CN117431616A - Method for growing near-stoichiometric lithium niobate crystal by floating zone method - Google Patents
Method for growing near-stoichiometric lithium niobate crystal by floating zone method Download PDFInfo
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- CN117431616A CN117431616A CN202210835846.1A CN202210835846A CN117431616A CN 117431616 A CN117431616 A CN 117431616A CN 202210835846 A CN202210835846 A CN 202210835846A CN 117431616 A CN117431616 A CN 117431616A
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- 239000013078 crystal Substances 0.000 title claims abstract description 98
- 238000000034 method Methods 0.000 title claims abstract description 62
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 title claims abstract description 45
- 239000002994 raw material Substances 0.000 claims abstract description 133
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 27
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 27
- 239000000155 melt Substances 0.000 claims abstract description 11
- 238000002844 melting Methods 0.000 claims abstract description 10
- 230000008018 melting Effects 0.000 claims abstract description 10
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims abstract description 8
- 229910052808 lithium carbonate Inorganic materials 0.000 claims abstract description 8
- 239000013589 supplement Substances 0.000 claims abstract description 4
- 238000001354 calcination Methods 0.000 claims description 41
- 239000000945 filler Substances 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 7
- 230000006835 compression Effects 0.000 claims description 6
- 238000007906 compression Methods 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 6
- 229910052724 xenon Inorganic materials 0.000 claims description 6
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims description 6
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Inorganic materials O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 claims description 5
- URLJKFSTXLNXLG-UHFFFAOYSA-N niobium(5+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Nb+5].[Nb+5] URLJKFSTXLNXLG-UHFFFAOYSA-N 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 4
- 238000005303 weighing Methods 0.000 claims description 4
- 238000000227 grinding Methods 0.000 claims description 3
- 239000004973 liquid crystal related substance Substances 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 230000001360 synchronised effect Effects 0.000 claims description 3
- 238000011049 filling Methods 0.000 claims description 2
- 238000002425 crystallisation Methods 0.000 abstract description 8
- 230000008025 crystallization Effects 0.000 abstract description 8
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 239000000463 material Substances 0.000 description 7
- 238000002360 preparation method Methods 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000005204 segregation Methods 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- 238000003860 storage Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 238000000462 isostatic pressing Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 239000002699 waste material Substances 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
- C30B13/00—Single-crystal growth by zone-melting; Refining by zone-melting
-
- 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
- C30B29/30—Niobates; Vanadates; Tantalates
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
The invention provides a method for growing near stoichiometric lithium niobate crystal by using a floating zone method, wherein the head raw material is a lithium-rich raw material, the rest part is a stoichiometric raw material, by observing the state of a raw material rod, the condition that when the temperature of a growth chamber reaches a temperature suitable for crystal growth, a seed crystal is moved and the raw material rod is connected together, so that the lithium-rich raw material part is always concentrated in the center of a heat source to keep melting, and along with crystal growth, the stoichiometric raw material supplements components in a melt at any time, so that the components in the melt are kept stable, and the components in crystal crystallization can be kept stable; according to the invention, through the optimal design of the structure of the raw material rod, the floating zone method is utilized for the first time to prepare the lithium niobate monocrystal with near stoichiometric ratio, the crystal components are closer to the stoichiometric ratio, and the crystallization efficiency is higher; the continuous charging can be completed by using a small amount of lithium-rich raw materials, and the use of expensive lithium carbonate is greatly reduced in the raw materials, so that the production cost is greatly reduced.
Description
Technical Field
The present application relates to the field of crystal growth process optimization. In particular to a preparation method of a lithium niobate crystal with optimized preparation of polycrystalline material and near stoichiometric ratio by a floating zone method.
