Modified (K0.5Na0.5)(Nb0.9Ta0.1)O3 ceramics with high Qm

Lead-free ceramics (K0.5Na0.5)(Nb0.9Ta0.1)O3 (KNNT)+x mol% K4CuNb8O23 (KCN)+y mol% MnO2 have been prepared using the conventional solid-state reaction technique. Crystalline structures and Microstructures were analyzed by X-ray diffraction and scanning electron microscope (SEM) at room temperature. The low dielectric loss tanδ and relatively high piezoelectric properties were obtained when KCN and MnO2 were added into KNNT ceramics. The ceramics with x=1.0, y=0.50 exhibited excellent piezoelectric properties: high mechanical quality factor Qm=1563, piezoelectric coefficient d33=96pC/N, electromechanical coupling coefficient kp=42.2%, kt=44.5%, k33=58.4%, relative dielectric constant ε′=308, tanδ=0.4%. This material is a promising candidate for the lead-free piezoelectric transformer applications.