Oxygen Bonding in Bismuth Layered Compounds SrBi_2Ta_2O_9

摘要

With the help of the high resolution Z-contrast scanning transmission electron microscopy (STEM), the near edge fine structures of the electron loss spectroscopy (EELS) arises from different layers are investigated in SBT. The EELS spectra are interpreted by comparing with the calculation using linearnized augment plane wave (LAPW) method within the density functional theory(DFT). The oxygen bonding nature in different layers are discussed. In Bi_2O_2 layer, oxygen 2p state interacted with the Bi 6p state leads to a high t2g state in density of state while in SrTa_2O_7 layer, oxygen 2p state hybridized with Ta 5d and Sr 5d, which leads a higher eg state than t2g state.