Ferroelectric relaxor behaviour of Na0.5Bi0.5TiO3-SrTiO3 ceramics

The dielectric properties of (Na0.5Bi0.5)(x)Sr1-xTiO3 (0 less than or equal to x less than or equal to 0.2) ceramic materials were studied from 10 to 300 K between 100 Hz and 1 MHz. At low substitution rates (0 less than or equal to x less than or equal to 0.02), two thermally activated relaxation modes were observed and attributed to non interacting dipoles. For x > 0.02, the highest temperature mode, independent on the composition, remains but its intensity decreases and eventually vanishes for x = 0.20. In addition the observed strong dispersion of the permittivity was connected with a relaxor behaviour the origin of which being due to the increasing density of interacting dipoles or dipole clusters. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.