Fabrication and Characterization of Binary Piezoelectric (Bi_1/2Na_1/2)TiO₃–Ba(Cu_1/3Nb_2/3)O₃ Solid Solutions

Abstract

Perovskite-structured solid solutions with compositions of 0.9963(1- x )(Bi 1/2 Na 1/2 )TiO 3 – x Ba(Cu 1.1/3 Nb 2/3 )O 3 + 0.0037MnO 2 , with x = 0–0.06 [abbreviated as (1- x )BNT– x BCN)], were fabricated by normal sintering, and their structural, and piezo- and ferroelectric properties were investigated in detail. The X-ray diffraction profiles of the (1- x )BNT– x BCN solid solutions with x = 0–0.06 suggested that the rhombohedral-tetragonal morphotropic phase boundary (MPB) in this material system is in the compositional region x = 0.0425–0.0460. The cross-sectional transmission electron microscopy (TEM) images and selected-area electron diffraction (SAED) patterns of the (1- x )BNT– x BCN samples with x = 0.0475 suggested that the present materials have a modulation structure arranged by a double period along the [111] direction. It is shown that the tetragonal BNT–BCN ( x = 0.0475) solid solution with a composition of 0.9490BNT·0.0473BCN·0.0037MnO 2 near the MPB has a piezoelectric coefficient ( d 33 ), a relative permittivity (ε 33 T /ε 0 ), and a remanent polarization ( P r ) of approximately 1.8, 3.2, and 2.8 times larger, respectively, than those of the BNT solid solution without BCN substitution.