The State of Trace Elements (In, Cu, Ag) in Sphalerite Studied by X-Ray Absorption Spectroscopy of Synthetic Minerals

Trofimov, N.D.; Trigub, A.L.; Tagirov, B.R.; Filimonova, O.N.; Evstigneeva, P.V.; Chareev, D.A.; Kvashnina, K.O.; Nickolsky, M.S.

Авторы: Trofimov Nikolay D., Trigub Alexander L., Tagirov Boris R., Filimonova Olga N., Evstigneeva Polina V., Chareev Dmitriy A., Kvashnina Kristina O., Nickolsky Maximilian S.
Журнал: Minerals
Том: 10
Номер: 7
Год издания: 2020
Первая страница: 640
Последняя страница: 640
DOI: 10.3390/min10070640
Аннотация: The oxidation state and local atomic environment of admixtures of In, Cu, and Ag insynthetic sphalerite crystals were determined by X-ray absorption spectroscopy (XAS). The sphaleritecrystals doped with In, Cu, Ag, In–Cu, and In–Ag were synthesized utilizing gas transport, salt flux,and dry synthesis techniques. Oxidation states of dopants were determined using X-ray absorptionnear edge structure (XANES) technique. The local atomic structure was studied by X-ray absorptionfine structure spectroscopy (EXAFS). The spectra were recorded at Zn, In, Ag, and Cu K-edges. In allstudied samples, In was in the 3+ oxidation state and replaced Zn in the structure of sphalerite, whichoccurs with the expansion of the nearest coordination shells due to the large In ionic radius. In thepresence of In, the oxidation state of Cu and Ag is 1+, and both metals can form an isomorphoussolid solution where they substitute for Zn according to the coupled substitution scheme 2Zn2+ ↔Me+ + In3+. Moreover, Ag K-edges EXAFS spectra fitting, combined with the results obtained forIn- and Au-bearing sphalerite shows that the Me-S distances in the first coordination shell in thesolid solution state are correlated with the ionic radii and increase in the order of Cu < Ag < Au.The distortion of the atomic structure increases in the same order. The distant (second and third)coordination shells of Cu and Ag in sphalerite are split into two subshells, and the splitting is morepronounced for Ag. Analysis of the EXAFS spectra, coupled with the results of DFT (Density FunctionTheory) simulations, showed that the In–In and Me+–In3+ clustering is absent when the metals arepresent in the sphalerite solid solution. Therefore, all studied admixtures (In, Cu, Ag), as well as Au,are randomly distributed in the matrix of sphalerite, where the concentration of the elements in the“invisible” form can reach a few tens wt.%.
Добавил в систему: Трофимов Николай Дмитриевич

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The State of Trace Elements (In, Cu, Ag) in Sphalerite Studied by X-Ray Absorption Spectroscopy of Synthetic Mineralsстатья Исследовательская статья

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