US3865550A
Expired / Lapsed
US
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Semi-conducting gas sensitive devices
Assignee: National Research Development Corp UK
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Filing: 1973-10-25
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Granted: 1975-02-11
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Expires: 1993-10-25
Abstract
Abstract An activated semiconducting element comprises a semiconducting oxide of a first metal with at least one further metal incorporated in its lattice system whereby the semiconductivity of the activated oxide alters in the presence of a gas to be detected, which may be at a low concentration in an atmosphere consisting largely of another gas. The first metal and the further metal can be chosen so that the activated semiconducting element is reactive to a chosen gas or group of gases. The activated element is usually prepared in a porous form by deposition from a molten solvent and is heated to a temperature of maximum sensitivity.
Inventors
- 👤 Barry Bott
- 👤 Jack Graham Firth
- 👤 Alan Jones
- 👤 Thomas Alwyn Jones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 01:44
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; H; H01; H01B; H01B1/00; H01B1/06; H01B1/08; Y; Y10; Y10T; Y10T436/00; Y10T436/20; Y10T436/204998; Y10T436/205831; Y10T436/21; Y10T436/214
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
164 words
A GAS-SENSITIVE DEVICE COMPRISING A SEMI-CONDUCTING ELEMENT HAVING A SURFACE WHICH CAN BE EXPOSED TO AN ATMOSPHERE CONTAINING THE GAS TO WHICH THE DEVICE IS SENSITIVE AND TWO ELECTRODES SEPARATELY IN CONTACT WITH THE SEMI-CONDUCTING ELEMENT WHEREBY AN ELECTRIC CURRENT CAN BE PASS BETWEEN THE ELECTRODES WHICH IS DEPENDENT UPON THE CONDUCTIVITY OF THE ELEMENT, THE ELEMENT CONSISTING ESSENTIALLY OF A SEMICONDUCTING OXIDE OF A FIRST METAL HAVING IN SOLID SOLUTION WITHIN ITS LATTICE SYSTEM AT LEAST ONE FURTHER METAL WHICH CONSTITUTES AN ACTIVATOR PROMOTING IN THE SYSTEM AT LEAST ONE METALLIC IONIC SPECIES WHICH REACTS MORE STRONGLY WITHIN A GIVEN TEMPERATURE RANGE TO THE PRESENCE OF THE GAS TO BE DETECTED THAN THE PREDOMINANT METALLIC IONIC SPECIES OF THE UNACTIVATED SEMICONDUCTING OXIDE, SAID AT LEAST ONE FURTHER METAL BEING PRESENT IN AN ACTIVATING AMOUNT, WITH THE RESULT THAT THE CONDUCTIVITY OF THE ELEMENT IS HIGHLY DEPENDENT WITHIN THE GIVEN TEMPERATURE RANGE ON THE CONCENTRATION OF THE GAS TO BE DETECTED IN THE ATMOSPHERE.
Claim 2
Dependent Claim
164 words
A GAS-SENSITIVE DEVICE COMPRISING A SEMI-CONDUCTING ELEMENT HAVING A SURFACE WHICH CAN BE EXPOSED TO AN ATMOSPHERE CONTAINING THE GAS TO WHICH THE DEVICE IS SENSITIVE AND TWO ELECTRODES SEPARATELY IN CONTACT WITH THE SEMI-CONDUCTING ELEMENT WHEREBY AN ELECTRIC CURRENT CAN BE PASS BETWEEN THE ELECTRODES WHICH IS DEPENDENT UPON THE CONDUCTIVITY OF THE ELEMENT, THE ELEMENT CONSISTING ESSENTIALLY OF A SEMICONDUCTING OXIDE OF A FIRST METAL HAVING IN SOLID SOLUTION WITHIN ITS LATTICE SYSTEM AT LEAST ONE FURTHER METAL WHICH CONSTITUTES AN ACTIVATOR PROMOTING IN THE SYSTEM AT LEAST ONE METALLIC IONIC SPECIES WHICH REACTS MORE STRONGLY WITHIN A GIVEN TEMPERATURE RANGE TO THE PRESENCE OF THE GAS TO BE DETECTED THAN THE PREDOMINANT METALLIC IONIC SPECIES OF THE UNACTIVATED SEMICONDUCTING OXIDE, SAID AT LEAST ONE FURTHER METAL BEING PRESENT IN AN ACTIVATING AMOUNT, WITH THE RESULT THAT THE CONDUCTIVITY OF THE ELEMENT IS HIGHLY DEPENDENT WITHIN THE GIVEN TEMPERATURE RANGE ON THE CONCENTRATION OF THE GAS TO BE DETECTED IN THE ATMOSPHERE.
Claim 3
Dependent Claim
27 words
A gas-sensitive device according to claim 1 having means to maintain the temperature of the activated metal oxide within said given temperature range of relatively high sensitivity.
Claim 4
Dependent Claim
16 words
A gas-sensitive device according to claim 1 in which the semi-conducting element has a porous structure.
