CN1233881C - Method for growing quadrivalent chromium-doped magnesium silicate crystal by vertical temperature gradient method - Google Patents
Method for growing quadrivalent chromium-doped magnesium silicate crystal by vertical temperature gradient method Download PDFInfo
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- 239000013078 crystal Substances 0.000 title claims abstract description 85
- 238000000034 method Methods 0.000 title claims abstract description 50
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 title claims description 11
- 239000000391 magnesium silicate Substances 0.000 title claims description 11
- 229910052919 magnesium silicate Inorganic materials 0.000 title claims description 11
- 235000019792 magnesium silicate Nutrition 0.000 title claims description 11
- 238000010438 heat treatment Methods 0.000 claims abstract description 20
- 239000011651 chromium Substances 0.000 claims abstract description 19
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000000463 material Substances 0.000 claims abstract description 17
- 239000000155 melt Substances 0.000 claims abstract description 15
- 239000000843 powder Substances 0.000 claims abstract description 12
- 238000007789 sealing Methods 0.000 claims abstract description 12
- 238000002156 mixing Methods 0.000 claims abstract description 10
- 229910052786 argon Inorganic materials 0.000 claims abstract description 9
- 238000003825 pressing Methods 0.000 claims abstract description 7
- 238000001816 cooling Methods 0.000 claims abstract description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 6
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910052681 coesite Inorganic materials 0.000 claims abstract description 5
- 229910052906 cristobalite Inorganic materials 0.000 claims abstract description 5
- CRGGPIWCSGOBDN-UHFFFAOYSA-N magnesium;dioxido(dioxo)chromium Chemical compound [Mg+2].[O-][Cr]([O-])(=O)=O CRGGPIWCSGOBDN-UHFFFAOYSA-N 0.000 claims abstract description 5
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 5
- 229910052682 stishovite Inorganic materials 0.000 claims abstract description 5
- 229910052905 tridymite Inorganic materials 0.000 claims abstract description 5
- 238000011068 loading method Methods 0.000 claims abstract description 4
- 229910052839 forsterite Inorganic materials 0.000 claims description 23
- 230000001681 protective effect Effects 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 2
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims description 2
- QDOXWKRWXJOMAK-UHFFFAOYSA-N chromium(III) oxide Inorganic materials O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 claims 1
- 238000004321 preservation Methods 0.000 abstract description 12
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 abstract description 9
- 229910000423 chromium oxide Inorganic materials 0.000 abstract description 9
- 230000001590 oxidative effect Effects 0.000 abstract description 7
- 230000003647 oxidation Effects 0.000 abstract description 3
- 238000007254 oxidation reaction Methods 0.000 abstract description 3
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 16
- 229910052750 molybdenum Inorganic materials 0.000 description 15
- 239000011733 molybdenum Substances 0.000 description 15
- 239000001095 magnesium carbonate Substances 0.000 description 13
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 13
- 230000002829 reductive effect Effects 0.000 description 12
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 229910052593 corundum Inorganic materials 0.000 description 7
- 238000002425 crystallisation Methods 0.000 description 7
- 230000008025 crystallization Effects 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 7
- 229910002804 graphite Inorganic materials 0.000 description 7
- 239000010439 graphite Substances 0.000 description 7
- 229910052741 iridium Inorganic materials 0.000 description 7
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 7
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 7
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 239000010410 layer Substances 0.000 description 6
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 6
- 229910052721 tungsten Inorganic materials 0.000 description 6
- 239000010937 tungsten Substances 0.000 description 6
- 229910001845 yogo sapphire Inorganic materials 0.000 description 6
- 238000000462 isostatic pressing Methods 0.000 description 5
- 238000004891 communication Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 4
- LJAOOBNHPFKCDR-UHFFFAOYSA-K chromium(3+) trichloride hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].[Cl-].[Cl-].[Cr+3] LJAOOBNHPFKCDR-UHFFFAOYSA-K 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910001430 chromium ion Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 239000010431 corundum Substances 0.000 description 1
- 238000002109 crystal growth method Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 229910052909 inorganic silicate Inorganic materials 0.000 description 1
