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Non-integral hybrid...
Non-integral hybrid ions in tourmaline: buffering and geo-thermometry
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- Ferrow, Embaie (författare)
- Lund University,Lunds universitet,Berggrundsgeologi,Geologiska institutionen,Naturvetenskapliga fakulteten,Lithosphere and Biosphere Science,Department of Geology,Faculty of Science
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(creator_code:org_t)
- Schweizerbart, 2009
- 2009
- Engelska.
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Ingår i: European Journal of Mineralogy. - : Schweizerbart. - 1617-4011 .- 0935-1221. ; 21:1, s. 241-250
- Relaterad länk:
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http://dx.doi.org/10...
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https://lup.lub.lu.s...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- The tourmaline group of minerals is indeed an enigma. Experimental data from optical spectroscopy, electron microscopy, and Mossbauer spectroscopy reveal a host of physical properties that lack a common structural clarification. For example, tourmaline samples change colour when irradiated with X-ray and gamma-ray radiations some reverting back when heated in air; exhibit simultaneous oxidation and reduction on annealing in an atmosphere of H-2; display different plane group symmetries under TEM; possess the most complicated Mossbauer spectra of all Fe-bearing silicates. In this study, four Brazilian samples were chosen for detailed study by Mossbauer spectroscopy to find out a common structural factor to the physical anomalies reported in the literature. It was found out that the tourmaline group of minerals contain multi-valence elements that are involved in electron exchange between the edge-sharing asymmetric Y and Z crystallographic sites. It is conceivable that the host of physical properties recorded in the literature could be due to the inherent structural misfit between the Y and Z sites and the mechanisms adopted to reduce the strain associated along the shared edges. The complexity of non-integral oxidation states possible - due to electron sharing among the different multi-valence elements present in the structure - further enhances the diverse physical properties observed. Moreover, on heating in air, no net oxidation or reduction takes place in the tourmaline group of minerals over a temperature range as long as there are electron donors and acceptors left in the structure, serving simultaneously as potential single-phase buffers and geo-thermometers.
Ämnesord
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geologi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geology (hsv//eng)
Nyckelord
- hybrid ions
- tourmaline
- Mossbauer
- buffer
- geo-thermometer
Publikations- och innehållstyp
- art (ämneskategori)
- ref (ämneskategori)
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