Magnetic property, Moessbauer spectroscopy and microwave reflection loss of maghemite nanoparticles (γ-Fe_2O_3) encapsulated in carbon nanotubes

摘要

Nanoparticles of maghemite (γ-Fe_2O_3) were prepared from FeCl_3 by using a reduction method using hydrazine hydrate as reducing agent. The prepared nanoparticles were incorporated in non-magnetic matrix of multi-walled carbon nanotubes (CNTs). The crystallographic phases of γ-Fe_2O_3 and γ-Fe_2O_3-CNT were confirmed by using X-ray diffractograms (XRD), high resolution transmission electron microscopy (HRTEM) and Moessbauer spectroscopy. The nanoparticles of γ-Fe_2O_3 were incorporated in CNTs. Dynamic magnetic properties of the samples were characterized at room temperature (RT) and static magnetic properties were measured from RT down to 5 K by using SQUID magnetometer which confirmed the presence of superparamagnetic (SPM) relaxation of the nanoparticles. High value reflection losses of the sample over (X and K_u bands) were observed, which would be suitable for applications in microwave devices.