CRYSTAL-STRUCTURE AND DOMAIN-WALL CONTRIBUTIONS TO THE PIEZOELECTRIC PROPERTIES OF STRONTIUM BISMUTH TITANATE CERAMICS

The piezoelectric properties of SrBi4Ti4O15 and Bi4Ti2.95Nb0.04O12 hav e been compared as a function of applied ac stress. Evidence of domain -wall motion was observed in Bi4Ti2.95Nb0.04O12 but not in SrBi4Ti4O15 . Examination of SrBi4Ti4O15 using transmission electron microscopy re vealed that the material had undergone an orthorhombic-orthorhombic, p araelectric-ferroelectric, phase transition in which no piezoelectrica lly active, non-180 degrees, domain walls could be created. However, f or the orthorhombic-monoclinic transformation in Bi4Ti2.95Nb0.04O12 ne w piezoelectrically active domain walls are allowed and were considere d to move under applied stress. (C) 1996 American Institute of Physics .