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Keywords = La Sassa quartz

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11 pages, 2927 KiB  
Article
Unusual Luminescence of Quartz from La Sassa, Tuscany: Insights on the Crystal and Defect Nanostructure of Quartz Further Developments
by Andrea Maurizio Monti, Giulia Ricci, Marco Martini, Anna Galli, Federico Lugli, Maria Chiara Dalconi and Gilberto Artioli
Minerals 2022, 12(7), 828; https://doi.org/10.3390/min12070828 - 29 Jun 2022
Viewed by 1927
Abstract
Quartz luminescence finds applications on many fields, but much work still needs to be done to precisely characterize it. In this work, we made further developments on the study of luminescence of quartz from La Sassa, Tuscany: a sample with unique properties in [...] Read more.
Quartz luminescence finds applications on many fields, but much work still needs to be done to precisely characterize it. In this work, we made further developments on the study of luminescence of quartz from La Sassa, Tuscany: a sample with unique properties in this regard. Photoluminescence (PL) measurements allowed study of the excitation profile of the previously reported luminescence, showing an excitation maximum at around 4.3 eV, among other minor ones. This kind of luminescence has also been studied as a function of X-ray irradiation, showing that ionizing radiation desensitizes the photoluminescence emissions. New radioluminescence (RL) measurements have been done to study the effect of thermal annealing at 1000 °C, showing a more complex emission picture in the red region (1.8–2.0 eV), with multiple emissions. The data presented here allow more precise assumptions regarding the assignment of the centers responsible for each emission. The assignment has been confirmed by chemical profiles measured by laser-ablation inductively coupled plasma (ICP) mass spectrometry. The previously tentative assignment of non-bridging oxygen hole centers (NBOHCs) has been disproved for the PL and LIF emissions and confirmed for the RL ones. Full article
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14 pages, 3196 KiB  
Article
Unusual Luminescence of Quartz from La Sassa, Tuscany: Insights on the Crystal and Defect Nanostructure of Quartz
by Giulia Ricci, Andrea Maurizio Monti, Renato Pagano, Marco Martini, Luisa Caneve and Gilberto Artioli
Minerals 2021, 11(12), 1345; https://doi.org/10.3390/min11121345 - 30 Nov 2021
Cited by 5 | Viewed by 3462
Abstract
Quartz from La Sassa (Tuscany, Italy) presents a unique luminescence related to intrinsic and extrinsic defects in the crystal lattice due to the growth mechanisms in hydrothermal conditions. The bright fluorescence under the UV lamp was apparent to collectors since the early 1970s, [...] Read more.
Quartz from La Sassa (Tuscany, Italy) presents a unique luminescence related to intrinsic and extrinsic defects in the crystal lattice due to the growth mechanisms in hydrothermal conditions. The bright fluorescence under the UV lamp was apparent to collectors since the early 1970s, and it entered the literature as a reference case of yellow-luminescent quartz. Early reports present the history of the discovery, the geological context, and preliminary luminescence measurements of the quartz nodules, suggesting various activators as potentially responsible of the peculiar luminescence effects: uranyl groups (UO22+), rare earths (Tb3+, Eu3+, Dy3+, Sm3+, Ce3+) and polycyclic aromatic compounds (PAH). Here, we report a full investigation of the La Sassa material, by a multi-analytical approach encompassing cathodoluminescence optical microscopy (OM-CL), laser-induced fluorescence (LIF), wavelength resolved thermally stimulated luminescence (WR-TSL), trace elements analysis by mass spectrometry (ICP-MS) and Raman spectroscopy (RS). The results provide a significant step forward in the interpretation of the luminescence mechanisms: the main luminescent centres are identified as alkali-compensated (mainly Li+ and Na+, K+ and H+) aluminum [AlO4/M+]0 centres substituting for Si, where the recombination of a self-trapped exciton (STE) or an electron at a nonbridging oxygen hole centre (NBOHC) are active. Full article
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