Phase structure and electrical properties of PSN–PMN–PZ–PT quaternary piezoelectric ceramics near the morphotropic phase boundary

Abstract

0.06Pb(Sb 1/2Nb 1/2)O 3–0.06Pb(Mn 1/3Nb 2/3)O 3–0.88Pb(Zr x Ti 1− x )O 3 (PSN–PMN–PZ–PT) quaternary piezoelectric ceramics with varying Zr/Ti ratios located near the morphotropic phase boundary (MPB) were prepared by powder solid-state reaction. The phase structure, dielectric and piezoelectric properties and temperature stability of the systems were investigated. In the present system the MPB, in which the tetragonal and rhombohedral phases coexist, is in a composition range of 0.49< x<0.52. The relative permittivity, dielectric dissipation, piezoelectric coefficient and electromechanical coupling factor reach maximum values, while the mechanical quality factor is lowest when x=0.50. These properties include ε 33 T/ ε 0=1730, tan δ=0.007, d 33=365 pC/N, d 31=−151 pC/N, k p =0.62, k 31=0.37 and Q m=1170. A Curie temperature of 308 °C was achieved when x=0.50. The resonant frequency changes from a positive to a negative value as the Zr/Ti ratio increases. The smallest temperature coefficient (Δ f r/Δ Tf r25 °C =3.08×10 −5/°C) was obtained between −50 and 120 °C in the sample when x=0.50. In the temperature range of 20–80 °C, the piezoelectric coefficient and electromechanical coupling factor show high temperature stability and the mechanical quality factor maintained a comparatively high value close to room temperature when x=0.50. The properties of this type of ceramics make it a very promising piezoelectric material for application in ultrasonic motors.