Ferroelectric-paraelectric transition in BiFeO3: crystal structure of the orthorhombic beta phase

Phys Rev Lett. 2009 Jan 16;102(2):027602. doi: 10.1103/PhysRevLett.102.027602. Epub 2009 Jan 16.


A detailed investigation using variable temperature powder neutron diffraction demonstrates that BiFeO3 undergoes a phase transition from the ferroelectric alpha phase (rhombohedral, R3c) to a paraelectric beta phase (orthorhombic, Pbnm) between 820 degrees C and 830 degrees C. Coexistence of both phases over a finite temperature interval, together with abrupt changes in key structural parameters, confirms that the transition is first order. The beta phase corresponds to a GdFeO3-type perovskite structure.