科研之友
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摘要
The parameters of the crystal structure of BiFeO3, described within the space group R3c, have been determined by high-resolution neutron powder diffraction for temperatures from 293 to 923 K. It was found that there is a local minimum for the rhombohedral angle alpha(rh), near the Neel temperature T-N similar or equal to 640 K, a gradual rotation of the FeO6 octahedra and an increase of the Fe - O - Fe angle. The displacement of the Bi3+ ions from the FeO6 octahedra which influence the electric polarization decreases with temperature. One of the Bi - Fe distances also has a local maximum near T-N. The atomic vibrations of Bi3+ and O2- ions show a significant anisotropy.
- 出版日期2007-8
