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EP-3608451-B1 - PRESSURE CONTAINER FOR CRYSTAL PRODUCTION

EP3608451B1EP 3608451 B1EP3608451 B1EP 3608451B1EP-3608451-B1

Inventors

  • KURIMOTO, KOUHEI
  • BAO, QUANXI
  • UEDA, MUTSUO
  • SASAGAWA, YUJI
  • MORIMOTO, MASAYA
  • ISHIGURO, TORU
  • CHICHIBU, SHIGEFUSA

Dates

Publication Date
20260506
Application Date
20180405

Claims (16)

  1. A pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production, the pressure container (1, 1A, 2, 2A, 3, 3A) being configured to produce a crystal using ammonia in a supercritical state and/or a subcritical state as a solvent, a raw material, a mineralizer, and a seed crystal inside the container, wherein the pressure container (1, 1A, 2, 2A, 3, 3A) comprises a pressure container main body (10, 20) having an opening (100); and a cover (11) configured to close the opening (100) of the pressure container main body (10, 20); wherein Ag is present at least on the entire surface of an exposed inner surface of the pressure container (1, 1A, 2, 2A, 3, 3A), characterized in that the Ag is disposed by an Ag liner (14), an Ag welding (15) and an Ag plating (16A, 16B, 16C), and that the entire surface where the Ag is present includes at least: an inner surface of the pressure container main body (10, 20) on which the Ag liner (14) is disposed; an exposed inner surface of a portion of the pressure container (1, 1A, 2, 2A, 3, 3A) which cannot be covered with the Ag liner (14), to which the Ag plating (16A) is applied; and an inner surface of the cover (11), to which the Ag plating (16C) is applied.
  2. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to claim 1, wherein the pressure container (1, 1A, 2, 2A, 3, 3A) is adapted for a nitride crystal.
  3. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to any one of claims 1 or 2, wherein the pressure container (1, 1A, 2, 2A, 3, 3A) is adapted for the mineralizer to be a fluorine-based mineralizer and not contain a halogen atom other than fluorine.
  4. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to claim 1, wherein the pressure container main body (10, 20) has a cylindrical shape, and the Ag liner (14) having a bottomed cylindrical shape and having an opening is disposed on an inner surface of the pressure container main body (10, 20).
  5. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to claim 4, further comprising: a gasket disposed in a gap between the pressure container main body (10, 20) and the cover (11).
  6. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to claim 4 or 5, wherein the pressure container main body (10, 20) is formed of a pressure container first main body member (10A, 20A) and a pressure container second main body member (10B, 20B), wherein the pressure container second main body member (10B, 20B) is located on a part or all of an inner surface side of the pressure container first main body member (10A, 20A), and wherein the pressure container second main body member (10B, 20B) is composed of a material that is more excellent in corrosion resistance than the pressure container first main body member (10A, 20A).
  7. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to claim 4 or 5, wherein the cover (11) is formed of a first cover member (11A) and a second cover member (11B), wherein the second cover member (11B) is located on a part or all of an inner surface side of the first cover member (11A), and wherein the second cover member (11B) is composed of a material that is more excellent in corrosion resistance than the first cover member (11A).
  8. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to any one of claims 4 to 7, wherein the pressure container main body (10, 20) and the cover (11) are formed of a Ni-based alloy, an iron alloy, and/or a cobalt-based alloy.
  9. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to any one of claims 4 to 8, wherein the Ag is disposed by at least one Ag liner (14) which is installed up to a mouth part (101) of the pressure container main body (10, 20) having an opening and has a thickness of from 0.5 mm to 20 mm.
  10. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to claim 6, wherein the pressure container second main body member (10B. 20B) is located on an outer periphery side of the Ag welding (15) and the Ag plating (14), and wherein the pressure container first main body member (10A, 20A) is located on an outer peripheral side of the pressure container second main body member (10B, 20B).
  11. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to claim 7, wherein the second cover member (11B) is located on an outer periphery side of the Ag welding (15) and the Ag plating (16A, 16B, 16C) , and wherein the first cover member (11A) is located on an outer peripheral side of the second cover member (11B).
  12. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to any one of claims 4 to 11, wherein the Ag welding (15) joins an upper portion of an opening of the Ag liner (14) and the pressure container main body (10, 20) to seal a gap between the Ag liner (14) and the pressure container main body (10, 20).
  13. The pressure container (1, 1A, 2, 2A, 3, 3A) for crystal production according to any one of claims 4 to 12, wherein the Ag plating (16A, 16B, 16C) is performed on: the inner surface of the pressure container main body (10, 20) except for the Ag liner (14) and an Ag welded portion (25); the inner surface of the cover (11); and an inner peripheral surface of a gasket, and wherein the Ag plating layer has a thickness of from 10 µm to 1000 µm.
  14. A method for crystal production in a pressure container(1, 1A, 2, 2A, 3, 3A), wherein the pressure container (1, 1A, 2, 2A, 3, 3A) comprises a main body (10, 20) having an opening (100); and a cover (11) configured to close the opening (100) of the pressure container main body (10, 20); and wherein Ag is present at least on the entire surface of an exposed inner surface of the pressure container (1, 1A, 2, 2A, 3, 3A); and wherein the method uses ammonia in a supercritical state and/or a subcritical state as a solvent, a raw material, a mineralizer, and a seed crystal inside the container, characterized in that the Ag is disposed by combining an Ag liner (14), an Ag welding (15) and an Ag plating (16A, 16B, 16C), and that the entire surface where the Ag is present includes at least: an inner surface of the pressure container main body (10, 20) on which the Ag liner (14) is disposed; an exposed inner surface of a portion of the pressure container (1, 1A, 2, 2A, 3, 3A) which cannot be covered with the Ag liner (14), to which the Ag plating (16A) is applied; and an inner surface of the cover (11), to which the Ag plating (16C) is applied.
  15. A method for crystal production according to claim 14, wherein the crystal is a nitride crystal.
  16. A method for crystal production according to claim 14 or 15, wherein the mineralizer is a fluorine-based mineralizer and does not contain a halogen atom other than fluorine.

