Polarized FTIR spectroscopic examination on hydroxylation in the minerals of the wolframite group, (Fe,Mn,Mg)[W,(Nb,Ta)][O,(OH)]₄

Author(s)

Dominik Talla, Anton Beran, Radek Skoda, Zdenek Losos

Abstract

Polarized FTIR spectroscopic measurements of eleven natural wolframite single crystals from different occurrences revealed the common presence of structurally bound OH groups in their crystal lattice, with potential influence on the properties of these geologically and technologically important group of compounds. Despite differences in the appearance of the OH absorption pattern, dependent among other on the endmember ratio, two types of ‘intrinsic’ OH defects could be discerned from detailed studies of the pleochroic behavior of the absorption bands both at 80 K and room temperature. The accompanying chemical analyses by the electron microprobe helped to clearly identify the substitution trend W6+ + O2- ? (Nb,Ta)5+ + OH- as the prevailing hydrogen incorporation mechanism into wolframite. The assignment of the observed IR absorption phenomena to hydrous defects was confirmed by the results of deuteration experiments and the negligible contribution of included impurities to the FTIR spectra in the OH absorption region. The results obtained in this study of natural wolframite crystals can be used to detect and analyze hydrous defects in synthetic technologically important tungstates.

Organisation(s)

Department of Mineralogy and Crystallography

External organisation(s)

Masaryk University

Journal

American Mineralogist: an international journal of earth and planetary materials

Volume

102

Pages

867-875

No. of pages

9

ISSN

0003-004X

DOI

https://doi.org/10.2138/am-2017-5664

Publication date

04-2017

Peer reviewed

Yes

Austrian Fields of Science 2012

104026 Spectroscopy, 105116 Mineralogy

Keywords

ASJC Scopus subject areas

Geochemistry and Petrology, Geophysics

Portal url

https://ucrisportal.univie.ac.at/en/publications/11d34721-30a8-4438-932b-42d08b155caa