Jahn-Teller distortion of Mn<sup>3+</sup>-occupied octahedra in red beryl from Utah indicated by optical spectroscopy
- Author(s)
- Jana Fridrichová, Peter Bačík, Andreas Ertl, Manfred Wildner, Július Dekan, Marcel Miglierini
- Abstract
Red beryl from Utah is chemically homogeneous and contains only Fe < 0.163, Mn < 0.018, and Mg < 0.016 apfu. Channel sites contain only up to Cs 0.011, K 0.009, Rb 0.004, and Na 0.004 apfu. This suggests only very slight tetrahedral (Cs,K,Rb)Li□
-1Be
-1 substitution, octahedral Na(Fe
2+,Mg)□
-1Al
-1 substitution can be excluded. Fe and Mn are trivalent as documented by Mössbauer spectroscopy and optical absorption spectroscopy. Red beryl optimized formula is ∼[(Cs,Rb,K)
0.02□
0.98]
Σ1.00□
1.00(Al
1.79Fe
3+
0.16Mn
3+
0.02Ti
4+
0.02Mg
0.01)
Σ2.00Be
3(Si
6O
18). Location of Mn
3+ was estimated to the octahedral Al
3+ site, other choices are improbable due to the bond-length requirements. No Mn
3+-induced Jahn-Teller structural distortion was detected due to site symmetry restrictions and small Mn
3+ content. However, optical spectroscopy shows broad band at ∼7190 cm
−1 assigned to the excited level of the spin-allowed pseudo-tetragonal split E ground state of elongated six-fold Mn
3+ coordination. Crystal field calculations indicate that the local Mn
3+ environment complies well with crystal chemical expectations for Jahn-Teller distorted Mn
3+O
6 octahedra.
- Organisation(s)
- Department of Mineralogy and Crystallography
- External organisation(s)
- Slovak University of Technology in Bratislava, Naturhistorisches Museum Wien (NHM), Comenius University Bratislava
- Journal
- Journal of Molecular Structure
- Volume
- 1152
- Pages
- 79-86
- No. of pages
- 8
- ISSN
- 0022-2860
- DOI
- https://doi.org/10.1016/j.molstruc.2017.09.081
- Publication date
- 09-2017
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 104026 Spectroscopy, 105116 Mineralogy, 105113 Crystallography
- Keywords
- ASJC Scopus subject areas
- Analytical Chemistry, Spectroscopy, Inorganic Chemistry, Organic Chemistry
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/d94289e7-bbfd-46f6-8f24-57dbc95acc84