Low-Temperature Sintering and Piezoelectric Properties of Pb(Fe2/3W1/3)O3-Doped 0.7Pb(Zr0.46Ti0.54)O3–0.1Pb(Zn1/3Nb2/3)O3–0.2Pb(Ni1/3Nb2/3)O3 Ceramics for Free-Standing Silver-Electrode Co-Fired Multilayer Piezoelectric Devices

In this study, the sintering behavior and electrical properties of 0.7Pb(Zr0.46Ti0.54)O3 (PZT)–0.1Pb(Zn1/3Nb2/3)O3 (PZN)–0.2Pb(Ni1/3Nb2/3)O3 (PNN) piezoelectric ceramics with different Pb(Fe2/3W1/3)O3 (PFW) doping contents were investigated to obtain a formulation that can be co-fired with silver (Ag) electrodes below 900 °C for multilayer ceramics. PFW was introduced as a sintering aid, which effectively reduced the sintering temperature of the ceramics from 1200 °C to 850 °C. The sample with x = 0.12 exhibited the largest average grain size of 1.72 μm, achieving excellent comprehensive properties with piezoelectric constant (d33) = 477 pC/N, planar electromechanical coupling factor (kp) = 0.68, dielectric loss tangent (tanδ) = 0.0154, and relative density of 98.2%. Furthermore, the feasibility of fabricating piezoelectric actuators based on this optimized composition was verified. Multilayer piezoelectric devices were prepared via screen printing combined with a carbon-based sacrificial layer method. No obvious interdiffusion was observed at the interface between the Ag internal electrodes and the ceramic matrix. The 9-layer device attained a high d33 = 1470 pC/N and produced a large displacement of 5.5 μm (corresponding to a strain = 1.83%) with a voltage of 500 V. The thickness of the multilayer piezoelectric film was approximately 0.3 mm. Through this, the feasibility of manufacturing a multilayered actuator with an Ag electrode was confirmed through the composition of 0.58PZT–0.1PZN–0.2PNN–0.12PFW.