Sol-gel synthesis of mesoporous assembly of Nd 2O 3 nanocrystals with the aid of structure-directing surfactant

The aim of this work was to demonstrate a simple route to synthesize mesoporous assembly of nanocrystalline neodymium oxide (Nd ₂O ₃) with predominant pore size distribution in the mesopore region, which was successfully done for the first time under mild conditions by a modified sol-gel process with the aid of structure-directing surfactant. Properly manipulated hydrolysis and condensation steps of neodymium n-butoxide modified with acetylacetone in the presence of laurylamine hydrochloride surfactant aqueous solution were performed to obtain the assembled Nd ₂O ₃ nanocrystal. Various techniques, including thermogravimetric and differential thermal analyses (TG-DTA), X-ray diffraction (XRD), N ₂ adsorption-desorption, Brunauer-Emmett-Teller (BET) surface area analysis, Barrett-Joyner-Halenda (BJH) pore size distribution analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected-area electron diffraction (SAED), were used to characterize the synthesized Nd ₂O ₃ nanocrystal. The N ₂ adsorption-desorption isotherm of the synthesized Nd ₂O ₃ nanocrystal calcined at 500 °C exhibited single hysteresis loop with IUPAC type IV-like pattern, indicating the existence of foremost mesopore. BJH pore size distribution result revealed that the synthesized Nd ₂O ₃ nanocrystals possessed mostly mesopore due to their assembly with a small extent of macropore, resulting in very small mean pore diameter in the mesopore region. The particle size determined from both SEM and TEM micrographs was also extremely small of approximately 10 nm.