Diffuse scattering, which was highly intensive and was confined (in reciprocal space) to a regular geometrical surface that exhibited the translational symmetry of the body-centered cubic reciprocal lattice, was observed by means of the electron diffractometry of material which was partially stabilized with Y2O3 and MgO. A 3-dimensional geometrical model was constructed for a diffuse scattering that was distributed in reciprocal space, and an analytical equation was established which corresponded to that model. In the reciprocal-space unit cell, the diffuse scattering was distributed on the surfaces of 8 rotational ellipsoids whose axes lay along the <111> directions of the body-centered cubic reciprocal lattice. Possible sources for the formation of diffuse scattering were considered. It was concluded that local ordering of O vacancies in the cubic phase matrix, which perhaps corresponded to a transition between the disordered cubic fluorite structure and an ordered superstructure, was the predominant factor that was responsible for the observed characteristic diffuse scattering.

Z.R.Dai, Z.L.Wang, Y.R.Chen, H.Z.Wu, W.X.Liu: Philosophical Magazine A, 1996, 73[2], 415-30