A method for producing microparticles and/or nanoparticles based on zero-valent metals directly inside a filtering media and/or for creating covering layers based on the zero-valent metals for covering. The filleting media includes the steps of introducing at least one solution containing metal salts in the filtering medium, introducing at least one solution containing inorganic reducing agents into the filtering medium. The steps of introducing the at least one solution containing metal salts and the at least one solution containing inorganic reducing agents inside the filtering medium is carried out in a way separated in time and/or in space to realize, in the filtering medium, a mixture of metal ions with the inorganic reducing agents as well as a chemical reduction of the zero-valent metals to form the microparticles and/or the nanoparticles and/or coverings based on the zero-valent metals inside of the filtering medium.

A method of making a supported catalytic species comprising an alloy of at least two metals, comprises the steps of: (i) combining a particulate support material, a solution of a first metal compound, a solution of a second metal compound, and a solution of an alkaline precipitating agent to form a slurry mixture; (ii) agitating the resultant mixture; and (iii) contacting the solids with a reducing agent, wherein the first metal in the first metal compound and the second metal in the second metal compound is each independently selected from the group consisting of gold, palladium, platinum, rhodium, iridium, silver, osmium and ruthenium; and wherein the first metal is not the same as the second metal.

A method of making a supported catalytic species comprising an alloy of at least two metals, comprises the steps of: (i) combining a particulate support material, a solution of a first metal compound, a solution of a second metal compound, and a solution of an alkaline precipitating agent to form a slurry mixture; (ii) agitating the resultant mixture; and (iii) contacting the solids with a reducing agent, wherein the first metal in the first metal compound and the second metal in the second metal compound is each independently selected from the group consisting of gold, palladium, platinum, rhodium, iridium, silver, osmium and ruthenium; and wherein the first metal is not the same as the second metal.

Alloyed Ag/Au nanospheres with high compositional homogeneity ensured by annealing at elevated temperatures show large extinction cross-sections, extremely narrow band-widths and remarkable stability in harsh chemical environments. A critical temperature has been found to be around 930 C., below which the resulting alloy nanospheres, although significantly more stable than pure silver nanoparticles, can still gradually decay upon extended exposure to harsh etchant. The nanospheres annealed above the critical temperature show homogeneous distribution of Ag and Au elements, minimal crystallographic defects, absence of structural and compositional interfaces, which account for the extremely narrow bandwidths of the surface plasmon resonance, and may render many plasmonic applications with high performance and long lifetime, especially for those involving corrosive species.

A metal sintering preparation containing (A) 50 to 90% by weight of at least one metal that is present in the form of particles having a coating that contains at least one organic compound, and (B) 6 to 50% by weight organic solvent. The mathematical product of tamped density and specific surface of the metal particles of component (A) is in the range of 40,000 to 80,000 cm.sup.1.

The present invention relates to a process for manufacturing a mechanical part based on at least two precious or noble metals or alloys thereof, the process comprising a step of atomizing the various precious metals, positioning the resulting powders in a mold so as to form an assembly of unmixed powders, and a step of sintering at temperatures below the melting temperatures of the metals used. The invention also covers a mechanical part produced by such a process, as well as a timepiece comprising such a mechanical part.

A compounds-derived method for synthesizing Rh and 2H Rh-based alloy nanomaterials is provided. The method includes preparing orthorhombic phase Rh.sub.2C NPLs; obtaining pure 2H Rh NPLs by extracting C atoms from the Rh.sub.2C NPLs; and obtaining 2H Rh-based alloy NPLs by simultaneously reducing the second metal during the C extraction. The preparing orthorhombic phase Rh.sub.2C NPLs includes dissolving Rh(acac).sub.3 or RhCl.sub.3 into a mixture solution containing oleylamine and oleic acid in a container and sonicating for a predetermined time; adding formaldehyde into the mixture solution; sealing the container and sonicating it; heating the container; and cooling the container to room temperature. Obtaining pure 2H Rh NPLs by extracting C atoms from the Rh.sub.2C NPLs includes re-dispersing the Rh.sub.2C NPLs in oleylamine by sonication; and heating the solution in an oil bath, while simultaneously flowing Ar/H.sub.2 mixture into the solution. Obtaining 2H Rh-based alloy NPLs by simultaneously reducing the second metal during the C extraction includes re-dispersing the Rh.sub.2C NPLs and dissolving a second metal precursor in oleylamine by sonication; and heating the solution in an oil bath, while simultaneously flowing Ar/H.sub.2 mixture into the solution. The pure 2H Rh NPLs obtained remain stable after annealing treatment at 300 C. for one hour under an inert atmosphere.

A compounds-derived method for synthesizing Rh and 2H Rh-based alloy nanomaterials is provided. The method includes preparing orthorhombic phase Rh.sub.2C NPLs; obtaining pure 2H Rh NPLs by extracting C atoms from the Rh.sub.2C NPLs; and obtaining 2H Rh-based alloy NPLs by simultaneously reducing the second metal during the C extraction. The preparing orthorhombic phase Rh.sub.2C NPLs includes dissolving Rh(acac).sub.3 or RhCl.sub.3 into a mixture solution containing oleylamine and oleic acid in a container and sonicating for a predetermined time; adding formaldehyde into the mixture solution; sealing the container and sonicating it; heating the container; and cooling the container to room temperature. Obtaining pure 2H Rh NPLs by extracting C atoms from the Rh.sub.2C NPLs includes re-dispersing the Rh.sub.2C NPLs in oleylamine by sonication; and heating the solution in an oil bath, while simultaneously flowing Ar/H.sub.2 mixture into the solution. Obtaining 2H Rh-based alloy NPLs by simultaneously reducing the second metal during the C extraction includes re-dispersing the Rh.sub.2C NPLs and dissolving a second metal precursor in oleylamine by sonication; and heating the solution in an oil bath, while simultaneously flowing Ar/H.sub.2 mixture into the solution. The pure 2H Rh NPLs obtained remain stable after annealing treatment at 300 C. for one hour under an inert atmosphere.

Undercooled liquid metallic core-shell particles, whose core is stable against solidification at ambient conditions, i.e. under near ambient temperature and pressure conditions, are used to join or repair metallic non-particulate components. The undercooled-shell particles in the form of nano-size or micro-size particles comprise an undercooled stable liquid metallic core encapsulated inside an outer shell, which can comprise an oxide or other stabilizer shell typically formed in-situ on the undercooled liquid metallic core. The shell is ruptured to release the liquid phase core material to join or repair a component(s).

Undercooled liquid metallic core-shell particles, whose core is stable against solidification at ambient conditions, i.e. under near ambient temperature and pressure conditions, are used to join or repair metallic non-particulate components. The undercooled-shell particles in the form of nano-size or micro-size particles comprise an undercooled stable liquid metallic core encapsulated inside an outer shell, which can comprise an oxide or other stabilizer shell typically formed in-situ on the undercooled liquid metallic core. The shell is ruptured to release the liquid phase core material to join or repair a component(s).