Claim 5
Dependent Claim
24 words
A gas-sensitive device according to claim 1 in which the semi-conducting element is in the form of substantially uniformly sized rounded particles sintered together.
Claim 6
Dependent Claim
23 words
A gas-sensitive device according to claim 4 in which the particles are virtually spherical particles of the order of one micron in diameter.
Claim 7
Dependent Claim
20 words
A gas-sensitive device according to claim 1 mounted on a glass bead with a heating element fused into the glass.
Claim 8
Dependent Claim
17 words
A gas-sensitive device according to claim 1 and wherein the device is mounted on the two electrodes.
Claim 9
Independent Claim
131 words
A method of producing a gas-sensitive device having a semi-conducting element consisting essentially of a semi-conducting metal oxide having in solid solution whithin its lattice system at least one furter metal which constitutes an activator promoting in the system at least one ionic species which reacts more strongly within a given temperature range to the presence of the gas to be detected than the predominant metallic ionic species of the unactivated semi-conducting oxide, which method compises positioning two electrodes, heating in an ionic salt complexes of the said metal oxide and the at least one furthEr metal to produce between the two electrodes a molten body in which said complexes are substantially dissolved, and evaporating the melt to leave a deposition of particles of the semi-conducting element between the two electrodes.
Claim 10
Independent Claim
131 words
A method of producing a gas-sensitive device having a semi-conducting element consisting essentially of a semi-conducting metal oxide having in solid solution whithin its lattice system at least one furter metal which constitutes an activator promoting in the system at least one ionic species which reacts more strongly within a given temperature range to the presence of the gas to be detected than the predominant metallic ionic species of the unactivated semi-conducting oxide, which method compises positioning two electrodes, heating in an ionic salt complexes of the said metal oxide and the at least one furthEr metal to produce between the two electrodes a molten body in which said complexes are substantially dissolved, and evaporating the melt to leave a deposition of particles of the semi-conducting element between the two electrodes.
Claim 11
Dependent Claim
31 words
A method according to claim 8 wherein the ionic salt is an ammonium salt and the complexes of the metal oxide and the at least one further metal are ammine complexes.
Claim 12
Dependent Claim
13 words
A method according to claim 8 wherein the ionic salt is ammonium nitrate.
Claim 13
Independent Claim
191 words
A method of producing a gas-sensitive device having a semi-conducting element consisting essentially of a semi-conducting metal oxide having in solid solution within its lattice system at least one further metal which constitutes an activator promoting in the system at least one ionic species which reacts more strongly within a given temperature range to the presence of the gas to be detected than the predominant metallic ionic species of the unactivated semi-conducting oxide, which method comprises positioning two electrodes, preparing a suspension in an aqueous ionic salt of a mixture of the metal oxide and a salt of the at least one further metal to give a desired concentration with respect to the metal oxide of the at least one further metal and to give a mole ratio of the oxide to the ionic salt of less than one, placing the sus pension between the two electrodes, heating the suspension to produce a molten body in which the complexes of the metal oxide and the at least one further metal are substantially dissolved, and evaporating the melt to leasve a deposition of particles of the semi-conducting element between the two electrodes.
Claim 14
Independent Claim
191 words
A method of producing a gas-sensitive device having a semi-conducting element consisting essentially of a semi-conducting metal oxide having in solid solution within its lattice system at least one further metal which constitutes an activator promoting in the system at least one ionic species which reacts more strongly within a given temperature range to the presence of the gas to be detected than the predominant metallic ionic species of the unactivated semi-conducting oxide, which method comprises positioning two electrodes, preparing a suspension in an aqueous ionic salt of a mixture of the metal oxide and a salt of the at least one further metal to give a desired concentration with respect to the metal oxide of the at least one further metal and to give a mole ratio of the oxide to the ionic salt of less than one, placing the sus pension between the two electrodes, heating the suspension to produce a molten body in which the complexes of the metal oxide and the at least one further metal are substantially dissolved, and evaporating the melt to leasve a deposition of particles of the semi-conducting element between the two electrodes.
Claim 15
Dependent Claim
32 words
A method according to claim 11 in which the ionic salt is an ammonium salt and the complexes of the metal oxide and the at least one further metal are ammine complexes.
Claim 16
Dependent Claim
26 words
A method according to claim 11 in which the ionic salt is ammomium nitrate and the melt is evaporated at a temperature between 200*C and 400*C.
Claim 17
Dependent Claim
24 words
A gas-sensitive device according to claim 1 wherein said at least one metallic ionic species is ions of said at least one further metal.
Claim 18
Dependent Claim
28 words
A gas-sensitive device according to claim 14 wherein the concentration of said at least one metallic ionic species is enhanced by the incorporation of a second further metal.
Claim 19
Dependent Claim
21 words
A gas-sensitive device according to claim 1 wherein said at least one metallic ionic species is ions of said first metal.
Claim 20
Dependent Claim
33 words
A gas-sensitive device according to claim 1 comprising a zinc oxide lattice containing up to 3 atomic percent of platinum and sensitive to hydrocarbons when held at a temperature of at least 500*C.
