Effect of excitation level on the photoluminescence of barium thiogallate activated with europium and cerium ions |
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Authors: | V. Z. Zubialevich E. V. Lutsenko A. V. Danilchyk E. V. Muravitskaya G. P. Yablonskii A. M. Pashaev B. G. Tagiev O. B. Tagiev S. A. Abushov |
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Affiliation: | (1) National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan |
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Abstract: | The photoluminescence of barium thiogallates doped with Eu2+, Ce3+, and Eu2+ + Ce3+ ions is studied over a wide range of excitation levels (10–3–106 W/cm2). Introduction of 3 at.% Eu and 3 at.% Ce instead of 5 at.% Eu into a BaGa2S4 matrix doubles the luminescence quantum yield of the phosphor. Doped BaGa2S4 exhibits a high linearity in its luminescence intensity as a function of excitation level (a constant efficiency) up to 2·104 W/cm2 for excitation pulse durations of 8 ns, which corresponds to cw pumping at a power density of about 5·102 W/cm2 in terms of the concentration of excited ions. It is shown that using BaGa2S4:Eu,Ce along with the “yellow” phosphor of a Nichia NS6L083 LED may increase its color rendering index from 0.64 to 0.80 with no reduction in its luminous efficiency. |
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