CN117385464A - Method for growing YAG series laser crystals on large-interface seed crystal plane interface - Google Patents
Method for growing YAG series laser crystals on large-interface seed crystal plane interface Download PDFInfo
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- 239000013078 crystal Substances 0.000 title claims abstract description 229
- 238000000034 method Methods 0.000 title claims abstract description 63
- 239000000463 material Substances 0.000 claims abstract description 55
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 16
- 239000011733 molybdenum Substances 0.000 claims abstract description 16
- 229910052741 iridium Inorganic materials 0.000 claims abstract description 14
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000010438 heat treatment Methods 0.000 claims description 29
- 239000000155 melt Substances 0.000 claims description 23
- 238000010304 firing Methods 0.000 claims description 12
- 239000002994 raw material Substances 0.000 claims description 12
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 11
- 230000001105 regulatory effect Effects 0.000 claims description 10
- 230000006698 induction Effects 0.000 claims description 7
- 229910017493 Nd 2 O 3 Inorganic materials 0.000 claims description 5
- 239000012778 molding material Substances 0.000 claims description 5
- 238000005056 compaction Methods 0.000 claims description 4
- 239000002019 doping agent Substances 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 abstract description 3
- 230000005693 optoelectronics Effects 0.000 abstract description 2
- 238000004904 shortening Methods 0.000 abstract description 2
- 238000001816 cooling Methods 0.000 description 10
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- 229910052786 argon Inorganic materials 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000000462 isostatic pressing Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 238000002109 crystal growth method Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/16—Oxides
- C30B29/22—Complex oxides
- C30B29/28—Complex oxides with formula A3Me5O12 wherein A is a rare earth metal and Me is Fe, Ga, Sc, Cr, Co or Al, e.g. garnets
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
- C30B15/36—Single-crystal growth by pulling from a melt, e.g. Czochralski method characterised by the seed, e.g. its crystallographic orientation
Abstract
The invention relates to the technical field of optoelectronic materials, and provides a method for growing YAG series laser crystals on a large-interface seed crystal plane interface. The invention adopts large-interface seed crystal with specific shape, and grows YAG series laser crystal by adopting a plane interface pulling method, and directly performs equal-diameter growth after pretensioning, thereby greatly reducing the operation difficulty and shortening the growth period of the crystal; in addition, the YAG series laser crystal is grown by adopting a plane interface pulling method, the obtained crystal has high quality, no core and side cores, and high selectable material rate. The method of the invention greatly shortens the growth period, reduces the volatilization amount of the iridium crucible or the molybdenum crucible, reduces the preparation cost and reduces the influence of the volatile matters such as molybdenum on the crystal growth. The example results show that the YAG series laser crystal with the diameter of 40-50 mm, the constant diameter of 100-155 mm and higher quality can be prepared, and the crystal has no core and side cores.
Description
Technical Field
The invention relates to the technical field of optoelectronic materials, in particular to a method for growing YAG series laser crystals on a large-interface seed crystal plane interface.
Background
The YAG series laser crystal is still the most widely used laser crystal at present due to excellent physical and chemical properties. In recent 10 years, with the rapid development and popularization of application of high-power solid laser technology, the demand for large-scale and high-quality YAG series laser crystals is increasing.
At present, a convex interface pulling method is generally adopted for YAG series laser crystals, and the method utilizes seed crystals to be pulled from a melt, and the seed crystals are slowly grown into target crystals by controlling the temperature and the pulling and rotating speed. The seed crystal used by the convex interface pulling method is usually a small single crystal (with the diameter of 5-10 mm), and the crystal growth process mainly comprises several process stages of shouldering, isodiametric pulling and pulling. The method has long growth period and great difficulty in operation in shouldering production stage, and the grown crystal inevitably has core and side cores, and the core and side cores of the crystal are areas concentrated by impurities, so that the areas are avoided during material selection, and the effective use area of the crystal is affected.
