在本研究中首先利用水熱法，調整前驅物種類(蔗糖或葡萄糖)及煆燒條件，合成出直徑為200 nm和900 nm的碳球。接著以溶膠凝膠法將二氧化鈰奈米顆粒披覆在碳球表面，形成CeO2@C核殼結構。最後再將此核殼結構在Ar+H2氣氛下進行還原退火。合成的樣品以X光繞射儀(X-ray diffraction, XRD)、掃描式電子顯微鏡(Scanning electron microscope, SEM)、穿透式電子顯微鏡(Transmission electron microscope, TEM)、拉曼光譜儀(Raman spectroscopy, Raman)、X光吸收光譜(X-ray absorption spectroscopy, XANES)進行結構上的分析，並進行室溫下的磁性量測，探討尺寸對CeO2@C磁性之影響。
實驗結果顯示，此製程條件無法在直徑為200 nm的碳球上形成連續均勻的CeO2殼層。但可以成功在900 nm的碳球表面形成連續的CeO2殼層，其厚度與前驅物中六水硝酸鈰的濃度成正比。此外殼層中缺陷數量較文獻中直徑為450 nm的碳球上形成的CeO2殼層為高。經過還原退火後，殼層中的缺陷濃度可進一步提高。所有樣品都具備室溫鐵磁性，飽和磁化強度與CeO2殼層厚度成反比；在500 ℃下還原的CeO2@C，飽和磁化強度較未還原前提高達四倍。但與在直徑為450 nm的碳球上形成的CeO2@C核殼結構相比，在直徑為900 nm的碳球上形成的CeO2@C核殼結構鐵磁強度均較低。

This study synthesized carbon spheres with 200 nm and 900 nm diameters by adjusting the type of precursor (sucrose or glucose) and sintering conditions by hydrothermal method. Then, the ceria nanoparticles were deposited on the carbon spheres by the sol-gel method to form a CeO2@C core-shell structure. Finally, the core-shell structure is annealed in an Ar+H2 atmosphere. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Raman spectroscopy (Raman spectroscopy, Raman), X-ray absorption spectroscopy (X-ray absorption spectroscopy, XANES) were utilized to investigate the structure and relate to the magnetic properties.
The results show that a continuous CeO2 shell cannot be deposited on carbon spheres with a diameter of 200 nm by this synthetic method. However, on the surface of carbon spheres with a diameter of 900 nm, a continuous CeO2 shell can be successfully formed, and its thickness is proportional to the concentration of cerium nitrate hexahydrate in the precursor. In addition, defect concentration in the shell is higher than that of the CeO2 shell formed on carbon spheres with a diameter of 450 nm in the literature. After reduction annealing, the defect concentration in the shell can be further increased. All samples are ferromagnetic at room temperature, and the saturation magnetization is inversely proportional to the CeO2 shell thickness. The saturation magnetization of CeO2@C reduced at 500 °C is up to four times higher than that of the unreduced sample. Compared with the CeO2@C core-shell structure formed on carbon spheres with a diameter of 450 nm, the ferromagnetic intensity of the CeO2@C core-shell structure formed on carbon spheres with a diameter of 900 nm is lower.

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