Correlation between ferroelectricity and electronic density of states near the Fermi level in BaTiO3
Correlation between ferroelectricity and electronic density of states near the Fermi level in BaTiO3
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BaTiO3 中铁电性与费米能级附近电子态密度的相关性
DOI：
10.1002/pssb.200301981
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
J. Lee
中科院分区：
文献类型：
--
作者：
M. Hidaka;N. Tokiwa;S. Takahashi;Jae;J. Lee
通过X射线吸收近边结构研究了BaTiO 3中Ti K边和Ba L边附近的电子态密度。Ti离子的4pπ带和Ba离子的5dπ带具有高密度空占态，占据费米能级（EF）的正上方的能级。边前峰表明，除了O2− 2 p价带之外，EF以下的电子态密度由Ti离子的负电荷转移带3d 1、3d 1 $ \underline {\rm L} $和3d 2 $ \underline {\rm L} $2以及Ba离子的4f 1、4f 1 $ \underline {\rm L} $和4f 2 $ \underline {\rm L} $2组成。Ti离子的3d 1、3d 1 $ \underline {\rm L} $和3d 2 $ \underline {\rm L} $2谱带表明，除了Ti 4+之外，还存在不同氧化态的Ti 2+和Ti 3+的混合物。4f 1，4f 1 $ \underline {\rm L} $和4f 2 $ \underline {\rm L} $2带是由Ba 2 + 4d和O2- 2 p轨道之间的杂化通过Ba离子的4f和4d轨道之间的电子组态相互作用引起的。铁电相中4f 1，4f 1 $ \underline {\rm L} $和4f 2 $ \underline {\rm L} $2带的消失表明Ba离子从立方钙钛矿型结构的理想离子位点的集体位移减少了Ba和O离子之间的杂化。这使得O离子上的有效电荷增加，并在O离子和Ti离子之间诱导大的偶极矩，其在铁电相中位于TiO 6八面体的偏心位置。（© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA，魏因海姆）
The electronic density of states in BaTiO3 is studied by means of X‐ray absorption near‐edge structure in a vicinity of a Ti K edge and Ba L edges. A 4pπ band of the Ti ion and a 5dπ band of the Ba ion having a high‐density unoccupied state occupy a level just above the Fermi level (EF). The pre‐edge peaks give that, in addition to an O2− 2p valence band, the electronic density of states below EF are composed of negative‐charge‐transfer bands 3d1, 3d1$ \underline {\rm L} $ and 3d2$ \underline {\rm L} $2 of Ti ions and 4f1, 4f1$ \underline {\rm L} $ and 4f2$ \underline {\rm L} $2 of Ba ions. The 3d1, 3d1$ \underline {\rm L} $ and 3d2$ \underline {\rm L} $2 bands of Ti ions gives that a mixture of the different oxidation states Ti2+ and Ti3+ is present in addition to Ti4+. The 4f1, 4f1$ \underline {\rm L} $ and 4f2$ \underline {\rm L} $2 bands are induced by a hybridization between Ba2+ 4d and O2– 2p orbitals via an electronic configuration interaction between the 4f and 4d orbitals of the Ba ion. The disappearance of the 4f1, 4f1$ \underline {\rm L} $ and 4f2$ \underline {\rm L} $2 bands in the ferroelectric phase suggests that the collective displacement of Ba ions from ideal ionic sites of the cubic perovskite‐type structure reduces the hybridization between the Ba and O ions. This gives that the effective charge on the O ions is increased and induces a large dipole moment between the O ions and the Ti ions, which are at an off‐center position of TiO6 octahedra in the ferroelectric phase. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
影响因子：
3.7
作者：
Farges, F;Brown, GE;Rehr, JJ
通讯作者：
Rehr, JJ