The diffuse scattering, in electron diffraction patterns, which was produced by O-vacancy local ordering in material that was stabilized with Y2O3 and MgO was analyzed. A 3-dimensional geometrical model in reciprocal space was developed for the description of the equal-intensity contours of diffuse scattering which were experimentally observed. Kinematic electron diffraction theory was used to calculate the diffuse scattering that was produced by O vacancies. A direct relationship was established between the local ordering parameters and the distribution of diffuse scattering intensity. By assuming that the intensity profile across the maximum-intensity contour, as defined by the surface of the geometrical model, was Gaussian the local ordering parameters of O vacancies were determined. The parameters were then used to calculate the distribution of diffuse scattering intensity, and the results exhibited good agreement with experimental observations. It was concluded that the O vacancies were linked to O vacancies by the r<200> and r<310> position vectors of the anionic sub-lattice (a/2, b/2, c/2) of the face-centered cubic fluorite structure. The O anions and O vacancies were linked by r<110>, r<211> and r<220>.

Z.R.Dai, Z.L.Wang, W.X.Liu: Philosophical Magazine A, 1996, 73[6], 1685-98