Impact of Annealing Time on Structural Evolution of Pure and Dy3+-Doped CeO2 Nanopowder, Rietveld Refinement and Optical Behavior

This work reports about annealing time effect on structural and optical properties of pure and Dy3+-doped CeO2 nanocrystallites. The nanopowders with an average grain size 13-15nm are successfully synthesized via a conducive and neoteric Pechini-type sol-gel technique. Surface morphology, composition, band gap and photoluminescence properties of the prepared samples are examined by multifarious characterization techniques like Rietveld refinement, FESEM, HRTEM, FTIR, UV-Vis spectroscopy and PL. The effects of annealing time on structural parameters including lattice parameter, bond distance, bond angle, strain, crystallite size and texture coefficient are computed for all prepared samples which are further ensured by Rietveld refinement. In absorption spectra, blue shift in the band gap of as-prepared samples has been observed due to well-known quantum size effect, however, red shift is noticed in further annealed samples. PL emission peaks are observed in violet, blue and green regions that are devoted to various defect levels and color centers such as F, F+, F++, etc. It is suggested that defects like oxygen vacancies play vital role in tailoring the band gap of prepared samples and therefore enhance its utility in photonics and oxygen storage appliances.

Automated summary

This study investigates the effects of annealing time on the structural and optical properties of pure and Dy3+-doped CeO2 nanocrystals. The results show that annealing time influences the lattice parameters, bond angles, and photoluminescence properties, leading to changes in the band gap of the nanocrystals. Defect levels and color centers, such as oxygen vacancies, are found to play a significant role in tailoring the properties of the nanocrystals, making them potentially useful in photonics and oxygen storage devices.