HR: 0830h
AN: V11D-0530    [PDF]
TI: First principles studies of the system $Fe_{2}O_{3}-FeTiO_{3}$; phase stability and magnetism
AU: * Burton, B P
EM: benjamin.burton@nist.gov
AF: NIST, A226/223 NIST 1 Bureau Dr, Gaithersburg, MD 20899 United States
AU: Chaka, A
EM: achaka@nist.gov
AF: NIST, A226/223 NIST 1 Bureau Dr, Gaithersburg, MD 20899 United States
AU: Singh, D
EM: singh@dave.nrl.navy.mil
AF: NRL, Naval Research Lab, Washington DC, WDC 20375 United States
AB: Spin polarized electronic structure (VASP) calculations of total energies and magnetic moments for ordered supercells in the system $Fe_{2}O_{3}-FeTiO_{3}$~ suggest that some {\bf layered} superstructures are more stable than an isocompositional mechanical mixture of hematite ($Fe_{2}O_{3}$) plus ilmenite ($FeTiO_{3}$). This result contradicts established ideas about hematite-ilmenite phase relations (e.g. Burton and Davidson, Adv. Phys. Geochem. V7, pp 86, 1988). It suggests that there may be stable phases which contribute to the "lamellar magnetism" named by Robinson et al. (Nature 418, 517- 2002). It is not clear if these results are artifacts of the approximations made in spin polarized local spin density functional calculations. In addition, the electronic structure of a 30 atom layered supercell [FTFFFT... F is an Fe-layer (T is a Ti-layer) perpendicular to the hexagonal c-axis] has been studied. Preliminary results indicate charge ordering similar to that predicted by Robinson et al. (2002).
DE: 3939 Physical thermodynamics
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting