising 89.9 to mol% of ZnO 0.1 to 20 mol% of Cr. ,O;, and 10 to 60 mol% of at least one of the third metal oxides selected from the group consisting of Li O, Na O, K 0, Rb O, Cu- O, BaO, SrO, CaO, PbO, MnO, NiO, C00, MgO. CdO, CuO, FeO. BeO, TiO GeO- ZrO MnO- TeO- SnO SiO CeO ThO HfO Nb O Ta O Sb O V 0 W0 M00 and TeO 2.
  • the third metal oxide is the oxide of the monovalent metal selected from the group consisting of Li- O, Na O. K 0, Rb O, C1120 and mixtures thereof.
  • a moisture sensitive element according to claim 1 wherein the third metal oxide is the oxide of the divalent metal selected from the group consisting of BaO, SrO, CaO, PbO. MnO, NiO, CoO, MgO, CdO, CuO, FeO, BeO and mixtures thereof.
  • a moisture sensitive element according to claim 1 wherein the third metal oxide is the oxide of the tetravalent metal selected from the group consisting of TiO GeO t ZrO MnO TeO- SnO SiOg, CeO ThO- HfO- and mixtures thereof.
  • a moisture sensitive element according to claim 1 wherein the third metal oxide is the oxide of the pentavalent metal selected from the group consisting of Nb O Ta O Sb O,-,. V 0 and mixtures thereof.
  • a moisture sensitive element according to claim 1 wherein the third metal oxide is the oxide of the hexavalent metal selected from the group consisting of W0 M00 TeO and mixtures thereof.
  • a moisture sensitive element according to claim 1 wherein said semiconductor comprises to 30 mol% of ZnO, 5 to 20 mol% of Cr. ,O and l5 to 50 mol% of the third metal oxide.
  • a moisture sensitive element according to claim 7 wherein said semiconductor comprises 60 mol% of ZnO, 10 mol% ofCr O and 30 mol% of the third metal oxide.

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  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
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US487533A 1973-07-13 1974-07-11 Moisture sensitive element Expired - Lifetime US3926858A (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
JP7847673A JPS5316915B2 (enrdf_load_stackoverflow) 1973-07-13 1973-07-13
JP7847773A JPS5316916B2 (enrdf_load_stackoverflow) 1973-07-13 1973-07-13
JP7847873A JPS5316917B2 (enrdf_load_stackoverflow) 1973-07-13 1973-07-13
JP10545673A JPS5318278B2 (enrdf_load_stackoverflow) 1973-09-20 1973-09-20
JP48105455A JPS5243487B2 (enrdf_load_stackoverflow) 1973-09-20 1973-09-20

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GB (1) GB1482584A (enrdf_load_stackoverflow)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4045764A (en) * 1974-10-15 1977-08-30 Tokyo Shibaura Electric Co., Ltd. Gas-sensing material
US4086556A (en) * 1975-09-18 1978-04-25 Matsushita Electric Industrial Co., Ltd. Humidity sensitive ceramic resistor
US4160748A (en) * 1977-01-06 1979-07-10 Tdk Electronics Co., Ltd. Non-linear resistor
US4174303A (en) * 1976-07-01 1979-11-13 Bbc Brown Boveri & Company Limited Ceramic electrical material with high nonlinear resistance
US4321577A (en) * 1980-02-25 1982-03-23 General Electric Company Integral humidity sensor/heater configurations
US4357426A (en) * 1980-12-22 1982-11-02 Murata Manufacturing Co., Ltd. Humidity sensitive ceramics
US4447352A (en) * 1982-02-17 1984-05-08 Nippondenso Co., Ltd. Humidity sensitive element
US4462930A (en) * 1981-12-07 1984-07-31 Kabushiki Kaisha Toyota Chuo Kenkyusho Humidity sensor
US4464647A (en) * 1981-02-12 1984-08-07 Marcon Electronics Co. Ltd. Humidity sensor made of metal oxide
EP0123385A1 (en) * 1983-02-24 1984-10-31 Kabushiki Kaisha Toshiba Humidity-sensitive resistive element
US4594569A (en) * 1982-02-12 1986-06-10 Matsushita Electric Industrial Co., Ltd. Humidity sensitive device
US4608549A (en) * 1982-12-28 1986-08-26 New Cosmos Electric Co. Ltd. Hydrogen-selective sensor and manufacturing method therefor
US20060255351A1 (en) * 2005-03-30 2006-11-16 Yungryel Ryu Metal oxide semiconductor films, structures and methods
US20070166547A1 (en) * 2003-08-05 2007-07-19 Thomas Dobbertin Use of a layer consisting of hydrophobic linear, or two-dimensional polycyclic aromatics as a barrier layer or an encapsulation and electric components constructed with a layer of this type and comprising organic polymers
CN104051106A (zh) * 2014-06-24 2014-09-17 铜陵三佳变压器有限责任公司 一种用于变压器的氧化硼基铁氧体磁芯材料
AU2020256373B2 (en) * 2020-01-07 2021-05-06 Nantong University Humidity sensor chip having three-electrode structure
CN117843346A (zh) * 2024-01-09 2024-04-09 汕头保税区松田电子科技有限公司 一种高稳定性低电阻率ntc热敏电阻介质材料及其制备方法

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4080564A (en) * 1975-10-02 1978-03-21 Matsushita Electric Industrial Co., Ltd. Humidity sensitive resistor device
DE2821266A1 (de) * 1978-05-16 1979-11-22 Siemens Ag Gassensoren
US9236622B2 (en) 2009-08-07 2016-01-12 Ford Global Technologies, Llc Fuel cell system with wetness sensor

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3766098A (en) * 1970-06-22 1973-10-16 Matsushita Electric Ind Co Ltd Voltage nonlinear resistors

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3766098A (en) * 1970-06-22 1973-10-16 Matsushita Electric Ind Co Ltd Voltage nonlinear resistors

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4045764A (en) * 1974-10-15 1977-08-30 Tokyo Shibaura Electric Co., Ltd. Gas-sensing material
US4086556A (en) * 1975-09-18 1978-04-25 Matsushita Electric Industrial Co., Ltd. Humidity sensitive ceramic resistor
US4174303A (en) * 1976-07-01 1979-11-13 Bbc Brown Boveri & Company Limited Ceramic electrical material with high nonlinear resistance
US4160748A (en) * 1977-01-06 1979-07-10 Tdk Electronics Co., Ltd. Non-linear resistor
US4321577A (en) * 1980-02-25 1982-03-23 General Electric Company Integral humidity sensor/heater configurations
US4357426A (en) * 1980-12-22 1982-11-02 Murata Manufacturing Co., Ltd. Humidity sensitive ceramics
US4464647A (en) * 1981-02-12 1984-08-07 Marcon Electronics Co. Ltd. Humidity sensor made of metal oxide
US4462930A (en) * 1981-12-07 1984-07-31 Kabushiki Kaisha Toyota Chuo Kenkyusho Humidity sensor
US4594569A (en) * 1982-02-12 1986-06-10 Matsushita Electric Industrial Co., Ltd. Humidity sensitive device
US4447352A (en) * 1982-02-17 1984-05-08 Nippondenso Co., Ltd. Humidity sensitive element
US4608549A (en) * 1982-12-28 1986-08-26 New Cosmos Electric Co. Ltd. Hydrogen-selective sensor and manufacturing method therefor
US4529540A (en) * 1983-02-24 1985-07-16 Tokyo Shibaura Denki Kabushiki Kaisha Humidity-sensitive resistive element
EP0123385A1 (en) * 1983-02-24 1984-10-31 Kabushiki Kaisha Toshiba Humidity-sensitive resistive element
US20100244019A1 (en) * 2002-08-28 2010-09-30 Yungryel Ryu Metal Oxide Semiconductor Films, Structures and Methods
US20070166547A1 (en) * 2003-08-05 2007-07-19 Thomas Dobbertin Use of a layer consisting of hydrophobic linear, or two-dimensional polycyclic aromatics as a barrier layer or an encapsulation and electric components constructed with a layer of this type and comprising organic polymers
US20060255351A1 (en) * 2005-03-30 2006-11-16 Yungryel Ryu Metal oxide semiconductor films, structures and methods
CN104051106A (zh) * 2014-06-24 2014-09-17 铜陵三佳变压器有限责任公司 一种用于变压器的氧化硼基铁氧体磁芯材料
CN104051106B (zh) * 2014-06-24 2016-08-24 铜陵三佳变压器有限责任公司 一种用于变压器的氧化硼基铁氧体磁芯材料
AU2020256373B2 (en) * 2020-01-07 2021-05-06 Nantong University Humidity sensor chip having three-electrode structure
CN117843346A (zh) * 2024-01-09 2024-04-09 汕头保税区松田电子科技有限公司 一种高稳定性低电阻率ntc热敏电阻介质材料及其制备方法

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GB1482584A (en) 1977-08-10
FR2241511B1 (enrdf_load_stackoverflow) 1977-06-24
DE2434129B2 (de) 1977-05-05
DE2434129A1 (de) 1975-01-30
FR2241511A1 (enrdf_load_stackoverflow) 1975-03-21

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