Ionic doping effects of various ions in Bi-layered ferroelectric SrBi 2 Nb 2 O 9 (SBN) ceramics were studied. Un-doped and doped SBN ceramics with Ba 2+ , Pb 2+ , Ca 2+ , Bi 3+ , La 3+ , Ti 4+ , Mo 6+ , and W 6+ ions were made with solid state reactions. Temperature dependent dielectric constants were measured. Ferroelectric transition temperature (T C ) decreased with Ba 2+ and Pb 2+ ions but increased with Ca 2+ ion which substitutes the 12-coordinated Sr 2+ site. T C increased with Ti 4+ , Mo 6+ , and W 6+ ions which substitute the 6-coordinated Nb 5+ sites. With trivalent Bi 3+ and La 3+ ions, T C increased with Bi 3+ ion but much decreased with La 3+ ion. These results showed that the ion size plays an important role in ferroelectricity of SBN ceramics.
Nonstoichiometric SrBi 2 Ta 2 O 9 (SBT) and SrBi 2 Nb 2 O 9 (SBN) ceramics were prepared by a solid state reaction method. X-ray diffraction analysis showed that single-phase of Bi-layered perovskite was obtained. With different Sr/Bi content ratios of SBT and SBN, Curie temperature (T C ), electromechanical factor (K p ) and mechanical quality factor (Q m ) were measured. T C of SBN (SBT) rose from 414 • C (314 • C) to 494 • C (426 • C) when Sr/Bi content ratio was increased from 0.55/2.3 to 1.2/1.8. In the most Sr-deficient/Bi-excess ratio of 0.55/2.3, the maximum values of Q m were obtained approximately 1013 and 3325 for SBT and SBN, respectively.
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