Piezoelectric Characteristics of 0.55Pb(Ni(1/3)Nb(2/3))O(3)-0.45Pb(Zr,Ti)O(3) Ceramics with Different MnO(2) Concentrations for Ultrasound Transducer Applications

In this study, we investigate the piezoelectric characteristics of 0.55Pb(Ni(1/3)Nb(2/3))O(3)-0.45Pb(Zr,Ti)O(3) (PNN-PZT) with MnO(2) additive (0, 0.25, 0.5, 1, 2, and 3 mol%). We focus on the fabrication of a piezoelectric ceramic for use as both actuator and sensor for ultrasound transducers. The actuator and sensor properties of a piezoelectric ceramic depend on the piezoelectric strain coefficient d and piezoelectric voltage coefficient g, related as g = d/ε(T). To increase g, the dielectric constant ε(T) must be decreased. PNN-PZT with MnO(2) doping is synthesized using the conventional solid-state reaction method. The electrical properties are determined based on the resonant frequencies and vibration modes measured by using an impedance analyzer. The MnO(2) addition initially improves the tetragonality of the PNN-PZT ceramic, which then saturates at a MnO(2) content of 1 mol%. Therefore, the dielectric constant and piezoelectric coefficient d(33) steadily decrease, while the mechanical properties (Q(m), Young’s modulus), tanδ, electromechanical coupling coefficient k, and piezoelectric voltage coefficient g were improved at 0.5–1 mol% MnO(2) content.