- 238000005499 laser crystallization Methods 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- MGRWKWACZDFZJT-UHFFFAOYSA-N molybdenum tungsten Chemical compound [Mo].[W] MGRWKWACZDFZJT-UHFFFAOYSA-N 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000007750 plasma spraying Methods 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
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Abstract
A method for growing tetravalent magnesium chromate silicate crystal by a vertical temperature gradient method comprises the following steps: placing oriented seed crystals in a seed crystal groove of a temperature gradient furnace crucible; selecting specific value of x in the range of 0-0.05, and preparing high-purity MgCO according to the proportion of (1+ x) to 13And SiO2A powder material, wherein 0.18-0.40 wt% of chromium oxide (Cr) is added to the powder material2O3) Mechanically mixing in a mixer; pressing into blocks by a material pressing machine, directly loading into a crucible, adding a crucible cover, sealing the crucible, and placing into a temperature gradient furnace; vacuumizing and heating to 600 ℃, and introducing high-purity argon; and continuously heating to the temperature of the melt of about 1890 +/-10 ℃, keeping the temperature for 1-3 hours, cooling at the speed of 5-10 ℃/hour, slowly cooling to room temperature after the crystal growth is finished, opening a furnace cover, and taking out the crystal. The invention avoids the oxidation pollution of the oxidizing atmosphere in the furnace to the heating body and the heat preservation material, effectively overcomes the problem that the melt components are volatilized due to the reducing atmosphere, and obviously improves the crystal quality.
Description
Technical Field
The invention relates to a tetravalent chromium-doped magnesium silicate crystal, in particular to a tetravalent chromium-doped magnesium silicate crystal grown by a vertical temperature gradient method. The magnesium silicate crystal doped with tetravalent chromium has important application value in the fields of laser and optical communication.
Background
Magnesium silicate (Cr) doped with tetravalent chromium4+:Mg2SiO4) The crystal must grow in oxidizing atmosphere, but in oxidizing atmosphere, the iridium crucible is seriously oxidized and has large loss, which increases the crystal growth cost, and Japanese scientist Y.Yamaguchi et al report 1993 that medium-frequency induction Czochralski method is used for growing high-quality Cr to Mg2SiO4A single Crystal having a size of phi 35X 100mm was obtained by laser crystallization (see prior art [1]Y. Yamaguchi, "The behavior of chromium ions for formation", published in The Journal of International Crystal Growth, No. 128, p. 996-1000 of 1993). Chinese scientist Yan Songhe et al in 1992 provided a method for protecting iridium crucibles from growing tetravalent chromium-doped high-temperature oxide crystals, application No. 92108460.9, publication No. CN1080334A, is a method of spraying a zirconia protective layer on the outer wall of an iridium crucible by using a plasma spraying technology, melting materials in a neutral atmosphere and maintaining the crystal growth in an oxygen atmosphere, so that the volatilization loss of iridium is reduced to a certain extent, and the loss in single growth is about 6 g. The 2001 Xujun et al, Chinese scientist, provides a method for growing tetravalent magnesium chromate silicate crystal, application No. 01139222.3, which adopts mixed flowing gas and staged oxygen introduction method to grow crystal, so as to greatly reduce the volatilization loss of iridium and make the single growth loss less than 3 g.
The three methods of the prior art all have obvious technical defects: (1) the zirconia coating is easy to separate from the crucible when growing, especially when the temperature is increased or decreased and the temperature change is large, and the loss of the iridium crucible is serious; (2) the crystal is grown by the pulling method, the surface of the fused mass has serious volatilization of different components,i.e., MgO and SiO2Non-proportional volatilization easily produces inclusions, crystal inner cores and other defects in the crystals, and the quality of the crystals is poor. It is difficult to meet the development requirements of laser technology and optical communication technology.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects of the prior art and provide a method for growing a tetravalent chromium-doped magnesium silicate crystal by a vertical temperature gradient method, so as to avoid using a noble metal iridium crucible, effectively overcome the reductive volatilization of melt components and the internal defects of the crystal, and meet the development requirements of a laser technology and an optical communication technology.
The key of the technical solution of the invention is that:
1. growing large-size tetravalent chromium-doped magnesium silicate crystal by Vertical Gradient Freezing (VGF) method from Cr4+:Mg2SiO4The bottom of the melt is crystallized, and a solid-liquid interface moves from bottom to top to grow crystals.
