US5397541A
Expired / Lapsed
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Thin film oxygen sensor
Assignee: National Research Council Canada
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Filing: 1993-09-10
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Granted: 1995-03-14
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Expires: 2013-09-10
Abstract
Abstract An oxygen sensor is based on a thin film of a compound oxide supported on a substrate such as quartz. The compound oxide has a general formula ABO2.5+x, where A is an element of the lanthanum family, alkaline earth metal or their mixture, and B is a transition metal or a mixture of transition metals. X is a variable number, changing from about 0 to about 0.5 between the reversible oxygen-deplete and oxygen-rich forms of the oxide. In an elevated temperature and oxygen-containing atmosphere, the thin film can undergo reversible bulk oxidation resulting in a detectable change of its physical properties such as mass, optical transmissivity and electrical resistance.
Inventors
- 👤 Michael L. Post
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:56
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N21/00; G01N21/75; G01N21/77; Y; Y10; Y10T; Y10T436/00; Y10T436/20; Y10T436/207497; Y10T436/208339
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
164 words
An oxygen sensor comprising: a thermally stable and chemically stable substrate, a thin uniform crystalline film of a nonstoichiometric compound oxide of the general formula ABO 2 .5+ x supported on the substrate, wherein A is an element of the lanthanum family, an alkaline earth metal or a mixture thereof, B is a transition metal or a mixture of transition metals, and x is a number which defines bulk oxygen stoichiometry of the oxide and is variable between about 0 for an oxygen deplete and less than 0.5 for an oxygen saturated crystalline phase of the compound oxide, the film being of a thickness such that the compound oxide can undergo reversible bulk reaction with oxygen at an elevated temperature in an oxygen-containing atmosphere thereby undergoing a transition between the oxygen saturated and oxygen-deplete crystalline phases, and a detecting means for detecting a change in physical properties of said film, said change being a function of the varying bulk oxygen stoichiometry of the film.
Claim 2
Dependent Claim
164 words
An oxygen sensor comprising: a thermally stable and chemically stable substrate, a thin uniform crystalline film of a nonstoichiometric compound oxide of the general formula ABO 2 .5+ x supported on the substrate, wherein A is an element of the lanthanum family, an alkaline earth metal or a mixture thereof, B is a transition metal or a mixture of transition metals, and x is a number which defines bulk oxygen stoichiometry of the oxide and is variable between about 0 for an oxygen deplete and less than 0.5 for an oxygen saturated crystalline phase of the compound oxide, the film being of a thickness such that the compound oxide can undergo reversible bulk reaction with oxygen at an elevated temperature in an oxygen-containing atmosphere thereby undergoing a transition between the oxygen saturated and oxygen-deplete crystalline phases, and a detecting means for detecting a change in physical properties of said film, said change being a function of the varying bulk oxygen stoichiometry of the film.
Claim 3
Dependent Claim
29 words
The sensor as defined in claim 1 wherein the thickness of the layer is such that an optical transmittance of the layer varies depending on the value of x.
Claim 4
Dependent Claim
17 words
The sensor as defined in claim 2 wherein said detecting means is an optical transmittance detecting means.
Claim 5
Dependent Claim
16 words
The sensor as defined in claim 1 wherein said detecting means is a weight detecting means.
Claim 6
Dependent Claim
17 words
The sensor according to claim 1 wherein said detecting means is a bulk electrical resistance detecting means.
Claim 7
Dependent Claim
22 words
The sensor according to claim 1 wherein the film has a surface area in the order of that of an epitaxial film.
Claim 8
Dependent Claim
16 words
The sensor according to claim 4 wherein the weight detecting means is a quartz crystal microbalance.
Claim 9
Dependent Claim
11 words
The sensor according to claim 1 wherein the substrate is sapphire.
Claim 10
Dependent Claim
23 words
The sensor according to claim 8 wherein a thin film of cerium oxide is interposed between the substrate and the compound oxide film.
Claim 11
Dependent Claim
16 words
The sensor according to claim 1 wherein A is strontium (Sr) and B is iron (Fe).
Claim 12
Independent Claim
155 words
A method of making an oxygen sensor, comprising providing a thermally stable and chemically stable substrate, applying onto the substrate in an oxygen-controlled atmosphere a uniform crystalline thin film of a non-stoichiometric compound oxide of the general formula ABO 2 .5+x, wherein A is an element of the lanthanum family, an alkaline earth metal or a mixture thereof, B is a transition metal or a mixture of transition metals, and x is a number which is variable between 0 for an oxygen deplete and less than 0.5 for an oxygen saturated crystalline phase of the compound oxide, the layer being of a thickness such that the compound oxide can undergo reversible bulk reaction with oxygen at an elevated temperature in an oxygen-containing atmosphere thereby undergoing transition between the oxygen saturated and oxygen-deplete crystalline phases, and providing a detecting means in association with the thin film for detecting a change in physical properties of said film.
Claim 13
Independent Claim
155 words
A method of making an oxygen sensor, comprising providing a thermally stable and chemically stable substrate, applying onto the substrate in an oxygen-controlled atmosphere a uniform crystalline thin film of a non-stoichiometric compound oxide of the general formula ABO 2 .5+x, wherein A is an element of the lanthanum family, an alkaline earth metal or a mixture thereof, B is a transition metal or a mixture of transition metals, and x is a number which is variable between 0 for an oxygen deplete and less than 0.5 for an oxygen saturated crystalline phase of the compound oxide, the layer being of a thickness such that the compound oxide can undergo reversible bulk reaction with oxygen at an elevated temperature in an oxygen-containing atmosphere thereby undergoing transition between the oxygen saturated and oxygen-deplete crystalline phases, and providing a detecting means in association with the thin film for detecting a change in physical properties of said film.
Claim 14
Dependent Claim
27 words
The method of claim 11 wherein a thin film of cerium dioxide is applied onto the substrate before the film of said compound oxide is applied thereon.
Claim 15
Dependent Claim
21 words
The method according to claim 11 wherein the substrate is a transparent material selected from sapphire, quartz and AT cut quartz.
Claim 16
Dependent Claim
17 words
The method according to claim 11 wherein the film is applied by means of pulsed laser ablation.
References Cited (Backward Citations)
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