Background
Near stoichiometric lithium niobate (NSLN, abbreviated as SLN) crystals have more pronounced optical, nonlinear and ferroelectric properties than commercially available homogeneous lithium niobate (CLN) crystals because they eliminate a large number of intrinsic defects in the crystal lattice. However, methods for preparing near stoichiometric lithium niobate mainly include a double crucible method, a suspension crucible method, a vapor transport equilibrium method, and the like. However, the growth methods have certain technical defects, such as blockage of a conveying pipe by a double-crucible method, increase of production cost, easy introduction of bubbles and inclusion in crystals by a suspension crucible method, and low efficiency by a vapor transport equilibrium method, and are limited to preparation of flaky crystals. The float zone method is a method in which a preform rod-shaped polycrystalline material is passed through a high-temperature zone to form a molten zone, and the molten zone is moved by moving the polycrystalline material to crystallize, thereby finally obtaining a single crystal of a desired material. The method does not need a crucible, has high purity and high growth efficiency, is commonly used for growth preparation of materials such as semiconductors, laser crystals and the like, is limited by a polycrystalline rod design and a growth process, and is not applied to growing the lithium niobate crystal with the near stoichiometric ratio at present.
Disclosure of Invention
The invention discloses a method for growing near-stoichiometric lithium niobate crystals by using a floating zone method, which is used for improving the preparation of lithium-rich polycrystal materials by optimizing a floating zone method device so as to realize the growth of the near-stoichiometric lithium niobate crystals more efficiently. The method can meet the requirement that the components of the melt are kept unchanged in the crystal growth process by virtue of the unique design of the polycrystalline material, and solves the problems of component fluctuation, bubbles, inclusion and the like introduced in the process of growing the lithium niobate crystal with near stoichiometric ratio by a continuous feeding method while greatly reducing the waste of raw materials relative to a pulling method. Accurate control of the near stoichiometric lithium niobate crystal growth components is achieved. The method is also suitable for other types of variable-component grown crystals, and has good application prospect.
For the floating zone method for growing the lithium niobate crystal with near stoichiometric ratio, the melting of the raw material and the crystal growth are almost completed at the same time, and the component segregation phenomenon exists, so the synthesis requirement for the raw material is more severe.
The method comprises two main steps, namely raw material synthesis and raw material rod processing.
For raw material synthesis, it is necessary to ensure a pure phase of raw material components to enable growth of high quality crystals; for the raw material rod, the raw material is required to be processed into the raw material rod with specific length and diameter, the raw material synthesized in the last step is required to be put into a specially-customized rubber mold, and the special-shaped rod with small diameter and large length is prepared by utilizing the isostatic pressing process of a cold isostatic press. Then the seed crystal and the raw material rod are filled into a crystal growth furnace to start crystal growth.
The method specifically comprises the following steps:
(1) Weighing lithium carbonate and niobium pentoxide according to the proportion of [ Li+ ]/[ Li++ Nb5+ ] =50%mol, and preparing the raw materials with stoichiometric ratio; weighing lithium carbonate and niobium pentoxide according to the proportion of 56%mol < [ Li+ ]/[ Li++ Nb5+ ] <59%mol, and preparing a lithium-rich raw material;
(2) Mechanically mixing the lithium-rich raw material and the stoichiometric raw material for more than 48 hours respectively;
(3) Respectively carrying out first-pass sectional calcination on the mixed lithium-rich raw material and stoichiometric ratio raw material;
(4) Naturally cooling the two raw materials subjected to the first-time sectional calcination to room temperature, respectively grinding, and respectively mechanically mixing the two grinded raw materials for more than 48 hours;
(5) Sequentially adding the two raw materials into a customized mold, firstly adding lithium-rich raw materials, wherein the weight of the filler is 5-15g, the height of the compacted raw materials is 15-25mm, then filling the raw materials with compacted stoichiometric ratio, the weight of the filler is 50-100g, and preparing a raw material rod by using a cold isostatic press after sealing;
