The relative free energies of grain boundaries in magnesia as a function of five macroscopic parameters

Using measurements of the geometric and crystallographic characteristics of approximately 104 triple junctions in a MgO polycrystal, the relative grain boundary energy has been determined as a function of five macroscopic parameters. The relative energy of a particular grain boundary is inversely correlated with its frequency of occurrence. At all misorientations, grain boundaries with {1 0 0} interface planes have relatively low energies. For low misorientation angle grain boundaries, the results are consistent with the predictions of dislocation models. At high misorientation angles, the population and energy are correlated to the sum of the energies of the free surfaces that comprise the boundary.