Annealing effects on the properties of Nd containing ZnO nanoparticles prepared by sol–gel process

Nd containing ZnO nanoparticles are prepared by sol–gel process. As-prepared nanoparticle exhibits a size of ∼25 nm and shows strong near-band-edge emission centered at 380 nm together with defect related deep level emission at ∼620 nm. Annealing causes re-crystallization and enabling of an additional luminescence band centered at 899 nm, which is due to the inner shell 4f transition of Nd3+ from 4F3/2 to 4I9/2. The intensity of Nd3+ emission at 899 nm reaches a maximum after annealing at 600 °C, while annealing at 1000 °C causes decomposition of ZnO and the formation of Nd2O3. Variable temperature photoluminescence study indicates that the emission at 899 nm is mainly due to energy transfer from deep level emission of host ZnO to Nd3+ ions.