The preparation of low-cost multilayer piezoelectric devices requires using cheap internal electrodes between the dielectric layers. A general strategy is to reduce the sintering temperature Ts of the ceramic layer by sintering aids which can form a liquid phase. Here, 0.2 wt% Li2CO3 was added as a sintering aid to tailor the sinterability and piezoelectricity of the commercial PZT ceramics. As verified from experiments, the piezoelectric ceramics could be densified at a sintering temperature above 940 °C, suitable for co-firing with the cheap internal electrode. The optimized sintering temperature of 980 °C can be confirmed for the 0.2 wt% Li2CO3-modified PZT ceramics due to its high piezoelectric coefficient d33 ~ 701 pC/N, planar coupling factor kp ~ 66.7%, and a low mechanical quality factor Qm ~ 71 with a transition temperature of Tc ~ 226 °C, presenting the characteristics of typical soft piezoelectric ceramics. Moreover, both the potential piezoelectric strain ~0.13% under 20 kV/cm and the good cycling fatigue characteristic (>104 cycles) of the studied piezo compositions indicates strong competitiveness in the field of multilayer piezoelectric devices.
Keywords: ceramics; multilayer; piezoelectric ceramics; sintering aids.