本研究以一階氧化還原法合成 Ag@CeO2 核殼結構奈米顆粒，並透過控制硝酸鈰濃度改變奈米顆粒的型態，所合成的樣品之成分、形貌、結構及金屬離子價態以 X 光繞射儀、穿透式電子顯微鏡、X光吸收光譜、拉曼光譜以及電子能量損失光譜進行分析。結果顯示，一階氧化還原法可成功製備出 Ag@CeO2，當前驅物中的鈰與銀
的比例為 1:3 時，可合成核直徑為 50 nm，殼厚度為 20 nm 的Ag@CeO2 核殼結構奈米顆粒。若降低前驅物中的硝酸鈰濃度、或提高銀離子濃度，則會形成多層結構，在 CeO2 殼層表面會沉積許多小尺寸的銀顆粒。XAS 分析則發現，不同於其他的核殼結構製程，以一階氧化還原法所合成脂 Ag@CeO2 核殼結構奈米顆粒在核殼界面處缺陷數量較少，樣品中 Ce3+會隨著 Ag 與 CeO2 界面面積提高而下降，此現象推測是由所進行的反應過程所造成。最後，在所合成的樣品中，只有多層結構的樣品具有微弱的室溫鐵磁特性，推測與其缺陷分佈有關。

In this study , Ag@CeO2 core-shell structure nanoparticles (NPs) were synthesized by one-pot redox reaction. X-rays diffraction (XRD), Transmission electron microscope (TEM), X-ray absorption spectroscopy (XAS), Raman spectra and EELS (electron energy loss spectroscopy) were utilized to investigate the morphology, crystal structure and valence state of cations. Our results showed that the morphology of Ag@CeO2 NPs
varied as changing the relative concentration between Ce and Ag in precursor. As the concentration ratio of Ce(NO3)/AgNO3 increased from 0.33 to 0.041, nanoparticles changed from Ag@CeO2 core-shell structure nanoparticles to multi-shell structure. Ag nanoparticles were observed on the surface of CeO2 shell. Different to Ag@CeO2 core-shell NPs prepared by two- step process, XAS analysis demonstrated there are fewer defects
present in this study, especially at the interface between Ag core and CeO2 shell. At last, most NPs are super-papamagnetic at room temperature. The weak ferromagnetism observed of the multi- shell NPs was attributed to the distribution of defects.

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