The stacking faults and their effects on ferroelectric properties were studied by transmission electron microscopy and ferroelectric hysteresis loop measurements. The structure consisted of Bi2O2 layers and double perovskite-type TaO6 octahedral units. There were 4 possible types of non-stoichiometric stacking fault: 2 intrinsic faults by removing either 1 or 2 perovskite layers and 2 extrinsic faults by inserting either one or two perovskite layers. Transmission electron microscopic investigation revealed that the stacking faults were of extrinsic type. Extrinsic stacking faults in high densities could possibly destroy the ferroelectricity. With excess Bi, the density could be held low efficiently, and with deficient Sr the stacking faults changed form.

Stacking Faults and their Effects on Ferroelectric Properties in Strontium Bismuth Tantalite. Y.Ding, J.S.Liu, J.S.Zhu, Y.N.Wang: Journal of Applied Physics, 2002, 91[4], 2255-61