Disclosure of Invention
In view of this, the present invention provides a method for growing YAG series laser crystals with large interface seed crystal plane interface. The method provided by the invention does not need shouldering growth, the growth period of the crystal is short, the obtained crystal has no core and side cores, and the selectable material rate is high.
In order to achieve the above object, the present invention provides the following technical solutions:
a method for growing YAG series laser crystals on a large-interface seed crystal plane interface comprises the following steps:
providing a large-interface seed crystal, wherein the large-interface seed crystal comprises a neck part and a cone part; the cone part is conical, the top surface of the cone part is connected with the neck part, and the diameter of the bottom surface of the cone part is 40-50 mm;
heating a polycrystal material for preparing YAG series laser crystals to obtain a melt; contacting the conical part of the large-interface seed crystal with the melt, and adopting a flat-interface pulling method to grow to obtain YAG series laser crystals; the plane interface pulling method comprises a pre-stretching stage, an equal-diameter growth stage and a pulling-out stage which are sequentially carried out.
Preferably, the neck of the large-interface seed crystal is a cylinder or a cuboid, the diameter of the cylinder is 6-10 mm, the cross section of the cuboid is a square, and the side length of the square is 5-10 mm; the height of the cone part is 50-80 mm.
Preferably, the neck of the large-interface seed crystal is fixed in the seed rod; the seed rod is a hollow tube with one end open; the length of the seed crystal rod is 150-300 mm, and the inner diameter is 6-10 mm; the seed rod is made of iridium or molybdenum.
Preferably, the preparation method of the polycrystal material comprises the following steps: the raw materials are respectively subjected to first burning and then are proportioned according to a preset proportion to obtain a base material; isostatic compaction is carried out on the obtained base material to obtain a formed material; performing second firing on the molding material to obtain a polycrystal material; the raw materials comprise Y 2 O 3 And Al 2 O 3 Or include Y 2 O 3 、Al 2 O 3 And a dopant; the doping material is Nd 2 O 3 Or CeO 2 The method comprises the steps of carrying out a first treatment on the surface of the The temperature of the first firing is 600-1100 ℃ and the time is 4-6 h; the temperature of the second firing is 1100-1300 ℃ and the time is 20-40 h.
Preferably, the heating mode is medium-frequency induction heating or resistance heating; the heating is carried out under the protection of inert gas; during heating, the polycrystalline material is placed in a crucible, and the crucible is an iridium crucible or a molybdenum crucible.
Preferably, before the pre-stretching stage, the method further comprises the step of adjusting the temperature to enlarge the diameter of the bottom surface of the cone part of the large-interface seed crystal by 2-4 mm, and then keeping the constant temperature for 1-2 h under the condition that the crystal transformation is 20-35 r/min.
Preferably, the pre-stretching stage comprises: the crystal is turned and regulated to 90-130 r/min, the temperature is regulated to reduce the diameter of the bottom surface of the cone part of the large-interface seed crystal by 1-2 mm, the large-interface seed crystal is sunk by 1-3 mm, and the pre-stretching is started after the constant temperature is maintained for 1-2 h; the pulling speed of the pretension is 0.8-1.5 mm/h; the length of the prestretching is 5-10 mm, the diameter of the crystal is 40-50 mm in the prestretching process, and the deviation of the crystal diameter is controlled within +/-2 mm.
Preferably, the constant diameter growth stage is performed by adopting a growth mode of continuously changing the pulling speed and the crystal rotation speed; the change range of the lifting speed is as follows: changing from 0.9-1.5 mm/h to 0.5-0.9 mm/h; the change range of the crystal rotation speed is as follows: varying from 110 to 120 revolutions per minute to 80 to 95 revolutions per minute.
Preferably, the pull-off stage comprises: after the end of the equal diameter growth, lifting the crystal by 5-10 mm to separate the crystal from the melt.
Preferably, the diameter of the YAG series laser crystal is 40-50 mm, and the equal diameter length is 100-155 mm.
