Crystal growth method and crystal growth device

Abstract

The invention belongs to the technical field of multi-component crystal preparation, and discloses a crystal growth method and a crystal growth device, multi-component crystals are grown by using a pure melt kyropoulos method, and the multi-component crystals are binary and more oxides. The crystal growth device comprises a hearth, a bearing seat, a crucible, a seed rod, a gas outlet pipe, a gas inlet pipe and three groups of annular heating assemblies, the hearth comprises a furnace body and a furnace cover, the furnace cover seals an opening in the top of the furnace body, and a heating area defined by a thermal insulation material is arranged in the furnace body; the bearing seat and the crucible are arranged in the heating area; the seed rod extends into the crucible; the three groups of annular heating assemblies are arranged on the inner wall of the heating area, the three groups of heating assemblies are respectively an upper heating assembly, a middle heating assembly and a lower heating assembly which are arranged at intervals from top to bottom, and the crucible is positioned in a middle-temperature area surrounded by the middle heating assembly. According to the invention, the polycrystal phenomenon and internal defects can be avoided, the multi-component crystal with larger size and high quality can be grown, and the production and manufacturing cost can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of multi-component crystal preparation, and in particular to a crystal growth method and a crystal growth device. Background Art

[0002] Multi-component crystals such as bismuth germanate (BGO), bismuth silicate (BSO), yttrium calcium oxyborate (YCOB), etc. have good working performance and are widely used in semiconductors, national defense, military industry, aerospace and other fields. Bismuth germanate crystals and bismuth silicate are binary oxides, and yttrium calcium oxyborate is a ternary oxide. At present, there are two main methods for preparing multi-component crystals such as bismuth germanate crystals, one is the descent method and the other is the pulling method. The devices used in the two preparation methods are different in structure.

[0003] The apparatus using the descending method, for example, has a publication number of CN102828230B and an application name of "Descent Method for Growing Wide Plate-Shaped Bismuth Germanate Crystals and Methods", which controls the vertical descent of the alumina lead crucible and the temperature gradient of the crystal growth interface to grow the crystal. However, the size of the furnace shell of the descending method growth apparatus is limited, and it is difficult to prepare large-sized crystals. The crystal growth process cannot be directly observed, and the growth cycle is relatively long.

[0004] An apparatus using the Czochralski method, for example, has a publication number of JP2001261485A and an application name of "Apparatus and method for producing single crystals". After the crystal grows to a target diameter but before reaching a target length, the melt is pulled by a pulling mechanism at a constant pulling speed and rotation speed to grow the crystal. However, the Czochralski method requires control of a slower pulling rate and a faster rotation rate, which is very disadvantageous for growing large-sized crystals for industrial applications.

[0005] The main difference between the Kyropoulos method and the Czochralski method is that the crystal can be continuously crystallized without pulling the seed crystal upwards in the equal diameter stage. It is generally used for sapphire crystal growth and is more suitable for large-size crystal growth. The temperature field structure design of the existing Kyropoulos crystal device is not reasonable, and it is not suitable for the growth of multi-component crystals. It is prone to polycrystals and internal defects. Summary of the invention

[0006] An object of the present invention is to provide a crystal growth method for preparing multi-component crystals by using the Kyropoulos method.

[0007] Another object of the present invention is to provide a crystal growth device for preparing multi-component crystals.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, a crystal growth method is provided, which uses a pure melt-soaking method to grow a multi-component crystal, wherein the multi-component crystal is a binary or higher oxide.

[0010] As an optional technical solution, the crystal growth is carried out in a heating zone; a low-temperature zone, a medium-temperature zone and a high-temperature zone with independent temperature control are arranged in the heating zone at intervals along the vertical direction, the temperature of the low-temperature zone is lower than the temperature of the medium-temperature zone, the temperature of the medium-temperature zone is lower than the temperature of the high-temperature zone, and the crucible is located in the medium-temperature zone. Through independent temperature control of multiple temperature zones, the temperature gradient is more uniform and stable, avoiding the occurrence of polycrystalline and internal defects.

