Spectral investigation on terbium activated yttrium
oxysulphide phosphors
Laura Mureşan1, Elisabeth-Jeanne Popovici1, Amalia Hristea1,
Emil Indrea 2 and Marilena Vasilescu3
1“Raluca- Ripan” Institute for Research in Chemistry, 30 Fântânele, 3400 Cluj-Napoca, Romania
2National Institute for Research and Development of Isotopic and Molecular Technologies Cluj-Napoca, P. O. Box 700, Romania
3I.G. Murgulescu" Institute of Physical Chemistry of the Romanian Academy, 202 Spl. Independentei, Bucureşti, Romania
Terbium activated yttrium oxysulfides phosphors Y2O2S:Tb are of great interest for the manufacture of X-ray intensifying screens [1,2]. Y2O2S:Tb utilization depends on particle size distribution and luminescent properties that are regulated during the phosphor synthesis stage [3].
The present work investigates the influence of synthesis conditions on optical and structural properties of Y2O2S:Tb phosphor prepared by solid state reaction route.
Homogeneous mixtures of Y2O3, Tb4O7, flux and sulfur were fired at 1200-1400ºC for 4-8 hours. The structural characteristics and luminescence properties were evaluated on the basis of X-ray diffraction patterns and excitation or emission spectra.
The activator concentration, flux composition and thermal treatement regime influences the phosphor optical properties i.e. photo- and cathodo-luminescence colour and efficiency. The relative intensity of the four characteristic emission bands namely 485 nm ( 5D4 7F6 ), 545 nm ( 5D4 7F5 ), 585 nm (5D4 7F4) and 620 nm (5D4 7F3 ) depends on terbium concentration (fig.1, fig.2).
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Fig.1 Emission spectrum of a representative sample of Y2O2S:Tb [7 mol%Tb; Na2CO3- Na3PO4;1200ºC; 4h]
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Fig.2. Intensity of the green emission band verus terbium concentration
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