The existence of two novel rare-earth incorporation mechanisms in cubic barium titanate is demonstrated using classical simulations. The dependence of solution, binding and modified solution energies with respect to the ionic radii of dopants is determined. Strong defect binding energies are obtained, similar to Er-doping, which has been reported previously. Dopants with small ionic size can potentially be incorporated via either the Bavac or Ti-vac mode, whereas large dopants prefer the Ti-vac mixed mode. Although the mixed modes reveal somewhat higher energies with respect to the traditional self-compensation mechanism, they are likely to be active under certain experimental conditions. The abstract figure shows two mixed incorporation mechanisms in doped BaTiO 3 labelled as (a) Tivac and (b) Ba-vac. Green, grey, blue, and red spheres correspond to Ba 2þ , Ti 4þ , rare-earth (RE 3þ ), and O 2-ions, respectively.