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

Abstract Lead-free ceramics (K 0.5 Na 0.5 )(Nb 0.9 Ta 0.1 )O 3 (KNNT) +  x  mol% K 4 CuNb 8 O 23 (KCN) +  y  mol% MnO 2 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 tan δ and relatively high piezoelectric properties were obtained when KCN and MnO 2 were added into KNNT ceramics. The ceramics with x  = 1.0, y  = 0.50 exhibited excellent piezoelectric properties: high mechanical quality factor Q m  = 1563, piezoelectric coefficient d 33  = 96pC/N, electromechanical coupling coefficient k p  = 42.2%, k t  = 44.5%, k 33  = 58.4%, relative dielectric constant e ′ = 308, tan δ  = 0.4%. This material is a promising candidate for the lead-free piezoelectric transformer applications.