The invention provides a method for growing YAG series laser crystals on a large-interface seed crystal plane interface, which comprises the following steps: providing a large-interface seed crystal, wherein the large-interface seed crystal comprises a neck part and a cone part; the cone part is conical, the top surface of the cone part is connected with the neck part, and the diameter of the bottom surface of the cone part is 40-50 mm; placing a polycrystal material for preparing YAG series laser crystals into a crystal growing device for heating to obtain a melt; contacting the cone part of the large-interface seed crystal with the melt, and adopting a plane interface pulling method to grow to obtain YAG series laser crystals; the plane interface pulling method comprises a pre-stretching stage, an equal-diameter growth stage and a pulling-out stage which are sequentially carried out. The method provided by the invention adopts the large-interface seed crystal with a specific shape, adopts the flat-interface pulling method to grow YAG series laser crystals, and ensures that the diameter of the cone part of the seed crystal is consistent with the target diameter of the YAG series crystals, thereby omitting the shouldering step, directly carrying out equal-diameter growth after pretensioning, greatly reducing the operation difficulty and shortening the growth period of the crystals; in addition, the YAG series laser crystal is grown by adopting a plane interface pulling method, and the high rotating speed is kept in the pre-stretching stage and the constant diameter growth stage, so that the solid-liquid interface in the crystal growth process is kept as a plane interface, the crystal quality is improved, the obtained crystal has no core or side core, and the selectable material rate is high. In addition, after the crystal growth is finished, the large-interface seed crystal can be cut from the head for repeated use, so that the growth cost of the crystal is further reduced.
In addition, the common methods for growing YAG series laser crystals comprise an intermediate frequency induction heating iridium crucible method or a resistance heating molybdenum crucible method, the growth period is long in the prior art, when the intermediate frequency induction heating iridium crucible method is adopted, the volatilization amount of the iridium crucible is large, the cost is high, and when the resistance heating molybdenum crucible method is adopted, the molybdenum crucible is large in volatilization amount due to the long growth period, and molybdenum volatile matters are easy to mix in YAG melt, so that certain difficulty is caused to the smooth growth of crystals, and particularly, the crystal growth seeding and shouldering stage is very difficult to control. In the technical scheme of the invention, the shoulder growing stage is omitted, so that the growing period is greatly shortened, the volatilization amount of the iridium crucible or the molybdenum crucible is reduced, the preparation cost is reduced, and the influence of the volatile matters such as molybdenum on the crystal growth is reduced.
The example results show that the YAG series laser crystal with the diameter of 40-50 mm, the constant diameter of 100-155 mm and higher quality can be prepared, and the crystal has no core and side cores.
Drawings
FIG. 1 is a schematic diagram of the present invention employing a seed rod to hold a large interface seed crystal, wherein: 1-seed rod, 2-neck of seed crystal with large interface, 3-cone of seed crystal with large interface;
FIG. 2 is a photograph of a Nd: YAG laser crystal blank of 50mm diameter and 120mm constant diameter grown in example 1 of the present invention;
FIG. 3 shows the results of the detection of the crystals grown in example 1 of the present invention under parallel light of red light;
FIG. 4 is a photograph of a blank of Nd, ce: YAG laser crystal grown in example 2 of the present invention, the diameter of the blank being 44mm, and the constant diameter being 150 mm;
FIG. 5 shows the results of the test of the crystal grown in example 2 of the present invention under parallel light of red light;
FIG. 6 shows the results of the detection of crystals grown in comparative example 1 of the present invention under parallel light of red light.
Detailed Description
The invention provides a method for growing YAG series laser crystals on a large-interface seed crystal plane interface, which comprises the following steps:
providing a large-interface seed crystal, wherein the large-interface seed crystal comprises a neck part and a cone part; the cone part is conical, the top surface of the cone part is connected with the neck part, and the diameter of the bottom surface of the cone part is 40-50 mm;
heating a polycrystal material for preparing YAG series laser crystals to obtain a melt; contacting the conical part of the large-interface seed crystal with the melt, and adopting a flat-interface pulling method to grow to obtain YAG series laser crystals; the plane interface pulling method comprises a pre-stretching stage, an equal-diameter growth stage and a pulling-out stage which are sequentially carried out.
