Co2+-doped diopside: crystal structure and optical properties

Skogby, Henrik (författare): Naturhistoriska riksmuseet,Enheten för geovetenskap

Hålenius, Ulf (författare): Naturhistoriska riksmuseet,Enheten för geovetenskap

(creator_code:org_t)

2017-12-09
2018
Engelska.
Ingår i: Physics and chemistry of minerals. - : Springer Science and Business Media LLC. - 0342-1791 .- 1432-2021. ; 45:5, s. 443-461

Relaterad länk:: https://urn.kb.se/re...; visa fler...; https://doi.org/10.1...; visa färre...

Abstract Ämnesord

Stäng

Synthetic clinopyroxenes along the CaMgSi2O6– CaCoSi2O6 join were investigated by a combined chemical-structuralspectroscopic approach. Single crystals were synthesized by flux growth methods, both from Ca-saturated and Ca-deficient starting compositions. Single crystal structure refinements show that the incorporation of Co2+ at the octahedrally coordinated cation sites of diopside, increases the unit-cell as well as the M1 and the M2 polyhedral volumes. Spectroscopic investigations (UV–VIS–NIR) of the Ca-rich samples reveal three main optical absorption bands, i.e. 4T1g → 4T2g(F), 4T1g → 4A2g(F) and 4T1g → 4T1g(P) as expected for Co2+ at a six-coordinated site. The bands arising from the 4T1g → 4T2g(F) and the 4T1g → 4T1g(P) electronic transitions, are each split into two components, due to the distortions of the M1 polyhedron from ideal Oh- symmetry. In spectra of both types, a band in the NIR range at ca 5000 cm−1 is caused by the 4A2g → 4T1g(F) electronic transition in Co2+ in a cubic field in the M2 site. Furthermore, an additional component to a band system at 14,000 cm−1, due to electronic transitions in Co2+ at the M2 site, is recorded in absorption spectra of Ca-deficient samples. No variations in Dq and Racah B parameters for Co2+ at the M1 site in response to compositional changes, were demonstrated, suggesting complete relaxation of the M1 polyhedron within the CaMgSi2O6– CaCoSi2O6 solid solution.

Av författaren/redakt...: Gori, Claudia; Tribaudino, Mari ...; Mezzadri, France ...; Skogby, Henrik; Hålenius, Ulf

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