Layered hydroxide salts: Synthesis, properties and potential applications

Nickel nanoparticles obtained by a modified polyol process: synthesis, characterization, and magnetic properties.

Kinetics of thermite reaction in Al-Fe2O3 system

Nickel nanoparticles were prepared by decomposition of the organometallic precursor Ni(COD)2 (COD=cycloocta-1,5-diene) dissolved in organic media in the presence of anthranilic acid as stabilizer. Transmission electron microscopy revealed nickel nanoparticles with a mean size of 4.2 ± 1.1 nm and selected area electron diffraction showed the formation of fcc nickel. FTIR spectroscopy confirmed the presence of modified anthranilic acid on the surface of the Ni nanoparticles suggesting that it is able to interact with the metal particles. The magnetic response of the nanoparticles was established as being of superparmagnetic character, for which a detailed quantitative analysis resulted in a mean magnetic moment of 2652 μB per particle together with a blocking temperature of 32 K.

Superparamagnetic nickel nanoparticles obtained by an organometallic approach

Mechanochemically synthesized Fe3Al–Al2O3 nanocomposite

The structural and magnetic properties of powdered composites consisting of nanosized Fe and Co particles embedded in alumina grains have been investigated. The composites were synthesized by a novel and simple method using co-precipitation from a hybrid gel solution containing layered double hydroxide and aluminium hydroxide. After a vacuum annealing procedure, the Fe composites have a negligible number of Fe+3 ions and a high concentration of crystalline α-Fe nanoparticles having truncated polyhedron shapes with an average diameter of 20 nm that are physically well separated from each other. Magnetization measurements as a function of temperature revealed a superparamagnetic-like behavior characteristic of an assembly of fine particles. A spurious ferromagnetism related to surface interaction between magnetic particles from different powder grains and the formation mechanism of the composites are also discussed.

Adriano R. de Moraes

Papers

Structural and magnetic properties of Fe and Co nanoparticles embedded in powdered Al2O3.