Relationship between Microstructure Evolution and the Luminescent Properties of Eu3+-doped Yttrium Aluminum Garnet and Y2O3 Nano-powders

Eu3+-doped yttrium aluminum garnet (YAG) and Y2O3 composite phase nanoparticles were synthesized using a modified hydrothermal method. Sintering was performed at 800 °C, which is considerably lower than the sintering temperature used in the conventional method. Y3+ in YAG and Y2O3 was partially substituted with Na+ by adding NaNO3 into the solution during sample synthesis. The microstructures and phase transformation process were characterized through X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The obtained results verified that the addition of Na+ promoted crystallinity and grain growth of the three phases, namely, Y2O3, Y4Al2O9, and Y3Al5O12. Highly efficient luminescence properties excited by 254 and 365 nm ultraviolet were achieved. In conclusion, the remarkable enhancement of the luminescence intensity with the addition of Na+ should be attributed to grain growth and improvement of crystallinity.