초록 ▼

A gas concentration sensing or pumping device is formed of a body of solid electrolyte material which exhibits ionic conduction when the concentration of gas is different between first and second surfaces of the body, or which, upon application of a voltage across the body, will cause gas on one sid

A gas concentration sensing or pumping device is formed of a body of solid electrolyte material which exhibits ionic conduction when the concentration of gas is different between first and second surfaces of the body, or which, upon application of a voltage across the body, will cause gas on one side of the body to be pumped to the other side. A thin film of a composition comprising an element selected from the group consisting of rare earth elements, alkaline earth metals, Ga Pb, In, Sn, Ti, Mo and W wherein Bi is the predominant element is formed on a major surface of the body to enhance conductivity at the electrode/body interface. Conductive electrode layers are formed over the film and an opposing major surface. The conductive layers may be formed of porous LaCrO 3 and the body may be formed of ZrO 2, CeO 2 or ThO 2 . An apertured disc or a layer of gas permeable material is formed over the sensor. A voltage is applied across the body of solid electrolyte causing transport of oxygen through the aperture or pores. The output current measures the oxygen concentration passing therethrough.

대표청구항 ▼

1. A gas sensor comprising: (a) a sensor body of switch electrolyte material which ionically conducts when the concentration of said gas is different between first and second surfaces of the sensor body; (b) a thin film on each said first and second surface of a composition comprising an element

1. A gas sensor comprising: (a) a sensor body of switch electrolyte material which ionically conducts when the concentration of said gas is different between first and second surfaces of the sensor body; (b) a thin film on each said first and second surface of a composition comprising an element selected from the group consisting of rare earth elements, alkaline earth metals, Ga, Pb, In, Sn, Ti, Mo and W and wherein Bi is the predominent element in the composition (c) an electrically conductive material formed over the thin film on the first surface of the sensor body; and (d) an electrically conductive material formed over the thin film on the second surface of the sensor body. 2. The sensor of claim 1 in which the gas is oxygen and the material of the sensor body comprises material selected from the group consisting of: ZrO 2, CeO 2 and ThO 2 . 3. The sensor of claim 2 in which the sensor body material includes a material from the group consisting of Y 2 O 3, Gd 2 O 3, CaO, SnO, MnO, La 2 O 3, MgO, and Sc 2 O 3 . 4. The sensor of claim 1 in which the electrically conductive material comprise porous LaCrO 3 and the sensor body comprises material selected from the group consisting of: ZrO 2, CeO 2 and ThO 2 . 5. An oxygen gas sensor comprising: (a) a sensor body of solid electrolyte material which exhibits ionic conduction in the presence of oxygen gas; (b) first and second electrodes permeable to oxygen gas formed over opposite first and second surfaces of said body; and (c) said electrodes each comprising a layer of Bi and in a predominant amount an element selected from the group consisting of a rare earth element, an alkaline earth metal, Ga, Pb, In, Sn, Ti, Mo, and W, and a layer of porous LaCrO 3 . 6. The sensor of claim 5 wherein the layer of porous LaCrO 3 is made porous by incorporating particles of carbon of lower combustion temperature into the electrodes as formed and heating the layer to a temperature which combusts the carbon particles having pores in the electrodes. 7. The sensor of claim 6 in which the particles in the first electrode are smaller than the particles in the second electrode. 8. The method of forming a gas sensor comprising the steps of: (a) forming a sensor body of solid electrolyte material ionically conductive in response to the concentration of said gas, said body having first and second opposing external surfaces; (b) forming a slurry comprising Bi and a rare earth metal on said first and second surfaces of said sensor body to obtain a first and a second film respectively; (c) forming a first electrically conductive material on said first film over said first surface of said sensor body; (d) forming a second electrically conductive material on said second film over said second surface of said sensor body. 9. A gas sensor made in accordance with the method of claim 8. 10. Apparatus comprising: a. a body of solid electrolyte material which ionically conducts in the presence of a gas; b. a film on a first surface of said body; said film being of a composition comprising an element selected from the group consisting of rare earth elements, alkaline earth metals, Ga, Pb, In, Sn, Ti, Mo and W wherein Bi is the predominant element in the composition; c. an electrically conductive electrode formed over the film on the first surface of the sensor body; and d. an electrically conductive electrode formed over an opposing second surface of the sensor body. 11. The apparatus of claim 10 in which the gas is oxygen and the material of the body comprises material selected from the group consisting of: ZrO 2, CeO 2 or ThO 2 . 12. The apparatus of claim 10 in which the electrodes are formed of porous LaCrO 3 and the body comprises material selected from the group consisting of: ZrO 2, CeO 2, or ThO 2 . 13. Apparatus comprising: (a) a body of solid electrolyte material which exhibits ionic conduction in the presence of a gas; (b) first and second electrodes permeable to said gas formed over opposite first and second surfaces of said body; and (c) one of said electrodes comprising a composition of Bi in a predominant amount and an element selected from the group consisting of a rare element, an alkaline earth metal, Ga, Pb, In, Sn, Ti, Mo and W, and a conductive element. 14. The apparatus of claim 13 wherein the conductive element is Pt, Ag or Au. 15. The apparatus of claim 13 wherein the conductive element is LaCrO 3 . 16. Apparatus comprising: (a) a first body of solid electrolyte material capable of ionic conduction between two major surfaces of the body in the presence of a gas concentration differential between said surfaces and capable of pumping gas from one such surface to the other upon application of a voltage across said surfaces; (b) electrodes formed over said two surfaces; (c) one of said electrodes including film means for improving the conductivity of the electrode/body interface formed between said one electrode and one of said surfaces; said film means being a composition comprising Bi in a predominant amount and an element selected from the group consisting of a rare earth element, an alkaline earth metal, Ga, Pb, In, Sn, Ti, Mo and W; (d) an apertured body disposed in spaced apart adjacent relation to said first body and having a thermal coefficient of expansion similar to said first body; and (e) bonding means for bonding said apertured body to said first body leaving a small enclosed volume which is hermetically sealed except for said aperture. 17. The apparatus of claim 16 wherein the bonding means comprises glass frit. 18. The apparatus of claim 16 wherein gas is pumped into said volume by applying a voltage across said electrodes.