[0011] As an optional technical solution, the following steps are included:

[0012] S1. Loading: loading the prepared raw materials into a crucible, placing the crucible in a heating zone of a furnace, mounting a seed crystal on a seed crystal rod and inserting the seed crystal rod into the crucible;

[0013] S2, heating: controlling the heating zone to heat up until the raw material is completely melted into a melt and then stopping the heating;

[0014] S3, seeding: controlling the seed crystal rod to descend, and pulling the seed crystal rod upward after the seed crystal contacts the liquid surface of the melt until the diameter of the grown crystal reaches a first target diameter;

[0015] S4, shoulder release: reducing the pulling speed of the seed crystal rod to expand the diameter of the crystal to a second target diameter;

[0016] S5, shoulder rotation: increasing the pulling speed of the seed rod to stabilize the crystal diameter at the second target diameter;

[0017] S6, equal diameter growth: stop pulling the seed crystal rod upward, control the heating zone to cool down at a preset cooling rate, and allow the melt to crystallize downward until the crystal reaches a preset weight;

[0018] S7, shrinking the tail: pulling the seed crystal rod upward to reduce the diameter of the crystal to a third target diameter;

[0019] S8, cooling: controlling the heating zone to cool down to room temperature.

[0020] As an optional technical solution, the multi-component crystal is a bismuth germanate scintillation crystal;

[0021] In the step S3, the pulling speed of the seed crystal rod is 3-5 mm / h, the rotation speed of the seed crystal rod is 3-5 rpm, and the first target diameter of the bismuth germanate scintillation crystal is 8-12 mm;

[0022] In the step S4, the pulling speed of the seed crystal rod is 0.1-1 mm / h, the rotation speed of the seed crystal rod is 3-5 rpm, and the second target diameter of the bismuth germanate scintillation crystal is 80-210 mm;

[0023] In step S5, the pulling speed of the seed crystal rod is 1-3 mm / h, and the rotation speed of the seed crystal rod is 3-5 rpm;

[0024] In step S6, the rotation speed of the seed rod is 3-5 rpm, and the preset cooling rate is 0.1-2° C. / h;

[0025] In step S7, the pulling speed of the seed rod is 3-5 mm / h, the rotation speed of the seed rod is 5-8 rpm, and the third target diameter is 0-20 mm;

[0026] In steps S2-S7, the radial temperature gradient of the heating zone is 0.5-2K / cm, and the axial temperature gradient is 0.5-2K / cm.

[0027] As an optional technical solution, the multi-component crystal is a bismuth silicate crystal;

[0028] In the step S3, the pulling speed of the seed rod is 3-5 mm / h, the rotation speed of the seed rod is 3-5 rpm, and the first target diameter of the bismuth silicate crystal is 8-12 mm;

[0029] In the step S4, the pulling speed of the seed rod is 0.1-1 mm / h, the rotation speed of the seed rod is 3-5 rpm, and the second target diameter of the bismuth silicate crystal is 70-130 mm;

[0030] In step S5, the pulling speed of the seed crystal rod is 1-3 mm / h, and the rotation speed of the seed crystal rod is 3-5 rpm;

[0031] In step S6, the rotation speed of the seed rod is 3-5 rpm, and the preset cooling rate is 0.1-1° C. / h;

[0032] In step S7, the pulling speed of the seed crystal rod is 3-5 mm / h, the rotation speed of the seed crystal rod is 5-8 rpm, and the third target diameter is 0-20 mm;

[0033] In steps S2-S7, the radial temperature gradient of the heating zone is 0.5-2K / cm, and the axial temperature gradient is 0.5-2K / cm.

[0034] As an optional technical solution, the multi-component crystal is calcium yttrium oxyborate crystal;

[0035] In the step S3, the pulling speed of the seed rod is 0.5-1 mm / h, the rotation speed of the seed rod is 3-5 rpm, and the first target diameter of the yttrium calcium oxyborate crystal is 8-12 mm;

[0036] In the step S4, the pulling speed of the seed rod is 0.2-0.5 mm / h, the rotation speed of the seed rod is 3-5 rpm, and the second target diameter of the yttrium calcium oxyborate crystal is 100-130 mm;

[0037] In the step S5, the pulling speed of the seed crystal rod is 0.5-0.8 mm / h, and the rotation speed of the seed crystal rod is 3-5 rpm;

[0038] In step S6, the rotation speed of the seed rod is 3-5 rpm, and the preset cooling rate is 5-8° C. / h;

[0039] In step S7, the pulling speed of the seed rod is 3-5 mm / h, the rotation speed of the seed rod is 5-8 rpm, and the third target diameter is 0-20 mm;

[0040] In steps S2-S7, the radial temperature gradient of the heating zone is 1-10K / cm, and the axial temperature gradient is 2-5K / cm.

