Crystal Structure and Ferroelectric Properties of (Bi0.5Na0.5)TiO3–Ba(Zr0.05Ti0.95)O3 Piezoelectric Ceramics
The crystal structure and ferroelectric properties of (1−x)(Bi0.5Na0.5)TiO3–xBa(Zr0.05Ti0.95)O3 (BNBZTx, x≤12%) lead-free piezoelectric ceramics were studied. The distance between the centers of cations and anions (dc–a) as well as the lattice parameters was carefully investigated by Rietveld refinement on X-ray diffraction patterns. It was found that the crystal phase was determined by the amount of Ba(Zr0.05Ti0.95)O3 added, whereas the pure rhombohedral and tetragonal phases are observed in compositions containing x≤4 and x≥8%, respectively. A rhombohedral–tetragonal morphotropic phase boundary (MPB) was found at around BNBZT6, which showed a maximum and minimum dc–a at its rhombohedral and tetragonal phases, respectively. According to the present study, the ferroelectric properties show a strong dependence on their crystal phases. For the single-phase compositions, the remanent polarization (Pr) generally increased with the value of dc–a while their coercive fields (Ec) were determined by their lattice parameters. Nevertheless, the behavior in Pr and Ec for MPB compositions is related to not only the lattice parameter but also the composed phases.
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Document Type: Research Article
Affiliations: Department of Resources Engineering, National Cheng Kung University, Tainan 70101, Taiwan
Publication date: May 1, 2009