Microparticles and methods for their production
First Claim
1. Method of making microparticles having a metal-containing core encapsulated in a graphitic shell containing hetero atoms, including the steps of (i) forming, in a liquid medium, colloidal particles containing a first metal in the form of a metal-oxo species, the first metal being selected from Fe, Co, Ni and Pd, the particles being colloidally stabilized by a surfactant and containing in addition to the first metal source material of carbon and the hetero atoms, and (ii) separating said particles from the liquid medium and pyrolyzing them in inert gas to yield the microparticles having said core and said graphitic shell containing said hetero atoms encapsulating the core.
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Accused Products
Abstract
Microparticles having a metal-containing core encapsulated in a graphitic shell containing hetero atoms are made by forming, in a liquid medium, colloidal particles containing a metal-oxo species of Fe, Co, Ni and Pd, colloidally stabilized by a surfactant and containing source material of carbon and the hetero atoms. These particles are pyrolyzed in inert gas to yield the microparticles. In an alternative method, silica gel coated particles are formed by colloidally stabilizing particles containing metal species and forming silica at the boundary of the stabilized particle.
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Citations
28 Claims
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1. Method of making microparticles having a metal-containing core encapsulated in a graphitic shell containing hetero atoms, including the steps of
(i) forming, in a liquid medium, colloidal particles containing a first metal in the form of a metal-oxo species, the first metal being selected from Fe, Co, Ni and Pd, the particles being colloidally stabilized by a surfactant and containing in addition to the first metal source material of carbon and the hetero atoms, and (ii) separating said particles from the liquid medium and pyrolyzing them in inert gas to yield the microparticles having said core and said graphitic shell containing said hetero atoms encapsulating the core.
- 12. Microparticles having a core containing a radionuclide encapsulated by a graphitic shell.
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16. Method of making solid microparticles having a metal-containing core surrounded by a silica coating, including the steps of
(i) forming, in a liquid medium, colloidal particles containing a metal-containing species and colloidally stabilized by a surfactant, and (ii) forming a silica coating around said colloidal particles by hydrolyzing a silicon compound in the region of the interface between the colloidal particle and the liquid medium.
- 23. Microparticles each having a core comprising at least one metal-containing species which is ferromagnetic and/or contains a radionuclide and a coating of silica gel encapsulating the core.
Specification