Synthesis and Optical Properties of R2O2S:Ln3+ (R = Gd, Y; Ln = Eu, Tb).

An (Y0.95Eu0.05)2O2S solid solution (hexagonal crystal system, sp. gr. P3m1, a = 3.810 Å, c = 6.62 Å, V = 83.269 Å3) has been prepared via hydrogen reduction of the (Y0.95Eu0.05)2(SO4)3 sulfate, followed by sulfidation of the reaction products. Heat treatment in flowing H2S of (Gd0.95Tb0.05)2(SO4)3 and (Gd0.95Tb0.05)2O3 prepared via cohydrolysis of gadolinium and terbium sulfates in a water–alcohol solution of urea and annealed in an inert atmosphere has been shown to yield (Gd0.95Tb0.05)2O2S (hexagonal crystal system, a = 3.852 Å, c = 6.668 Å, V = 89.53 Å3). We have determined the phase composition of the synthesized samples, investigated their morphology, and examined the effect of the synthesis method on the shape and size of their particles. Investigation of the optical properties of the synthesized phosphors has demonstrated that all of them exhibit efficient luminescence in the green spectral region under UV excitation. [ABSTRACT FROM AUTHOR]