Chemistry: analytical and immunological testing – Oxygen containing – Molecular oxygen
Patent
1996-01-29
1998-08-11
Stucker, Jeffrey
Chemistry: analytical and immunological testing
Oxygen containing
Molecular oxygen
422 98, 204424, 204426, 338 34, G01N 3112
Patent
active
057926662
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an oxygen sensor based on complex metal oxides of the general formula y is a value from 0.001 to 0.1, particularly an oxygen sensor which contains n- and/or p-semiconducting sensor materials, and to a process for the manufacturing of the sensor and to its use.
Gas detectors which contain sensor materials of the general formula example, in the form of the complex oxide La.sub.1.4 Sr.sub.0.6 NiO.sub.4, not for detecting oxygen but for detecting oxidizable gases.
However, the cuprates which fall in the above formula are used only marginally in a non-doped form in the above-mentioned document and their capability for detecting oxidizable gases is not particularly distinctive.
SUMMARY OF THE INVENTION
It surprisingly was found that cuprates from the group of rare earths, even in a non-doped form, have an excellent oxygen sensing behavior if the oxygen stoichiometric deviation is set to a value of 4+y in the material.
It is therefore an object of the present invention to provide new oxygen sensors based on complex metal oxides of the general formula vehicles, for example.
This object is achieved by means of an oxygen sensor based on complex metal oxides of the general formula and y is a value from 0.001 to 0.1. In a preferred embodiment y is in the range of from 0.01 to 0.02. The sensor is preferably produced by applying the sensor materials to a metal oxide substrate. It is preferred that the substrate be non-conducting. The application of the sensor materials to the substrate is preferably by screen printing onto a metal oxide substrate, such as Al.sub.2 O.sub.3.
In one embodiment according to the invention, the oxygen sensor may be arranged in a bridge circuit with one oxygen sensor with p-conducting sensor materials and one with n-conducting sensor materials. The sensors are connected to the same input for the input voltage in different bridge branches of the bridge circuit. In another embodiment, there is an arrangement in a bridge circuit of a series connection of one oxygen sensor with p-conducting sensor materials and another with n-conducting materials in one bridge branch, and in the other bridge branch, a series connection of two oxygen sensors of an n- and p- conducting material, respectively, being provided in such a manner that the oxygen sensor with the n-conducting sensor material in the one bridge branch is situated opposite the oxygen sensor with a p-conducting sensor material in the other bridge branch.
The oxygen stoichiometric deviation y is in the range from 0.001 to 0.1, preferably in the range of from 0.01 to 0.02.
The oxygen sensors according to the invention can be produced as follows:
The corresponding metal oxides, carbonates and/or oxycarbonates from the group of rare earths and copper are finely mixed by grinding with the addition of an organic solvent, such as cyclohexane. The ingredients are preferably mixed at the stoichiometric ratio. Grinding is preferably carried out in a suitable mill. The ground material is then caused to settle. The solvent is decanted and the ground material is dried. The powder is then calcined, in which case the calcining operation may be interrupted for a better mixing by another grinding. After the calcining, another grinding takes place, whereby a fine cuprate powder is obtained.
For setting the oxygen stoichiometric deviation of the thus obtained cuprate powders, they are glowed at high temperatures of preferably 850.degree. to 1,100.degree. C. in an oxygen-containing atmosphere, preferably pure oxygen.
By the addition of a paste matter and/or solvents, the thus obtained powder is processed to a paste, and the paste is applied by means of a thick film technique, for example, by screen printing, to a preferably non-conducting metal oxide substrate, such as Al.sub.2 O.sub.3. The thus produced layer is dried and burnt, for example, by drying at temperatures above 100.degree. C. and is subsequently fired at rising temperatures, optionally with a temperature profile in which rising temperatu
REFERENCES:
patent: 4314996 (1982-02-01), Sekido et al.
patent: 4789454 (1988-12-01), Badwal et al.
patent: 4834051 (1989-05-01), Tanaka et al.
patent: 5071626 (1991-12-01), Tuller
Nozaki et al. "Oxygen-Sensitive Resistivity of La.sub.2 CuO.sub.4 at High Temperatures", Japanese Journal of Applied Physics, vol. 26, No. 11(Nov. 1987), pp.L1881-L1883.
Blase Rainer
Hardtl Karl-Heinz
Schonauer Ulrich
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