(6) Performing second-pass sectional calcination on the raw material rod;
(7) Naturally cooling to obtain a raw material rod for growing near-stoichiometric lithium niobate crystals by a floating zone method, wherein the diameter of the near-stoichiometric lithium niobate raw material rod is 7-12mm, the length of the near-stoichiometric lithium niobate raw material rod is 150-200mm, and the volume compression rate is 55-65%;
(8) Vertically mounting the near-stoichiometric lithium niobate raw material rod onto a raw material rod, mounting one side of the lithium-rich raw material rod downwards, mounting a seed crystal on a seed crystal rod, turning on a xenon lamp heat source, heating through an ellipsoidal mirror, and moving one side of the lithium-rich raw material rod into a high-temperature region to keep synchronous rotation speeds of the seed crystal and the near-stoichiometric lithium niobate raw material rod;
(9) When the temperature of the growth chamber reaches the temperature suitable for crystal growth, the seed crystal and a near stoichiometric ratio lithium niobate raw material rod are connected together, the descending speed of the seed crystal is 1-15mm/h, the descending speed of the raw material rod is 1-10mm/h, the rotating speed of the seed crystal and the raw material rod is 4-10rpm, the lithium-rich raw material part is concentrated in the center of a heat source to keep melting, and along with crystal growth, the stoichiometric ratio raw material supplements components in the melt at any time, so that the components in the melt keep stable;
(10) When the crystal growth is finished, the crystal and the raw material are separated, and the cooling program of the crystal is set.
Further, the first pass staged calcination includes: the first stage of calcination, wherein the temperature is 600-800 ℃, and the calcination is carried out for 4-6 hours; and the second stage of calcination, wherein the temperature is 1000-1100 ℃, and the calcination is carried out for 6-8 hours.
Further, the second pass staged calcination includes: the first stage of calcination, wherein the temperature is 600-800 ℃, and the calcination is carried out for 2-4 hours; and the second stage of calcination, wherein the temperature is 1100-1150 ℃ and the calcination is 8-12 hours.
Further, in the step (4), the average particle diameter of the milled particles is 50 to 150. Mu.m.
Further, in the step (5), the diameter of the die is 15-20mm, the height of the die is 200-300mm, the die is of a single-face sealed rubber barrel-shaped structure, and the opening is sealed by a rubber plug and a clamp.
Further, in the step (5), the cold isostatic press is used for preparing the raw material rod with the diameter of 8-12mm and the length of 150-300mm under the pressure condition of 150-200MPa for 30-60 seconds, and the volume compression rate is 30-60%.
Further, in the step (8), the molten state of the near-stoichiometric lithium niobate raw material rod is observed through a liquid crystal screen, and the input power of the xenon lamp is adjusted to 2.5-4.5kw, so that the temperature required by crystal growth is reached.
Compared with the prior art, the invention has the following beneficial technical effects:
through the optimal design of the structure of the raw material rod, the floating zone method is utilized for the first time to prepare the lithium niobate single crystal with near stoichiometric ratio, and the scheme has the advantages that the crystal components are closer to the stoichiometric ratio, and the crystallization efficiency is higher; the continuous charging can be completed by using a small amount of lithium-rich raw materials, and the use of expensive lithium carbonate is greatly reduced in the raw materials, so that the production cost is greatly reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort to a person skilled in the art.
FIG. 1 is a schematic diagram of a near stoichiometric lithium niobate feedstock rod;
FIG. 2 is a schematic diagram of a floating zone method for growing near stoichiometric lithium niobate.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
For the growth of the lithium niobate crystal with near stoichiometric ratio by the floating zone method, the melting of the raw materials and the growth of the crystal are almost completed simultaneously, and the component segregation phenomenon exists, so that the synthesis requirement on the raw materials is more severe, and the key is that:
1. and (5) raw material rod structural design.
