Show simple item record

Files in this item

Thumbnail

Item metadata

dc.contributor.authorHorsburgh, Nicola J.
dc.contributor.authorFinch, Adrian A.
dc.contributor.authorFriis, Henrik
dc.date.accessioned2023-04-27T15:30:05Z
dc.date.available2023-04-27T15:30:05Z
dc.date.issued2023-04-27
dc.identifier283883983
dc.identifier98264810-e024-4254-8f27-6b57dc209d21
dc.identifier85158068832
dc.identifier.citationHorsburgh , N J , Finch , A A & Friis , H 2023 , ' Lanthanide and yttrium substitution in natural fluorite ' , Physics and Chemistry of Minerals , vol. 50 , 15 . https://doi.org/10.1007/s00269-023-01239-4en
dc.identifier.issn0342-1791
dc.identifier.otherORCID: /0000-0002-3689-1517/work/134055981
dc.identifier.urihttps://hdl.handle.net/10023/27476
dc.descriptionFunding: Samples NJH-16-39 and NJH-16-41 were collected during fieldwork associated with the HiTech AlkCarb project, which was supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 689909. NJH gratefully acknowledges PhD funding from the NERC SoS RARE consortium NE/M010856/1 and the University of St Andrews. The luminescence spectroscopy facility used in the present study was funded by NERC grant NE/H002715/1. EPMA data were collected at the University of Edinburgh, UK, with the assistance of Dr Chris Hayward. For the purpose of open access, the authors have applied a CC BY public copyright licence to any Accepted Author Manuscript version arising.en
dc.description.abstractFluorite is one of the most common minerals in the crust and is of widespread economic importance. It shows strong UV-excited luminescence, variously attributed to defects within the fluorite structure and lanthanide substitutions. We present here a detailed chemical characterisation of a suite of natural fluorite samples, chosen to represent the range of compositions observed in nature. We perform X-ray excited luminescence spectroscopy on the samples as a function of temperature (20–673 K) in the wavelength range 250–800 nm to provide insights into physical defects in the lattice and their interactions with lanthanide substituents in natural fluorite. Most broad bands in the UV are attributed to electronic defects in the fluorite lattice, whereas sharp emissions are attributed to intra-ion energy cascades in trivalent lanthanides. Lanthanides are accommodated in fluorite by substitution for Ca2+ coupled with interstitial F−, O2− (substituting for F−) and a variety of electronic defect structures which provide local charge balance. The chondrite-normalised lanthanide profiles show that fluorite accommodates a greater proportion of heavy lanthanides (and Y) as the total Rare Earth Element (REE) concentration increases; whereas cell parameters decrease and then increase as substitution continues. Luminescence intensity also goes through a maximum and then decreases as a function of REE concentration. All three datasets are consistent with a model whereby lanthanides initially act as isolated centres, but, beyond a critical threshold (~ 1000 ppm), cluster into lanthanide-rich domains. Clustering results in shorter REE-O bond distances (favouring smaller heavier ions), a larger unit cell but more efficient energy transfer between lanthanides, thereby promoting non-radiative energy loss and a drop in the intensity of lanthanide emission.
dc.format.extent14
dc.format.extent4170705
dc.language.isoeng
dc.relation.ispartofPhysics and Chemistry of Mineralsen
dc.subjectXEOLen
dc.subjectRadioluminescenceen
dc.subjectDefect clusteringen
dc.subjectLanthanidesen
dc.subjectRare earthsen
dc.subjectQD Chemistryen
dc.subjectGE Environmental Sciencesen
dc.subjectDASen
dc.subjectMCCen
dc.subject.lccQDen
dc.subject.lccGEen
dc.titleLanthanide and yttrium substitution in natural fluoriteen
dc.typeJournal articleen
dc.contributor.sponsorEuropean Commissionen
dc.contributor.sponsorNERCen
dc.contributor.institutionUniversity of St Andrews. Centre for Energy Ethicsen
dc.contributor.institutionUniversity of St Andrews. School of Earth & Environmental Sciencesen
dc.contributor.institutionUniversity of St Andrews. Scottish Oceans Instituteen
dc.contributor.institutionUniversity of St Andrews. St Andrews Isotope Geochemistryen
dc.identifier.doi10.1007/s00269-023-01239-4
dc.description.statusPeer revieweden
dc.identifier.grantnumber689909en
dc.identifier.grantnumberNE/M010856/1en


This item appears in the following Collection(s)

Show simple item record