[0041] In a second aspect, a crystal growth device is provided, comprising:

[0042] A furnace, the furnace comprising a furnace body and a furnace cover, the furnace cover seals the top opening of the furnace body, and a heating zone surrounded by a heat-insulating material is provided inside the furnace body;

[0043] A support seat and a crucible are both arranged in the heating zone, and the crucible is placed above the support seat;

[0044] A seed crystal rod, which can be raised and lowered in a vertical direction and can be inserted into the heating zone and extend into the crucible;

[0045] The furnace cover is provided with an observation port, the heating zone is provided with a first observation hole, and the midpoints of the observation port and the first observation hole are located in the same straight line;

[0046] An air outlet pipe, provided at a first mounting opening on the side wall of the furnace body, for evacuating the furnace chamber;

[0047] An air inlet pipe, located at a second installation opening on the side wall of the furnace body, for introducing gas into the furnace;

[0048] Three groups of annular heating components are arranged on the inner wall of the heating zone. The three groups of heating components are respectively an upper heating component, a middle heating component and a lower heating component which are arranged at intervals from top to bottom. The crucible is located in the medium temperature zone surrounded by the middle heating component.

[0049] As an optional technical solution, the height difference between the highest point of the crucible and the highest point of the upper heating assembly is more than 8 cm, and the height difference between the lowest point of the crucible and the lowest point of the lower heating assembly is more than 8 cm.

[0050] As an optional technical solution, the height difference between the highest point of the crucible and the highest point of the upper heating assembly is greater than 8 cm and less than 12 cm, and the height difference between the lowest point of the crucible and the lowest point of the lower heating assembly is greater than 8 cm and less than 12 cm.

[0051] As an optional technical solution, the observation port is made of glass.

[0052] Beneficial effects of the present invention:

[0053] The present invention provides a crystal growth method, which uses a pure melt blastoplastics method to grow multi-component crystals instead of a flux blastoplastics method. The multi-component crystals are binary or higher oxides, which can avoid polycrystals, reduce internal defects, and are conducive to the preparation of large-sized and high-quality multi-component crystals.

[0054] The present invention also provides a crystal growth device, which includes a furnace chamber, a supporting seat, a crucible, a seed crystal rod, an air outlet pipe, an air inlet pipe and three groups of annular heating components, the furnace chamber includes a furnace body and a furnace cover, the furnace cover seals the top opening of the furnace body, and the interior of the furnace body is provided with a heating zone surrounded by heat-insulating material; the supporting seat and the crucible are both arranged in the heating zone, and the crucible is placed above the supporting seat; the seed crystal rod can be raised and lowered in the vertical direction and can be inserted into the heating zone and extend into the crucible; the furnace cover is provided with an observation port, and the heating zone is provided with a first observation hole, and the observation port and the first observation hole are located in the same straight line; the air outlet pipe is provided at a first mounting port on the side wall of the furnace body, and is used to evacuate the furnace chamber; the air inlet pipe is located at a second mounting port on the side wall of the furnace body, and is used to introduce gas into the furnace chamber; three groups of annular heating components are arranged on the inner wall of the heating zone, and the three groups of heating components are respectively an upper heating component, a middle heating component and a lower heating component arranged from top to bottom, and the crucible is located in the medium temperature zone surrounded by the middle heating component.

[0055] Placing the crucible in the medium temperature zone surrounded by the middle heating assembly, due to the presence of the upper heating assembly and the lower heating assembly, is more conducive to forming a stable temperature gradient environment, greatly avoiding polycrystalline phenomena and internal defects, and being able to grow larger, high-quality multi-component crystals, especially crystals larger than 5 inches. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is a cross-sectional view of a crystal growth apparatus of the present invention;

[0057] Figure 2 yes Figure 1 A partial enlarged view of position A in the middle;

[0058] Figure 3 This is a cross-sectional view of the heating zone of Experimental Example 5.