The head raw material is a lithium-rich raw material with the proportion of 56-59%, the weight of the filler is 5-15g, and the height is 15-25mm; the rest is 50% of stoichiometric raw materials, and the weight of the filler is 50-100g; the raw material rod has the following dimensions: the diameter is 8-15mm, and the length is 200-300mm. The basis for setting the structure is that the segregation characteristic in the crystallization process of near-stoichiometric lithium niobate is that the loss of the head lithium-rich part in the growth process is supplemented by the raw materials in the stoichiometric ratio, and the stability of the melt components in the crystal growth process is maintained.
2. Innovation of the growth process.
By observing the state of the raw material rod, judging that when the temperature of a growth chamber reaches a temperature suitable for crystal growth, moving the seed crystal and the raw material rod to be connected together, setting the descending speed of the seed crystal to be 1-15mm/h, setting the descending speed of the raw material rod to be 1-10mm/h, setting the rotating speed of the seed crystal and the raw material rod to be 4-10rpm, enabling the lithium-rich raw material part to be always concentrated at the center of a heat source to keep melting, enabling the height of a melting zone to be 5-15mm, and enabling the components in a melt to be kept stable by supplementing the raw material with a stoichiometric ratio at any time along with the crystal growth.
The method comprises the following specific steps:
(1) Lithium carbonate and niobium pentoxide are used as raw materials, and are respectively weighed and prepared according to the proportion of [ Li+ ]/[ Li++ Nb5+ ] = 50%mol and [ Li+ ]/[ Li++ Nb5+ ] = 58%mol;
(2) Mechanically mixing the raw material powder with the two proportions for 48 hours by using a mixer;
(3) Respectively placing the mixed two raw materials into a platinum crucible, and carrying out first-time sectional calcination by utilizing a muffle furnace: the first pass of the staged calcination includes: the first stage of calcination, wherein the temperature is 800 ℃ and the calcination is carried out for 6 hours; the second stage of calcination, wherein the temperature is 1000 ℃ and the calcination is carried out for 6 hours;
(4) Naturally cooling the two proportions of raw materials after the first calcination, respectively grinding to ensure that the particles are uniform and the average particle size reaches 100 mu m, and mechanically mixing the ground raw materials for 48 hours;
(5) Sequentially adding the two proportions of raw materials subjected to first calcination into a customized rubber mold, wherein the size of the rubber mold is 20mm in diameter and 300mm in height, the rubber mold is of a single-sided sealed rubber barrel-shaped structure, and the opening is sealed by a rubber plug and a clamp; firstly adding lithium-rich raw materials, wherein the weight of the filler is 10g, the height of the compacted raw materials is about 20mm, then the compacted raw materials with the stoichiometric ratio are filled, the weight of the filler is 50g, after sealing, the raw material rod with the diameter of 12mm and the length of 300mm is prepared by using a cold isostatic press under the pressure condition of 200MPa for 60 seconds, and the volume compression rate is about 45%; the structure is set according to segregation characteristics in the crystallization process of the near stoichiometric lithium niobate, so as to keep components stable in the crystal growth process;
(6) Carrying out second-time sectional calcination on the raw material rod by utilizing a muffle furnace, wherein the second-time sectional calcination comprises the following steps: the first stage of calcination, wherein the temperature is 800 ℃ and the calcination is carried out for 2 hours; a second stage of calcination, wherein the temperature is 1130 ℃ and the calcination is carried out for 10 hours;
(7) After the second step of sectional calcination, naturally cooling to obtain a near stoichiometric lithium niobate raw material rod for crystal growth by a floating zone method, wherein the raw material rod has a size of 10mm and a length of 250mm, and the volume compression rate is about 60%;
