The crystalline structure, microstructure and dielectric properties of the (Sr1-1.5-xBix)TiO3 (0less than or equal toxless than or equal to0.267) ceramics were studied. Cubic solid solutions were determined for xless than or equal to0.2 at room temperature. However, lattice distortion was detected by Raman spectra. A dense microstructure with the grain sizes of 2-4 mum was obtained for (Sr1-1.5xBix)TiO3 (0less than or equal toxless than or equal to0.2) 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. (C) 2003 Kluwer Academic Publishers.