کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5403805 | 1392768 | 2008 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
On the spectra luminescence properties of charoite silicate
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله

چکیده انگلیسی
Charoite is a hydrous alkali calcium silicate mineral [K4NaCa7Ba0.75Mn0.2Fe0.05(Si6O15)2(Si2O7)Si4O9(OH)·3(H2O)] exhibiting an intense lilac colour related to Mn2+ and Fe3+ colour centres. These ions also contribute to a strong luminescence at â¼585 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+, H2+ and 4He+ ions at RT and LT. The main peak, â¼585 nm, is linked to a transition 4T1,2 (G)â6A7(S) in Mn2+ ions in distorted six-fold coordination and the emission at â¼705 nm with Fe2+âFe3+ 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 Îa=0.219 Ã
, Îb=0.182Â Ã
; Îc=0.739Â Ã
. 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 340Â nm emission. Extrinsic defects such as the alkali (or hydrogen)-compensated [AlO4/M+] centres could be linked with the 390Â nm emission. Large variations in 585 and 705Â 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 4He+. The SRS-CL demonstrates strong spatial heterogeneity in the luminescence of the charoite.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Luminescence - Volume 128, Issue 3, March 2008, Pages 403-412
Journal: Journal of Luminescence - Volume 128, Issue 3, March 2008, Pages 403-412
نویسندگان
J. Garcia-Guinea, P.D. Townsend, N. Can, V. Correcher, L. Sanchez-Muñoz, A.A. Finch, D. Hole, M. Avella, J. Jimenez, M. Khanlary,