
TY  - JOUR
A1  - Duncun, JF 
A1  - Johnson, JH 
T1  - Single-crystal <sup>57</sup>Fe M&#246;ssbauer studies of the site positions in cordierite
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1974
VL  - 27
IS  - 2
SP  - 249
EP  - 258
KW  - 
UR  - https://doi.org/10.1071/CH9740249 
N2  - Mossbauer (57Fe) absorption spectra of different orientations of single crystals of cordierite (Mg,Fe)2AI3 [Si5AIO18] have been determined. The variation of the ratio of the peak areas of the quadrupole split lines with orientation has enabled the determination of the electric field gradient directions, and the site positions and occupancies of the Fe2+ and Fe3+ ions. Of a total iron content of 1.85% w/w, 79% is present as Fe2+ replacing Mg2+ in the octahedral sites; 19% as Fe2+ occupying the larger of two channel sites; and 1% as Fe3+ replacing Al3+ in the larger of the two tetrahedral sites. A possible interpretation of the observed pleochroism in terms of Fe2+-Fe2+ and Fe2+-Fe3+ electranic interactions along the directions of the electric field gradients of these ions is suggested. 
ER  -

