Synthesis and characterization of Nd₂O₃ nanoparticles in a radiofrequency thermal plasma reactor

The synthesis of nanocrystalline Nd₂O₃ through an inductively coupled radiofrequency thermal plasma route is reported. Unlike in conventional synthesis processes, plasma-synthesized nanoparticles are directly obtained in a stable hexagonal crystal structure with a faceted morphology. The synthesized nanoparticles are highly uniform with an average size around 20 nm. The nanoparticles are characterized in terms of phase formation, crystallinity, morphology, size distribution, nature of chemical bonds and post-synthesis environmental effects using standard characterization techniques. X-ray diffraction, transmission electron microscopy, and scanning electron microscopy are used for structural and morphological studies. The thermo-gravimetric technique, using a differential scanning calorimeter, is used to investigate the purity of phase. Fourier transform infrared spectroscopy is used to investigate the nature of existing bonds. The optical response of the nanoparticles is investigated through the electronic transition of Nd³⁺ ions in its crystalline structure via UV-visible spectroscopy. The presence of defect states and corresponding activation energies in the nanocrystalline Nd₂O₃ compared to those of the precursors are studied using thermoluminescence.