10 research outputs found
Interplay of Chemical Bonding and Magnetism in Fe_4N, Fe_3N, Fe_2N
Using spin density functional theory we have carried out a comparative study
of chemical bonding and magnetism in Fe_4N, Fe_3N and Fe_2N. All of these
compounds form close packed Fe lattices, while N occupies octahedral
interstitial positions. High spin fcc Fe and hypothetical FeN with rock salt
structure have been included in our study as reference systems. We find strong,
covalent Fe-N bonds as a result of a substantial \sigma-type p-d hybridisation,
with some charge transfer to N. Those Fe d orbitals which contribute to the p-d
bonds, do no longer participate in the exchange splitting of the Fe d bands.
Because of the large exchange fields, the majority spin d bands are always
fully occupied, while the minority spin d bands are close to half-filling, thus
optimizing the Fe d-d covalent bonding. As a consequence, in good approximation
the individual Fe moments decrease in steps of 0.5 \mu_B from fcc iron (2.7
\mu_B) via Fe_4N (2.7 and 1.97 mu_B}), \chem{Fe_3N} (1.99 \mu_B) to \zeta -
Fe_2N (1.43 \mu_B).Comment: 16 pages, 15 figure
Elektronische Struktur und physikalische Eigenschaften der Eisennitride und einiger Nitride des Si, Ge und Sn
In this thesis the calculation of the Fe-N binding and the N diffusion as well as the equations of state of Ge_3N_4 and Sn_3N_4 are described. (HSI)SIGLEAvailable from: http://eldorado.uni-dortmund.de / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman