Piezo-/dielectric properties of perovskite-structure high-temperature relaxor ferroelectrics: The Pb(Lu_1/2Nb_1/2)O₃–Pb(Zn_1/3Nb_2/3)O₃–PbTiO₃ ternary ceramics

Graphical abstract: - Highlights: • Pb(Zn_1/3Nb_2/3)O₃-based ternary ferroelectric ceramics were prepared by solid-state synthesis method. • Morphotropic phase boundary region has been determined by XRD, di-/piezoelectric properties. • The compositions near MPB region exhibit excellent piezoelectric properties. - Abstract: A new compositional system of relaxor ferroelectrics was investigated based on the high piezoelectricity Pb(Zn_1/3Nb_2/3)O₃–PbTiO₃ ferroelectric perovskite family. Compositions were fabricated near an estimated morphotropic phase boundary (MPB) of the Pb(Lu_1/2Nb_1/2)O₃–Pb(Zn_1/3Nb_2/3)O₃–PbTiO₃ (PLZNT) ternary system by a two-step synthetic process. Their structures have been analyzed by means of X-ray diffraction technique. On the basis of X-ray powder diffraction, the morphotropic phase boundary (MPB) region for the ternary system was obtained. The Curie temperature T_C of ternary system varied from 240 °C to 330 °C and the coercive fields E_cs > 10 kV/cm. The values of piezoelectric coefficients d₃₃ vary in the range of 260–450 pC/N with different PZN contents. It is worth noting that the optimum compositions were located at MPB region but near the tetragonal phase. The new PLZNT ceramics exhibit wider range of T_Cs and E_cs, making it a promising material for high-powder ultrasound transducers using in a large temperature range