Self-Organization of Magnetic Nanoparticles and Inclusion of Hydrogen by Borohydride Reduction

 Different structures of the interglobular space or voids between self-organized nanoparticles lead to differences in the measurable magnetic properties of single-domain particle chains of similar composition, grain size, and amorphous structure of the single globules. The volumes and radii of nanoparticles obtained by application of a magnetic field (3 to 15 nm) are larger than those determined without application of a magnetic field during the borohydride reduction process. Two types of hydrogen containing nanotubes with diameters of up to 2 (small-size containers) and 5 nm (large-size containers) are produced using as a driving force the domain wall formation energy between ferromagnetic nanoparticles with quantum size effected dimensions prepared by this reduction method at room temperature and ambient atmosphere. Nanoscale hydrogen containers can be used instead of MeH nanoparticle electrodes as perfect energy charge transfer media of high efficiency (close to 100%) using Li ion electrolytes. No influence on the electrode temperature and no participation of OH⁻ and H₂O in the main charge/discharge transfer reactions were observed.     

Study of the interglobular structure of metal powders obtained by a borohydride reduction process

The effect of borohydride reduction duration and magnetic field in the specific surface area, metal particle size and form, and form and dimensions of the textural arrangement of pores in metal powders is investigated. It is established that the particle chains formed involve interglobular voids, i.e. the chains may be considered as consisting of successivly ordered globule layers. The interglobular void is found to possess definite dimensions and configuration. Powders obtained in a magnetic field have tetrahedral voids, while octahedral voids correspond to powders prepared without a magnetic field. The magnetic parameters of the powders have displayed a similar difference which needs additional studies.     

Self-Organization of Magnetic Nanoparticles and Inclusion of Hydrogen by Borohydride Reduction

Summary.  Different structures of the interglobular space or voids between self-organized nanoparticles lead to differences in the measurable magnetic properties of single-domain particle chains of similar composition, grain size, and amorphous structure of the single globules. The volumes and radii of nanoparticles obtained by application of a magnetic field (3 to 15 nm) are larger than those determined without application of a magnetic field during the borohydride reduction process. Two types of hydrogen containing nanotubes with diameters of up to 2 (small-size containers) and 5 nm (large-size containers) are produced using as a driving force the domain wall formation energy between ferromagnetic nanoparticles with quantum size effected dimensions prepared by this reduction method at room temperature and ambient atmosphere. Nanoscale hydrogen containers can be used instead of MeH nanoparticle electrodes as perfect energy charge transfer media of high efficiency (close to 100%) using Li ion electrolytes. No influence on the electrode temperature and no participation of OH⁻ and H₂O in the main charge/discharge transfer reactions were observed. Received October 25, 2001. Accepted (revised) January 3, 2002     

Gram-scale synthesis of monodisperse gold colloids by the solvated metal atom dispersion method and digestive ripening and their organization into two- and three-dimensional structures

We describe a synthetic procedure for preparation of large quantities of monodisperse thiol-stabilized gold colloids in toluene solution. The method is based on the solvated metal atom dispersion technique (SMAD), which is very suitable for preparation of large amounts of metal colloidal solutions, as well as of metal sulfide, metal oxide, and other types of dispersed compounds in different solvents. A combination of two different solvents like acetone and toluene is used for the preparation of the gold colloids. The necessity of initially carrying out the SMAD reaction in acetone comes from its high degree of solvation of gold particles. Acetone acts as a preliminary stabilizing agent. After its removal from the system, the particles are stabilized by dodecanethiol molecules, which enable their very good dispersion in toluene solution. A digestive ripening procedure is carried out with the gold-toluene colloid, and for this purpose pure toluene as solvent is necessary. This has a dramatic effect on the narrowing of particle size distribution and almost monodisperse colloids are obtained (some discussion of the probable mechanism of this remarkable digestive ripening step is given). These colloidal solutions have a great tendency to organize in two- and three-dimensional structures (nanocrystal superlattices, NCSs). We believe that this procedure provides a real opportunity to synthesize large amounts of gold nanocrystals as well as NCSs.