# US 11,114,600 B2 · Polycrystalline magnesium silicide and use thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,114,600 B2 - Document ID: US11114600B2 - Status: Granted - Kind: B2 - Application number: 16/314,841 - Filed: 2017-07-05 - Published: 2019-08-08 - Granted: 2021-09-07 - Earliest claimed: 2016-07-12 - Assignees: Tokyo University of Science Foundation - Applicants: Tokyo University of Science Foundation - Inventors: Tsutomu Iida; Syunsuke Kondo; Mitsunobu Nakatani - Web page: https://patentgrep.com/patent/US11114600B2 ## CPC - H10N 10/851: comprising inorganic compositions - B22F 3/10: Sintering only - C01B 33/06: Metal silicides (alloys C22) - C04B 35/58: based on borides, nitrides, {i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides} or silicides {(containing free binder metal C22C29/00)} - C22C 1/02: by melting {(C22C1/1036 takes precedence)} - C22C 23/00: Alloys based on magnesium - H10N 10/01: Manufacture or treatment - H10N 10/10: operating with only the Peltier or Seebeck effects - H10N 10/8556: {comprising compounds containing germanium or silicon} - H10N 10/857: comprising compositions changing continuously or discontinuously inside the material - B22F 2302/45: Others, including non-metals - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - C22C: ALLOYS (treatment of alloys C21D, C22F) ## Abstract Polycrystalline magnesium silicide containing only carbon as a dopant and having carbon distributed at the crystal grain boundaries and within the crystal grains, a thermoelectric conversion material obtained using the polycrystalline magnesium silicide, a sintered compact, a thermoelectric conversion element, and a thermoelectric conversion module, and methods for producing polycrystalline magnesium silicide and a sintered compact. ## Claims ### Claim 1 Polycrystalline magnesium silicide comprising an isoelectronic impurity of silicon as a dopant, wherein the isoelectronic impurity consists of carbon atoms, wherein the carbon atoms are distributed within crystal grains and at crystal grain boundaries of the polycrystalline magnesium silicide, and wherein the carbon atoms that replace a portion of the silicon atoms within the crystal grains of the polycrystalline magnesium silicide function as the dopant. ### Claim 2 (depends on 1) The polycrystalline magnesium silicide according to claim 1, wherein the polycrystalline magnesium silicide contains 0.05 at % to 3.0 at % of carbon in an atomic weight ratio. ### Claim 3 (depends on 1) A thermoelectric conversion material comprising the polycrystalline magnesium silicide according to claim 1. ### Claim 4 A method for producing polycrystalline magnesium silicide, the method comprising heating and melting a starting material composition containing magnesium, silicon, and a carbon source in a reducing atmosphere at a temperature of 1085° C. or higher and lower than 1410° C. to produce a melted and solidified material, wherein during the heating and melting, carbon generated by thermal decomposition of the carbon source is distributed within crystal grains and at crystal grain boundaries of the polycrystalline magnesium silicide. ### Claim 5 (depends on 4) The method according to claim 4, wherein the carbon source is fullerene. ### Claim 6 (depends on 4) The method according to claim 4, further comprising pulverizing the melted and solidified material to produce a pulverized material. ### Claim 7 (depends on 6) A method for producing a sintered body, the method comprising sintering a pulverized material obtained by the method according to claim 6 using a spark plasma sintering method in an inert gas atmosphere under conditions of sintering temperature of 600° C. to 1,000° C. and sintering pressure of 5 MPa to 60 MPa. ### Claim 8 (depends on 1) The polycrystalline magnesium silicide according to claim 1, wherein the polycrystalline magnesium silicide is a melted and solidified material of a starting material composition obtained by mixing magnesium, silicon and fullerene and the carbon distributed within crystal grains and at crystal grain boundaries is derived from the fullerene. ### Claim 9 (depends on 3) The thermoelectric conversion material according to claim 3, wherein the thermoelectric conversion material comprises no unreacted magnesium. ### Claim 10 (depends on 1) A sintered body obtained by sintering the polycrystalline magnesium silicide according to claim 1. ### Claim 11 (depends on 10) The sintered body according to claim 10, wherein the sintered body has a relative density of 98% or more. ### Claim 12 (depends on 10) A thermoelectric conversion material configured by the sintered body according to claim 10. ### Claim 13 (depends on 12) The thermoelectric conversion material according to claim 12, wherein the thermoelectric conversion material comprises no unreacted magnesium. ### Claim 14 (depends on 3) A thermoelectric conversion element, comprising the thermoelectric conversion part configured by the thermoelectric conversion material according to claim 3; and a first electrode and a second electrode provided to the thermoelectric conversion part. ### Claim 15 (depends on 14) A thermoelectric conversion module, comprising the thermoelectric conversion element according to claim 14. ### Claim 16 (depends on 12) A thermoelectric conversion element, comprising the thermoelectric conversion part configured by the thermoelectric conversion material according to claim 12; and a first electrode and a second electrode provided to the thermoelectric conversion part. ### Claim 17 (depends on 16) A thermoelectric conversion module, comprising the thermoelectric conversion element according to claim 16. ### Claim 18 (depends on 4) The method for producing a polycrystalline magnesium silicide according claim 4, wherein a ratio of the carbon source in the starting material composition is 0.05 at % to 3.0 at % in an atomic weight ratio.