Electromechanical effect in metal oxides

Abstract

This invention provides an electromechanical device comprising an active material comprising a metal oxide such as Ce 0.8 Gd 0.2 O 1.9 wherein the elastic modulus of metal oxide can be modulated by applying external electric field. The Ce 0.8 Gd 0.2 O 1.9 layer in a substrate\electrode\Ce 0.8 Gd 0.2 O 1.9 \electrode structure or conductive substrate\Ce 0.8 Gd 0.2 O 1.9 \electrode structure develops a stress upon applying an electric field. This invention provides methods for tailoring the elastic modulus of materials using an electric field for the generation of an electromechanical response.

What is claimed is: 
     
         1 . A process for making an electromechanical device, said process comprising:
 forming a first conductive layer,   forming a layer of a ceria-based material in contact with said first conductive layer; and   forming a second conductive layer in contact with said ceria-based material layer;   wherein upon application of an electric field said ceria-based material generates displacement, stress or a combination thereof.   
     
     
         2 . The process of  claim 1 , wherein said first conductive layer is formed on a substrate by electron beam deposition. 
     
     
         3 . The process of  claim 1 , wherein said layer of said ceria-based material is formed by radio frequency magnetron sputtering. 
     
     
         4 . The process of  claim 1  wherein said first and said second conductive layers are connected to a power supply. 
     
     
         5 . The process of  claim 1 , wherein said ceria-based material is doped by a metal ion. 
     
     
         6 . The process of  claim 5 , wherein said metal ion is a lanthanide. 
     
     
         7 . The process of  claim 6 , wherein said metal ion is Gd. 
     
     
         8 . The process of  claim 1 , wherein said ceria-based material is Ce x Gd y O z  wherein x ranges between 0.95-0.63, said y ranges between 0.05-0.37 and said z ranges between 2−(y/2). 
     
     
         9 . The process of  claim 2 , wherein said Ce x Gd y O z  is Ce 0.8 Gd 0.2 O 1.9 . 
     
     
         10 . The process of  claim 1 , wherein said ceria-based material is strain-free. 
     
     
         11 . The process of  claim 1 , wherein the in-plane strain of said ceria-based material ranges between 0.1%-0.4%. 
     
     
         12 . The process of  claim 1 , wherein said ceria-based material is poled. 
     
     
         13 . The process of  claim 1 , wherein said displacement is at least 100 pm/V. 
     
     
         14 . The process of  claim 1 , wherein said stress developed in said ceria-based material is at least 100 MPa. 
     
     
         15 . The process of  claim 1 , wherein said device further comprises conductive contacts. 
     
     
         16 . The process of  claim 15 , wherein said conductive contacts comprising Cr, Al, Ag, Ti, or combination thereof.