High resolution electron microscopy of bismuth oxides with perovskite layers

Abstract

Layered bismuth oxides of the general formula (Bi2O2)2+ (An-1BnO3 n+1)2- where A = Bi or Ba, B = Ti, Fe, W and n = number of perovskite layers have been investigated by high resolution electron microscopy. Lattice images obtained for n = 1 to 6 members show stacking of (n - 1) perovskite layers sandwiched between dark bands due to the (Bi2O2)2+ layers. It has been possible to resolve the perovskite layer structures in some of the oxides. A highly ordered structure is observed upto the n = 3 member, whereas higher members show superstructures, dislocations and stacking faults arising from the side-stepping of (Bi2O2)2+ layers as well as ferroelectric domain walls. © 1987 the Indian Academy of Sciences.