Highly Uniform Gd(OH)₃ and Gd₂O₃:Eu³⁺ Nanotubes: Facile Synthesis and Luminescence Properties

Uniform Gd(OH) 3 nanotubes have been prepared via a simple wet-chemical route at ambient pressure and low temperature, without any catalysts, templates, or substrates, in which Gd(NO 3 ) 3 was used as the gallium source and ammonia as the alkali. SEM and TEM images indicate that the as-obtained Gd(OH) 3 entirely consists of uniform nanotubes in high yield with diameters of about 40 nm and lengths of 200−300 nm. The temperature-dependent morphological evolution and the formation mechanism of the Gd(OH) 3 nanotubes were investigated in detail. Furthermore, the Gd 2 O 3 and Eu 3+ -doped Gd 2 O 3 nanotubes, which inherit their parents’ morphology, were obtained during a direct annealing process in air. The corresponding Gd 2 O 3:Eu 3+ nanotubes exhibit the strong red emission corresponding to the 5 D 0 − 7 F 2 transition of the Eu 3+ ions under UV light or low-voltage electron beam excitation, which might find potential applications in the fields such as light-emitting phosphors, advanced flat panel displays, or biological labeling.