Role of Fe Doping on Local Structure and Electrical and Magnetic Properties of PbTiO 3

The local structure and multiferroic properties of iron-doped lead titanate (PbTi 1– x Fe x O 3−δ ) samples was investigated over the entire composition range ( x = 0–1). Inherent polarization in PbTiO 3 decreases due to Fe 3+ 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–O n ). The charge compensating oxygen vacancies induce local tilting of the Fe–O n 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 PbFe 12 O 19 with increased Fe doping. PbTi 1– x Fe x O 3−δ ( x ≥ 0.3) samples therefore have separate origins for the ferroelectric (PbTi 1– x Fe x O 3−δ ) and magnetic (PbFe 12 O 19 ) phases.