Published online by Cambridge University Press: 21 February 2011
The structure of different grain boundaries and phase boundaries are discussed by reference to a series of specific examples. The chosen examples of grain boundaries include the <l10>{l10} tilt boundary, the (001) twist boundary and the first-order twin boundary in spinel and the basal twin and the (1123) twin in Al2O3 . The phase boundaries discussed are the β'''-alumina/spinel interface, the wustite/spinel interface and the spinel/alumina interface. It is shown that these interfaces do have properties which result specifically from the ionic nature of the material and the large unit cells involved in each case.