Crystalline structure and dielectric properties of (Sr1−1.5xBix) TiO3 ceramics

The crystalline structure, microstructure and dielectric properties of the (Sr1−1.5xBix)TiO3 (0 ≤ x ≤ 0.267) ceramics were studied. Cubic solid solutions were determined for x ≤ 0.2 at room temperature. However, lattice distortion was detected by Raman spectra. A dense microstructure with the grain sizes of 2–4 μm was obtained for (Sr1−1.5xBix)TiO3 (0 ≤ x ≤ 0.2) ceramics. The Bi concentration was examined and found to be in agreement with the nominal composition and overall uniformly distributed in the sample. Different from the observations in the earlier literature for other doped quantum paraelectrics, where only an induced dielectric anomaly was reported, there are three Bi induced dielectric modes A, B, and C in the Bi doped SrTiO3 samples. The occurrence of the “impurity modes” and the “ferroelectric relaxor mode” and their evolution are demonstrated as a function of Bi concentration.