[0059] In the figure:

[0060] 1. furnace chamber; 11. furnace body; 111. cooling channel; 12. furnace cover; 121. observation port; 13. heating zone; 13a. low temperature zone; 13b. medium temperature zone; 13c. high temperature zone; 14. insulation bottom plate; 15. insulation enclosure; 16. insulation cover plate; 17. first installation port; 18. second installation port;

[0061] 2. Bearing seat;

[0062] 3. Crucible;

[0063] 4a, upper heating assembly; 4b, middle heating assembly; 4c, lower heating assembly;

[0064] 5. Seed crystal rod;

[0065] 6. Temperature control thermocouple;

[0066] 7. Crucible cover; 71. Second observation hole. DETAILED DESCRIPTION

[0067] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0068] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0069] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0070] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0071] like Figure 1 and Figure 2 As shown, the present embodiment provides a crystal growth device, which includes a furnace 1, a bearing seat 2, a crucible 3, a seed crystal rod 5, an air outlet pipe, an air inlet pipe and three groups of annular heating components. The furnace 1 includes a furnace body 11 and a furnace cover 12. The furnace cover 12 seals the top opening of the furnace body 11. The interior of the furnace body 11 is provided with a heating zone 13 surrounded by heat-insulating materials. The bearing seat 2 and the crucible 3 are both arranged in the heating zone 13, and the crucible 3 is placed above the bearing seat 2. The seed crystal rod 5 can be raised and lowered in the vertical direction and can be inserted into the heating zone 13 and extend into the crucible 3. The seed crystal rod 5 can also rotate while being raised and lowered. The specific structure is consistent with the prior art and will not be further described here. The furnace cover 12 is provided with an observation port 121, and the heating zone 13 is provided with a first observation hole. The midpoints of the observation port 121 and the first observation hole are located in the same straight line, so that the operator can view the melting state of the raw material through the observation port 121. The gas outlet pipe is arranged at the first installation opening 17 of the side wall of the furnace body 11, and is used to evacuate the furnace 1; the gas inlet pipe is located at the second installation opening 18 of the side wall of the furnace body 11, and is used to introduce gas into the furnace 1. Three groups of annular heating components are arranged on the inner wall of the heating zone 13, and the three groups of heating components are respectively an upper heating component 4a, a middle heating component 4b and a lower heating component 4c arranged from top to bottom, and the crucible 3 is located in the middle temperature zone 13b surrounded by the middle heating component 4b; each group of the heating components is equipped with a temperature-controlling thermocouple 6.

[0072] Specifically, the heating assembly is a nickel-cadmium-aluminum heating body. The area surrounded by the heating assembly 4c is the high temperature zone 13c, the area surrounded by the middle heating assembly 4b is the middle heating zone 13b, and the area surrounded by the upper heating assembly 4a is the low temperature zone 13a. The crucible 3 is placed in the middle temperature zone 13b surrounded by the middle heating assembly 4b. Due to the presence of the upper heating assembly 4a and the lower heating assembly 4c, it is more conducive to forming a stable temperature gradient environment, greatly avoiding polycrystalline phenomena and internal defects, and being able to grow larger-sized, high-quality multi-component crystals. The preparation of large-sized crystals can reduce production costs.

[0073] The multi-component crystals prepared by the crystal growth device provided in this embodiment can be used in the fields of semiconductors, national defense and military industry, and aerospace.

[0074] Optionally, the furnace 1 is made of stainless steel, and the side wall of the furnace 1 is a hollow structure with a cooling channel 111 provided inside. The cooling channel 111 is used to pass a cooling medium to reduce the temperature of the furnace 1 .

[0075] Optionally, the furnace cover 12 is provided with at least one observation port 121, which is made of glass. The interior of the furnace 1 can be observed through the glass, and the glass can prevent heat from escaping.

[0076] Optionally, the heat-insulating material of the enclosed heating zone 13 may be mullite, or may be alumina or other heat-insulating materials.

[0077] Optionally, the interior of the furnace body 11 is provided with an insulating bottom plate 14, an insulating enclosure 15 and an insulating cover plate 16. The insulating enclosure 15 surrounds the outer periphery of the heating component, that is, the heating component is fixed around the inner wall of the insulating enclosure 15, and the insulating cover plate 16 is covered on the top of the insulating enclosure 15. The insulating bottom plate 14, the insulating enclosure 15 and the insulating cover plate 16 form a heating zone 13. The supporting seat 2 and the crucible 3 are both located in the heating zone 13. A through hole is provided in the middle of the insulating cover plate 16 for the seed rod 5 to pass through, and a first observation hole is provided on the insulating cover plate 16.

[0078] Optionally, the material of the support base 2 can be alumina. The crucible 3 is a platinum crucible, the top of which is open and closed by a crucible cover 7, and the crucible cover 7 is provided with a second observation hole 71. The midpoints of the observation port 121, the first observation hole, and the second observation hole 71 are located in the same straight line, and the operator or visual equipment can observe the melting and growth of the raw materials inside the crucible 3 through the observation port 121, the first observation hole, and the second observation hole 71.

