# US 6,773,823 B2 · Sequential synthesis of core-shell nanoparticles using reverse micelles > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,773,823 B2 - Document ID: US6773823B2 - Status: Granted - Kind: B2 - Application number: 09/829,401 - Filed: 2001-04-09 - Published: 2002-06-06 - Granted: 2004-08-10 - Earliest claimed: 2000-04-07 - Assignees: University of New Orleans Research and Technology Foundation, Inc. - Inventors: Charles J. O'Connor; Everett E. Carpenter; Jessica Ann Sims - Web page: https://patentgrep.com/patent/US6773823B2 ## CPC - G01R 33/093: {using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00)} - B82Y 5/00: Nanobiotechnology or nanomedicine, e.g. protein engineering or drug delivery - B82Y 25/00: Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance - G11B 5/712: characterised by the surface treatment or coating of magnetic particles - H01F 1/0054: {Coated nanoparticles, e.g. nanoparticles coated with organic surfactant} - H01F 1/44: of magnetic liquids, e.g. ferrofluids (particles in a bonding agent H01F1/28, H01F1/36, {H01F1/37}) - Y10S 428/90: Magnetic feature - Y10T 428/12014: having metal particles - Y10T 428/12028: Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.] - Y10T 428/12181: Composite powder [e.g., coated, etc.] - Y10T 428/12319: Composite - Y10T 428/2991: Coated - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract By utilizing the sequential synthesis afforded reverse micelles, nanocomposite materials can be synthesized which have a diamagnetic core surrounded by a thin shell of ferromagnetic material passivated with a second shell of a diamagnet. Using gold as the diamagnetic material and iron as the ferromagnetic material, nanocomposites can be synthesized where there is a thin layer of the magnetic material, which is passivated and protected from oxidation. In this case, all of the spins of the magnetic layer lie within the surface of the particle. ## Claims ### Claim 1 A nanocomposite comprising: a diamagnetic core; a layer of magnetic material fanned on the diamagnetic core; a passivating layer of diamagnetic material formed on the layer of magnetic material. ### Claim 2 (depends on 1) The nanocomposite of claim 1, wherein: the layer of magnetic material is thin. ### Claim 3 (depends on 1) The nanocomposite of claim 1, wherein: the diamagnetic core is a material from the group consisting of gold, silver, copper, and platinum; the magnetic material is a material from the group consisting of iron and cobalt and alloys containing iron and/or cobalt; the passivating layer is a material from the group consisting of gold, silver, platinum, and copper, and alloys containing these materials. ### Claim 4 (depends on 3) The nanocomposite of claim 3, wherein: the layer of magnetic material is thin. ### Claim 5 (depends on 1) The nanocomposite of claim 1, comprising: a gold core; a thin layer of iron formed on the gold core; a passivating layer of gold on the layer of iron. ### Claim 6 (depends on 5) The nanocomposite of claim 5, wherein: the layer of magnetic material is thin. ### Claim 7 (depends on 1) The nanocomposite of claim 1, produced with a reverse micelle synthesis technique. ### Claim 8 (depends on 7) The nanocomposite of claim 7, wherein: the layer of magnetic material is thin. ### Claim 9 (depends on 1) The nanocomposite of claim 1, synthesized using cetyltrimethylammonium bromide, n-butanol, octane and aqueous reactants. ### Claim 10 (depends on 9) The nanocomposite of claim 9, wherein: the layer of magnetic material is thin. ### Claim 11 (depends on 1) The nanocomposite of claim 1, wherein: the diamagnetic core is a material from the group consisting of gold, silver, copper, and platinum; the magnetic material is a material from the group consisting of iron and cobalt and platinum alloys containing iron and/or cobalt; the passivating layer is a material from the group consisting of gold, silver, platinum, and copper, and alloys containing these materials. ### Claim 12 (depends on 11) The nanocomposite of claim 11, wherein: the layer of magnetic material is thin. ### Claim 13 (depends on 1) The nanocomposite of claim 1, wherein the nanocomposite is annealed. ### Claim 14 (depends on 13) The nanocomposite of claim 13, wherein: the layer of magnetic material is thin. ### Claim 15 (depends on 13) The nanocomposite of claim 13, wherein the nanocomposite is annealed at a temperature of about 300 K. ### Claim 16 (depends on 15) The nanocomposite of claim 15, wherein: the layer of magnetic material is thin. ### Claim 17 (depends on 1) Ferrofluids made with the nanocomposite of claim 1. ### Claim 18 (depends on 17) The ferrofluids of claim 17, wherein: the layer of magnetic material is thin. ### Claim 19 (depends on 1) Granular GMR materials made with the nanocomposite of claim 1. ### Claim 20 (depends on 19) The granular GMR materials of claim 19, wherein: the layer of magnetic material is thin. ### Claim 21 (depends on 1) Inductor materials made with the nanocomposite of claim 1. ### Claim 22 (depends on 21) The inductor materials of claim 21, wherein: the layer of magnetic material is thin. ### Claim 23 (depends on 1) Storage media made with the nanocomposite of claim 1. ### Claim 24 (depends on 23) The storage media of claim 23, wherein: the layer of magnetic material is thin. ### Claim 25 (depends on 1) Giant magnetoresistance sensors made with the nanocomposite of claim 1. ### Claim 26 (depends on 25) The giant magnetoresistance sensors of claim 25, wherein: the layer of magnetic material is thin. ### Claim 27 (depends on 1) Directed drug delivery agents made with the nanocomposite of claim 1. ### Claim 28 (depends on 27) The directed drug delivery agents of claim 27, wherein: the layer of magnetic material is thin. ### Claim 29 (depends on 1) Agents for targeted sensing for in vivo applications made with the nanocomposite of claim 1. ### Claim 30 (depends on 29) The agents of claim 29, wherein: the layer of magnetic material is thin.