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 twocharge 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 Ti(4+)ions changing to Ti(3+)is critical to understanding the donor-doped perovskites.