Li Yongxiu, Wang Xueliang, Ding Linmin, Li Yao, He Rucheng, Li Jing
School of Chemistry and Chemical Engineering, Nanchang University Nanchang Jiangxi 330031 China
Institute of Rare Earths, Nanchang University Nanchang Jiangxi 330031 China.
RSC Adv. 2022 Jun 6;12(26):16554-16560. doi: 10.1039/d2ra02367a. eCollection 2022 Jun 1.
Ceria octahedrons with different microstructure and surface characteristics were prepared by calcining an octahedral CeO precursor self-assembled from spherical primary nanocrystals of about 5 nm at 500-900 °C. Structural characterization revealed that with the calcination temperature increasing from 500 to 700 °C, the products maintained a hierarchical structure and primary nanocrystals changed from spherical to octahedral particles. Significant fusion occurred between the primary nanocrystals and the surface of the octahedrons became smooth at the calcination temperature of 800 °C. Single crystal CeO octahedrons were formed when the calcination temperature reached 900 °C. The change in microstructure induced by elevated calcination temperature led to increased mechanical hardness and decreased surface chemical activity (specific surface area and surface Ce concentration) of the octahedrons, which had an impact on their polishing performance. The polishing experiments on K9 glass showed that the polishing rate first increased and then decreased with the increment of calcination temperature, indicating that in addition to the mechanical hardness, the surface chemical activity of the octahedrons is also important for material removal. Owing to the best matching of chemical activity and mechanical hardness, CeO octahedrons calcinated at 700 °C exhibited the highest polishing rate and the best surface quality for K9 glass.
通过在500-900℃煅烧由约5nm球形初级纳米晶体自组装而成的八面体CeO前驱体，制备了具有不同微观结构和表面特性的二氧化铈八面体。结构表征表明，随着煅烧温度从500℃升高到700℃，产物保持分级结构，初级纳米晶体从球形变为八面体颗粒。在800℃煅烧温度下，初级纳米晶体之间发生显著融合，八面体表面变得光滑。煅烧温度达到900℃时形成了单晶CeO八面体。煅烧温度升高引起的微观结构变化导致八面体的机械硬度增加，表面化学活性（比表面积和表面Ce浓度）降低，这对它们的抛光性能产生了影响。对K9玻璃的抛光实验表明，随着煅烧温度的升高，抛光速率先增加后降低，这表明除了机械硬度外，八面体的表面化学活性对材料去除也很重要。由于化学活性和机械硬度的最佳匹配，700℃煅烧的CeO八面体对K9玻璃表现出最高的抛光速率和最佳的表面质量。
