H. Okudera et al., TEMPERATURE-DEPENDENCE OF STRUCTURE PARAMETERS IN NATURAL MAGNETITE -SINGLE-CRYSTAL X-RAY STUDIES FROM 126-K TO 773-K, Acta crystallographica. Section B, Structural science, 52, 1996, pp. 450-457
Structural parameters and their thermal changes in natural magnetite,
Fe3O4, have been studied using the single crystal X-ray diffraction me
thod in the temperature range 126-773 K. The cell dimensions, oxygen c
oordinate and atomic mean square displacements (m.s.d.'s) reversibly c
hange as a function of temperature. The coordinate of oxygen remains a
lmost constant at x = 0.2549(1) below similar to 600 K, but increases
with increasing temperature above this temperature. This characteristi
c behavior of the oxygen coordinate with temperature indicates that th
e cation disordering over the tetrahedral (ii) and octahedral (B) cati
on sites occurs above 600 K. All atomic m.s.d.'s increase monotonously
with temperature rise. The m.s.d.'s of the B atom show a unique tempe
rature dependence. At lower temperatures the B atom prefers to vibrate
along [111], but this preference is reduced with a temperature rise u
p to 630 K, above which the m.s.d. normal to [111] becomes dominant.