# US 10,246,768 B2 · Process for preparation of micron-sized single curved crystals of metals > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,246,768 B2 - Document ID: US10246768B2 - Status: Granted - Kind: B2 - Application number: 14/675,829 - Filed: 2015-04-01 - Published: 2015-10-08 - Granted: 2019-04-02 - Earliest claimed: 2014-04-02 - Assignees: Technion Research & Development Founda - Applicants: Technion Research & Development Foundation Limited - Inventors: Boaz Pokroy; Maria Koifman Khristosov - Web page: https://patentgrep.com/patent/US10246768B2 ## CPC - C23C 14/18: on other inorganic substrates - C23C 14/5806: {Thermal treatment} - C23C 14/5873: {Removal of material} - C23F 1/00: Etching metallic material by chemical means (manufacture of printing surfaces B41C; manufacture of printed circuits H05K) - C23F 1/40: for etching other metallic material - C30B 21/00: Unidirectional solidification of eutectic materials - C30B 29/02: Elements - C30B 29/60: characterised by shape - C30B 33/02: Heat treatment (C30B33/04, C30B33/06 take precedence) - Y10T 428/12014: having metal particles - Y10T 428/25: Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25 - C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract The present invention relates to metal micron-sized single crystals having a controlled curvature, which can be either fully or partially nanoporous; and to a process for growing of such single crystals from the confined volume of droplets of a eutectic composition melt comprising said metal as one of the two eutectic components, with no need of any fabrication steps. ## Claims ### Claim 1 A process for the preparation of micron-sized particles having a controlled curvature, said particles spread over a supporting substrate and including a single-crystal first metal wrapped in a nanoporous structure, said process comprising: (i) providing said substrate; (ii) depositing vapours of the first metal and of a second metal on a surface of said substrate, thus forming a substrate deposited with either a thin film comprising said first and second metals, or two thin films each comprising a different metal of said first and second metals, wherein said metals deposited on said substrate are selected from Au, Ag, Ge, Cu, and Pt, and the atomic percentage ratio between said first metal and said second metal is such that upon annealing said film(s), said first metal and said second metal form a eutectic melt; (iii) annealing said film(s) for a sufficient time period to form said eutectic melt that spontaneously dewets into micron-sized droplets spread over said substrate; (iv) (a) cooling said eutectic melt to room temperature, or (b) continuing the annealing of step (iii) in an environment that contains oxygen, thereby removing the second metal from said eutectic melt, to consequently grow a single crystal of the first metal, wherein according to a phase diagram of the eutectic melt, in each one of said droplets, said single crystal is grown in the confined space of said droplet, has a controlled curvature determined by the curved shape of said confining droplet and is wrapped in a two-phase eutectic microstructure comprising the first metal and the second metal; (v) cooling the grown single crystals of the first metal wrapped in the two-phase eutectic microstructure comprising the first metal and the second metal to obtain micron-sized particles of the single-crystal first metal wrapped in a solid phase comprising said two metals; and (vi) removing the second metal from said solid phase, thereby obtaining the micron-sized particles of the single-crystal first metal wrapped in the nanoporous structure, said particles having a controlled curvature and being spread over the supporting substrate; wherein said substrate is inert relative to said thin film(s) formed in step (ii); and the eutectic melt in step (iii) dewets within a temperature range allowing dewetting to occur prior to diffusion intermixing with said substrate and/or oxidation. ### Claim 2 (depends on 1) The process of claim 1, wherein upon continuing the annealing in step (iv) in an environment that contains oxygen, the second metal is oxidized, sublimes and is removed by evaporation of the corresponding oxide. ### Claim 3 (depends on 1) The process of claim 1, wherein upon cooling in step (v), the grown single crystals of the first metal continue growing by inducing crystallization of the first metal inside the two-phase eutectic microstructure, wherein growth of the first metal single crystal is accompanied by repeated nucleation and growth of the second metal crystal at the surface of the first metal single crystal, thereby obtaining micron-sized particles of the single crystal first metal wrapped in a solid phase comprising said two metals. ### Claim 4 (depends on 1) The process of claim 1, wherein said removal of the second metal from the solid phase in step (vi) comprises wet etching of said metal. ### Claim 5 (depends on 1) The process of claim 1, wherein said eutectic melt formed in step (iii) comprises the eutectic concentration of said two metals. ### Claim 6 (depends on 1) The process of claim 1, wherein said vapors of said first and second metals are deposited on the surface of said substrate at any sequential order or concurrently. ### Claim 7 (depends on 1) The process of claim 1, wherein the annealing in step (iii) is carried out under N2, forming gas or argon atmosphere, or under vacuum. ### Claim 8 (depends on 1) The process of claim 1, wherein said substrate comprises silicon dioxide (silica), titanium dioxide (titania), magnesium oxide (magnesia), aluminium oxide (alumina), or a spinel such as MgAl2O4. ### Claim 9 (depends on 1) The process of claim 1, wherein said first and second metals are Au and Ge, or Ag and Ge, respectively. ### Claim 10 (depends on 1) The process of claim 1, wherein the shape of the micron-sized droplets formed in step (iii) is controlled by modulating the contact angle and the droplet curvature, which is affected by the surface tension. ### Claim 11 (depends on 10) The process of claim 10, wherein the contact angle and the surface tension of said micron-sized droplets is controlled by altering the oxygen partial pressure in the annealing environment. ### Claim 12 (depends on 1) The process of claim 1, further comprising the step of segregating said micron-sized particles from said supporting substrate.