Flame aerosol deposition and annealing of Y3Al5O12:Tb phosphor coatings

Sub-micrometer-sized powders of Y3Al5O12:Tb phosphor (d(SEM) = 320 nm) were prepared by flame-assisted spray pyrolysis of aqueous precursors in a premixed propane/air flame and in situ deposited onto quartz substrates. Phosphor screens with densities of up to 0.7 mg cm(-2) could be produced within 20 min. As-deposited coatings were amorphous and required a thermal post-treatment. After annealing in an oven for 2 h (T >= 900 degrees C), the yttrium aluminum garnet phase (YAG:Tb) was obtained. Alternatively, the phosphor coatings were treated by an impinging flame in the same setup used for the deposition. Quasi-amorphous Y3Al5O12:Tb coatings demonstrated bright green photoluminescence upon flame annealing at T approximate to 1100 degrees C for just several minutes and could outperform YAG:Tb when excited in the wavelength ranges 205-220 nm and 230-260 nm. For example, brightness of emission from the quasi-amorphous coatings was up to five times higher than that of the fully crystalline YAG:Tb phosphor at a technically important wavelength of 254 nm. (C) 2012 Elsevier B.V. All rights reserved.