The method comprises the steps of firstly providing a large-interface seed crystal, wherein the direction of the large-interface seed crystal is preferably <111>; the large-interface seed crystal comprises a neck part and a cone part; the cone part is conical, the top surface of the cone part is connected with the neck part, and the diameter of the bottom surface of the cone part is 40-50 mm; the neck is cylindrical or cuboid, the diameter of the cylindrical shape is preferably 6-10 mm, the cross section of the cuboid is square, and the side length of the square is preferably 5-10 mm; the invention has no special requirement on the length of the neck, and can fix the seed crystal with large interface into the seed rod; the height of the cone part is preferably 50-80 mm; the top surface of the cone part is a small-size surface, and the size of the small-size surface is matched with that of the neck part. In a specific embodiment of the present invention, the large-interface seed crystal is preferably obtained by cutting from the head of a YAG-series crystal grown using a conventional small seed crystal, is easy to obtain, and can be repeatedly used.
In the invention, the neck of the large-interface seed crystal is preferably fixed in a seed rod; the seed rod is preferably a hollow tube with one end open; the length of the seed crystal rod is preferably 150-300 mm, and the inner diameter is preferably 6-10 mm; the seed rod is preferably made of iridium or molybdenum. The invention preferably installs the neck of the large-interface seed crystal into one end of the seed rod opening, and then uses molybdenum wire to bind and fix the seed rod. FIG. 1 is a schematic illustration of the present invention employing a seed rod to hold a large interface seed crystal.
The invention heats the polycrystal material for preparing YAG series laser crystal to obtain melt. In the invention, the YAG series laser crystal is preferably a pure YAG laser crystal, nd, ce-YAG laser crystal or Nd-YAG laser crystal, wherein the doping concentration of Nd in the Ce-YAG is preferably 1-1.2 at%, and the doping concentration of Ce is preferably 0.08-0.15 at%; the Nd concentration in YAG is preferably 0.8-1.1 at%. The present invention preferably doses and prepares polycrystalline material according to the kind of the target laser crystal.
In the present invention, the method for preparing the polycrystalline material preferably comprises the steps of: the raw materials are respectively subjected to first burning and then are proportioned according to a preset proportion to obtain a base material; isostatic compaction is carried out on the base material to obtain a formed material; performing second firing on the molding material to obtain a polycrystal material; the raw materials comprise Y 2 O 3 And Al 2 O 3 Or include Y 2 O 3 、Al 2 O 3 And a dopant; the doping material is Nd 2 O 3 Or CeO 2 The method comprises the steps of carrying out a first treatment on the surface of the The purity of the raw materials is more than 4N, more preferably more than 5N; specifically, when preparing a YAG laser crystal, the raw material is Y 2 O 3 And Al 2 O 3 When preparing Nd, ce and YAG laser crystal, the raw material is Y 2 O 3 、Al 2 O 3 、Nd 2 O 3 And CeO 2 When preparing the Nd-YAG laser crystal, the raw material is Y 2 O 3 、Al 2 O 3 And Nd 2 O 3 。
In the invention, the temperature of the first firing is preferably 600-1100 ℃, more preferably 800-1000 ℃, and the time is preferably 4-6 h, more preferably 4.5-5.5 h; the invention preferably prepares and weighs the raw materials after the first firing according to a preset proportion after naturally cooling, loads the prepared base materials into a container, fully mixes the prepared base materials, loads the mixed materials into a mould, seals the mould and performs isostatic compaction.
In the present invention, the temperature of the second firing is preferably 1100 to 1300 ℃, more preferably 1150 to 1200 ℃, and the time is preferably 20 to 40 hours, more preferably 25 to 35 hours.
