Nd-oxide-based nanoparticle-embedded transparent and photoluminescent composite films

In this study, we fabricated Nd-based PL composites by embedding Nd compounds in a transparent resin and investigated the relationship between the size of Nd-based particles and PL properties. Nd(iii)-based photoluminescent composite films were fabricated using neodymium nitrate hexahydrate and transparent urethane resin. The resulting Nd-based composite film was pale blue in color. The composite films exhibited near-infrared PL properties with a peak at 1.06 μm (⁴F_3/2 → ⁴I_11/2) by irradiation with UV-visible-near-infrared light using a halogen lamp. In the case of the composite film, further irradiation with UV light (using a Hg lamp) for 2 h or less resulted in the film showing strong PL at 1.06 μm under halogen lamp irradiation. Upon UV irradiation for more than 2 h, the film turned brown owing to the reaction of urethane with nitric acid derived from the Nd raw material, and the PL intensity became weaker. The Nd₂O₃ nanoparticles in the composite film were measured using transmission electron microscopy, and the particle size ranged from 15.0-35.1 nm. The PL intensity of the composite films was strongest when the size of the Nd-based particles was approximately 20 nm.