2. In Cr4+:Mg2SiO4In the raw material formula for crystal growth, magnesium carbonate (MgCO) is adopted3) And silicon oxide (SiO)2) The raw materials are mixed according to the proportion of (1+ x) to 1(x is 0-0.05), and 0.18-0.40 wt% of chromium oxide (Cr) is doped2O3) Pressing into blocks, directly loading into crucible, and sealing the crucible. Instead of pre-sintering to MgCO as in the prior art3Decomposition and CO removal2. Thus, the sealed crucible is made to contain CO2And O2So as to satisfy both magnesium silicate (Cr) doped with tetravalent chromium4+:Mg2SiO4) The crystal needs to grow in the oxidizing atmosphere, the oxidation pollution of the oxidizing atmosphere in the furnace to the heating body and the heat-insulating material is avoided, and the problem that the melt components are volatilized due to the reducing atmosphere is effectively solved.
The invention relates to a method for growing tetravalent magnesium chromate silicate crystal by a vertical temperature gradient method, which comprises the following steps:
<1>placing oriented seed crystals in a seed crystal groove of a crucible of a temperature gradient furnace;
<2>selecting specific value of x in the range of 0-0.05, and preparing high-purity MgCO according to the proportion of (1+ x) to 13And SiO2A powder material, wherein chromium oxide (Cr) is added in an amount of 0.18 to 0.40wt% based on the total amount of the powder material2O3) Mechanically mixing the raw materials into a mixture in a mixer;
pressing the mixture into blocks by using a material pressing machine, directly loading the blocks into a crucible, adding a crucible cover, sealing the crucible and then placing the crucible into a temperature gradient furnace;
heating to 600 ℃ while vacuumizing<4>, and filling high-purity argon (Ar);
and (5) continuously heating to the melt temperature of 1890 +/-10 ℃, keeping the temperature for 1-3 hours, cooling at the speed of 5-10 ℃/hour, slowly cooling to room temperature after the crystal growth is finished, opening a furnace cover, and taking out the crystal.
Mg of the present invention2SiO4The main chemical reactions involved in the melt are:
wherein x is 0-0.05, namely MgCO considering that MgO can generate partial reductive volatilization in crystal growth3In excess of the amount in the reaction scheme0～5％。
With Cr of the prior art4+:Mg2SiO4Compared with the crystal growth method, the vertical temperature gradient method of the invention grows crystals from the bottom of the crucible, and magnesium carbonate (MgCO) is adopted as the raw material3) So that the sealed crucible contains CO2And O2So as to satisfy both magnesium silicate (Cr) doped with tetravalent chromium4+:Mg2SiO4) The crystal needs to grow in the oxidizing atmosphere, the oxidation pollution of the oxidizing atmosphere in the furnace to the heating body and the heat-insulating material is avoided, and the problem that the melt components are volatilized due to the reducing atmosphere is effectively solved. And the quality of the crystal is obviously higher than that of the crystal grown by the existing method, thereby meeting the development requirements of the laser technology and the optical communication technology.
