Photocatalytic Activity and Optical Properties of Blue Persistent Phosphors under UV and Solar Irradiation

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C.R GARCIA

Blue phosphorescent strontium aluminosilicate powders were prepared by combustion synthesis route and a postannealing
treatments at different temperatures. X-ray diffraction analysis showed that phosphors are composed of two main hexagonal
phases: SrAl2O4 and Sr3Al32O51.The morphology of the phosphors changed from micrograins (1000∘C) to a mixture of bars and
hexagons (1200∘C) and finally to only hexagons (1300∘C) as the annealing temperature is increased. Photoluminescence spectra
showed a strong blue-green phosphorescent emission centered at ?em = 455 nm, which is associated with 4f65d1 → 4f6 (8S7/2
)
transition of the Eu2+. The sample annealed at 1200∘C presents the highest luminance value (40 Cd/m2) with CIE coordinates
(0.1589, 0.1972). Also, the photocatalytic degradation of methylene blue (MB) under UV light (at 365 nm) was monitored. Samples
annealed at 1000∘C and 1300∘C presented the highest percentage of degradation (32% and 38.5%, resp.) after 360 min. In the case
of photocatalytic activity under solar irradiation, the samples annealed at 1000∘C, 1150∘C, and 1200∘C produced total degradation
of MB after only 300 min. Hence, the results obtained with solar photocatalysis suggest that our powders could be useful for water
cleaning in water treatment plants.

Artículo-CEGRG 1 2016


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