Piezoelectric Element and Method for Manufacturing the Piezoelectric Element

Abstract

A piezoelectric element includes a piezoelectric ceramic body containing an internal electrode. The piezoelectric ceramic body is mainly made of a perovskite complex oxide containing an alkali metal niobate-based compound containing at least one element selected from among K, Li, and Na. The internal electrode is made of a base metal material, such as Ni or Cu. The piezoelectric element is produced by co-sintering the internal electrode and the piezoelectric ceramic body. Thus, there is provided an inexpensive piezoelectric element that can be properly used in practice even though it has been fired in a reducing atmosphere.

1 . A piezoelectric element comprising:
 a piezoelectric ceramic body, the piezoelectric ceramic body comprising a perovskite complex oxide containing an alkali metal niobate-based compound as a main component thereof; and   an internal electrode buried in the piezoelectric ceramic body and co-sintered with the piezoelectric ceramic body, the internal electrode comprising a base metal material.   
     
     
         2 . The piezoelectric element according to  claim 1 , wherein the alkali metal niobate-based compound contains at least one element selected from the group consisting of K, Li, and Na. 
     
     
         3 . The piezoelectric element according to  claim 2 , wherein the alkali metal niobate-based compound further contains at least one element selected from the group consisting of Ag, Mg, Ca, Sr, Ba, Y, Nd, La, Ta, Ti, Sb, Sn, In, Sc, Hf, Mn, Fe, Cu, Ni, Zn, Dy, Ce, Co, Si, and Al. 
     
     
         4 . The piezoelectric element according to  claim 1 , wherein the base metal material contains Ni or Cu. 
     
     
         5 . The piezoelectric element according to  claim 4 , wherein the base metal material contains Ni as a main component. 
     
     
         6 . A method for manufacturing a piezoelectric element, the method comprising:
 preparing a piezoelectric ceramic material containing a perovskite complex oxide having an alkali metal niobate-based compound as a main component;   forming the piezoelectric ceramic material into compacts having a predetermined shape;   applying an electroconductive paste to form internal electrode onto the compacts;   stacking the compacts onto which the electroconductive paste has been applied to form a multilayer structure; and   co-sintering the multilayer structure in a reducing atmosphere.   
     
     
         7 . The method for manufacturing a piezoelectric element according to  claim 6 , wherein the multilayer structure is co-sintered at a temperature of 1000° C. to 1400° C. 
     
     
         8 . The method for manufacturing a piezoelectric element according to  claim 6 , wherein the piezoelectric ceramic material is formed into green sheets. 
     
     
         9 . The method for manufacturing a piezoelectric element according to  claim 6 , wherein the co-sintered multilayer structure is polarized in a thickness direction.