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Materials Science at Oregon State University

The Unusual Behavior of Bi(Zn0.5Ti0.5)O3 in Perovskite Solid Solutions

Date: Thursday, Apr 26th
Presenter: David Cann, OSU Materials Science

Abstract


The presentation will summarize recent results on the crystal structure, dielectric properties, and piezoelectric properties of perovskite solid solutions with Bi(Zn0.5Ti0.5)O3 (BZT) as a component. With a tolerance factor of t = 0.95, BZT is not stable under normal atmospheres and pressures. However, recent work has shown that BZT can form solid solutions with a large number of stable perovskites such as PbTiO3, BaTiO3, NaNbO3, and (Bi,Na)TiO3. The addition of the Bi(Zn0.5Ti0.5)O3 phase has a profound impact on the phase transition in a normal ferroelectric such as BaTiO3 or an antiferroelectric such as NaNbO3. These systems exhibit a diffuse phase transition and a slim quasi-linear dielectric response with no measurable remanent polarization, which may be an indication of weakly-coupled relaxor behavior. This presentation will highlight recent findings on the influence of the microstructure and engineered point defects (i.e. non-stoichiometry and doping) on the dielectric response. In particular, we will show that cation deficient compositions exhibit an increase in relative permittivity, an increase in the insulation resistance, and a reduction in dielectric loss. It will also be shown that many BZT-based solid solutions also exhibit an unusual electromechanical strain behavior that is characterized by large hysteretic strains under E-fields above 50 kV/cm.