Piezoelectric ceramic, method for producing piezoelectric ceramic, and piezoelectric oscillator

Abstract

A piezoelectric ceramic comprising lead titanate as a primary component, wherein the primary component contains a titanium oxide crystalline phase. Methods for producing the ceramic, and piezoelectric oscillators making use of the ceramic are also disclosed.

What is claimed is:  
     
         1 . A piezoelectric ceramic comprising a lead titanate containing a titanium oxide crystalline phase.  
     
     
         2 . The piezoelectric ceramic according to    claim 1    having an electrode on a surface thereof.  
     
     
         3 . A piezoelectric ceramic according to    claim 2   , wherein the average grain size of the titanium oxide crystalline phase is about 4-28 μm.  
     
     
         4 . A piezoelectric ceramic according to    claim 1   , wherein the average grain size of the titanium oxide crystalline phase is about 4-28 μm.  
     
     
         5 . A method for producing a piezoelectric ceramic comprising firing a lead titanate piezoelectric ceramic at 1230-1245° C.  
     
     
         6 . The method of    claim 5    wherein the ceramic in the form of a compact is fired.  
     
     
         7 . A method for producing a piezoelectric ceramic comprising the following steps of: 
 (1) providing a piezoelectric ceramic material mixture comprising lead oxide and titanium oxide;    (2) firing the mixture to thereby produce a calcined product;    (3) crushing the calcined product and adding titanium oxide powder and a binder to the crushed product to thereby produce a binder-containing mixture;    (4) molding the binder-containing mixture to thereby produce a compact; and    (5) firing the compact.    
     
     
         8 . The method according to    claim 7    wherein the compact is fired at about 1230-1295° C.  
     
     
         9 . A piezoelectric oscillator comprising an insulating substrate, a piezoelectric ceramic element, lead terminals and a resin covering for the piezoelectric ceramic element, wherein 
 the insulating substrate has patterned electrodes thereon;    the piezoelectric ceramic element comprises the piezoelectric ceramic according to    claim 2    and the electrodes on the surface of the ceramic are electrically connected to the patterned electrodes; and    the lead terminals are electrically connected to the patterned electrodes.    
     
     
         10 . A piezoelectric oscillator according to    claim 9   , wherein the average grain size of the titanium oxide crystalline phase is about 4-28 μm.  
     
     
         11 . A piezoelectric oscillator comprising a piezoelectric ceramic element, upper and lower substrates sandwiching the piezoelectric ceramic element and external electrodes, wherein 
 the piezoelectric ceramic element comprises a piezoelectric ceramic according to    claim 2    having electrodes formed on two main surfaces of the ceramic, and    the external electrodes are on sides surfaces of the piezoelectric ceramic element and side surfaces of the upper and lower substrates and are electrically connected to the internal electrodes on the main surfaces of the ceramic.    
     
     
         12 . A piezoelectric oscillator according to    claim 11   , wherein the average grain size of the titanium oxide crystalline phase is about 4-28 μm.