According to one or more embodiments presently described, a mixture of lead oxide and lead metal particles may be formed by a method that includes forming a molten metal lead material from a solid lead metal supply material, introducing the molten metal lead material into a reaction zone of a reactor, and contacting the molten metal lead material with an oxidizing gas in the reaction zone to oxidize a portion of the molten metal lead material and form at least solid lead oxide particles and solid lead metal particles. The molten metal lead material may be introduced to the reaction zone in a laminar flow or as atomized molten particles. The weight ratio of formed solid lead oxide particles to solid lead metal particles may be less than 99:1.

A method for producing a Fe—Co alloy powder suitable for an antenna includes steps, wherein when introducing an oxidizing agent into an aqueous solution containing Fe ions and Co ions to generate crystal nuclei and cause precipitation and growth of a precursor having Fe and Co as components, Co in an amount corresponding to 40% or more of the total amount of Co used for the precipitation reaction is added to the aqueous solution at a time after the start of the crystal nuclei generation and before the end of the precipitation reaction to obtain the precursor. Then, a dried product of the precursor is reduced to obtain a Fe—Co alloy powder. This Fe—Co alloy powder has a mean particle size of 100 nm or less, a coercive force Hc of 52.0 to 78.0 kA/m, and a saturation magnetization ss of 160 Am.sup.2/kg or higher.

A method for producing a Fe—Co alloy powder suitable for an antenna includes steps, wherein when introducing an oxidizing agent into an aqueous solution containing Fe ions and Co ions to generate crystal nuclei and cause precipitation and growth of a precursor having Fe and Co as components, Co in an amount corresponding to 40% or more of the total amount of Co used for the precipitation reaction is added to the aqueous solution at a time after the start of the crystal nuclei generation and before the end of the precipitation reaction to obtain the precursor. Then, a dried product of the precursor is reduced to obtain a Fe—Co alloy powder. This Fe—Co alloy powder has a mean particle size of 100 nm or less, a coercive force Hc of 52.0 to 78.0 kA/m, and a saturation magnetization ss of 160 Am.sup.2/kg or higher.

The invention relates to nano-particles comprising metallic ferromagnetic nanocrystals combined with either amorphous or graphitic carbon in which or on which chemical groups are present that can dissociate in aqueous solutions. According to the invention there is provided nano-particles comprising metal particles of at least one ferromagnetic metal, which metal particles are at least in part encapsulated by graphitic carbon. The nano-particles of the invention are prepared by impregnating carbon containing bodies with an aqueous solution of at least one ferromagnetic metal precursor, drying the impregnated bodies, followed by heating the impregnated bodies in an inert and substantially oxygen-free atmosphere, thereby reducing the metal compounds to the corresponding metal or metal alloy.

The invention relates to nano-particles comprising metallic ferromagnetic nanocrystals combined with either amorphous or graphitic carbon in which or on which chemical groups are present that can dissociate in aqueous solutions. According to the invention there is provided nano-particles comprising metal particles of at least one ferromagnetic metal, which metal particles are at least in part encapsulated by graphitic carbon. The nano-particles of the invention are prepared by impregnating carbon containing bodies with an aqueous solution of at least one ferromagnetic metal precursor, drying the impregnated bodies, followed by heating the impregnated bodies in an inert and substantially oxygen-free atmosphere, thereby reducing the metal compounds to the corresponding metal or metal alloy.

Provided is a method for controlling generation of scaling in a reaction vessel to reduce time and cost required for removal of the scaling in the process of producing nickel powder from a solution containing a nickel ammine sulfate complex. This is a method for producing nickel powder, including: adding, to the solution containing the nickel ammine sulfate complex, seed crystals in an amount of 0.3 times or more and 3 times or less the weight of nickel in the solution to form a slurry; and blowing hydrogen gas into the slurry to reduce a nickel complex ion and to thereby form a nickel precipitate.

Provided is a method for controlling generation of scaling in a reaction vessel to reduce time and cost required for removal of the scaling in the process of producing nickel powder from a solution containing a nickel ammine sulfate complex. This is a method for producing nickel powder, including: adding, to the solution containing the nickel ammine sulfate complex, seed crystals in an amount of 0.3 times or more and 3 times or less the weight of nickel in the solution to form a slurry; and blowing hydrogen gas into the slurry to reduce a nickel complex ion and to thereby form a nickel precipitate.

Provided is a method of producing a nickel nanopowder, the method capable of preventing coagulation between particles and, accordingly, providing a nickel nanopowder having a small average particle size and a low coagulation rate. According to an embodiment of the present invention, the method of producing a nickel nanopowder includes providing a nickel salt and a shell-forming material; nucleating and growing nickel core particles from the nickel salt; forming a shell layer on surfaces of the nickel core particles using the shell-forming material; and removing the shell layer to form the nickel nanopowder.

Provided is a method of producing a nickel nanopowder, the method capable of preventing coagulation between particles and, accordingly, providing a nickel nanopowder having a small average particle size and a low coagulation rate. According to an embodiment of the present invention, the method of producing a nickel nanopowder includes providing a nickel salt and a shell-forming material; nucleating and growing nickel core particles from the nickel salt; forming a shell layer on surfaces of the nickel core particles using the shell-forming material; and removing the shell layer to form the nickel nanopowder.

Provided is a nickel powder manufacturing method capable of efficiently manufacturing a high-quality nickel powder using as little ammonium gas or ammonium water as possible. The nickel powder manufacturing method according to the present invention is characterized by comprising: a first step for generating a post-neutralization slurry including nickel hydroxide by mixing a nickel sulfate aqueous solution and a neutralizing agent; a second step for causing a complex-forming reaction by mixing an ammonium sulfate aqueous solution with the post-neutralization slurry and obtaining a post-complexation slurry including a nickel ammine complex aqueous solution; and a reducing step for obtaining a nickel powder and a post-reduction solution by contacting hydrogen gas with the nickel ammine complex aqueous solution. Further, it is preferable that a post-complexation solution obtained in the reduction step be repeatedly used as the ammonium sulfate aqueous solution to be added to the post-neutralization slurry.