Shedding light onto the spectra of lime, part 2: Raman spectra of Ca and Mg carbonates, and the role of d-block element luminescence

Schmid, Thomas; Kraft, Ronja; Dariz, Petra (2021). Shedding light onto the spectra of lime, part 2: Raman spectra of Ca and Mg carbonates, and the role of d-block element luminescence Journal of Raman Spectroscopy, 52(8), pp. 1462-1472. John Wiley & Sons 10.1002/jrs.6174

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We previously described the observation of a characteristic narrowband red luminescence emission of burnt lime (CaO), whose reason was unknown so far. This study presents Raman spectra of Mg5(CO3)4(OH)2∙4H2O, Mg5(CO3)4(OH)2, MgCO3, CaMgCO3, and CaCO3 (in limestone powder) as well as luminescence spectra of their calcination products. Comparison of the latter revealed MgO:Cr3+ as the source of the red lime luminescence in all studied samples, containing magnesium oxide either as major component, minor component, or trace. Spectral characteristics and theoretical background of the luminescence emission of d-block elements integrated in crystal lattices are discussed with the aim of sharpening the awareness for this effect in the Raman community and promoting its application in materials analysis. The latter is demonstrated by the Raman microspectroscopic imaging of the distributions of both, Raman-active and Raman-inactive phases in clinker remnants in a 19th-century meso Portland cement mortar sample, which contain relatively high amounts of free lime detected in the form of both, luminescing CaO and Raman-scattering Ca(OH)2, owing to exposure of the surface of the thin section to humid air. A combination of light and Raman spectroscopy revealed a calcium-magnesium-iron sulphide phase, indicating sulphurous raw materials and/or solid fuels employed in the calcination process, which in contrast to previously described morphologies of sulphides in cement clinker form extensive greenish black layers on free lime crystals.

Item Type:	Journal Article (Original Article)
Division/Institute:	Bern Academy of the Arts Bern Academy of the Arts > Institute Materiality in Art and Culture Bern Academy of the Arts > Institute Materiality in Art and Culture > Material analyses
Name:	Schmid, Thomas; Kraft, Ronja and Dariz, Petra
Subjects:	N Fine Arts > NA Architecture N Fine Arts > NK Decorative arts Applied arts Decoration and ornament Q Science > QD Chemistry T Technology > TH Building construction
ISSN:	0377-0486
Publisher:	John Wiley & Sons
Funders:	[UNSPECIFIED] Deutsche Forschungsgemeinschaft
Language:	English
Submitter:	Petra Dariz
Date Deposited:	25 Jan 2022 15:37
Last Modified:	25 Jan 2022 15:37
Publisher DOI:	10.1002/jrs.6174
Uncontrolled Keywords:	Luminescence, magnesium carbonates, calcium carbonates, MgO:Cr3+, meso Portland cement
ARBOR DOI:	10.24451/arbor.16498
URI:	https://arbor.bfh.ch/id/eprint/16498