Crystalline BiFeO3 （BFO） films each with a crystal structure of a distorted rhombohedral perovskite are characterized by X-ray diffraction （XRD） and high-resolution electron microscopy （HRTEM）. The diffusion of silicon atoms from the substrate into the BiFeO3 film is detected by Rutherford backscattering spectrometry （RBS）. The element analysis is per- formed by energy dispersive X-ray spectroscopy （EDS）. Simulation results of RBS spectrum show a visualized distribution of silicon. X-ray photoelectron spectroscopy （XPS） indicates that a portion of silica is formed in the diffusion process of silicon atoms. Ferroelectric and weak ferromagnetic properties of the BFO films are degraded due to the diffusion of silicon atoms. The saturation magnetization decreases from 6.11 down to 0.75 emu/g, and the leakage current density increases from 3.8 × 10^-4 upto7.1 × 10^-4 A/cm-2.
Soil samples taken from Xilamuren Grassland,Resonant Sand Bay,Inner Mongolia,and Yichang,western Hubei Province were investigated by Mssbauer spectroscopy at room temperature and 20 K.This was supplemented with phase identification and elemental analysis to obtain information about the composition and structure types of Fe-containing compounds.The samples collected from both Xilamuren Grassland and Resonant Sand Bay,Inner Mongolia were found to have small amount of iron 1%-2%.The main phases were determined as silica,albite,and microcline.Two or three dominant doublets were observed in the Mssbauer spectra of these samples,respectively and identified as corresponding to the valence states of Fe2＋and Fe3＋.A sextet observed in all the spectra is attributed to the hematite phase.Low temperature Mssbauer measurements have revealed Morin transition.
Pelenovich V OCHEN YilongXIAO RenzhengLIU ShouyinFU Dejun
