Investigation of inorganic fillers on properties of 2-2 connectivity cement/polymer based piezoelectric composites

The 2-2 cement/polymer based piezoelectric composites containing inorganic fillers were prepared. The influences of filler content and composite thickness on the composite properties were investigated. The results show that graphite powder shows larger effect on dielectric property of the composites than silicon powder and strontium ferrite (Sr-ferrite) powder, especially when graphite powder is larger than 10 wt.%. The Sr-ferrite can improve the thickness electromechanical coupling properties of the composites. When Sr-ferrite powder content is 15 wt.%, the composite has a kt value of 68.6% at a 2 mm thickness. The electromechanical quality factor (Qm) of the composites shows fluctuation variation between 10 and 60 with increasing the composite thickness, which is far less than that of the pure ceramic. The coupling resonance effects between planar mode and thickness mode of the composites was reduced by decreasing the composite thickness, and the pure thickness mode resonance can be obtained at a small composite thickness.