TY - JOUR
T1 - Determination of the locations of Mn and Fe in Mn-bearing andalusite by anomalous X-ray scattering and X-ray absorption fine structure analyses
AU - Arima, Hiroshi
AU - Tani, Yuki
AU - Sugiyama, Kazumasa
AU - Yoshiasa, Akira
N1 - Publisher Copyright:
© 2018 Japan Association of Mineralogical Sciences.
PY - 2018/12/1
Y1 - 2018/12/1
N2 - Local structural features around Mn and Fe in Mn-bearing andalusite from Västanåberget, Sweden were investigated by anomalous X-ray scattering (AXS) and X-ray absorption fine structure (XAFS). The X-ray absorption near edge structure (XANES) spectra indicate that all of the Mn and Fe atoms are in +3 oxidation state. Both the electron density map of Mn obtained by AXS and simulated multiple-scattering extended X-ray absorption fine structure (EXAFS) spectra indicate that the Mn atoms exclusively occupy Al1 sites. Further, the EXAFS analysis indicates that the first neighbor coordinated to Mn at the Al1 site shows a complete structural relaxation and Jahn-Teller distortion owing to Mn3+. In addition, the EXAFS analyses reveal that Fe occupies both Al1 and Al2 sites. The Fe site occupancy ratio (Fe at Al2 to total Fe) in the Mn-bearing andalusite sample is 40-50%. Employing the local structural information around Mn and Fe, a conventional single-crystal structural refinement converged at R = 2.34% with a structural formula of (Al0.82Mn0.16Fe0.02)[6](Al0.99Fe0.01)[5]SiO5 (space group Pnnm with a = 7.8538(9), b = 7.9463(9), c = 5.5867(6) Å).
AB - Local structural features around Mn and Fe in Mn-bearing andalusite from Västanåberget, Sweden were investigated by anomalous X-ray scattering (AXS) and X-ray absorption fine structure (XAFS). The X-ray absorption near edge structure (XANES) spectra indicate that all of the Mn and Fe atoms are in +3 oxidation state. Both the electron density map of Mn obtained by AXS and simulated multiple-scattering extended X-ray absorption fine structure (EXAFS) spectra indicate that the Mn atoms exclusively occupy Al1 sites. Further, the EXAFS analysis indicates that the first neighbor coordinated to Mn at the Al1 site shows a complete structural relaxation and Jahn-Teller distortion owing to Mn3+. In addition, the EXAFS analyses reveal that Fe occupies both Al1 and Al2 sites. The Fe site occupancy ratio (Fe at Al2 to total Fe) in the Mn-bearing andalusite sample is 40-50%. Employing the local structural information around Mn and Fe, a conventional single-crystal structural refinement converged at R = 2.34% with a structural formula of (Al0.82Mn0.16Fe0.02)[6](Al0.99Fe0.01)[5]SiO5 (space group Pnnm with a = 7.8538(9), b = 7.9463(9), c = 5.5867(6) Å).
KW - Anomalous X-ray scattering
KW - Local structure
KW - Mn-bearing andalusite
KW - X-ray absorption fine structure
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U2 - 10.2465/jmps.180520
DO - 10.2465/jmps.180520
M3 - Article
AN - SCOPUS:85059262492
VL - 113
SP - 273
EP - 279
JO - Journal of Mineralogical and Petrological Sciences
JF - Journal of Mineralogical and Petrological Sciences
SN - 1345-6296
IS - 6
ER -