Twin boundaries in perovskite

Abstract

The twin behaviour of natural and synthetic perovskite (CaTiO3) was examined by high-resolution electron microscopy (HREM) and selected-area electron diffraction (SAD). Pseudosymmetric twinning yields domains related to each other by either a 180 ° or a 90 ° rotation about an axis perpendicular to { 101}. A third type of twin involving a 180 ° rotation about the normal to ( 121 ) had previously been reported but this was not observed in the present study. The boundaries between twin domains were often complex and consisted of intergrowths on the finest possible scale of the various composition planes. It was confirmed that the most common composition planes were {101}; however, interface surfaces on {010} and {121} were also observed. For the simpler twin boundaries structural models were proposed and described using the Glazer notation.

Microstructural Study of the Li+Ion Substituted Perovskites Li0.5−3xNd0.5+xTiO3

“…1a (subindex d refers to the diagonal cell while subindex p refers to the basic cubic perovskite cell). , &(2a unit cell, where in each domain the b-axis is oriented along one of the three different crystallographic directions (11,12). The microdomains appear randomly distributed so that the electron diffraction pattern obtained in Fig.…”

The Crystal Structures, Microstructure and Ionic Conductivity of Ba2In2O5 and Ba(In Zr1−)O3−/2

“…Note how in the inset B, the satellite re#ections mentioned before are present while in inset A, only strong Bragg re#ections from the underlying orthorhombic structure appear. From these digital di!ractograms, crystallographic relationships can be worked out in terms of a basic cubic perovskite structure (24). Thus, a twin boundary relating the [101] with the [010] direction can be formed only by breaking the OTOT 2 stacking sequence and tilting a domain 903 with respect to the other domain.…”

Electron microscopy study of domain structure due to phase transitions in natural perovskite

“…Bowman (1908) carried out an extensive optical microscopy study and described the following three twinning relations: (1) 180 ~ rotation about the normal to (110), (2) 90 ~ rotation about the normal to (110), and (3) 180 ~ rotation about the normal to (112). The same classification scheme was adapted in the transmission electron microscopy (TEM) study of White et al (1985). However, since the structure is centrosymmetric, these twinning relations may also be described as reflection twins across the {110} and {112} planes, which correspond to Bowman's type (1), and types (2) and (3), respectively (Doukhan and Doukhan 1986;Hu et al 1992;Wang et al 1990Wang et al , 1992.…”