Using high-resolution transmission electron microscopy, an asymmetrical Σ5 [001] grain boundary with an inclination 2.5° away from the symmetrical (310) plane was studied. A de-faceting transition was observed between 1500 and 1600C. From 1520 to 1570C, the grain boundary faceted into symmetrical (310) and asymmetrical (100)||(430) planes. At 1590C, the grain boundary was observed to be de-faceted, which implied that the de-faceting occurred between 1570 and 1590C. The faceted structure which was observed between 1500 and 1590C was explained in terms of the step free-energy of the asymmetrical (100)||(430) facet orientation. The faceting to de-faceting transition was schematically represented as a temperature evolution of the equilibrium grain shape.

Faceting Behavior of an Asymmetric SrTiO3 Σ5 [001] Tilt Grain Boundary Close to its De-Faceting Transition. S.B.Lee, W.Sigle, M.Rühle: Acta Materialia, 2003, 51[15], 4583-8