Dielectric audio-frequency dispersion in Ba(Ti Sn)O ferroelectrics

Dielectric audio-frequency dispersion behavior exists in both BaTiO3 ferroelectric and Ba(Ti1−xSnx)O3 relaxors. It is suggested that defect dipoles trapped by random electric fields E r are the origin of the dielectric audio-frequency dispersion. E r originates from ferroelectric domains and polar regions, and becomes weaker as temperature increases. Consequently, defect dipoles are being continually released from trapped states to take part in the dielectric response under an applied ac field with increasing temperature. The temperature T m of maximum permittivity ε m for Ba(Ti1−xSnx)O3 ceramics becomes frequency-dependent when the permittivity contributed by defect dipoles is large enough.