Elsevier

Materials Letters

Volume 76, 1 June 2012, Pages 120-123
Materials Letters

Electromagnetic properties of Nd3 + substituted iron oxide on graphite nanosheet

https://doi.org/10.1016/j.matlet.2012.02.070Get rights and content

Abstract

Nd3 + substituted iron oxide (Fe3O4) was chemically precipitated on the surface of graphite nanosheet (NanoG) to get the composite NdxFe3 -xO4/NanoG. The structure of the composite was characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Results show that under basic conditions, FeCl3.6H2O, NdCl3 and FeSO4.7H2O can carry out coprecipitation reaction to obtain NdxFe3 -xO4 on the surface of NanoG. Measurement of electromagnetic parameters shows that when x = 0.06 and the mass ratio of NdxFe3 -xO4 to NanoG reaches 4:1, Nd0.06Fe2.94O4/NanoG has good microwave absorbing properties (Rmin =  17.13 dB at 11.90 GHz) in the X band (8.2–12.4 GHz).

Graphical abstract

Highlights

► Nd3 + substituted iron oxide (Fe3O4) was chemically precipitated on the NanoG. ► The composites were characterized by SEM, XRD and EDS. ► The composites are soft ferrites with high saturation magnetization. ► Nd0.06Fe2.94O4/NanoG has high microwave absorbing properties.

Introduction

Iron ferrites Fe3O4 have reverse spinal crystal structure and are widely used as catalysts, magnetofluids, microwave devices and microwave absorbing materials [1], [2], [3], [4]. But their heavy weight and easy oxidization restrain them from being wildly used. Graphite is a kind of material with light weight, low price and stable properties. By oxidation, rapid thermal treatment and ultrasonic dispersion, graphite nanosheet (NanoG) can be prepared from graphite [5], [6]. By coprecipitation reaction, Fe3O4 can be chemically precipitated on the NanoG's surface.

To improve their magnetic properties and enlarge their application area, rare earth ions with larger ionic radius such as Pr3 + [7], Sm3 + [8], Gd3 + [9], La3 + [10], Nd3 + [11], Ho3 + [12], Dy3 + [13], Er3 + [14] are usually introduced into the ferrites. In this work, rare earth ion Nd3 + substituted Fe3O4 precipitating on the surface of NanoG is prepared. The structures of as prepared samples are characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. Microwave absorbing properties of them are measured.

Section snippets

Experimental

NanoG was prepared as reference [15], [16] and pretreated by KH550 in a flask. Then an amount of FeCl3.6H2O, FeSO4.7H2O and NdCl3 (mole ratio 2:1:x, x = 0.03, 0.06, 0.09) were added into the flask with vigorous stirring and the solution was heated to 30 °C in a water bath. A mixture solution of NH3.H2O with SDBS was then dropped into the solution and the pH was adjusted to 9–10. After that, the reaction was carried out for about 3 h at 70 °C with constant stirring. The products were isolated by

SEM images and EDS of Nd0.06Fe2.94O4 and Nd0.06Fe2.94O4/NanoG

By coprecipitation reaction, NdxFe3 -xO4 can be obtained under basic condition. Fig. 1(a, b) show the structure of Nd0.06Fe2.94O4 with magnification of 10,000 and 40,000, respectively. It can be seen that Nd0.06Fe2.94O4 has cubic spinal crystal structure and the average diameter of it is around 100 nm. The structure of NanoG is shown in Fig. 1(c). It has a width about 1–20 μm and a thickness about 30–90 nm, indicating a large aspect ratio (300–500). Fig. 1(d) shows the structure of Nd0.06Fe2.94O4

Conclusions

In this paper, the reverse spinal crystal Nd0.06Fe2.94O4 with diameter of about 100 nm is well dispersed on the NanoG's surface for the high aspect ratio of NanoG (300–500). The composites are soft ferrites with high saturation magnetization. Measurement of electromagnetic parameters shows that when x = 0.06 and the mass ratio of NdxFe3 -xO4 to NanoG reaches 4:1, Nd0.06Fe2.94O4/NanoG has good microwave absorbing properties (Rmin =  17.13 dB at 11.90 GHz) in the X band (8.2–12.4 GHz).

Acknowledgments

The work is supported by graduate starting seed fund of Northwestern Polytechnical University (2012242).

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