Carbon-coated Ni Nanoparticles Research Articles

On polystyrene–block polyisoprene–block polystyrene filled with carbon-coated Ni nanoparticles

The manuscript focuses on the dispersion of magnetic nanoparticles within self-assembling block copolymers, on the preferential localization of nanoparticles and on the effect of their concentration on the magnetic properties of the nanocomposites and on the self-assembly features of the matrix. Carbon-coated nickel nanoparticles dispersed within polystyrene–block polyisoprene–block polystyrene have been investigated by Raman, X-ray, SQUID, differential scanning calorimetry, and electron microscopy. The effect of nanofiller on the self-assembly features of the block copolymer is reported. Preferential localization of nanofiller within the soft phase was noticed below 20 wt% nanofiller. Higher loadings with nanoparticles showed an uniform distribution of nanofiller within the block copolymer, consistent with the destruction of self-assembly. The effect of nanoparticles’ concentration on blocking temperature is discussed.

Synthesis and study of magnetic properties of high temperature stable Ni nanoparticles in a nearly amorphous AlPO4 matrix in an oxidative atmosphere

Graphitized carbon coated Ni nanoparticles were synthesized in an AlPO4 matrix in situ in an oxidative atmosphere without using any foreign reducing agent.

Synthesis of Hierarchical Tree-Like and Jellyfish-Like Silicon Oxide Nanostructures

Hierarchical tree-like and jellyfish-like SiOx nanostructures have been synthesized by annealing a mixture of carbon coated Ni nanoparticles (Ni@C) and SiO2 powers under argon atmosphere at 1400 degrees C. The synthesized products were characterized by electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The tree-like SiOx nanostructures consisting of the trunks and many branches and subbranches with diminishing diameters have been observed for the first time. The diameters of the trunks are about 150-1000 nm, and the branches become more slender for each branching, ultimately to 20-40 nm in diameter for the ends. The jellyfish-like SiOx nanostructures are constructed by the catalyst heads with sizes of about 1-10 microm and many connected quasi-aligned SiOx nanowires with diameters about 20-40 nm. The Ni species of the Ni@C nanoparticles acts as the catalyst and the surface carbon as the reducing agent for carbothermal reduction of SiO2. The experimental results suggest that the formation of different SiOx nanostructures mainly depend on the dimensions of the congregated Ni catalyst droplets during the reaction process and the growth mechanism is reasonably discussed.