Journal
JOURNAL OF LUMINESCENCE
Volume 129, Issue 5, Pages 416-422Publisher
ELSEVIER
DOI: 10.1016/j.jlumin.2008.10.019
Keywords
Phosphors; Photoluminescence; Decay time; Temperature sensing; Quenching rate; X-ray diffraction
Categories
Funding
- Engineering and Physics Sciences Research Council (EPSRC)
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This research is aimed at developing an optical sensor for remotely measuring human skin temperature in electromagnetically hostile environments, such as within a magnetic resonance imaging (MRI) scanner. In this feasibility study, various concentrations of europium-doped lanthanum oxysulphide (La2O2S: Eu-0.1-15 mol% (m/o)) and terbium-doped lanthanum oxysulphide (La2O2S: Tb-0.005-50 m/o) have been investigated in terms of crystallinity, photoluminescent (PL) spectral and decay time characteristics. For both phosphors, X-ray diffraction (XRD) has shown that as dopancy increases, the (1 0 0) and (0 0 2) reflections merge and there is a reduction in the c-axis parameter as well as the crystallite size. Photoluminescent characterisation (337 nm excitation) has also shown a dependency to dopant concentration through variance of peak intensity. Temperature dependent decay time measurements were carried out over a low temperature range 5-60 degrees C. Optimum brightness of these temperature dependent lines is achieved at concentrations of I and 10 m/o for La2O2S: Eu and La2O2S: Tb respectively. However, optimum temperature dependency is achieved at lower concentration for La2O2S: Eu, specifically at 0.1 m/o. In comparison to conventional phosphor temperature dependent characteristic, La2O2S: Tb showed an increase in decay time with respect to temperature for concentrations above 2 m/o. (C) 2008 Elsevier B.V. All rights reserved.
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