Synthesis of Yttrium Oxide Nanoneedles with Carbon Dioxide Carbonization

In this study, a CO₂ carbonization method is introduced for the preparation of 1D yttrium oxide powders. Using YCl₃ as the raw material, sodium hydroxide was initially used to completely precipitate Y³⁺ into yttrium hydroxide, and then CO₂ was introduced into the yttrium hydroxide slurry for homogenization-like carbonization to obtain yttrium carbonate precipitation. Then, by studying the effects of carbonization conditions, such as the temperature, CO₂ flow rate, and stirring speed, on the morphology and phases of yttrium carbonate, the temperature was observed to exert a greater effect than the other experimental parameters on the morphology and structure of the carbonized products. Finally, Y₂(CO₃)₃·2H₂O nanoneedles were obtained at optimal conditions. The carbonized crystals of the acicular yttrium carbonate precipitate because of the solution supersaturation and then quickly complete their crystal growth process through the oriented attachment (OA) and Ostwald ripening (OR) mechanisms. After heat treatment, yttrium carbonate retained a good crystal morphology and produced Y₂O₃ nanoneedles with a length of 1-2 μm and a width of 20-30 nm.