Dielectric Properties of Lanthanum-Doped Bismuth Layer-Structured Ferroelectrics

Abstract

Dielectric permittivities of Bi4−x La x Ti3O12,SrBi4−x La x Ti4O15, (Bi,La)4Ti3O12-Sr(Bi,La)4Ti4O15, and Sr2Bi4−x La x Ti5O18 ceramics were investigated at different frequencies. The rare earth, La, content determined the ferroelectric characteristics of the compounds: for small La content, they behaved as typical ferroelectrics, but all of them tended to become relaxors as x increased. The existence of relaxor behavior was attributed to a ferroelectric microdomain state induced by random strain fields.