Japan Atomic Energy Agency, Reaction Dynamics Research Division, 1-1-1, Kouto, Sayo-cho Sayo-gun, Hyogo 679-5148, Japan.
J Phys Condens Matter. 2011 Jan 12;23(1):015902. doi: 10.1088/0953-8984/23/1/015902. Epub 2010 Dec 6.
The electronic structure of BiFeO₃ (BFO), BiFeO₃-PbTiO(3) solid solution (BFO-PT), and Mn-doped BFO-PT (BFM-PT) films fabricated by chemical solution deposition was investigated by x-ray absorption fine structure (XAFS). The BiFeO₃ shows a large leakage current owing to the mixed valance state of Fe(2 +) and Fe(3 +). The BFO film has a blunt absorption edge jump indicating the charge fluctuated state of the iron ions. The BFO-PT and BFM-PT films have sharp absorption edges, and the absorption energy of these films shifted to opposite energy. The valence fluctuation of the iron ions was closely connected with the leakage current properties. The charge fluctuated BFO film showed a leaky feature, and the charge unfluctuated BFO-PT and BFM-PT films had improved leakage current properties. The valence fluctuation of the iron ions can be controlled by Mn substitution and by making solid solutions.
采用化学溶液沉积法制备了 BiFeO₃（BFO）、BiFeO₃-PbTiO₃固溶体（BFO-PT）和 Mn 掺杂 BFO-PT（BFM-PT）薄膜，并通过 X 射线吸收精细结构（XAFS）研究了它们的电子结构。BiFeO₃由于 Fe(2+)和 Fe(3+)的混合价态表现出较大的漏电流。BFO 薄膜具有较钝的吸收边跃变，表明铁离子的电荷波动状态。BFO-PT 和 BFM-PT 薄膜具有尖锐的吸收边，这些薄膜的吸收能向相反的能量移动。铁离子的价态波动与漏电流特性密切相关。电荷波动的 BFO 薄膜表现出漏电流特性，而电荷不波动的 BFO-PT 和 BFM-PT 薄膜则改善了漏电流特性。铁离子的价态波动可以通过 Mn 取代和形成固溶体来控制。