Description

TECHNICAL FIELD The present invention relates to a pressure container for crystal production a method for crystal production in a pressure container using ammonia in a supercritical state and/or subcritical state as a solvent, a raw material, a mineralizer, and seed crystal. BACKGROUND ART An ammonothermal method is a crystal production method using ammonia in a supercritical or subcritical state as a solvent, and is particularly known as a method useful for producing nitride crystal of group 13 element in the periodic table with high purity. In production with this method, a solvent, a raw material, and a seed crystal are put in a pressure container for crystal production and the pressure container for crystal production is sealed, and a high temperature area and a low temperature area are formed by heating the pressure container for crystal production, a difference in temperature causes the raw material dissolved in the solvent to be recrystallized on the seed crystal. For example, a desired crystal can be produced by dissolving GaN polycrystal which is a raw material in supercritical ammonia and recrystallizing the GaN polycrystal on a GaN single crystal which is a seed crystal. Since the raw material such as GaN has extremely low solubility with respect to ammonia in the critical or subcritical state, a mineralizer is added to improve the solubility and promote crystal growth. The mineralizers are classified into acid mineralizers represented by ammonium halide (NH4X, X = F, Cl, Br, I) and basic mineralizers represented by alkali amide (NH2 X, X = Li, Na, K). An ammonia environment in the supercritical or subcritical state containing mineralizer is a very severe corrosive environment, and there are problems such as deterioration of container safety and contamination of metal impurities into the produced crystal due to corrosion of container structure materials. As measures against the above problems, it has been proposed to use another material excellent in corrosion resistance as a corrosion resistant portion on the inner surface of the pressure container in contact with the solvent, or to use a reaction container such as a capsule inside the pressure container in some cases. For example, in PTL 1 to 3, a Ni-based alloy is used as a material of the corrosion resistant portion. In PTL 4, the fluorine-containing film is used as a corrosion resistant portion. In PTL 5, a capsule of a malleable metal such as Au, Ag, Cu, or Pt is used as a corrosion resistant portion. In PTL 6, Pt, Ir, Pt-Ir alloy or the like are used as a corrosion resistant portion. In PTL 7, Pt, Ir, Au, Ti, V, Zr, Nb, Ta, W and alloys thereof are used as a corrosion resistant portion. In PTL 8, it is preferable to line or coat a part in contact with ammonia other than a shield portion with a noble metal, and examples of the noble metal include platinum (Pt), gold (Au), iridium (Ir), ruthenium (Ru), rhodium (Rh), palladium (Pd), rhenium (Re), silver (Ag), and alloys having these elements as a main component. Among them, platinum, iridium, or an alloy thereof is considered to be preferable in view of excellence in corrosion resistance. PTL 9 and PTL 10 disclose pressure containers for crystal production having the features of the preamble of claim 1. CITATION LIST PATENT LITERATURE PTL 1: JP-A-2007-56320PTL 2: JP-A-2010-222247PTL 3: JP-A-2015-140288PTL 4: JP-A-2013-203652PTL 5: JP-T-2006-513122PTL 6: JP-A-2006-193355PTL 7: JP-A-2012-017212PTL 8: JP-T-2012-176318PTL 9: JP 2015-040170 APTL 10: JP 2012-171863 A SUMMARY OF INVENTION TECHNICAL PROBLEM However, in a case of the Ni-based alloys and fluorine-containing film of PTL 1 to 4, the corrosion in the ammonia environment including the mineralizer cannot be sufficiently prevented. In a case where a capsule of a malleable metal such as Au, Ag, Cu, or Pt disclosed in PTL 5 is used as a corrosion resistant portion, there is a problem in that since the metals are soft and thus the capsule is deformed, it cannot be used repeatedly for a long period of time. In PTL 6 to 8, although Pt or Ir liners are mainly used as a corrosion resistant material and can prevent the corrosion in the ammonia environment including the mineralizer, Pt is expensive, thereby leading to an increase in container production cost. In addition, it is clear that Pt forms a reaction layer by alloying with Ga, and there is a risk of becoming brittle and breaking in use for a long period of time. Also, no specific use has been described for other noble metals. An object of the present invention is to solve the problems in the related art as described above, and there is provided a pressure container for crystal production which has high corrosion resistance and can be used repeatedly for a long period of time. SOLUTION TO PROBLEM To solve the above object, a pressure container for crystal production and a method for crystal production in a pressure container according to the invention are as specified in claims 1 and 14. Prefe