Nanostructures and photoluminescence properties of Gd2O 3:Eu red-phosphor prepared via hydrothermal route

Abstract

Various nanostructures (nanorods, nanowires, nanotubes, nanospheres) of Gd0.96Eu0.04(OH)3 have been prepared by hydrothermal reactions at different pHs and temperatures. The aspect ratios of one-dimensional nanostructures are strongly dependent on the solution pH. Subsequent dehydrations of these hydroxides at higher than 500°C lead to the formation of Gd2O3:Eu phosphors with different nanostructures. Interestingly, the shapes of nanorod and nanowire obtained under hydrothermal pressures are retained after the structural transformation from hexagonal Gd(OH)3:Eu to cubic Gd2O3:Eu at high temperatures. Gd2O3:Eu nanowires can grow up to 20-30 nm in diameter and several tens of micrometers in length. In contrast, the nanotube structure of Gd(OH)3:Eu is collapsed to produce the spherical Gd2O3:Eu nanoparticles after dehydration process. A significant change of morphology induced by an adjustment of pH of the initial solution for hydrothermal synthesis of Gd(OH)3:Eu strongly affect the photoluminescence efficiency of Gd2O3:Eu phosphor. The relative emission intensity of Gd2O3:Eu is reduced with increasing the aspect ratio of nanoparticles, the weakest emission being observed with nanowires of the highest aspect ratio.