(8) Vertically mounting a raw material rod on the raw material rod, wherein one side of a lithium-rich raw material is downwards mounted, and a seed crystal is mounted on a seed crystal rod, wherein the seed crystal corresponds to a seed crystal, provides crystallization sites for crystal growth, and is processed by a lithium niobate crystal with a good stoichiometric ratio; closing a crystal growth chamber, then adjusting the position of a raw material rod, opening a xenon lamp heat source, heating through an ellipsoidal mirror, then moving one side of a lithium-rich raw material into a high-temperature area, setting a rotation speed at which seed crystals and the raw material rod keep synchronous, observing the melting state of the raw material rod through a liquid crystal screen, and adjusting the input power of a xenon lamp of a control cabinet to enable the input power to reach the temperature required by crystal growth, wherein the input power is 3.6kw;
(9) By observing the state of the raw material rod, judging that when the temperature of a growth chamber reaches a temperature suitable for crystal growth, moving a seed crystal and the raw material rod to be connected together, setting the descending speed of the seed crystal to be 8mm/h, setting the descending speed of the raw material rod to be 4mm/h, setting the rotating speeds of the seed crystal and the raw material rod to be 4rpm, enabling a lithium-rich raw material part to be always concentrated in the center of a heat source to keep melting, enabling the height of a melting zone to be 10mm, and enabling a 50% stoichiometric ratio raw material to supplement components in a melt component at any time along with crystal growth, so that the components in the melt are kept stable, and the components in crystal crystallization can be kept stable;
(10) When the crystal growth is finished, the input power is adjusted to separate the crystal from the raw material, and then a cooling program is set.
A schematic of a floating zone method for growing near stoichiometric lithium niobate is shown in fig. 2. (a) charging, installing a raw material rod and a seed crystal; (b) heating to connect the seed crystal and the raw material rod together; (c) During the growth process, the proper speed of the seed crystal and the raw material rod is reduced; (d) And after the cooling is finished, the temperature of the floating zone is reduced, so that the crystals and the raw materials are separated.
According to the invention, through the optimal design of the structure of the raw material rod, the floating zone method is utilized for the first time to prepare the lithium niobate single crystal with near stoichiometric ratio, and the invention has the advantages that the crystal components are closer to the stoichiometric ratio, and the crystallization efficiency is higher; the continuous charging can be completed by using a small amount of lithium-rich raw materials, and the use of expensive lithium carbonate is greatly reduced in the raw materials, so that the production cost is greatly reduced.
While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and substitutions of equivalents may be made and equivalents will be apparent to those skilled in the art without departing from the scope of the invention. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a smart phone, a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention.
Claims (7)
1. A method for growing near stoichiometric lithium niobate crystals by a floating zone method, which is characterized by comprising the following steps:
(1) Weighing lithium carbonate and niobium pentoxide according to the proportion of [ Li+ ]/[ Li++ Nb5+ ] =50%mol, and preparing the raw materials with stoichiometric ratio; weighing lithium carbonate and niobium pentoxide according to the proportion of 56%mol < [ Li+ ]/[ Li++ Nb5+ ] <59%mol, and preparing a lithium-rich raw material;
(2) Mechanically mixing the lithium-rich raw material and the stoichiometric raw material for more than 48 hours respectively;
(3) Respectively carrying out first-pass sectional calcination on the mixed lithium-rich raw material and stoichiometric ratio raw material;
(4) Naturally cooling the two raw materials subjected to the first-time sectional calcination to room temperature, respectively grinding, and respectively mechanically mixing the two grinded raw materials for more than 48 hours;
(5) Sequentially adding the two raw materials into a customized mold, firstly adding lithium-rich raw materials, wherein the weight of the filler is 5-15g, the height of the compacted raw materials is 15-25mm, then filling the raw materials with compacted stoichiometric ratio, the weight of the filler is 50-100g, and preparing a raw material rod by using a cold isostatic press after sealing;
(6) Performing second-pass sectional calcination on the raw material rod;
(7) Naturally cooling to obtain a raw material rod for growing near-stoichiometric lithium niobate crystals by a floating zone method, wherein the diameter of the near-stoichiometric lithium niobate raw material rod is 7-12mm, the length of the near-stoichiometric lithium niobate raw material rod is 150-200mm, and the volume compression rate is 55-65%;
