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Growth equipment for preparation of magnesium fluoride crystals with multi-crucible descending method and growth method of magnesium fluoride crystals

A technology for preparing magnesium fluoride and a growth method, which is applied in crystal growth, polycrystalline material growth, single crystal growth, etc., can solve the problems of low growth efficiency, achieve high production efficiency, easy control of shape and size, and excellent optical quality Effect

Inactive Publication Date: 2017-02-22
SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art, and propose a method and growth equipment for preparing magnesium fluoride crystals by the multi-crucible descending method. The problem of low growth efficiency

Method used

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  • Growth equipment for preparation of magnesium fluoride crystals with multi-crucible descending method and growth method of magnesium fluoride crystals
  • Growth equipment for preparation of magnesium fluoride crystals with multi-crucible descending method and growth method of magnesium fluoride crystals
  • Growth equipment for preparation of magnesium fluoride crystals with multi-crucible descending method and growth method of magnesium fluoride crystals

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Embodiment 1: The selected crucible is a 15-hole graphite crucible, and the crystal growth area is all cylindrical, with a diameter of 33 mm and a length of 200 mm. Load the preferred magnesium fluoride crystal seed crystal into the seed crystal area, assemble the graphite crucible, load 8.2 kg of crystal raw material magnesium fluoride powder into the crystal growth area and the feed bin, and cover the crucible lid. Put the crucible into the crystal growth furnace, and evacuate until the vacuum degree reaches 1.0×10 -3 After Pa, filled with 60%:40% Ar and CF 4The mixed gas makes the pressure in the furnace reach 0.11MPa. Turn on the medium-frequency induction heating power supply, start to heat up the molten material at a heating rate of 10-100°C / h, and after the magnesium fluoride raw material is completely melted, perform a constant temperature overheating treatment for 10 hours, and then prepare magnesium fluoride crystals at a falling rate of 2.0mm / h. After falli...

Embodiment 2

[0029] Embodiment 2: The selected crucible is a 3-hole graphite crucible, and the crystal growth area is all cylindrical, with a diameter of 76 mm and a length of 200 mm. Load the preferred magnesium fluoride crystal seed crystal into the seed crystal area, assemble the graphite crucible, load 8.3 kg of crystal raw material magnesium fluoride powder into the crystal growth area and the feed bin, and cover the crucible lid. Put the crucible into the crystal growth furnace, and evacuate until the vacuum degree reaches 1.0×10 -3 After Pa, fill with 60%:40% Ar and CF 4 The mixed gas makes the pressure in the furnace reach 0.11MPa. Turn on the medium-frequency induction heating power supply, start to heat up the molten material at a heating rate of 10-100°C / h, and after the magnesium fluoride raw material is completely melted, perform a constant temperature overheating treatment for 10 hours, and then prepare magnesium fluoride crystals at a falling rate of 1.5mm / h. After falling...

Embodiment 3

[0031] Embodiment 3: The selected crucible is an 8-hole graphite crucible, and the crystal growth area is all cylindrical, with a diameter of 40 mm and a length of 200 mm. Load the preferred magnesium fluoride crystal seed crystal into the seed crystal area, assemble the graphite crucible, load the crystal raw material magnesium fluoride powder 6.4kg into the crystal growth area and the feed bin, and cover the crucible lid. Put the crucible into the crystal growth furnace, and evacuate until the vacuum degree reaches 1.0×10 -3 After Pa, fill with 70%:30% Ar and CF 4 The mixed gas makes the pressure in the furnace reach 0.11MPa. Turn on the medium-frequency induction heating power supply, start to heat up the molten material at a heating rate of 10-100°C / h, and after the magnesium fluoride raw material is completely melted, perform a constant temperature overheating treatment for 10 hours, and then prepare magnesium fluoride crystals at a falling rate of 2.0mm / h. After fallin...

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Abstract

The invention discloses growth equipment for preparation of magnesium fluoride crystals with a multi-crucible descending method and a growth method. A porous graphite crucible comprises four parts including a seed crystal zone, a crystal growth zone, a bin zone and a crucible lid; the growth equipment further comprises a furnace hearth, a descending device and a copper induction heating coil, ventilating holes are formed in the upper side and the lower side of the furnace hearth, the inner wall of the furnace hearth, and the copper induction coil and a descending rod surface are plated with a nickel layer or a high-temperature-resistant organic resin layer which can resist corrosion of gases such as hydrogen fluoride and the like. The preparation method comprises steps as follows: parameter setting, furnace charging, vacuum pumping, introduction of protecting gases, waiting for complete melting of raw materials and forming of melts, starting of descending after seed crystals are melted to be thin and preparation of the magnesium fluoride crystals. The prepared magnesium fluoride crystals have excellent optical quality, and the transmittance of 190 nm wavelength can reach 93.5%; the appearance and the size of the magnesium fluoride crystals are easy to control; the magnesium fluoride crystals grow simultaneously in multiple crucibles, the growth efficiency is high, and industrial production is facilitated.

Description

technical field [0001] The invention relates to a method for preparing magnesium fluoride crystals, in particular to a method and growth equipment for preparing magnesium fluoride crystals by using a porous graphite crucible descent method, and belongs to the technical field of crystal growth. Background technique [0002] Magnesium fluoride crystals (chemical formula MgF 2 ) is a common alkaline earth metal fluoride crystal. It has many excellent properties, including high thermal stability and high hardness; low chemical activity and high corrosion resistance at high temperature; small refractive index and high laser damage threshold; from vacuum ultraviolet 120nm to ordinary ultraviolet 400nm It has very excellent transmittance. These properties determine that magnesium fluoride crystal is an excellent ultraviolet optical window material, and other commonly used fluoride crystals such as LiF, GaF 2 、BaF 2 The performance used as a UV window cannot be compared with tha...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C30B29/12C30B11/14C30B11/02
CPCC30B11/02C30B11/14C30B29/12
Inventor 李百中李铮施振华侯印春
Owner SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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