Low-temperature co-fired PNN-PZT-based multilayer piezoelectric actuator with low cost and high reliability

Abstract

Developing low-temperature co-fired MLAs for the commercial application of micro-nano actuation and manipulation has recently become a research highlight. To simultaneously achieve high piezoelectric response and low co-firing temperature below 960 °C, a PNN-PZT-0.02 Sr piezoceramic incorporated with Li2O-Bi2O3-CuO sintering additives and its MLA with the dimension of 7×7×3 mm3 were prepared using tape-casting and subsequent co-firing methods. The piezoceramic mainly composed of a triple phase (M, R, and T) co-existence shows a dense microstructure, indicating a good sintering-assistance effect. Even sintering at 920 °C, the piezoceramic possesses d33 ∼ 683 pC/N and kp ∼ 0.64, possibly surpassing most reported PZT-based piezoceramics. The MLA co-fired at 940 °C possesses a good Ag-ceramic interface without holes, aggregation or delamination. Also, it shows high maximum displacement (≥ 20 μm), high stiffness (118.5 N/μm @ 150 V), excellent thermal stability and 109-cycle reliability. A flat and defect-free electrode morphology is conducive to decreased leakage current. However, high tanδ primarily induced by the residual glassy phase and (Pb, Bi) oxides is the drawback. These findings give a novel paradigm for low-cost and high-reliability MLAs using pure Ag as inner electrodes by triple-phase controlling and nano-heterogeneity.