Piezoelectric properties and densification based on control of volatile mass of potassium and sodium in (K0.5Na0.5)NbO3 ceramics

Recently lead-free ceramic systems have been intensively studied in order to fabricate environmentally friendly piezoelectric ceramics and replace widely used lead-free piezoelectric ceramics. The (K0.5Na0.5)NbO3 (KNN) piezoelectric ceramics with non-lead piezoelectric ceramics were manufactured by conventional solid-state synthesis, and we obtained sintered bodies with relative densities over 97.4% by adding excess K (0.44 mol %)/Na (0.22 mol %) to improve sinterability. The composition of the sintered bodies was close to stoichiometric compounds. The electromechanical coupling factor (k(p)) and piezoelectric constant (d(33)) of KNN + excess K (0.44 mol %)/Na (0.22 mol %) composition ceramics showed optimal values of 0.341 and 126pC/N, respectively.