Description of the drawings:
FIG. 1 is a sectional view showing an internal structure of a Vertical Gradient Furnace (VGF)
FIG. 2 is a sectional view of the crucible 1
The specific implementation mode is as follows:
the invention grows Cr by the vertical temperature gradient method4+:Mg2SiO4The apparatus used for the crystal is called a temperature gradient furnace,as shown in figure 1, the bell-jar vacuum resistance furnace is characterized in that the structure inside the furnace body comprises a crucible and a heating body, the crucible 1 is arranged in the center position in the furnace body, a cylindrical graphite heating body 2 is arranged around the crucible 1, a side heat preservation screen 9 is arranged on the periphery of the heating body 2, an upper heat preservation screen 8 which is tightly closed with the side heat preservation screen 9 is arranged at the top of the heating body 2, a crucible support 3 is arranged at the bottom of the crucible 1, an electrode plate 6 connected with the heating body 2 is supported by a support ring 7, a lower heat preservation screen 10 is arranged in the support ring 7, a cooling water support rod 5 is arranged in the crucible support 3 after penetrating through the centers of the lower heat preservation screen 10 and the electrode plate 6, and. A vacuum system, a 60KW Sockmann A2S1047 UPS, a 818P4 Ou-road precise temperature control system, and a W/Re3-W/Re25 thermocouple 4 for monitoring and measuring temperature are additionally arranged outside the furnace body. The crucible is made of molybdenum (Mo) material. Zirconia (ZrO) for crucible support 32) The supporting ring 7 is made of a corundum ring. The upper, side and lower heat-insulating screens 8, 9 and 10 are made of molybdenum sheets or tungsten-molybdenum sheets. The center of the crucible bottom 14 is provided with a seed crystal groove 15, which ensures that the crystallization material is fully melted and the seed crystal is not melted, the crucible bottom 14 is conical to prevent twin crystals or polycrystal from being generated during the crystal growth, and the crucible wall 12 isconical cylinder with the taper 13, so that the crystal can be taken out easily after being crystallized without destroying the crucible. The crucible top end is provided with a crucible cover 11 made of molybdenum sheet for sealing, as shown in figure 2, and Cr is effectively inhibited4+:Mg2SiO4The melt is volatilized. The crucible 1 is placed in the circular groove of the molybdenum crucible positioning rod through the seed crystal groove 15.
The invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention.
Example 1:
cr is carried out by the vertical temperature gradient method, the temperature gradient furnace and the process flow4+:Mg2SiO4The crystal grows, the size of a molybdenum (Mo) crucible 1 is phi 76 multiplied by 80mm, the taper of the crucible bottom 14 is 100 degrees, and the taper 13 of the crucible wall 12 is 1: 40. The graphite heating body 2 is a barrel-shaped molybdenum barrel with tungsten sheets lined in the inner layer of the heat preservation screen. [100]And orienting the seed crystal. 1.05: 1 (i.e. x ═ 0.05) non-stoichiometric MgCO3And Al2O3Powder material, doped with 0.18 wt% chromium oxide (Cr)2O3) After mixing in a blender for 24 hours, use 2t/cm2The isostatic pressing is forged into blocks, the blocks are directly arranged in a crucible 1, a crucible cover 11 is added for sealing, the blocks are arranged in a temperature gradient furnace, the temperature is raised to 600 ℃ while vacuumizing is carried out, and high-purity argon is filled to 1 block under the protective atmosphereAnd (3) continuously raising the temperature to the melt temperature of 1890 ℃ under the atmospheric pressure, keeping the temperature for 2 hours, and reducing the temperature for 48hours at the speed of 6.6 ℃/hr. After the crystallization is finished, the temperature is reduced to the room temperature at the speed of 1 ℃/min, and the whole growth process is finished. Taking out Cr4+:Mg2SiO4The crystal, crystal integrity and transparency are obviously higher than those of other methods, and the intrinsic quality of the crystal reaches low dislocation density without inclusion and bubbles.
Example 2:
by the vertical temperature gradient method, the temperature gradient furnace andcr is carried out in the process flow4+:Mg2SiO4The crystal grows, the size of a molybdenum (Mo) crucible 1 is phi 76 multiplied by 80mm, the taper of the crucible bottom 14 is 100 degrees, and the taper 13 of the crucible wall 12 is 1: 40. The graphite heating body 2 is a barrel-shaped molybdenum barrel with tungsten sheets lined in the inner layer of the heat preservation screen. [100]And orienting the seed crystal. 1.05: 1 (i.e. x ═ 0.05) non-stoichiometric MgCO3And Al2O3Powder material, doped with 0.30 wt% chromium oxide (Cr)2O3) After mixing in a blender for 24 hours, use 2t/cm2The isostatic pressing is carried out to form a block, the block is directly arranged in a crucible 1, a crucible cover 11 is added for sealing, the block is arranged in a temperature gradient furnace, the temperature is raised to 600 ℃ while vacuumizing is carried out, high-purity argon protective atmosphere is filled to 1 atmospheric pressure, the temperature is continuously raised to the melt temperature of 1890 ℃, the temperature is kept for 2 hours, and the temperature is reduced for 48 hours at the speed of 6.6 ℃/hr. After the crystallization is finished, the temperature is reduced to the room temperature at the speed of 1 ℃/min, and the whole growth process is finished. Taking out Cr4+:Mg2SiO4The crystal, crystal integrity and transparency are all obviously higher than other methods. The intrinsic quality of the crystal reaches low dislocation density without inclusions and bubbles.