Claim 21
Dependent Claim
16 words
A gas-sensitive device according to claim 17 and cotaining up to 3 atomic percent of gallium.
Claim 22
Dependent Claim
36 words
A gas-sensitive device according to claim 1 comprising a ferrous oxide lattice containing up to 3 atomic percent of tin and which is sensitive to basic gases when held at a temperature of at least 150*C.
Claim 23
Dependent Claim
15 words
A gas-sensitive device according to claim 19 and containing up to 3 atomic percent lithium.
Claim 24
Dependent Claim
37 words
A gas-sensitive device according to claim 1 comprising a ferric oxide lattice containing up to 3 atomic percent thallium and which is sensitive to acidic and oxidising gases when held at a temperature of at least 150*C.
Claim 25
Dependent Claim
15 words
A gas-sensitive device according to claim 21 and containing up to 3 atomic percent cerium.
Claim 26
Dependent Claim
34 words
A gas-sensitive device according to claim 1 comprising a nickel oxide lattice containing up to 3 atomic percent gallium which when maintained at a temperature of at least 250*C is sensitive to reducing gases.
Claim 27
Dependent Claim
34 words
A gas-sensitive device according to claim 1 comprising a stannous oxide lattice containing up to 3 atomic percent lithium which when held at a temperature of at least 150*C is sensitive to basic gases.
Claim 28
Dependent Claim
36 words
A gas-sensitive device according to claim 1 comprising a silver oxide lattice containing up to 3 atomic percent gallium wHich when held at a temperature of at least 150*C is sensitive to acidic and oxidising gases.
Claim 29
Dependent Claim
41 words
A gas-sensitive device according to claim 1 comprising a uranium oxide lattice containing up to 0.5 atomic percent iridium and which when held at a temperature of at least 300*C is sensitive to low concentrations of carbon monoxide and of methane.
Claim 30
Dependent Claim
52 words
A gas-sensitive device according to claim 1 comprising a uranium oxide lattice containing up to 0.5 atomic percent palladium and up to 1.0 atomic percent manganese and which when held at a temperature of at least 400*C is sensitive to low concentrations of carbon monoxide even in the presence of a hydrocarbon.
Claim 31
Dependent Claim
52 words
A gas-sensitive device according to claim 1 comprising a uranium oxide lattice containing up to 0.5 atomic percent palladium and up to 1.0 atomic percent cerium and which when held at a temperature of at least 400*C is sensitive to low concentrations of carbon monoxide even in the presence of a hydrocarbon.
Claim 32
Dependent Claim
55 words
A gas-sensitive device according to claim 1 comprising a uranium oxide lattice containing up to 0.5 atomic percent platinum and which when held at a temperature of at least 350*C is sensitive to hydrocarbons at concentrations of the order 10, 000 parts per million even in the presence of a low concentration of carbon monoxide.
Claim 33
Dependent Claim
26 words
A gas-sensitive device according to claim 1 in which the proportion of said further metal in the lattice system does not substantially exceed 3 atomic percent.
Claim 34
Dependent Claim
25 words
A gas-sensitive device according to claim 1 in which said first metal is selected from the group consisting of zinc, nickel, iron, tin and silver.
Claim 35
Dependent Claim
26 words
A gas-sensitive device according to claim 31 in which said further metal is selected from the group consisting of platinum, tin, thallium, gallium, lithium and cerium.
Claim 36
Dependent Claim
14 words
A gas-sensitive device according to claim 1 in which said first metal is uranium.
Claim 37
Dependent Claim
23 words
A gas-sensitive device according to claim 33 in which said further metal is selected from the group consisting of iridium, palladium and platinum.
Claim 38
Independent Claim
125 words
A method of detecting a gas in an atmosphere comprising: exposing to said atmosphere a semiconducting element consisting essentially of a semiconducting oxide of a first metal having in solid solution within its lattice system at least one further metal which constitutes an activator promoting in the system at least one metallic ionic species which reacts more strongly within a given temperature range to the presence of said gas than the predominant metallic ionic species of the unactivated semi-conducting oxide, said at least on further metal being present in an activating amount; maintaining said semiconducting element within said given temperature range; and detecting changes in the conductivity of said semi-conducting element while it is exposed to said atmosphere and maintained within said given temperature range.
Claim 39
Independent Claim
125 words
A method of detecting a gas in an atmosphere comprising: exposing to said atmosphere a semiconducting element consisting essentially of a semiconducting oxide of a first metal having in solid solution within its lattice system at least one further metal which constitutes an activator promoting in the system at least one metallic ionic species which reacts more strongly within a given temperature range to the presence of said gas than the predominant metallic ionic species of the unactivated semi-conducting oxide, said at least on further metal being present in an activating amount; maintaining said semiconducting element within said given temperature range; and detecting changes in the conductivity of said semi-conducting element while it is exposed to said atmosphere and maintained within said given temperature range.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-10 | 1978-08-12 | 1979-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-10 | 1982-08-12 | 1983-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-10 | 1986-08-12 | 1987-02-11 | $7700.00 | Window Closed / Lapsed |