Ferroelastic twins in LaAlO3 polycrystals

Characteristics of twins in LaAlO3 (LAO) polycrystals were investigated usi ng transmission electron microscopy. A simple wedge-shaped twin structure w as observed and this was attributed to no volume change during the cubic to rhombohedral phase transition. In LAO polycrystals (1 0 0) twin rather tha n (1 1 0) twin was predominant as in LAO single crystals. To determine the origin of predominance of (1 0 0) twin, strain tensors for the two twin geo metries were calculated with the aid of phenomenological crystallographic t heory. As a result, it was found that (1 0 0) twin had smaller strain after the transition than did (1 1 0) twin, This result theoretically confirms t hat (1 0 0) twin is energetically more favorable than(1 1 0) twin, (C) 1999 Elsevier Science B.V. All rights reserved.