Lizhu Tong

Magnetic properties of nanocrystalline Fe/Fe3C composites

Nanocrystalline Fe/Fe3C composites have been fabricated by an efficient solid-state synthesis route. In this reaction process, we choose the organic compound melamine as the carbon source and hydrothermally prepared nanocrystalline Fe/Fe3O4 composite as metal precursor. X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy and vibrating sample magnetometry have been used to characterize the composites. The experimental results show that changing reaction temperature, reaction time and the amount of melamine allows control over the composition of Fe/Fe3C composites, particle morphology and magnetic properties. The possible formation mechanisms of as-prepared nanostructures with different morphologies are discussed briefly. Magnetization measurements indicate that the composites display ferromagnetic properties at room temperature.

Preparation and properties of multifunctional Fe3O4 @YVO4:Eu3+ or Dy3+ core-shell nanocomposites as drug carriers

In this study, the synthesis and characterization is reported for Fe3O4/YVO4:Eu3+ or Dy3+ luminomagnetic nanocomposites. The nanocomposites show a spherical morphology with size distribution around 250 nm. In addition, they exhibit relatively high magnetization (17.86 emu g−1) which can make the nanocomposites respond to an external magnetic field quickly and strong red emission (yellow green for Dy) under UV irradiation. The results also indicate that the nanocomposites may have potential applications for optical imaging or drug delivery. Moreover, we discussed the magnetic field effects on the luminescence intensity.

Effect of Eu, Tb codoping on the luminescent properties of multifunctional nanocomposites

The synthesis (by a facile two-step co-precipitation process) and characterization, are reported for good dispersed core–shell structured Fe3O4@SiO2@Y2O3:Eu3+, Tb3+ nanocomposites with luminescent and magnetic properties. XRD patterns show that Fe3O4 core has crystallized with a good face-centered cubic structure; SiO2 layer is amorphous and Y2O3 layer is cubic. TEM images show the synthesis of core–shell structured composite microspheres of uniform size with rough surface. For nanocomposites with same host (Y2O3), upon excitation with UV irradiation, fluorescent spectra show that there is a strong emission at around 610 nm corresponding to the forced electric dipole 5D0–7F2 transition of Eu3+ and at around 545 nm corresponding to 5D4–7F5 transition of Tb3+. We speculate that there exists energy transfer from Tb3+ to Eu3+ ions from excitation spectra. Therefore, the multifunctional nanocomposites are expected to develop many potential applications in biomedical fields.