PNN-PST-PT ferroelectric ceramics with ultrahigh piezoelectricity and superior electromechanical performance for high quality piezo-sensors

A novel ferroelectric ceramic system, Pb(Ni_1/3Nb_2/3)O₃–Pb(Sc_1/2Ta_1/2)O₃–PbTiO₃ (PNN-PST-PT), with ultrahigh piezoelectricity and super electromechanical performance is developed. The microstructure and crystal structure of PNN-PST-PT ceramics, along with their electrical properties, were examined regarding PNN content. The results indicated that the room-temperature dielectric constant was considerably enhanced with PNN content increasing and the values of P_r, P_max, and E_c steadily declining. The optimal performance was achieved in the 0.4PNN-0.235PST-0.365 PT composition with a high piezoelectric coefficient (d₃₃) of 1028 pC/N and an electromechanical coupling factor (k_p) of 0.69. Strong piezoelectric response is attributed to the coexistence of R and T phases as well as the enhanced relaxation characteristics, which manifest as a specific polarization configuration resulting from the local structural distortion caused by the co-occupation of ions with different radii at the B-site. These suggest that PNN-PST-PT ceramics can be a desirable material for applications in high-quality piezosensors, actuators, etc.