Synthesis of nano-scaled yttrium aluminum garnet phosphor by co-precipitation method with HMDS treatment

The present paper describes the process of preparing nano-scaled and well-crystallized cerium-doped yttrium aluminum garnet (YAG:Ce) crystalline phosphors synthesized by co-precipitation method with the addition of hexamethyldisilazane (HMDS) as OH-scavenging reagent. Thermal analyzer and X-ray diffractometer measurements showed that pure YAG phase could be got at the temperature of 900 °C lower than that by solid-state method. It was also found that smaller size crystallites (∼33 nm) were made after the HMDS treatment under the transmission electron microscope (TEM) observation. We inferred that it was achieved by reducing the surface condensing hydroxyl groups and by restricting the grain boundary motion due to second-phase particles pinning. Meanwhile, optical properties of YAG:Ce prepared in the present work were examined and showed that the photoluminescence intensity of the co-precipitated YAG:Ce crystallites plus HMDS treatment was better than those prepared by solid-state reaction or co-precipitation without any further treatment. It was proposed that the existing second-phase particles as well as higher specific surface area of nano-scaled YAG:Ce crystallites enhance the absorption of excitation.