Charge effects in donor-doped perovskite ferroelectrics

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.