Abstract

The effects of MnO_2 doping on the crystal structure, ferroelectric, and piezoelectric properties of (K,Na)NbO_3 (KNN) ceramics have been investigated. MnO_2 was found to be effective in enhancing the densification and grain growth during sintering. X-ray diffraction analysis indicated that Mn ions substituted B-site Nb ions up to 2 mol%, however, further doping induced unwanted secondary phases. In comparison with undoped KNN ceramics, the well developed microstructure and the substitution to B-sites in 2 mol% Mn-doped KNN ceramics resulted in significant improvements in both piezoelectric coupling coefficient and electromechanical quality factor.

• Keywords: Lead-free piezoelectric ceramics;Bismuth sodium potassium titanate;Mn doping;Electric-fieldinduced strain;