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2014
ACL
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Y.Ledemi, A.A.Trudel, V.Rivera, S.Chenu, E.Véron, L.A.O.Nunes, M.Allix, Y.Messaddeq, 'White Light and Multicolor Emission Tuning in Triply Doped Yb3+/Tm3+/Er3+ Novel Fluoro-phosphate Transparent Glass-ceramics', J. Mater. Chem. C 2 5046 (2014) doi:10.1039/c4tc00455h
New Yb3+, Er3+ and Tm3+ doped fluoro-phosphate glasses belonging to the system NaPO3-YF3-BaF2-CaF2 and containing up to 10 wt.% of rare-earth ion fluorides were prepared and characterized by differential scanning calorimetry, absorption spectroscopy and up-conversion emission spectroscopy under excitation by a 975 nm laser diode. Transparent and homogeneous glass-ceramics have been reproducibly obtained in view to manage the red, green and blue emission bands and generate white light. X-ray diffraction as well as electron microscopy techniques have confirmed the formation of fluorite-type cubic nanocrystals at the beginning of crystallization process while complex nanocrystalline phases are formed after longer heat-treatment. The prepared glass-ceramics exhibit high optical transparency even after 170h of thermal treatment. An improvement of up-conversion emissions intensity - from 10 to 160 times larger - was measured in the glass-ceramics if compared to the parent glass, suggesting an important incorporation of the rare-earth ions into the crystalline phase(s). The involved mechanisms and lifetime were described in details as a function of heat-treatment time. Finally, a large range of designable color rendering (from orange to turquoise through white) can be observed in these materials by controlling the laser excitation power and the crystallization rate.
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