Synthesis and Magnetic Properties of Maghemite (γ-Fe2O3) Short-Nanotubes

We report a rational synthesis of maghemite (γ-Fe2O3) short-nanotubes (SNTs) by a convenient hydrothermal method and subsequent annealing process. The structure, shape, and magnetic properties of the SNTs were investigated. Room-temperature and low-temperature magnetic measurements show that the as-fabricated γ-Fe2O3 SNTs are ferromagnetic, and its coercivity is nonzero when the temperature above blocking temperature (TB). The hysteresis loop was operated to show that the magnetic properties of γ-Fe2O3 SNTs are strongly influenced by the morphology of the crystal. The unique magnetic behaviors were interpreted by the competition of the demagnetization energy of quasi-one-dimensional nanostructures and the magnetocrystalline anisotropy energy of particles in SNTs

In situ formation of 1D nanostructures from ceria nanoparticle dispersions by liquid cell TEM irradiation

Deliberate electron irradiation of cerium oxide nanoparticles in water is used to trigger chemical reactions in a liquid cell transmission electron microscope. Formation of nanorods and nanoneedles is observed starting from predominantly octahedral shape nanoparticles. Detailed morphologies found include free-standing needles, needles connected to specific octahedral ceria facets and star-shaped multi-needle patterns. It is found that rod-axis orientations and crystallographic directions are aligned. It is suggested that high ion and radical concentration of radiolysed water dissolves layers of the original CeO2 particles which re-arrange as needles in the direction of energetically preferred facets

Co-precipitation synthesis and characterization of faceted MoS2 nanorods with controllable morphologies

Molybdenum disulfide (MoS2) nanopowder has been prepared using a co-precipitation method. This paper describes the thermal effect on the morphology enhancement of MoS2 sphere-like structures into nanorods with a winding structure. For the reduction in precursors, the as-obtained MoS2 nanopowder was calcinated at 250, 400, 600, and 800 degrees C for 1 h in an N-2 environment. The calcined samples were characterized using a particle size analyzer, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with X-ray analysis (EDAX) and transmission electron microscopy, HRTEM and X-ray photoelectron spectroscopy. The results show the MoS2 sphere-like structure with diameter in the range of 50-100 nm and rod-like winding structure with diameter in the range of 20-150 nm, and a few tens of micrometers in length with a high degree of size homogeneity. The FT-IR spectra show the obtained bands at 480 and 900 cm(-1) are corresponding to the Mo-S bond and the S-S bond. The TG-DTA curves confirm the thermal stability of the prepared samples. It is observed that the band gap energy for the MoS2 nanorods is lower than for the nanospherical structure MoS2, which leads to achieve high electron and hole recombination rate.ope