Mixed potential hydrocarbon sensor with low sensitivity to methane and CO

Abstract

A hydrocarbon sensor is formed with an electrolyte body having a first electrolyte surface with a reference electrode depending therefrom and a metal oxide electrode body contained within the electrolyte body and having a first electrode surface coplanar with the first electrolyte surface. The sensor was formed by forming a sintered metal-oxide electrode body and placing the metal-oxide electrode body within an electrolyte powder. The electrolyte powder with the metal-oxide electrode body was pressed to form a pressed electrolyte body containing the metal-oxide electrode body. The electrolyte was removed from an electrolyte surface above the metal-oxide electrode body to expose a metal-oxide electrode surface that is coplanar with the electrolyte surface. The electrolyte body and the metal-oxide electrode body were then sintered to form the hydrocarbon sensor.

What is claimed is:  
     
         1 . A hydrocarbon sensor comprising: 
 an electrolyte body having a first electrolyte surface with a reference electrode depending therefrom;    a metal oxide electrode body contained within the electrolyte body and having a first electrode surface coplanar with the first electrolyte surface, wherein the electrolyte body is compressed and sintered about the metal oxide electrode body for intimate contact therebetween.    
     
     
         2 . The hydrocarbon sensor according to  claim 1 , where the metal oxide electrode body is formed from La 1-x A x CrO 3 , where A is selected from the group consisting of Sr, Ca, and Mg, and 0≦x≦0.5.  
     
     
         3 . The hydrocarbon sensor according to  claim 2 , where A is Sr and x=0.2.  
     
     
         4 . The hydrocarbon sensor according to  claim 1 , where the electrolyte body is yttria stabilized zirconia with a porosity produced by sintering at a temperature effective to produce a density less than about 81% of theoretical maximum density.  
     
     
         5 . A method for forming a hydrocarbon sensor comprising: 
 forming a sintered metal-oxide electrode body;    placing the metal-oxide electrode body within an electrolyte powder;    pressing the electrolyte powder with the metal-oxide electrode body to form a pressed electrolyte body containing the metal-oxide electrode body;    removing electrolyte from an electrolyte surface above the metal-oxide electrode body to expose a metal-oxide electrode surface that is coplanar with the electrolyte surface; and    sintering the electrolyte body with the metal-oxide electrode body to form the hydrocarbon sensor.    
     
     
         6 . The method of  claim 5 , where the metal oxide electrode body is formed from La 1-x A x CrO 3 , where A is selected from the group consisting of Sr, Ca, and Mg, and 0≦x≦0.5.  
     
     
         7 . The method of  claim 6 , where the A is Sr and x=0.2.  
     
     
         8 . The method of  claim 5  where the electrolyte is yttria-stabilized zirconia.  
     
     
         9 . The method of  claim 8 , where the metal oxide electrode body is formed from La 1-x A x CrO 3 , where A is selected from the group consisting of Sr, Ca, and Mg, and 0≦x≦0.5.  
     
     
         10 . The method of  claim 9 , where A is Sr and x=0.2.  
     
     
         11 . The method of  claim 10 , wherein the electrolyte body with the metal-oxide electrode body is sintered at a temperature effective to produce a density less than about 81% of theoretical density.