Organized defect clusters in non-stoichiometric LiNbO3 were known to dominate macroscale ferroelectric properties; yet the detailed nature of these defects was currently unknown. Here, the relative stabilities of various defect cluster arrangements of lithium vacancies around a niobium antisite in LiNbO3 were determined using density functional theory combined with thermodynamic calculations. Their effects on the ferroelectricity of the system were also considered. It was found that at room temperature the non-uniaxial dipole moments associated with the defect clusters could affect the properties of the system locally. The diffusion mechanism was predicted to be through first nearest neighbour jumps on the Li sub-lattice. The diffusivity of the lithium vacancy was found to be extremely low at room temperature, which indicated that the defect complexes should be rather stable.

Structure and Diffusion of Intrinsic Defect Complexes in LiNbO3 from Density Functional Theory Calculations. H.Xu, D.Lee, S.B.Sinnott, V.Dierolf, V.Gopalan, S.R.Phillpot: Journal of Physics - Condensed Matter, 2010, 22[13], 135002