dc.contributor.author | Garcia-Guinea, J; Townsend, PD; Can, N; Correcher, V; Sanchez-Munoz, L; Finch, AA; Hole, D; Avella, M; Jimenez, J; Khanlary, M | |
dc.date.accessioned | 2020-07-01T08:48:27Z | |
dc.date.available | 2020-07-01T08:48:27Z | |
dc.date.issued | MAR | |
dc.date.issued | 2008 | |
dc.identifier.uri | http://hdl.handle.net/20.500.12481/9141 | |
dc.description.abstract | Charoite is a hydrous alkali calcium silicate mineral [K4NaCa7Ba0.75Mn0.2Fe0.05(Si6O15)(2)(Si2O7)Si4O9(OH) center dot 3(H2O)] exhibiting an intense lilac colour related to Mn2+ and Fe3+ colour centres. These ions also contribute to a strong luminescence at similar to 585 and 705 nm. This work studies the thermal dependence of these luminescent centres by (i) thermoluminescence (TL) of pre-heated and pre-irradiated charoite aliquots, (ii) by time-resolved cathodoluminescence (TRS-CL) at room and cryogenic temperatures (RT and CT), (iii) by spatially resolved spectra CL under scanning electron microscopy (SRS-CL-SEM) and (iv) by ion beam spectra luminescence (IBL) with H+, H-2(+) and He-4(+) ions at RT and LT. The main peak, similar to 585 nm, is linked to a transition T-4(1,2)(G)->(6)A(7)(S) in Mn2+ ions in distorted six-fold coordination and the emission at similar to 705 nm with Fe2+ -> Fe3+ oxidation in Si4+ lattice sites. Less intense UV-blue emissions at 340 and 390 nm show multi-order kinetic TL glow curves involving continuous processes of electron trapping and de-trapping along with an irreversible phase transition of charoite by de-hydroxylation and lattice shortening of Delta a = 0.219 angstrom, Delta b = 0.182 angstrom; Delta c = 0.739 angstrom. The Si-O stressed lattice of charoite has non-bridging oxygen or silicon vacancy-hole centres, and Si-O bonding defects which seem to be responsible for the 340 nm emission. Extrinsic defects such as the alkali (or hydrogen)-compensated [AlO4/M+] centres could be linked with the 390 nm emission. Large variations in 585 and 705 nm intensities are strongly temperature dependent, modifying local Fe-O and Mn-O bond distances, short-range-order luminescence centres being very resistant under the action of the heavy ion beam of He-4(+). The SRS-CL demonstrates strong spatial heterogeneity in the luminescence of the charoite. (C) 2007 Elsevier B.V. All rights reserved. | |
dc.title | On the spectra luminescence properties of charoite silicate | |
dc.title.alternative | JOURNAL OF LUMINESCENCE | |
dc.identifier.DOI-ID | 10.1016/j.jlumin.2007.09.008 | |
dc.identifier.volume | 128 | |
dc.identifier.issue | 3 | |
dc.identifier.startpage | 403 | |
dc.identifier.endpage | 412 | |
dc.identifier.issn/e-issn | 0022-2313 | |
dc.identifier.issn/e-issn | 1872-7883 | |