Doping is a widely used method to tune the physical properties of ferroelectric perovskites. Since doping can induce effective charges, it is important to understand how charges affect the chemical and physical properties of the doped perovskites. Here, we propose two charge compensation models, by adding the charge‐dipole interaction to the effective Hamiltonian, which has not been done previously, and numerically investigate how lanthanum doping affects the ferroelectric phase transition temperature and the hysteresis loop in BaTiO3. The consequences of the charge compensation models are compared and discussed, revealing that the electron compensation mechanism with some Ti4+ ions changing to Ti3+ is critical to understanding the donor‐doped perovskites.

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Domains and domain walls are among the key factors that determine the performance of ferroelectric materials. In recent years, a unique type of domain walls, i.e., the sawtooth shaped domain walls, has been observed in BiFeO 3 and PbTiO 3 . Here, we build a minimal model to reveal the origin of these sawtooth shaped domain walls. Incorporating this model into Monte-Carlo simulations shows that (i) the competition between the long-range Coulomb interaction (due to bound charges) and short-range interaction (due to opposite dipoles) is responsible for the formation of these peculiar domain walls and (ii) their relative strength is critical in determining the periodicity of these sawtooth shaped domain walls. Necessary conditions to form such domain walls are also discussed.

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