Piezo-/dielectric properties of perovskite-structure high-temperature relaxor ferroelectrics: The Pb(Lu_(1/2)Nb_(1/2)O_3-Pb(Zn_(1/3)Nb_(2/3))O_3-PbTiO_3 ternary ceramics

摘要

A new compositional system of relaxor ferroelectrics was investigated based on the high piezoelectricity Pb(Zn_(1/3)Nb_(2/3))O_3-PbTiO_3 ferroelectric perovskite family. Compositions were fabricated near an estimated morphotropic phase boundary (MPB) of the Pb(Lu_(1/2)Nb_(1/2)O_3-Pb(Zn_(1/3)Nb_(2/3))O_3-PbTiO_3 (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 ℃ to 330 ℃ and the coercive fields E_cs＞10 kV/cm. The values of piezoelectric coefficients d_(33) 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.