Bright white up-conversion emission from sol–gel derived Yb3+/Er3+/Tm3+: Y2SiO5 nanocrystalline powders

Bright white up conversion emission has been observed in sol–gel derived Yb3+/Er3+/Tm3+: Y2SiO5 nanocrystalline powders when excited with the 950 nm emission of a laser diode. Measurements of the sample emission intensity dependence on the pumping power were performed to explain the up conversion mechanism. The CIE chromaticity coordinates (x, y) for white emission in X2–Y2SiO5 nanocrystalline form were found to be (0.334, 0.332) under 950 nm laser diode excitation.