한국자기학회

Nguyen Van Minh(Center of Nano Science and Technology, Hanoi National University of Education), Phung Kim Phu(Center of Nano Science and Technology, Hanoi National University of Education), Nguyen Minh Thuan(Center of Nano Science and Technology, Hanoi National University of Education), In-Sang Yang*

(Department of Physics and Division of Nano-Sciences, Ewha Womans University)

Abstract

In this report, we present the results of a study on the effects of the particle size on the properties of the Prussian blue (PB) analog Na_sMn_y[Fe(CN)₆]. A novel synthesis method of the Na_sMn_y[Fe(CN)₆] nano-particles using an organic solvent, formamide, is employed. The size of the PB particles is found to be 100-150 nm for the samples prepared in the formamide solvent, which is much smaller than that of the samples prepared using water only. The broadening of the X-ray diffraction peaks of the nano-sized PB samples is attributed to the lattice disorder and a dramatic reduction in the particle size. The compositions of the samples are confirmed by an energy-dispersive X-ray analysis (EDAX), and the result proves that the samples are actually Na_sMn_y[Fe(CN)₆] Prussian blue. The UV-vis spectra show a broad intervalence charge-transfer (CT) band in the visible region between 400 and 700 nm, and the absorption decreases abruptly in the green region for the nano-sized PB sample. A divergence between the field cooled (FC) and zero field cooled (ZFC) magnetization curves is observed for the nano-sized PB sample at 11 K, indicating that nanoparticles in the sample are single domain superparamagnets with a blocking temperature of 11 K. Our results reveal that the nano-sized PB samples show significantly different optical and magnetic properties than those of the bulk PB samples.

Keywords: Prussian blue; nanoparticles; magnetization

DOI: 10.4283/JMAG.2008.13.4.149

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