Dielectric properties and relaxor behavior of Ba<inf>0.67</inf>Sr<inf>0.33</inf>TiO<inf>3</inf>-CaBi<inf>4</inf>Ti<inf>4</inf>O<inf>15</inf> ceramics

Abstract

1-x)Ba 0.67 Sr 0.33 TiO 3 (BST)+xCaBi 4 Ti 4 O 15 (CBT) (x=0, 2%, 4%, 6% and 8%) lead-free relaxor ferroelectric ceramics with submicro grain size of about 200nm were prepared by solidstate reactions. Structure and dielectric properties of BST-CBT have been investigated. X-ray diffraction patterns show a relative low degree of solubility as a result of coupled substitutions of Bi 3+ and Ca 2+ both on the A site and the specific structure of CBT. The temperature and frequency dependences of the dielectric constant indicate a crossover from a normal ferroelectric to relaxor behavior. The degrees of diffuseness and relaxor behavior are found to increase with the increasing amount of CBT. The frequency dependence of the temperature of dielectric peak Tm can be well described by Vogel-Fulcher relation. The activation energy Ea increases with x increasing, indicating the more and more energy for the polarization reversal of micropolar regions, which is associated with the enhanced interactions of polar domains.

Acoustic emission pronounced field‐induced response near critical point in Ba0.6Sr0.4TiO3 ferroelectrics

“…It is interesting to note that Ba x Sr 1− x TiO 3 is shown to possess the canonical RFE properties, i.e., the frequency dependence of T m when x < 0.035 is clearly visible, whereas it possesses the cubic–tetragonal–ferroelectric phase transition when x ≈ 1.0–0.2 . Accordingly, the T c of Ba 0.67 Sr 0.33 TiO 3 ceramic, for example, is known not to exhibit any frequency dispersion , characteristic of ordered FEs. However, both Ba 0.65 Sr 0.35 TiO 3 and Ba 0.6 Sr 0.4 TiO 3 ceramics demonstrate the nontrivial behavior of their T c in dependence on E , characteristic of RFEs .…”