Patent ID: 8179025

Claim:
A lead-free piezoelectric ceramic material having the formula: Bi i-x RE x FeO 3 where Bi is bismuth, Fe is iron, O is oxygen, RE is one or more of: La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and wherein: 0.125≦x≦0.3 for La, Pr, Nd, or Pm; 0.125<x≦0.3 for Sm; and 0<x≦0.3 for Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu, and the composition of said material has an x value that is within 0.010 of the x value of the morphotropic phase boundary of such material.