Synthesis and White Light Emission of Rare Earth‐Doped HfO 2 Nanotubes

Luminescent nanotubes based on rare earth (RE) (Eu, Tb)‐doped hafnia (HfO 2 ) were prepared by radio frequency (RF) sputtering with electrospun polyvinylpyrolidone (PVP) nanofibers as templates. The nanotubes annealed at 500°C have a uniform structure with desired tubular morphologies. Various colors of photoluminescence (PL) could be easily obtained by tuning the concentrations of the RE ions in the HfO 2 host. The Eu‐ and Tb‐codoped HfO 2 (HfO 2 :Eu&Tb) nanotubes exhibited white light emissions under a 325 nm excitation. Good Commission International de I'Eclairage (CIE) coordinates (0.333, 0.323) and color temperature ( T c ) (5465 K) were achieved in the HfO 2 :Eu&Tb nanotubes. Experimental evidence showed that the presence of blue emission originates from the defect states in HfO 2 nanotubes, the green and the red emissions can be attributed to the inner 4 f shell transitions of corresponding Tb 3+ ions and Eu 3+ ions in HfO 2 shells, respectively. Compared with RE‐doped HfO 2 films, the nanotube samples showed intense white light emissions, revealing that the HfO 2 :Eu&Tb nanotubes are an efficient white light‐emission material.