Structural phase-transition region and electrical properties of Pb(Ni_(1/3)Nb_(2/3))O_3-Pb(Zn_(1/3)Nb_(2/3))O_3-PbTiO_3 ceramics

摘要

The phase structures, and dielectric and piezoelectric properties of three series of ceramic compositions in the Pb(Ni_(1/3)Nb_(2/3))O_3-Pb(Zn_(1/3)Nb_(2/3))O_3-PbTiO_3 ternary system have been systematically investigated. The existence of the morphotropic phase boundary (MPB) line is proposed and a wide linear MPB region is verified. The contents of the coexisting rhombohedral and tetragonal phases vary irregularly along the MPB line, while the sole increase of PT with a fixed ratio of Ni/Zn leads to the decrease of the rhombohedral phase in the MPB region. Compositions on the Ni-rich side of the MPB line show better electrical properties than those on the Zn-rich side. The MPB composition of 0.56Pb(Ni_(1/3)Nb_(2/3))O_3-0.14Pb(Zn_(1/3)Nb_(2/3))O_3-0.30PbTiO_3 was found to be with high values of ε_m and d_(33)(ε_m=24 500 and d_(33) = 740 pC/N), which is superior to those of many reported ferroelectric ceramics.