Structural and spectral properties of red light emitting Eu3+ activated TiO2 nanophosphor for white LED application

The structural and luminescent properties of Eu3+ doped TiO2 nanophosphors synthesized by low cost combustion method were investigated. The X-ray diffraction analysis revealed that crystallite size decreases with doping concentration. Lattice volume expansion occurred due to the substitution of Ti4+ ions by larger ionic radii ions Eu3+. FESEM images showed prepared phosphors to be nano size spherical shaped particles. Energy band gap of 3 mol% Eu3+ doped samples decreased to 3.15 eV due to doping effect. The Eu3+ doped TiO2 nanophosphors exhibited main red emission peak centered at 616 nm under 395 nm UV light excitation. Concentration quenching was observed at 3 mol% doping, that has been ascribed to dipole-dipole interaction. The covalent nature of Eu-O bond and environment around Eu3+ ions were discussed using Judd-Ofelt (J-O) intensity parameters. Internal quantum efficiency was calculated using excited state lifetime 5D0 state of Eu3+ ion and J-O theory. The CIE colour coordinates and colour purity were calculated using the spectral energy distribution function. Low excited state life time indicated that Eu3+ doped TiO2 can be used as red emitting phosphor for white light emitting diode applications.