The present invention relates to a method for producing a platinum-based alloy powder, the method comprising a heat treatment of a mixed powder containing a platinum-based powder composed of at least one selected from the group consisting of platinum and platinum compound, a platinum group metal-based powder composed of at least one selected from the group consisting of iridium, rhodium, palladium, and compound containing at least one of them, and an alkaline-earth metal compound, wherein specific surface area of the platinum group metal-based powder is 30 m.sup.2/g or more and D90 of the mixed powder is 1.0 μm or less. According to the method for producing a platinum-based alloy powder of the invention, it is possible to produce a platinum-based alloy powder that has a desired particle diameter, also has a sharp particle size distribution, and has high purity and crystallinity.

The present invention provides an alloy fine particle including palladium and ruthenium, the alloy fine particle including at least one first phase in which the palladium is more abundant than the ruthenium and at least one second phase in which the ruthenium is more abundant than the palladium, the at least one first phase and the at least one second phase being separated by a phase boundary, the palladium and the ruthenium being distributed in the phase boundary in such a manner that the molar ratio of the palladium and the ruthenium continually changes, a plurality of crystalline structures being present together in the phase boundary.

To be provided is a metal paste from which an electrode having high electrode activity as a sensor electrode of various gas sensors can be produced. The present invention is a metal paste for forming a gas sensor electrode obtained by dispersing a conductive particle including Pt or a Pt alloy and a ceramic powder including zirconia or stabilized zirconia, or any of zirconia and stabilized zirconia and one or more oxides of La, Ce, Pr, Nd, Sm, and Hf in a solvent, the metal paste further including an inorganic oxide particle containing alumina and an insoluble particle that is insoluble in the solvent, in which 0.5 or more to 3.0 mass % or less of the inorganic oxide particle and 1.0 to 5.0 mass % of the insoluble particle are dispersed based on the mass of the solid content of the conductive particle, the ceramic powder, the inorganic oxide particle, and the insoluble particle.

Method of selective extraction of a metal of the family of platinoids, from a ceramic support containing said metal, comprising the following successive steps: a) said ceramic support containing said metal is brought into contact, in an extraction chamber, with an extraction medium consisting of a pressurized dense fluid containing an organic ligand that is selective for the metal and that is capable of forming a complex with said metal in the 0 state; whereby are obtained, on the one hand, a ceramic support depleted in said metal, or even free of said metal, and, on the other hand, a medium consisting of the pressurized dense fluid containing the complex of the organic ligand with the metal in the 0 state; b) said pressurized dense fluid containing the complex of the organic ligand with the metal in the 0 state is brought back to atmospheric pressure and to ambient temperature, whereby the complex of the organic ligand with the metal in the 0 state separates from the fluid; c) the ceramic support depleted in said metal, or even free of said metal, and the complex of the organic ligand with the metal in the 0 state, are recovered.

Provided are metal particles for an adhesive paste, a solder paste composition including the same, and a method of preparing the metal particles for an adhesive paste. The metal particles for an adhesive paste may include a core including one or more metal materials; and a shell arranged on part or an entirety of the core and including one or more metal materials. The metal material of the core may have a melting point higher than that of the metal material of the shell. An intermetallic compound is capable of being formed between the metal material of the core and the metal material of the shell. A ratio (D90/D10) of the 90% cumulative mass particle size distribution (D90 size) to the 10% cumulative mass particle size distribution (D10 size) in a particle size distribution of the metal particles may be 1.22 or less.

The present invention relates to a process for the production of metal alloy nanoparticles which catalyse the oxygen reduction reaction (ORR) for use in proton exchange membrane fuel cells (PEMFC) or electrolyser cells. In particular, the present invention relates to a process for producing alloy nanoparticles from platinum group metals and other metals under reductive conditions. In particular the present invention relates to a process for producing alloy nanoparticles comprising the steps of mixing a salt of at least one metal, a material comprising a platinum group metal, a nitrogen-rich compound, and optionally a support material, to provide a precursor mixture, and heating said precursor mixture to a temperature of at least 400° C., in the presence of a gas comprising hydrogen (H.sub.2), to provide said alloy nanoparticles.

A method for producing mesoporous platinum nanoparticles without using templating agents is provided. The method involves preparing a solution comprising water, platinum nanoparticle seeds, a platinum salt and a reducing agent, and heating the solution to a temperature between 150° C. and 250° C. at a rate of between 1° C./min and 15° C./min under a pressure of between 5 and 20 atm. The method allows obtaining mesoporous platinum nanoparticles having controlled shape and controlled pore dimensions. The mesoporous platinum nanoparticles are useful as catalysts in chemical precision reactions and for the production of artificial enzymes for diagnostics and nanomedicine applications.

Provided is a sputtering target capable of reducing generation of particles, and a method for producing the same. The sputtering target includes: 10 mol % or more and 85 mol % or less of Co, 0 mol % or more and 47 mol % or less of Pt, and 0 mol % or more and 47 mol % or less of Cr, as metal components; and at least B.sub.6O as an oxide component.

The invention includes apparatus and methods for instantiating precious metals in a nanoporous carbon powder.

A method of forming a metal nanomaterial comprises forming a precursor solution comprising a metal precursor and a metal oxide precursor. A complexing agent is added to the precursor solution, and the metal precursor and the metal oxide precursor are hydrolyzed to form a sol. The sol is heated to form a gel, which is calcined to incorporate metal cations from the metal precursor into a metal oxide lattice from the metal oxide precursor. The calcined gel is exposed to a reducing agent to exsolve the metal from the metal oxide lattice and to form a metal nanomaterial comprising a metal and a metal oxide is formed. Additional methods of forming a metal nanomaterial are also disclosed.