Synthesis and Characterization of Iron-Oxide@Carbon Core-Shell Nanoparticles
Cheng-Tai Tso1*, Cheng-Jhih Jhang1, Yih-Jaan Tsai1, Tan-Xuan Wu1, Huang-Huei Sung2, Jung-Chuan Fan3, Mei-Li Chen4, Kun-Yauh Shih5, Yaw-Teng Tseng1, Jiann-Shing Lee1, Hung-Yi Chen1, Chun-Rong Lin1
1Department of Applied Physics, National Pingtung University, Pingtung 90003, Taiwan
2Department of Materials Science and Engineering, Da-yeh University, Changhua 51591, Taiwan
3Department of Electrical Engineering, Da-yeh University, Changhua 51591, Taiwan
4Department of Electro-optical Engineering, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan
5Department of Applied Chemistry, National Pingtung University, Pingtung 90003, Taiwan
* presenting author:CHENG-TAI TSOU,
Carbon-encapsulated iron-oxide nanoparticles (NPs) with typical core/shell structure were successfully synthesized from oleic acid, oleyamine and iron nitrate by one-pot reaction process at different reaction temperatures (TR). The structure of core/shell NPs was studied using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). XRD displays that the TR was set to 360 ℃, pure magnetite (Fe3O4) NPs began to form, but the peaks related to pure wustite (Fe1-xO) were shown up only when the TR was increased to as high as 400℃. Based on TEM images, the particle size of synthesized iron-oxide NPs is about 30~35 nm. Raman spectra indicated the magnetite exhibits a strong band at approximately 665 cm-1, assigned as the A1g mode, accompanied with a weak transition near 534 cm-1 due to the T2g mode. It was also shown that the wustite spectrum could be characterized by a band at about 655 cm-1. Moreover, Raman spectra and TEM images confirmed the formation of nanographitic shells around these iron-oxide NPs with a G-band centered at 1600 cm-1 and a D-band centered at 1356 cm-1. Magnetic measurements indicate that the synthesized wustite NPs is a weak ferromagnet due to their low magnetization. The magnetite NPs show a ferromagnetic character with saturation magnetization of 68.5 emu/g and coercive force of 80 Oe at room temperature.

Keywords: nanoparticles, Fe3O4, core-shell, Raman spectroscopy