Study of interface structure of ferromagnetic Ag@CeO₂ core-shell nanoparticles
Eric Nestor Tseng1*, Shih-Yun Chen1, Chi-Hang Tsai1, Yi-Ta Lai1, William Lee1
1Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan
* presenting author:Eric Nestor Tseng,
The Ag@CeO₂ core-shell nanoparticles were synthesized successfully via two steps method. Ag nanoparticles (NPs) were first synthesized on TiO₂ substrate by thermal assisted photoreduction method (TAP) then CeO₂ NPs were deposited on the surface of Ag NPs by chemical reduction. Crystal structure analysis was investigated by X-ray diffraction (XRD) and transmission electronic microscope (TEM). X-ray absorption spectroscopy (XAS) and electron energy loss spectroscopy (EELS) were utilized to study the defects structure introduced by interface, including the valence state of Ce and the distribution of Ce3+. It is demonstrated that after introducing interface, the ratio of Ce3+ was enhanced, which was attributed to the charge transfer from Ag to CeO₂. In addition, room temperature ferromagnetism (RTFM) was observed in all Ag@CeO₂ core-shell nanoparticles with different shell thickness. After optimizing the ratio of interface/surface of CeO₂ shell, RTFM was enhanced obviously.

Keywords: Core shell structure, Defect, Ferromagnetism, Cerium oxides nanoparticles