# US 2020/0395162 A1 · Particle-based, anisotropic composite materials for magnetic cores > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0395162 A1 - Document ID: US20200395162A1 - Status: Published application - Kind: A1 - Application number: 16/442,699 - Filed: 2019-06-17 - Published: 2020-12-17 - Earliest claimed: 2019-06-17 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Arvind Raj, Mahankali Sridhar; Thomas Brunschwiler; Suiying Ye; Luca Del Carro; Jens Oliver Ammann - Web page: https://patentgrep.com/patent/US20200395162A1 ## CPC - H01F 27/255: made from particles (H01F27/26 takes precedence) - H01F 41/16: the magnetic material being applied in the form of particles, e.g. by serigraphy {, to form thick magnetic films or precursors therefor} (H01F41/18 {-H01F41/24} take precedence) - H01F 1/22: pressed, sintered, or bound together - H01F 1/24: the particles being insulated - H01F 1/28: dispersed or suspended in a bonding agent - H01F 1/36: in the form of particles {(H01F1/346, H01F1/348 and H01F1/38 take precedence)} - H01F 1/37: in a bonding agent - H01F 3/08: made from powder (powder coatings on sheets H01F3/02; on strips or ribbons H01F3/04; on wires H01F3/06) - H01F 41/02: for manufacturing cores, coils, or magnets (H01F41/14 takes precedence; for dynamo-electric machines H02K15/00) - H01F 1/447: {characterised by magnetoviscosity, e.g. magnetorheological, magnetothixotropic, magnetodilatant liquids (electrorheological fluids C10M171/001)} - Y10T 428/32: Composite [nonstructural laminate] of inorganic material having metal-compound-containing layer and having defined magnetic layer - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A magnetic core comprises an anisotropic, composite material, which itself includes a matrix material (e.g., a dielectric, non-magnetic material, preferably a paramagnetic material), and magnetically aligned, ferromagnetic particles. The latter may for instance include micrometer- and/or nanometer-length scale particles. Such particles form chains of particles within the matrix material, wherein the chains form percolation paths of magnetic conduction. The paths extend along a first direction, whereby the chains extend, each, substantially along this first direction, while being distinct and distant from each other along a second direction that is perpendicular to the first direction and, possibly, to a third direction that is perpendicular to both the first direction and the second direction. Necking bridges are preferably formed between the particles. Related devices (e.g., inductor, amplifiers, transformers, etc.) and fabrication methods are also disclosed. ## Claims ### Claim 1 A magnetic core comprising: an anisotropic, composite material including at least: a matrix material; and magnetically aligned, ferromagnetic particles forming chains of said particles within said matrix material, the chains forming percolation paths of magnetic conduction extending along a first direction, whereby the chains extend, each, along the first direction, while being distinct and distant from each other along a second direction that is perpendicular to the first direction. ### Claim 2 (depends on 1) The magnetic core according to claim 1, wherein said particles comprise micrometer-length scale particles. ### Claim 3 (depends on 1) The magnetic core according to claim 1, wherein said particles include first particles of a first type and second particles of a second type, the second particles having a smaller average diameter than the first particles, and the second particles form necking bridges between the first particles along the first direction. ### Claim 4 (depends on 3) The magnetic core according to claim 3, wherein said first particles comprise micrometer-length scale particles, while said second particles comprise nanometer-length scale particles. ### Claim 5 (depends on 3) The magnetic core according to claim 3, wherein said first particles and second particles have an average sintering temperature that is substantially less than a melting temperature of the matrix material. ### Claim 6 (depends on 1) The magnetic core according to claim 1, wherein said chains are substantially arranged according to one of: a parallel line configuration, a configuration of concentric tori, and a racetrack configuration of the chains of particles. ### Claim 7 (depends on 1) The magnetic core according to claim 1, wherein said matrix material is a dielectric, non-magnetic material. ### Claim 8 (depends on 7) The magnetic core according to claim 7, wherein said matrix material is a paramagnetic material. ### Claim 9 (depends on 1) The magnetic core according to claim 1, wherein said composite material comprises between 10 and 50 volume percent of ferromagnetic particles. ### Claim 10 (depends on 1) The magnetic core according to claim 1, wherein said chains of the particles form percolation paths of magnetic conduction extending along both the first direction and a third direction that is perpendicular to both the first direction and the second direction. ### Claim 11 A magnetic device comprising a magnetic core, the latter comprising: an anisotropic, composite material including at least: a matrix material; and magnetically aligned, ferromagnetic particles forming chains of said particles within said matrix material, the chains forming percolation paths of magnetic conduction extending along a first direction, whereby the chains extend, each, along the first direction, while being distinct and distant from each other along a second direction that is perpendicular to the first direction. ### Claim 12 (depends on 11) The magnetic device according to claim 11, wherein the device is one of: an inductor, a transformer, an amplifier, and a power-supply device. ### Claim 13 A method of fabrication of a magnetic core, the method comprising: providing a matrix material including ferromagnetic particles; and applying a magnetic field to magnetically align the ferromagnetic particles in the matrix material and thereby form an anisotropic, composite material for the magnetic core, in which chains of said particles are formed within said matrix material, the chains forming percolation paths of magnetic conduction extending along a first direction, whereby the chains extend, each, along the first direction, while being distinct and distant from each other along a second direction that is perpendicular to the first direction. ### Claim 14 (depends on 13) The method according to claim 13, wherein the ferromagnetic particles comprise micrometer-length scale particles. ### Claim 15 (depends on 14) The method according to claim 14, wherein the applied magnetic field has a strength of at least 20 mT. ### Claim 16 (depends on 13) The method according to claim 13, wherein the ferromagnetic particles in the matrix material represent between 10 and 50 volume percent of the composite material formed. ### Claim 17 (depends on 13) The method according to claim 13, wherein the ferromagnetic particles comprise first particles of a first type, as well as second particles of a second type, the second particles having a smaller average diameter than the first particles, and the method further comprises forming necking bridges between the first particles, while applying said magnetic field, so as to bridge the latter thanks to the second particles along the first direction. ### Claim 18 (depends on 17) The method according to claim 17, wherein forming said necking bridges includes sintering the first particles and the second particles. ### Claim 19 (depends on 13) The method according to claim 13, wherein the method further comprises immobilizing the chains in the anisotropic, composite material formed. ### Claim 20 (depends on 17) The method according to claim 17, wherein the first particles comprise micrometer-length scale particles, while the second particles comprise nanometer-length scale particles. ### Claim 21 (depends on 13) The method according to claim 13, wherein said magnetic field is applied so as for the chains to be arranged according to one of: a parallel line configuration, a configuration of concentric tori, and a racetrack configuration of the chains of particles. ### Claim 22 (depends on 13) The method according to claim 13, wherein said magnetic field is applied using one or each of permanent magnets and an electromagnet. ### Claim 23 (depends on 13) The method according to claim 13, wherein said anisotropic, composite material is formed by successively forming layers of this composite material, by repeating the steps of claim 13. ### Claim 24 (depends on 13) The method according to claim 13, wherein the matrix material is provided in a structured template, so as to constrain the shape of the composite material eventually formed. ### Claim 25 (depends on 13) The method according to claim 13, wherein the method further comprises integrating the magnetic core obtained in a device.