Stabilized Wüstite Formed from Zn(II)-and Mn(II)-Wüstite below 575°C

抄録

  The transformation of the Zn(II)-and Mn(II)-wüstite into spinel-type compound was studied to investigate the effect of foreign cations (Zn(II), Mn(II) ions) on FeO-wüstite disproportionation into α-Fe and Fe₃O₄ bellow 575°C. In these transformation reactions, the Fe(III) ions in the Zn(II)- and Mn(II)-wüstites (Zn²⁺_xFe²⁺_yFe³⁺_zO, Mn²⁺_xFe²⁺_yFe³⁺_zO, x+y+y<1) form the spinel type structure in Ar gas at 500°C(Zn(II)-wüstite) and 450°C(Mn(II)-wüstite), but no α-Fe phase appeared, indicating that the presence of those foreign cations in the FeO-wüstite interferes with the disproportionation into α-Fe and Fe₃O₄. No manganese oxides were formed from Mn(II)-wüstite at 450°C, while the ZnO was formed from the Zn(II)-wüstite. This difference came from the fact that the Mn(II) ion does not have a site preferency and Zn(II) ion has a tetrahedral site preferency.