Provided are methods for making hollow gold nanospheres.

A method of forming composite materials includes mixing a first metal precursor with a chelating agent to form a first metal-chelate complex. The first metal-chelate complex is added to a polymer binder having terminating hydroxyl groups to form a polymer binder-first metal-chelate. The polymer binder first metal-chelate complex is mixed with an aluminum precursor. The aluminum precursor decomposes forming aluminum nanoparticles dispersed in a continuous phase material having metallic aluminum cores. At least one of the first metal-chelate complex and the first metal is dissolved in the continuous phase. The aluminum nanoparticles can have a passivating coating layer thereon provided by the polymer binder, or can have a passivating coating layer formed by including an epoxide, alcohol, carboxylic acid, or amine in the adding that forms passivating compound(s) which add further protection that can provide complete protection from oxidation of the metallic aluminum cores by air.

A process for the synthesis of nanostructured metallic hollow spherical particles, in which the metal is deposited onto sacrificial masks formed in a polymeric colloidal solution by the electroless autocatalytic deposition method. Deposition releases only gaseous products (N.sub.2 and H.sub.2) during the oxidation thereof, which evolve without leaving contaminants in the deposit. The particulate material includes nanostructured metallic hollow spherical particles with average diameter ranging from 100 nm to 5 m and low density with respect to the massic metal. A process for compacting and sintering a green test specimen are also described.

A method of making metal nanostructures having a nanometer size in at least one dimension includes preparing an aqueous solution comprising a cation of a first metal and an anion, and mixing commercial elemental powder particles of an elemental second metal having a greater reduction potential than the first metal with the aqueous solution in an amount that reacts and dissolves all of the second metal and precipitates the first metal as metal nanostructures. The temperature and concentration of the aqueous solution and the selection of the anions and the second metal are chosen to produce metal nanostructures of a desired shape, for example ribbons, wires, flowers, rods, spheres, hollow spheres, scrolls, tubes, sheets, hexagonal sheets, rice, cones, dendrites, or particles.

Provided is a thermosetting resin composition containing: (A) silver particles including secondary particles having an average particle size from 0.5 to 5.0 m, the secondary particles being formed by aggregation of primary particles having an average particle size from 10 to 100 nm; and (B) a thermosetting resin.