Synthesis and Eu3+ concentration-dependent photoluminescence of Gd2−xEuxO3 nanowires

The nanowire growth behavior and photoluminescence characteristics of red-emitting oxide phosphor Gd2−xEuxO3 have been investigated in the function of activator (Eu3+) concentrations (x=0.08, 0.12, 0.16, 0.20, and 0.24). Nanowires of Gd2−xEuxO3 phosphor were prepared by the dehydration of corresponding hydroxides Gd1−x/2Eux/2(OH)3 obtained by the hydrothermal reaction. Highly uniform nanowires of 20-30 nm in diameter can grow up to several tens of micrometers in length. A number of defects on the surface of Gd1.92Eu0.08O3 nanowires, which are induced during structural transformation from hexagonal hydroxide to cubic oxide, strongly decrease the luminescence efficiency in comparison with that of the bulk phosphor. In contrast, the photoemission intensity of nanowires is significantly improved with increasing Eu3+ content (x) of Gd2−xEuxO3 solid solution. The highest relative emission intensity of nanowires is observed when the x value is close to x=0.20. This content is much higher than the optimal concentration of Eu3+ (x=0.08-0.10) for the bulk Gd2O3:Eu powder.