In this study, a new type of piezoelectric damping composites was prepared by embedding thin plates of piezoelectric ceramic (Pb (Zr x T 1−x ) O 3 , PZT ) with various sizes in epoxy resin matrix. An external electric resistor was connected to the piezoelectric plates of the composites to improve the damping behaviors of the composite structure. Dynamic Mechanical Analyzer (DMA8000 manufactured by Perkin Elmer) was used to study the PZT/epoxy piezoelectric composite system at different temperature and frequency range. The experimental results were discussed in terms of the damping and viscoelastic effect of the PZT-epoxy composite system.

Lead-free piezoelectric ceramics of (Na0.8K0.2)0.5Bi0.5TiO3+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 Qm 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: d33=158 pC·N-1, tanδ=2.9% at 1 kHz, Qm=110 and kp=30%. The P-E loops show that remnant polarization Pr and coercive field Ec decrease slightly with the amount of the Mn2+ increasing up to 0.2wt.% and then increase as the content of Mn2+ increases further. NKBT-0.5wt. % Mn exhibits strong ferroelectricity with remnant polarization Pr = 38μC/cm2.