Example 3:
cr is carried out by the vertical temperature gradient method, the temperature gradient furnace and the process flow4+:Mg2SiO4The crystal grows, the size of a molybdenum (Mo) crucible 1 is phi 76 multiplied by 80mm, the taper of the crucible bottom 14 is 100 degrees, and the taper 13 of the crucible wall 12 is 1: 40. The graphite heating body 2 is a barrel-shaped molybdenum barrel with tungsten sheets lined in the inner layer of the heat preservation screen. [100]And orienting the seed crystal. 1.05: 1 (i.e. x ═ 0.05) non-stoichiometric MgCO3And Al2O3Powder material, doped with 0.40wt% chromium oxide (Cr)2O3) After mixing in a blender for 24 hours, use 2t/cm2The isostatic pressing is forged into blocks, the blocks are directly arranged in a crucible 1, a crucible cover 11 is added for sealing, the blocks are arranged in a temperature gradient furnace, the temperature is raised to 600 ℃ while vacuumizing is carried out, and high-purity argon is filled to 1 block under the protective atmosphereAnd (3) continuously raising the temperature to the melt temperature of 1890 ℃ under the atmospheric pressure, keeping the temperature for 2 hours, and reducing the temperature for 48 hours at the speed of 6.6 ℃/hr. After the crystallization is finished, the temperature is reduced to the room temperature at the speed of 1 ℃/min, and the whole growth process is finished. Taking out Cr4+:Mg2SiO4The crystal, crystal integrity and transparency are all obviously higher than other methods. The intrinsic quality of the crystal reaches low dislocation density without inclusions and bubbles.
Example 4:
cr is carried out by the vertical temperature gradient method, the temperature gradient furnace and the process flow4+:Mg2SiO4The crystal grows, the size of a molybdenum (Mo) crucible 1 is phi 76 multiplied by 80mm, the taper of the crucible bottom 14 is 100 degrees, and the taper 13 of the crucible wall 12 is 1: 40. The graphite heating body 2 is a barrel-shaped molybdenum barrel with tungsten sheets lined in the inner layer of the heat preservation screen. [100]And orienting the seed crystal. 1.05: 1 (i.e. x ═ 0.05) non-stoichiometric MgCO3And Al2O3Powder material, doped with 0.30 wt% chromium oxide (Cr)2O3) After mixing in a blender for 24 hours, use 2t/cm2The isostatic pressing is carried out to form a block, the block is directly arranged in a crucible 1, a crucible cover 11 is added for sealing, the block is arranged in a temperature gradient furnace, the temperature is raised to 600 ℃ while vacuumizing is carried out, high-purity argon protective atmosphere is filled to 1 atmospheric pressure, the temperature is continuously raised to the melt temperature of 1890 ℃, the temperature is kept for 2 hours, and the temperature is reduced for 50 hours at the speed of 5.0 ℃/hr. After the crystallization is finished, the temperature is reduced to the room temperature at the speed of 1 ℃/min, and the whole growth process is finished. Taking out Cr4+:Mg2SiO4The crystal, crystal integrity and transparency are all obviously higher than other methods. The intrinsic quality of the crystal reaches low dislocation density without inclusions and bubbles.
Example 5:
cr is carried out by the vertical temperature gradient method, the temperature gradient furnace and the process flow4+:Mg2SiO4The crystal grows, the sizeof a molybdenum (Mo) crucible 1 is phi 76 multiplied by 80mm, the taper of the crucible bottom 14 is 100 degrees, and the taper 13 of the crucible wall 12 is 1: 40. The graphite heating body 2 is a barrel-shaped molybdenum barrel with tungsten sheets lined in the inner layer of the heat preservation screen. [100]And orienting the seed crystal. 1.05: 1 (i.e. x ═ 0.05) non-stoichiometric MgCO3And Al2O3Powder material, doped with 0.30 wt% chromium oxide (Cr)2O3) After mixing in a blender for 24 hours, use 2t/cm2The isostatic pressure is forged into blocks, the blocks are directly arranged in a crucible 1, a crucible cover 11 is added for sealing, the blocks are arranged in a temperature gradient furnace, the temperature is raised to 600 ℃ while vacuumizing is carried out, and high-purity argon is filled for protectionAtmosphere to 1And (3) continuously raising the temperature to the melt temperature of 1890 ℃ under the atmospheric pressure, keeping the temperature for 2 hours, and reducing the temperature at the speed of 10 ℃/hr for 25 hours. After the crystallization is finished, the temperature is reduced to the room temperature at the speed of 1 ℃/min, and the whole growth process is finished. Taking out Cr4+:Mg2SiO4The crystal, crystal integrity and transparency are all obviously higher than other methods. The intrinsic quality of the crystal reaches low dislocation density without inclusions and bubbles.
Example 6:
cr is carried out by the vertical temperature gradient method, the temperature gradient furnace and the process flow4+:Mg2SiO4The crystal grows, the size of a molybdenum (Mo) crucible 1 is phi 76 multiplied by 80mm, the taper of the crucible bottom 14 is 100 degrees, and the taper 13 of the crucible wall 12 is 1: 40. The graphite heating body 2 is a barrel-shaped molybdenum barrel with tungsten sheets lined in the inner layer of the heat preservation screen. [100]And orienting the seed crystal. 1.01: 1 (i.e. x ═ 0.01) non-stoichiometric MgCO3And Al2O3Powder material, doped with 0.30 wt% chromium oxide (Cr)2O3) After mixing in a blender for 24 hours, use 2t/cm2The isostatic pressing is carried out to form a block, the block is directly arranged in a crucible 1, a crucible cover 11 is added for sealing, the block is arranged in a temperature gradient furnace, the temperature is raised to 600 ℃ while vacuumizing is carried out, high-purity argon protective atmosphere is filled to 1 atmospheric pressure, the temperature is continuously raised to the melt temperature of 1890 ℃, the temperature is kept for 2 hours, and the temperature is reduced for 48 hours at the speed of 6.6 ℃/hr. After the crystallization is finished, the temperature is reduced to the room temperature at the speed of 1 ℃/min, and the whole growth process is finished. Taking out Cr4+:Mg2SiO4The crystal, crystal integrity and transparency are all obviously higher than other methods. The intrinsic quality of the crystal reaches low dislocation density without inclusions and bubbles.
Claims (2)
1. A method for growing tetravalent magnesium chromate silicate crystal by vertical temperature gradient method is characterized in that: in Cr4+:Mg2SiO4In the crystal growth raw material formula, MgCO is adopted3And SiO2Mixing the raw materials according to the proportion of (1+ x) to 1, wherein the value range of x is 0-0.05, and then adding 0.18-0.40 wt% of Cr2O3Is pressed intoDirectly loading into crucible, sealing, and growing magnesium silicate crystal doped with quadrivalent chromium by vertical temperature gradient method4+:Mg2SiO4The bottom of the melt is crystallized, and a solid-liquid interface moves from bottom to top to grow crystals.
2. The method for growing the tetravalent magnesium chromate silicate crystal according to claim 1, which comprises the following steps:
<1>placing oriented seed crystals in a seed crystal groove of a crucible of a temperature gradient furnace;
<2>selecting specific value of x in the range of 0-0.05, and preparing high-purity MgCO according to the proportion of (1+ x) to 13And SiO20.18-0.40 wt% of Cr is added into the powder according to the total weight of the powder2O3Mechanically mixing in a mixer;
pressing the mixture into a block by using a material pressing machine, directly putting the block into a crucible, adding a crucible cover, sealing the crucible, and placing the crucible into a temperature gradient furnace;
heating to 600 ℃ while vacuumizing, and introducing high-purity argon protective atmosphere to 1 atmosphere;
and (5) continuously heating to the temperature of the melt of about 1890 +10 ℃, keeping the temperature for 1-3 hours, cooling at the speed of 5-10 ℃/hour, slowly cooling to the room temperature after the crystal growth is finished, opening a furnace cover, and taking out the crystal.
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| CN1542170A CN1542170A (en) | 2004-11-03 |
| CN1233881C true CN1233881C (en) | 2005-12-28 |
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