On the presence of hydrous defects in differently coloured wulfenites (PbMoO4): an infrared and optical spectroscopic study
- Author(s)
- D. Talla, M. Wildner, Anton Beran, R. Skoda, Zdenek Losos
- Abstract
Several samples of wulfenite, PbMoO4, varyingin colour from colourless to yellow, orange and red, havebeen characterised by means of IR and optical absorptionspectroscopy and by microprobe analyses. A distinctpleochroic band group with absorption maxima centred at3,380 and 3,150 cm-1 can be seen in the IR spectra ofwulfenite single-crystals, indicating the presence ofhydroxyl groups. The pleochroic and thermal behaviour ofthe OH stretching bands along with deuteration experiments,as well as results obtained from synthetic fluxgrownsamples, exclude the presence of submicroscopichydrous mineral inclusions as their primary origin. Thepleochroic scheme and the band positions were used topostulate a model for the OH incorporation mode, based onthe assumption of vacancies on Mo and Pb sites in thestructure of this ‘nominally anhydrous mineral’. Opticalabsorption spectra of coloured natural samples show abroad and polarised band around 23,000-24,000 cm-1,preceding the fundamental UV absorption edge, which hasbeen identified as the reason for the colour of the mineral.The comparison with synthetic PbMoO4 single-crystals,doped with variable amounts of Cr6?, yielded conclusiveevidence that trace amounts of the CrO42- anion group,substituting for MoO42-, determine the variable colour.Besides, in one sample, trace amounts of Nd3? have beenspectroscopically identified.
- Organisation(s)
- Department of Mineralogy and Crystallography
- External organisation(s)
- Masaryk University
- Journal
- Physics and Chemistry of Minerals
- Volume
- 40
- Pages
- 757-769
- No. of pages
- 13
- ISSN
- 0342-1791
- DOI
- https://doi.org/10.1007/s00269-013-0610-8
- Publication date
- 11-2013
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 1030 Physics, Astronomy, 105116 Mineralogy
- Keywords
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/ef7152a3-7740-4ac5-ac53-328615a7c57a