Role of Fe Doping on Local Structure and Electrical and Magnetic Properties of PbTiO<sub>3</sub>
Hasitha Ganegoda, Soham Mukherjee, Beihai Ma, Daniel T. Olive, James McNeely, James A. Kaduk, Jeff Terry, Håkan Rensmo, Carlo U. Segre
Abstract
The local structure and multiferroic properties of iron-doped lead titanate (PbTi1–xFexO3−δ) samples was investigated over the entire composition range (x = 0–1). Inherent polarization in PbTiO3 decreases due to Fe3+ incorporation up to the solubility limit (x ∼ 0.3), although homogeneous doping persists only up to x = 0.1. Ti prefers highly distorted oxygen octahedra for any x value, while Fe prefers more symmetric O-deficient polyhedra (Fe–On). The charge compensating oxygen vacancies induce local tilting of the Fe–On polyhedra beyond a critical x value (x ≥ 0.2), promoting magnetic interaction between two adjacent Fe atoms. The strain induced by local heterogeneity could act as a coupling force between magnetic and ferroelectric properties. Fe-rich clusters evolve into ferromagnetic PbFe12O19 with increased Fe doping. PbTi1–xFexO3−δ (x ≥ 0.3) samples therefore have separate origins for the ferroelectric (PbTi1–xFexO3−δ) and magnetic (PbFe12O19) phases.