Effects of Mn-doping on the Piezoelectric and Ferroelectric Properties of (Na_(0.8)K_(0.2))_(0.5)Bi_(0.5)TiO_3 Ceramics

摘要

Lead-free piezoelectric ceramics of (Na_(0.8)K_(0.2))_(0.5)Bi_(0.5)TiO_3+x wt.% Mn (abbreviated as NBKT-x% Mn, x=0～0.5) were synthesized by solid-state reaction. The grain growth of the ceramics was restrained by Mn-doping at a certain extent. The mechanical quality factor Q_m increases and the dielectric loss tanδ decreases with the increase of Mn-doping. Best piezoelectric properties were obtained for the composition of NKBT-0.2%Mn: d_(33)=158 pC·N~(-1), tanδ=2.9% at 1 kHz, Q_m=110 and k_p=30%. The P-E loops show that remnant polarization P_r and coercive field E_c decrease slightly with the amount of the Mn~(2+) increasing up to 0.2wt.% and then increase as the content of Mn~(2+) increases further. NKBT-0.5wt. % Mn exhibits strong ferroelectricity with remnant polarization P_r = 38μC/cm~2.