Phase control of yttrium (Y)-doped TiO₂ nanofibers and intensive visible photoluminescence

Highlights: • Yttrium (Y)-doped TiO₂ nanofibers were successfully fabricated by electrospinning. • The incorporation of Y into TiO₂ facilitates the anatase phase growth. • The optical band gap energy increased with Y-doping. • Y-doped TiO₂ nanofibers PL intensity enormously increased due to defect-related centers on the surface. - Abstract: Yttrium (Y)-doped TiO₂ nanofibers were successfully fabricated by electrospinning and the subsequent calcination of the as-spun nanofibers. The X-ray diffraction and Raman scattering results showed that the incorporation of Y into TiO₂ impedes the rutile-phase growth, facilitates the anatase phase growth. Estimated grain sizes are reduced from 15.71 nm to 8.8 nm with increasing Y-doping concentration. Raman scattering studies confirm the existence of slight brookite phase in case of Y-doped TiO₂ nanofibers. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) images revealed that the nanofibers comprised of nanoparticles and that Y-doping reduced the nanoparticle size. The optical band gap energy increased with increasing Y-doping, which can be ascribed to both quantum confinement effect and pure anatase phase transformation from mixed rutile-anatase phase. Y-doping induced a blue-shift of the broad visible photoluminescence (PL) peak and an increase of PL intensity with the concurrent decrease grain size. For 3 at.% Y-doped TiO₂ nanofibers PL intensity enormously increased due to defect-related centers on the surface