Broad-band dielectric spectroscopy of SrTiO3:Bi ceramics -: art. no. 144104

Lattice dynamics and dielectric relaxation phenomena of (Sr1-1.5xBix)TiO3 ceramics with x=0.0067-0.133 were studied in the temperature range of 10-400 K. The polar TO1 soft mode in the IR spectra is strongly stiffened by Bi doping and its softening on cooling is gradually stopped. Increasing degree of local polar distortion induced by doping was detected by progressive activation of TO2 and TO4 polar modes in the Raman spectra. Wide range (10(2)-1.8x10(9); 10(11)-2x10(13) Hz) dielectric spectra were determined and carefully fitted with an appropriate model of relaxation time distribution. At least four relaxation regions were revealed and the dominant thermally activated region was assigned to nanocluster polarization dynamics. The enhanced absorption in the submillimeter range was assigned to anharmonic quasi-Debye losses.