Orthorhombic Jahn-Teller distortion and Si-OH in mozartite, CaMn₃₁O[SiO₃OH]

Autor(en)

Daniel Nyfeler, Christina Hoffmann, Thomas Armbruster, Martin Kunz, Eugen Libowitzky

Abstrakt

The structure of mozartite, CaMn3+O[SiO3OH], was refined in space group P212121 from x-ray single-crystal data collected at 100 K(R = 2.45%, Rw = 2.62%), 300 K (R = 2.60%, Rw = 2.68%), and 500 K (R = 2.79%, Rw = 2.81%). The Mn3+O6 octahedron shows approx. orthorhombic geometry, which is explained by a combination of a tetragonally compressed Jahn-Teller effect with lattice-induced stress. Comparison with isostructural vuagnatite, CaAl(OH)SiO4, which shows no distortions due to electronic effects, indicates that the distorted octahedral geometry in mozartite causes shifts in valence sums of the O atoms that are hydrogen bonded. As a result, the OH group in mozartite is located at the isolated SiO4 apex and is not linked to the octahedron as reported for isostructural minerals. Isostructural minerals of the adelite group with tetrahedral As5+ and V5+ exhibit a different Jahn-Teller distortion with tetragonally elongated geometry for octahedral Cu2+O6.

Organisation(en)

Institut für Mineralogie und Kristallographie

Externe Organisation(en)

Universität Bern, European Synchotron Radiation Facility

Journal

The American mineralogist

Seiten

841-848

Anzahl der Seiten

8

ISSN

0003-004X

Publikationsdatum

1997

Peer-reviewed

Ja

ÖFOS 2012

104026 Spektroskopie, 105116 Mineralogie, 105113 Kristallographie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/74056c41-8e8f-4eb2-b57b-5daffd77e1e1