title: Atomic displacements in BiFeO(3) as a function of temperature: neutron diffraction study.
abstract: The parameters of the crystal structure of BiFeO(3), 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 Néel temperature T(N) approximately 640 K, a gradual rotation of the FeO(6) octahedra and an increase of the Fe-O-Fe angle. The displacement of the Bi(3+) ions from the FeO(6) 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 Bi(3+) and O(2-) ions show a significant anisotropy.
authors.affiliation: Institute of Experimental Physics, Warsaw University, Hoza 69 PL 00-681, Warsaw, Poland. radek@fuw.edu.pl
authors.forename: A
authors.initials: A
authors.lastname: Palewicz
authors.forename: R
authors.initials: R
authors.lastname: Przeniosło
authors.forename: I
authors.initials: I
authors.lastname: Sosnowska
authors.forename: A W
authors.initials: AW
authors.lastname: Hewat