Incorporation of iron into ferroelectric lead titanate with ABO3 perovskite structure is widely utilized to fabricate materials with... Show moreIncorporation of iron into ferroelectric lead titanate with ABO3 perovskite structure is widely utilized to fabricate materials with ferroelectric and ferromagnetic order. These solid solutions exhibit room temperature ferromagnetic properties at iron concentration as low as 1 mole%. Iron (Fe3+) is highly compatible with titanium (Ti4+) in ionic radii and obviously incompatible in the valence state. Magnetoelectric coupling has been observed in 50 mole% Fe substituted lead titanate. The molecular mixing of precursor materials in wet chemical synthesis such as sol-gel has advantage over conventional solid state sintering in achieving higher solubility of the substituent. A series of Pb(FexTi1−x)O3− solid solution in the composition range x = 0 to 1 has been synthesized using sol-get route, followed by a moderate temperature (700 C) calcination. The structure and properties of samples were characterized using x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), dielectric spectroscopy, Raman spectroscopy, and magnetic measurements. SEM results indicated a gradual change in sample morphology, changing from individual particles to nano-aggregates with Fe concentration. EDX confirmed uniform distribution of dopants when Fe concentration x 0.3 and Fe concentration close to nominal composition with possibility of lead loss. XRD results indicated a rapid reduction of tetragonal distortion upon Fe substitution, Fe solubility limit of 10 mole%, and PbFe12O19 impurity phase formation at compositions x 0.4. XAS clearly indicated that Ti prefers a 6 coordinated distorted oxygen octahedra and Fe is surrounded by 5 oxygens situated at a similar distance. Other measurements suggested that ferroelectric and ferromagnetic ordering may arise in Ti-rich and Fe-rich phases, respectively. None of the samples below x = 0.2 was found to be ferromagnetic at room temperature. PH.D in Physics, December 2012 Show less
