Effect of temperature on the photoluminescence of EU3+ doped TiO2 nanofibers prepared by electrospinning

Eu3+ doped titania (TiO2:Eu3+) nanofibers were synthesized by the electrospinning technique. The samples were calcined at different temperature in air. The structural and spectral information of the samples was characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), Raman spectrum, photoluminescence (PL). FESEM reveal that the nanofibers have the diameter between 30 and 70 nm. XRD measurements show that the crystal structure transforms from anatase to rutile phase with the increasing of calcined temperature. The photoluminescence spectra exhibit visible emission peaks centered at 550, 590, and 612, 660 nm due to D-5(1)-F-7(1), D-5(0)-F-7(1), D-5(0)-F-7(2) and D-5(0)-F-7(3) transition of Eu3+ ions and the PL intensities increase with the increasing of calcined temperature. Atlower temperature this is attributed to the energy transfer from TiO2 host to the Eu3+ ions. But at higher calcined temperature, near-infrared photoluminescence peaking at 815 nm appears due to the rutile TiO2 and the intensity of visible photoluminescence decreases, which is attributed to pure phase TiO2 host and the energy back transfer from Eu3+ ions to the TiO2 host.