Sensors for hydrogen, ammonia
First Claim
1. A sensor apparatus for sensing hydrogen or ammonia in air, comprisinga hydrogen and ammonia gas sensitive material based on Cr2O3, wherein a small percentage of chromium cation sites in the Cr2O3 are replaced and occupied by transition metal ions having a valency greater than four, but still having a corundum crystal structure,first and second electrodes in contact with the gas sensitive material, and whereinthe transition metal ions having a valency greater than four are selected from the group consisting of tungsten ions and molybdenum ions.
1 Assignment
0 Petitions
Accused Products
Abstract
A sensor for detecting hydrogen or ammonia gas uses a gas sensitive material based on Cr2O3 with a small percentage of the chromium replaced by transition metal ions having a valency greater than four, but still having a corundum crystal structure. Electrodes in contact with the gas sensitive material are connected by conductors to electrical measuring means for measuring the resistance, conductance, capacitance, or impedance of the gas sensitive material. A temperature sensing means and heating means allow the temperature of the gas sensitive material to be regulated. The gas sensitive material is formed on an insulator substrate over one or both electrodes. One electrode can be on the non-substrate side of the gas sensitive material. The gas sensitive material can be formed by deposition from a suspension or colloidal dispersion and firing. The gas sensitive material is contacted with gas and changes in electrical properties of the material are observed.
51 Citations
19 Claims
-
1. A sensor apparatus for sensing hydrogen or ammonia in air, comprising
a hydrogen and ammonia gas sensitive material based on Cr2O3, wherein a small percentage of chromium cation sites in the Cr2O3 are replaced and occupied by transition metal ions having a valency greater than four, but still having a corundum crystal structure, first and second electrodes in contact with the gas sensitive material, and wherein the transition metal ions having a valency greater than four are selected from the group consisting of tungsten ions and molybdenum ions.
-
8. A method for producing a sensor apparatus for sensing hydrogen or ammonia in air, comprising
providing an insulating substrate, applying a first electrode to the insulating substrate, forming a layer of gas sensitive material over a portion of the first electrode and insulating substrate, and applying a second electrode, wherein the gas sensitive material is based on Cr2O3, wherein a small percentage of chromium cation sites in the Cr2O3 are replaced and occupied by transition metal ions having a valency greater than four, but still having a corundum crystal structure, and wherein the transition metal ions having a valency greater than four are selected from the group consisting of tungsten ions and molybdenum ions.
-
18. A hydrogen or ammonia gas sensing method, comprising
providing a hydrogen or ammonia gas sensor comprising a gas sensitive material based on Cr2O3, wherein a small percentage of chromium cation sites in the Cr2O3 are replaced and occupied by transition metal ions having a valency greater than four, but still having a corundum crystal structure, and first and second electrodes connected by conductors to an electrical measuring means for measuring resistance, conductance, capacitance, or impedance, contacting the hydrogen or ammonia gas sensor with a gas or gaseous mixture, and measuring the resistance, conductance, capacitance, or impedance of the gas sensitive material with the electrical measuring means, and wherein the transition metal ions having a valency greater than four are selected from the group consisting of tungsten ions and molybdenum ions.
-
19. A sensor apparatus for sensing hydrogen or ammonia in air, comprising
an insulating substrate, a first electrode to the insulating substrate, a layer of gas sensitive material over a portion of the first electrode and insulating substrate, and a second electrode in contact with the gas sensitive material, wherein the gas sensitive material is based on Cr2O3, wherein a small percentage of chromium cation sites in the Cr2O3 are replaced and occupied by transition metal ions having a valency greater than four, but still having a corundum crystal structure, and wherein the transition metal ions having a valency greater than four are selected from the group consisting of tungsten ions and molybdenum ions.
Specification