X-Ray Study of the Phase Transition in Magnetite

Temperature dependence of the lattice parameters of magnetite in cubic and monoclinic phases were measured accurately between 80 K and 295 K by means of single crystal X-ray diffraction. It was shown that the monoclinic distortion of the lattice in the low temperature phase has a tendency to become large with the lowering of temperature. A discontinuous increase of the unit cell volume at the transition temperature on cooling was clarified. Several superlattice reflections were also investigated, and possibility of the atomic displacements modulated with the wave vectors k =[100], [010] and [001] with X 1 symmetry is discussed.