THE SPECIATION OF NI AND CO IN SILICATE MELTS FROM OPTICAL ABSORPTION SPECTRA TO 1500°C
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dc.contributor.author | Keppler H. | |
dc.contributor.author | Bagdassarov N. | |
dc.date.accessioned | 2021-01-09T02:42:59Z | |
dc.date.available | 2021-01-09T02:42:59Z | |
dc.date.issued | 1999 | |
dc.identifier | https://elibrary.ru/item.asp?id=127898 | |
dc.identifier.citation | Chemical Geology, 1999, , 1, 105-115 | |
dc.identifier.issn | 0009-2541 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/22396 | |
dc.description.abstract | The optical absorption spectra of Co2+ and Ni2+ in haplogranitic glass and melt were measured from room temperature to 1500°C. For Co2+, a continuous decrease of the intensity of all bands with increasing temperature is observed both below and above the glass transition. This is attributed to a decrease of extinction coefficients with temperature. Co2+ is in a distorted tetrahedral environment both in the melt and in the quenched glass. The decrease of extinction coefficients with temperature may be related to a reduction of tetrahedral distortion. At low temperatures, a small fraction of Co2+ may be octahedrally coordinated, but spectroscopic evidence is not conclusive. Ni2+ is mostly in a distorted octahedral environment in the glass. Up to the glass transition temperature, the extinction coefficients of the bands of octahedral Ni2+ decrease slightly; however, beyond the glass transition, the intensity of the octahedral bands decrease rapidly and above 1300°C, the optical spectra are dominated by a band due to tetrahedral Ni2+, indicating a change of coordination with temperature. The equilibrium constant for the reaction Nioctahedral2+#Nitetrahedral2+ is estimated to be lnK=8.42-11.13 K/T, corresponding to a reaction enthalpy of 92 kJ/mol. Preliminary measurements suggest that the speciation of Ni2+ and Co2+ in basaltic systems is similar to that observed in haplogranite. Our results imply that the partitioning of Ni2+ between minerals and silicate melts should depend more strongly on temperature than for Co2+ and most other trace elements. | |
dc.subject | SILICATE MELTS | |
dc.subject | GLASSES | |
dc.subject | NICKEL | |
dc.subject | COBALT | |
dc.subject | OPTICAL SPECTROSCOPY | |
dc.title | THE SPECIATION OF NI AND CO IN SILICATE MELTS FROM OPTICAL ABSORPTION SPECTRA TO 1500°C | |
dc.type | Статья |
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