Electron-Nuclear Hyperfine Interactions of 53Cr 3+ in Mg2SiO4 (Forsterite)
Abstract The magnetic hyperfine interaction between the electron and nuclear spin system of 53Cr3+ was studied at the Mg sites, M1 and M2, in Mg2SiO4. The study was undertaken at room temperature and 9.52 GHz. The hyperfine structure data exhibit a covalent Cr-O bonding of approximately 10% indicating a mainly but not purely ionic bonding. Including the corresponding results obtained for 57Fe 3+ [1] and 55Mn2+ [2] in Mg2SiO4, this is interpreted such that the bonding of transition metal ions is mainly dominated by the oxygen sublattice in Mg2SiO4 and less by the properties of the transition metal ions themselves. The small variation of the hyperfine splitting parameters found for 53Cr3+ at M1 and M2, and also for 57Fe3+ at these positions indicates that the hyperfine interaction varies also with varying average metal oxygen distances as well as with changes in the oxygen coordination size.
