Ce–Nd codoping effect on the structural and optical properties of TiO2 nanoparticles

We report the changes in the structural and optical property of TiO2 nanoparticles on codoping Ce–Nd ions. X-ray diffraction clearly demonstrates the structural changes occurring in the codoped TiO2 nanoparticle. Oxygen defects disturb the TiO bonds in the TiO6 octahedra and result in the shifting and broadening of the Raman Eg peak. Pure TiO2 nanoparticles show absorption peak in the UV region. However, codoped TiO2 nanoparticles exhibit absorption peaks in the visible region corresponding to the f–d and f–f electronic transition of Ce3+ and Nd3+ in the crystalline environment of TiO2. The visible emission peaks of pure and codoped TiO2 nanoparticles are mainly associated with oxygen vacancies. Incorporation of cerium intensifies the visible emission peaks of TiO2 nanoparticles. On the other hand, codoping of Nd forms some non radiative recombination centres and increases the possibility of emission energy transfer among dopants, defects, thereby quenching the intensity of the visible emission peaks.

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► Codoping of Ce–Nd distorts the TiO2 lattice and generates oxygen vacancies.
► These oxygen defects decreases the crystallinity and shift the position of Eg Raman peak of TiO2.
► Absorption edge of TiO2 is shifted from UV to visible region on codoping.
► Doping of cerium increases the emission intensity of TiO2 nanoparticles.
► Codoping of Ce–Nd quenches the emission intensity of TiO2 by increasing the non radiative oxygen vacancies.