Crystal field spectra of Fe2 olivines

5 Crystal field spectra of transition metal ions 

The fayalite, with 96 mole percent Fe2Si04, is from Rockport, Massachusetts. 

Compositional variations of the olivine spectra across the forsterite-fayalite series (fig. 5.10) indicate ranges of A0 and CFSE of Fe2+ ions to be 

For the pseudo-tetragonally elongated Ml octahedral site in the olivine structure, an alternative method for obtaining the CFSE of Fe2+ ions in this site is to evaluate the ligand field splitting parameters in the equatorial plane and along the axial direction using eqs (3.14) to (3.16). The crystal field spectral data for the fayalite Ml site (see fig. 5.11a) yield values for 10 Dq(m) and 10 Dq(eq) of 8,172 cm-1 and 9,327 cm-1, respectively. The mean 10 Dq value of 8,942 cm-1 and the CFSE of 4,133 cm-1 compare favourably with A0 = 8,830 cm-1 and CFSE = 4,250 cm-1 for Fe2+ in the fayalite Ml sites determined by the baricentric method (fig. 5.11a). 

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