Reliability enhancement in nickel-particle-dispersed alkaline niobate piezoelectric composites and actuators

Piezoceramics and related devices are naturally fragile. Here we have produced piezoelectric composites of Ni-particle-dispersed Li-doped (K,Na)NbO3 (LKNN/Ni), and used these composites to make actuators with functionally graded microstructure (FGM). The mechanical properties of the LKNN/Ni composites were greatly enhanced by the incorporation of Ni particles. An LKNN–20%Ni composite exhibited double the fracture toughness of the monolithic LKNN ceramic. An LKNN/Ni piezoelectric FGM actuator subjected to a large number of cycles of electrical loading still maintained acceptable driven performance. The enhancement of reliability in the LKNN/Ni composites and actuators is attributed to the uniformly dispersed Ni particles in the piezoceramic matrix. Deformation of these Ni particles absorbs the energy of crack propagation and thus greatly strengthens the composites and devices. These new FGMs contribute further to the reliability enhancement of piezoelectric actuators.