Phase stabilization and luminescence properties of Gd3Al5O12: Ce nanopowders prepared by Pechini method: Effect of pH and annealing temperature

Gd3Al5O12: 1 at. % Ce3+ (GAG: Ce) nanopowders have been synthesized by the Pechini sol-gel method. The effect of pH of the solution and the annealing temperature on phase stabilization, secondary phase evolution, particle morphology and luminescence properties of GAG: Ce3+ were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and photoluminescence spectroscopy. XRD analysis indicated that the growth of cubic structure of garnet is strongly influenced by the pH of the solution and the annealing temperature. Mixed phases of Gd3Al5O12, GdAlO3 in orthorhombic and hexagonal phases have been observed. The powder prepared with pH = 7 was suitable for obtaining more stable GAG phase. Rietveld refinement revealed that the percentage of the cubic phase increased from 38% to 79% when increasing the annealing temperature from 1000 degrees C to 1500 degrees C. FE-SEM/EDS observations showed that increasing annealing temperatures from 1000 degrees C to 1500 degrees C resulted in an increase of average particle size from 700 nm to 1.5 mu m and a decrease of Gd/Al from 0.79 to 0.59. The characteristic emission band of Ce3+ ions from the 5d -> 4f transition localized at 530 nm was observed for all samples. The higher emission intensity was obtained for the sample prepared with pH = 7 and annealed at 1500 degrees C showing that the annealing at higher temperatures enhances the phase stability to form a purer garnet structure and increases the emission performance of GAG: Ce3+ nanopowders prepared at neutral pH.

Automated summary

Gd3Al5O12: 1 at. % Ce3+ (GAG: Ce) nanopowders were synthesized by the Pechini sol-gel method. The effect of solution pH and annealing temperature on phase stabilization, particle morphology, and luminescence properties of GAG: Ce3+ was investigated. The study found that the appropriate pH and higher annealing temperature can enhance the stability and luminescence performance of GAG: Ce3+.