Fabrication and Characterization of Binary Piezoelectric (Bi1/2Na1/2)TiO3–Ba(Cu1/3Nb2/3)O3 Solid Solutions

Perovskite-structured solid solutions with compositions of 0.9963(1-x)(Bi1/2Na1/2)TiO3–xBa(Cu1.1/3Nb2/3)O3 + 0.0037MnO2, with x = 0–0.06 [abbreviated as (1-x)BNT–xBCN)], 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–xBCN 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–xBCN 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·0.0037MnO2 near the MPB has a piezoelectric coefficient (d 33), a relative permittivity (ε33 T/ε0), 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.