(8) Vertically mounting the near-stoichiometric lithium niobate raw material rod onto a raw material rod, mounting one side of the lithium-rich raw material rod downwards, mounting a seed crystal on a seed crystal rod, turning on a xenon lamp heat source, heating through an ellipsoidal mirror, and moving one side of the lithium-rich raw material rod into a high-temperature region to keep synchronous rotation speeds of the seed crystal and the near-stoichiometric lithium niobate raw material rod;
(9) When the temperature of the growth chamber reaches the temperature suitable for crystal growth, the seed crystal and a near stoichiometric ratio lithium niobate raw material rod are connected together, the descending speed of the seed crystal is 1-15mm/h, the descending speed of the raw material rod is 1-10mm/h, the rotating speed of the seed crystal and the raw material rod is 4-10rpm, the lithium-rich raw material part is concentrated in the center of a heat source to keep melting, and along with crystal growth, the stoichiometric ratio raw material supplements components in the melt at any time, so that the components in the melt keep stable;
(10) When the crystal growth is finished, the crystal and the raw material are separated, and the cooling program of the crystal is set.
2. The method of float-zone growth of near stoichiometric lithium niobate crystals of claim 1, wherein the first pass staged calcination comprises: the first stage of calcination, wherein the temperature is 600-800 ℃, and the calcination is carried out for 4-6 hours; and the second stage of calcination, wherein the temperature is 1000-1100 ℃, and the calcination is carried out for 6-8 hours.
3. The method of float-zone growth of near stoichiometric lithium niobate crystals of claim 1, wherein the second pass staged calcination comprises: the first stage of calcination, wherein the temperature is 600-800 ℃, and the calcination is carried out for 2-4 hours; and the second stage of calcination, wherein the temperature is 1100-1150 ℃ and the calcination is 8-12 hours.
4. The method for growing near stoichiometric lithium niobate crystals according to the floating zone method of claim 1, wherein in the step (4), the average particle diameter of the milled particles is 50 to 150 μm.
5. The method for growing near stoichiometric lithium niobate crystals by a floating zone method according to claim 1, wherein in the step (5), the diameter of the mold is 15-20mm, the height is 200-300mm, the mold is a single-face sealed rubber barrel-shaped structure, and the opening is sealed by a rubber plug and a clamp.
6. The method for growing near stoichiometric lithium niobate crystals by the float zone method according to claim 1, wherein in the step (5), the cold isostatic press is used for preparing a raw material rod with a diameter of 8-12mm and a length of 150-300mm under a pressure condition of 150-200MPa for 30-60 seconds, and the volume compression rate is 30-60%.
7. The method for growing near stoichiometric lithium niobate crystal according to the floating zone method of claim 1, wherein in the step (8), the molten state of the near stoichiometric lithium niobate raw material rod is observed through a liquid crystal screen, and the input power of the xenon lamp is adjusted to 2.5-4.5kw so as to reach the temperature required by the crystal growth.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210835846.1A CN117431616A (en) | 2022-07-15 | 2022-07-15 | Method for growing near-stoichiometric lithium niobate crystal by floating zone method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210835846.1A CN117431616A (en) | 2022-07-15 | 2022-07-15 | Method for growing near-stoichiometric lithium niobate crystal by floating zone method |
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| Publication Number | Publication Date |
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| CN117431616A true CN117431616A (en) | 2024-01-23 |
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| CN202210835846.1A Withdrawn CN117431616A (en) | 2022-07-15 | 2022-07-15 | Method for growing near-stoichiometric lithium niobate crystal by floating zone method |
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| Country | Link |
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| CN (1) | CN117431616A (en) |
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- 2022-07-15 CN CN202210835846.1A patent/CN117431616A/en not_active Withdrawn
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Application publication date: 20240123 |