Abstract
BaTiO 3 - δ (BTO) and BaTi 0.88 Fe 0.12 O 3 - δ polycrystalline samples were investigated to understand the role that Fe dopant and oxygen vacancy play on their various properties. Their structures were examined using X-ray diffraction and X-ray absorption spectroscopy. Their optical and conduction properties were also characterized at room temperature. Our results show that BTO is a tetragonal-phase ferroelectric material with a wide band gap Eg ≈ 3.51 eV while BTFO is a hexagonal-phase multiferroic material with smaller band gap Eg ≈ 3.40 eV. Fe doping ions, which exist in both Fe 3+ and Fe 4+ forms, give rise to positively-charged oxygen vacancies to create donor impurity levels in the forbidden band. The UV-VIS absorption spectrum of BTFO exhibits a broadening in the visible region. The red shift is observed in both the absorption and photoluminescence spectra relative to those of BTO. The leakage current is larger in BTFO than in BTO. © 2012 The Physical Society of the Republic of China.