Synthesis and White Light Emission of Rare Earth-Doped HfO2 Nanotubes

Luminescent nanotubes based on rare earth (RE) (Eu, Tb)‐doped hafnia (HfO2) 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 HfO2 host. The Eu‐ and Tb‐codoped HfO2 (HfO2: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 (Tc) (5465 K) were achieved in the HfO2:Eu&Tb nanotubes. Experimental evidence showed that the presence of blue emission originates from the defect states in HfO2 nanotubes, the green and the red emissions can be attributed to the inner 4f shell transitions of corresponding Tb3+ ions and Eu3+ ions in HfO2 shells, respectively. Compared with RE‐doped HfO2 films, the nanotube samples showed intense white light emissions, revealing that the HfO2:Eu&Tb nanotubes are an efficient white light‐emission material.