Effect of Cu and Li substitution on the piezoelectric properties of potassium sodium niobate lead-free ceramics

Recently, (K, Na) NbO
₃
(KNN) ceramics and, based on KNN, (K,Na,Li) NbO
₃
ceramics, (K,Na,Li)(Nb,Ta,Sb)O
₃
(LF4) perovskite ceramics were reported to show excellent piezoelectric properties and has been regarded as candidates of lead-free piezoelectric materials. In this study, the effect of CuO addition to Li-modified KNN were investigated. The CuO-doping changed it to "hard" piezoelectric ceramics but the Q
_m
can be improved to above 400 for Li-modified KNN with a high piezoelectric constant d
₃₃
of 100 pC/N.