Stacking faults and their effects on ferroelectric properties in strontium bismuth tantalate

The stacking faults and their effects on ferroelectric properties in strontium-bismuth-tantalate SrBi2Ta2O9 have been studied by transmission electron microscopy (TEM) and ferroelectric hysteresis loop measurement. The structure of SrBi2Ta2O9 consists of Bi2O2 layers and double perovskite type TaO6 octahedral units. There are four possible types of nonstiochiometric stacking faults: two intrinsic faults by removing either one or two perovskite layers and two extrinsic faults by inserting either one or two perovskite layers. TEM investigation reveals that the stacking faults are the extrinsic type. The extrinsic stacking faults in high density might destroy the ferroelectricity, and the reasons are discussed. With excess Bi, the density can be held low efficiently, and with deficient Sr the stacking faults change its form.(C) 2002 American Institute of Physics.