ISSN:
1572-9540
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Physik
Notizen:
Abstract Using67Zn Mössbauer absorption and emission spectroscopy, we have investigated the electronic structure at the A and B sites in the normal spinels (Zn)[Al2]O4, (Zn)[Fe2]O4 and (Zn)[Ga2]O4. Within each system, the center shift Sc at the A site is more positive. In all systems investigated, the electric field gradientV u at the B site is negative. The values for SC andV U scale with oxygen nearest-neighbour distance to Zn. In the Fe spinel, a transferred magnetic hyperfine field is observed at the Zn site below the antiferromagnetic ordering temperatureT N=10 K. For a more detailed discussion of the chemical bond, we have performed ab initio Hartree-Fock cluster calculations for the Al and Fe spinels. Our experimental and theoretical results show that all hyperfine parameters are essentially determined by covalency effects. Our data on the Ga spinel raise the question of a partially inverse structure.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF02069139
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