After the polycrystal material is obtained, the polycrystal material is heated to obtain a melt. In the invention, the heating mode is preferably medium-frequency induction heating or resistance heating; the heating is performed under the protection of an inert gas, preferably argon; when heating, the polycrystalline material is placed in a crucible, wherein the crucible is an iridium crucible or a molybdenum crucible; specifically, when intermediate frequency induction heating is used, an iridium crucible is preferably used, and when resistance heating is used, a molybdenum crucible is preferably used. The method comprises the steps of placing a polycrystal material in a crucible, placing the crucible in a crystal growing device, and heating under the protection of argon gas to melt the polycrystal material to obtain a melt, wherein the heating temperature is preferably 1970 ℃; in the specific embodiment of the invention, compared with the conventional crystal growth method adopting small single crystals as seed crystals, the power of the invention can be reduced by 1-2 kilowatts under the same heat preservation system, and the smaller the power is, the smaller the volatilization amount of iridium is.
After a melt is obtained, the cone part of the large-interface seed crystal is contacted with the melt, and a flat-interface Czochralski method is adopted for growth to obtain YAG series laser crystals; the plane interface pulling method comprises a pre-stretching stage, an equal-diameter growth stage and a pulling-out stage which are sequentially carried out. In the specific embodiment of the invention, the large-interface seed crystal is preferably slowly moved down and contacted with the melt, the temperature is adjusted to enlarge the diameter of the bottom surface of the cone of the large-interface seed crystal by 2-4 mm, then the constant temperature is maintained for 1-2 h under the condition that the crystal is converted into 20-35 r/min, and then the pre-stretching is carried out.
In the present invention, the pre-stretching stage preferably comprises: the crystal is turned and regulated to 90-130 r/min, the temperature is regulated to reduce the diameter of the bottom surface of the cone part of the large-interface seed crystal by 1-2 mm, the large-interface seed crystal is sunk by 1-3 mm, and the pre-stretching is started after the constant temperature is maintained for 1-2 h; the pulling speed of the pretension is preferably 0.8-1.5 mm/h, more preferably 1-1.2 mm/h; the length of the pre-stretching is preferably 5-10 mm, more preferably 6-8 mm, the diameter of the crystal is preferably controlled to be 40-50 mm during the pre-stretching, and the deviation of the crystal diameter is controlled to be within +/-2 mm.
In the invention, the constant diameter growth stage is preferably carried out by adopting a growth mode of continuously changing the pulling speed and the crystal rotation speed; the change range of the pulling speed is preferably as follows: changing from 0.9-1.5 mm/h to 0.5-0.9 mm/h; the change range of the crystal rotation speed is as follows: varying from 110 to 120 revolutions per minute to 80 to 95 revolutions per minute. In the invention, the pulling speed and the crystal rotation speed are preferably changed at a constant speed from the beginning of the equal diameter growth to the end of the equal diameter growth, in the specific embodiment of the invention, the change of the pulling speed and the crystal rotation speed is preferably controlled by a program, the change range of the pulling speed is preferably 0.001-0.005 mm/time, and the change range of the crystal rotation speed is preferably 0.001-0.01 rotation/time; in the equal diameter growth process, the diameter deviation of the crystal is preferably controlled within +/-2 mm. The invention keeps higher rotating speed in the pre-stretching stage and the equal-diameter growth stage, so that the solid-liquid interface in the crystal growth process is kept as a flat interface, thereby improving the crystal quality, and the obtained crystal has no core and side cores and has high material availability.
In the present invention, the pull-off stage includes: after the end of the equal diameter growth, lifting the crystal for 5-10 mm to separate the crystal from the melt; in a specific embodiment of the invention, the isodiametric growth can be considered to be finished after the isodiametric length of the crystal reaches the requirement.
After the pulling-off, the crystal is preferably cooled to room temperature, and then the furnace is opened to take out the crystal, wherein the cooling rate is preferably 0.2-2 kW/h, more preferably 0.2-1.3 kW/h.
In the present invention, the diameter of the YAG laser crystal is preferably 40 to 50mm, and the isodiametric length is preferably 100 to 155mm.
The following description of the embodiments of the present invention will clearly and fully describe the technical solutions of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
YAG laser crystal with the diameter of 50mm and the constant diameter of 120mm is grown by adopting a large-interface seed crystal, and the method comprises the following steps:
(1) And (3) batching: nd having a purity of 5N or higher 2 O 3 、Y 2 O 3 、Al 2 O 3 Burning at a constant temperature of 800 ℃ for 6 hours, naturally cooling, preparing and weighing according to a preset proportion (Nd concentration is 1.0 at%), filling the prepared base material into a container, fully mixing, filling the uniformly mixed base material into a mould, sealing, and performing isostatic pressing to obtain the molding material.
(2) Melting material: firing the molding material at 1300 ℃ for 25 hours to form a polycrystalline material, placing the polycrystalline material into a crystal growth device, heating an iridium crucible by medium frequency induction under an argon protective atmosphere to melt the polycrystalline material to obtain a melt, slowly moving down a large-interface seed crystal and contacting the melt, wherein the large-interface seed crystal comprises a neck part and a cone part, the neck part is a cuboid, the section of the neck part is square, the side length of the neck part is 5mm, the diameter of the bottom surface of the cone part is 50mm, the height of the cone part is 50mm, and the direction of the large-interface seed crystal is <111>; the temperature is slowly adjusted to enlarge the diameter of the seed crystal by 3mm, the crystal is rotated for 35 revolutions per minute, and the constant temperature is maintained for 1h.
(3) Pretension: after the crystal rotation is continuously regulated to 120 revolutions per minute, the temperature is regulated slowly until the diameter of the seed crystal is reduced by 1mm, the crystal is sunk by 2mm after the crystal is stabilized, the prestretching is started after the crystal is kept at the constant temperature for 1h, the prestretching diameter is controlled to be 50+/-2 mm, the prestretching length is 6mm, the pulling speed is 0.9mm/h, and the diameter deviation is controlled to be within +/-2 mm.
(4) And (3) equal-diameter growth: after the pre-pulling growth of the crystal is finished, the crystal directly enters an equal-diameter growth stage, the equal-diameter stage is carried out by adopting a continuous variable pulling speed and crystal rotating speed growth mode, the pulling speed is continuously changed from 0.9mm/h to 0.8mm/h at a constant speed, the crystal rotating speed is continuously changed from 120 to 90 revolutions/min at a constant speed, the pulling speed and the crystal rotating speed are continuously reduced, the diameter deviation is controlled within +/-2 mm, and when the equal-diameter length reaches 120mm, the crystal is lifted by 10mm, so that the crystal is separated from a melt. In the step (3) and the step (4), the crystal growth interface is made to be a plane interface by controlling the above-mentioned operation conditions.
(5) And (3) cooling: cooling the crystal to room temperature at a cooling rate of 0.2-1.3 kW/hr, and taking out the crystal after opening the furnace.
FIG. 2 is a photograph of a Nd: YAG laser crystal blank of 50mm diameter and 120mm constant diameter grown in example 1 of the present invention. The crystal is shown in fig. 2 to have a smooth surface and no inclusion defects inside. The result shows that the method provided by the invention can effectively obtain Nd-YAG single crystals with better quality. And, the crystal grown in example 1 is polished and then tested under the parallel light of red light, the result is shown in fig. 3, and the result in fig. 3 proves that the crystal obtained in this example has no core and no side core, and the material selection rate of the crystal can be effectively improved.
Example 2
A large-interface seed crystal is adopted to grow Nd, ce and YAG laser crystals with the diameter of 44mm and the constant diameter of 150mm, and the method comprises the following steps:
(1) And (3) batching: nd having a purity of 4N or higher 2 O 3 、CeO 2 、Y 2 O 3 、Al 2 O 3 Burning for 4 hours at the constant temperature of 900 ℃, preparing and weighing according to the preset proportion (Nd concentration is 1.0at percent and Ce concentration is 0.1at percent) after natural cooling, filling the prepared base material into a container, fully mixing, filling the evenly mixed base material into a mould, sealing and performing isostatic pressing.
(2) Melting material: firing the formed raw material at 1100 ℃ for 24 hours to form a polycrystal material, placing the polycrystal material into a crystal growth device, heating a molybdenum crucible in a resistance under an argon protection atmosphere to enable the polycrystal material to be melted to obtain a melt, slowly moving down a large-interface seed crystal and contacting the melt, wherein the large-interface seed crystal comprises a neck part and a cone part, the neck part is a cuboid, the section of the neck part is square, the side length of the neck part is 5mm, the diameter of the bottom surface of the cone part is 44mm, the height of the cone part is 45mm, and the direction of the large-interface seed crystal is <111>; the temperature is slowly adjusted to enlarge the diameter of the seed crystal by 4mm, the crystal is rotated for 30 revolutions per minute, and the constant temperature is maintained for 1.5 hours.
(3) Pretension: after the crystal rotation is continuously regulated to 110 revolutions per minute, the temperature is regulated slowly until the diameter of the seed crystal is reduced by 1mm, the crystal is sunk by 1.5mm after the crystal is stabilized, the prestretching is started after the crystal is kept at a constant temperature for 1.5h, the prestretching diameter is controlled to be 44+/-2 mm, the prestretching length is 5mm, the pulling speed is 1.0mm/h, and the diameter deviation is controlled to be within +/-2 mm.
(4) And (3) equal-diameter growth: after the pre-pulling growth of the crystal is finished, the crystal directly enters an equal-diameter growth stage, the equal-diameter stage is carried out by adopting a continuous variable pulling speed and crystal rotating speed growth mode, the pulling speed is continuously changed from 1.0mm/h to 0.9mm/h at a constant speed, the crystal rotating speed is continuously changed from 110 revolutions per minute to 95 revolutions per minute at a constant speed, the pulling speed and the crystal rotating speed are continuously reduced, the diameter deviation is controlled within +/-2 mm, and when the equal-diameter length reaches 150mm, the crystal is lifted by 8mm, so that the crystal is separated from a melt. In the step (3) and the step (4), the crystal growth interface is made to be a plane interface by controlling the above-mentioned operation conditions.
(5) And (3) cooling: cooling the crystal to room temperature at a cooling rate of 0.3 kW-2 kW/h, and then opening the furnace to take out the crystal.
FIG. 4 is a photograph of a blank of Nd, ce: YAG laser crystal grown in example 2 of the present invention, which has a diameter of 44mm and a constant diameter of 150 mm. The crystal is shown in fig. 4 to have a smooth surface and no inclusion defects inside. The result shows that the method provided by the invention can effectively obtain Nd-YAG single crystals with better quality. And, the crystal grown in example 1 is polished and then tested under the parallel light of red light, the result is shown in fig. 5, and the result in fig. 5 proves that the crystal obtained in this example has no core and no side core, and the material selection rate of the crystal can be effectively improved.
Comparative example 1
Other conditions are the same as in example 1, the crystal rotation speed is controlled to be 20 revolutions per minute only in the pre-stretching stage, the pulling speed is controlled to be 0.9mm/h, the pulling speed is controlled to continuously and uniformly change from 0.9mm/h to 0.8mm/h in the constant diameter growth stage, the crystal rotation speed is continuously and uniformly changed from 20 revolutions per minute to 14 revolutions per minute, and the crystal growth interface is made to be a convex interface by controlling the operating conditions.
The crystal obtained in comparative example 1 was cut off and polished and then examined under a parallel light of red light, and the result is shown in FIG. 6. As can be seen from FIG. 6, the obtained crystal had a distinct core and side core (as indicated by the arrow in FIG. 6).
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (10)
1. The method for growing YAG series laser crystals on the large-interface seed crystal flat interface is characterized by comprising the following steps:
providing a large-interface seed crystal, wherein the large-interface seed crystal comprises a neck part and a cone part; the cone part is conical, the top surface of the cone part is connected with the neck part, and the diameter of the bottom surface of the cone part is 40-50 mm;
heating a polycrystal material for preparing YAG series laser crystals to obtain a melt; contacting the conical part of the large-interface seed crystal with the melt, and adopting a flat-interface pulling method to grow to obtain YAG series laser crystals; the plane interface pulling method comprises a pre-stretching stage, an equal-diameter growth stage and a pulling-out stage which are sequentially carried out.
2. The method according to claim 1, wherein the neck of the large-interface seed crystal is a cylinder or a cuboid, the diameter of the cylinder is 6-10 mm, the cross section of the cuboid is a square, and the side length of the square is 5-10 mm; the height of the cone part is 50-80 mm.
3. The method of claim 1, wherein the neck of the large interface seed crystal is fixed within a seed rod; the seed rod is a hollow tube with one end open; the length of the seed crystal rod is 150-300 mm, and the inner diameter is 6-10 mm; the seed rod is made of iridium or molybdenum.
4. The method according to claim 1, wherein the method of preparing the polycrystalline material comprises the steps of: the raw materials are respectively subjected to first burning and then are proportioned according to a preset proportion to obtain a base material; isostatic compaction is carried out on the base material to obtain a formed material; performing second firing on the molding material to obtain a polycrystal material; the raw materials comprise Y 2 O 3 And Al 2 O 3 Or include Y 2 O 3 、Al 2 O 3 And a dopant; the doping material is Nd 2 O 3 Or CeO 2 The method comprises the steps of carrying out a first treatment on the surface of the The temperature of the first firing is 600-1100 ℃ and the time is 4-6 h; the temperature of the second firing is 1100-1300 ℃ and the time is 20-40 h.
5. The method according to claim 1, wherein the heating is by intermediate frequency induction heating or resistance heating; the heating is carried out under the protection of inert gas; during heating, the polycrystalline material is placed in a crucible, and the crucible is an iridium crucible or a molybdenum crucible.
6. The method of claim 1, further comprising, before the pre-stretching stage, adjusting the temperature to expand the diameter of the conical bottom surface of the large-interface seed crystal by 2-4 mm, and then maintaining the constant temperature for 1-2 h under the condition that the crystal is turned to 20-35 rpm.
7. Method according to claim 1 or 6, characterized in that the pre-stretching phase comprises: the crystal is turned and regulated to 90-130 r/min, the temperature is regulated to reduce the diameter of the bottom surface of the cone part of the large-interface seed crystal by 1-2 mm, the large-interface seed crystal is sunk by 1-3 mm, and the pre-stretching is started after the constant temperature is maintained for 1-2 h; the pulling speed of the pretension is 0.8-1.5 mm/h; the length of the prestretching is 5-10 mm, the diameter of the crystal is 40-50 mm in the prestretching process, and the deviation of the crystal diameter is controlled within +/-2 mm.
8. The method of claim 1, wherein the isodiametric growth stage is performed using a continuously variable pull rate and crystal rotation rate growth mode; the change range of the lifting speed is as follows: changing from 0.9-1.5 mm/h to 0.5-0.9 mm/h; the change range of the crystal rotation speed is as follows: varying from 110 to 120 revolutions per minute to 80 to 95 revolutions per minute.
9. The method according to claim 1, wherein the pull-off phase comprises: after the end of the equal diameter growth, lifting the crystal by 5-10 mm to separate the crystal from the melt.
10. The method of claim 1, wherein the YAG-series laser crystal has a diameter of 40 to 50mm and an isodiametric length of 100 to 155mm.
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