[0079] Further, the height difference between the highest point of the crucible 3 and the highest point of the upper heating assembly 4a is 8 cm or more, such as 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, 13 cm. Preferably, the height difference between the highest point of the crucible 3 and the highest point of the upper heating assembly 4a is 8 cm or more and 12 cm or less. The height difference between the lowest point of the crucible 3 and the lowest point of the lower heating assembly 4c is 8 cm or more, such as 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, 13 cm. Preferably, the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating assembly 4c is 8 cm or more and 12 cm or less. The highest point of the crucible 3 here does not regard the crucible cover 7 as a part of the crucible 3, that is, the highest point of the crucible cover 7 is not used as a standard.

[0080] The present embodiment provides a crystal growth method, which uses a pure melt scintillation method to grow multi-component crystals, and the multi-component crystals are binary or higher oxides. Specifically, it can be a bismuth germanate scintillation crystal, a bismuth silicate crystal, a calcium yttrium borate crystal, or other multi-component crystals. The heating zone 13 for crystal growth is composed of three sections of independent temperature control. Specifically, the heating zone 13 is vertically spaced with independently controlled low-temperature zones 13a, medium-temperature zones 13b and high-temperature zones 13c. The temperature of the low-temperature zone 13a is lower than the temperature of the medium-temperature zone 13b, and the temperature of the medium-temperature zone 13b is lower than the temperature of the high-temperature zone 13c. The crucible 3 for holding the raw materials is located in the medium-temperature zone 13b.

[0081] The use of pure melt-growing multi-component crystals can avoid polycrystallinity, reduce internal defects, and facilitate the preparation of large-sized and high-quality multi-component crystals.

[0082] The crystal growth method comprises the following steps:

[0083] S1. Loading: Load the prepared raw materials into the crucible 3 , place the crucible 3 in the heating zone 13 of the furnace 1 , install the seed crystal on the seed crystal rod 5 and insert the seed crystal rod 5 into the crucible 3 .

[0084] Before charging, the furnace 1 can be evacuated and oxygen can be introduced.

[0085] S2, heating: controlling the heating zone 13 to heat up, and then stopping the heating until the raw material is completely melted into a melt.

[0086] S3, seeding: controlling the seed crystal rod 5 to descend, and after the seed crystal contacts the liquid surface of the melt, pulling the seed crystal rod 5 upward until the diameter of the grown crystal reaches the first target diameter.

[0087] S4, shoulder release: reduce the pulling speed of the seed crystal rod 5 to expand the diameter of the crystal to a second target diameter.

[0088] S5, shoulder rotation: increasing the pulling speed of the seed crystal rod 5 to stabilize the crystal diameter at the second target diameter.

[0089] S6, equal diameter growth: stop pulling the seed crystal rod 5 upward, control the heating zone 13 to cool down at a preset cooling rate, and allow the melt to crystallize downward until the crystal reaches a preset weight.

[0090] S7, shrinking the tail: pulling the seed crystal rod 5 upward to reduce the diameter of the crystal to a third target diameter.

[0091] S8, cooling: controlling the heating zone 13 to cool down to room temperature.

[0092] Experimental Example 1

[0093] like Figure 1 and 2As shown, the crystal growth device includes a furnace 1, a bearing seat 2, a crucible 3, a seed crystal rod 5, an air outlet pipe, an air inlet pipe and three groups of annular heating components. The furnace 1 includes a furnace body 11 and a furnace cover 12. The furnace cover 12 seals the top opening of the furnace body 11. The furnace body 11 has a heating zone 13 surrounded by mullite. The bearing seat 2 and the crucible 3 are both arranged in the heating zone 13, and the crucible 3 is placed above the bearing seat 2. The seed crystal rod 5 can be lifted and lowered in the vertical direction and can be inserted into the heating zone 13 and extend into the crucible 3. 12 is provided with an observation port 121, and the heating zone 13 is provided with a first observation hole, and the midpoints of the observation port 121 and the first observation hole are located in the same straight line; the air outlet pipe is provided at the first installation port 17 of the side wall of the furnace body 11; the air inlet pipe is located at the second installation port 18 of the side wall of the furnace body 11; the heating assembly is a nickel-cadmium-aluminum heating body, and three groups of annular heating assemblies are arranged on the inner wall of the heating zone 13, and the three groups of heating assemblies are respectively an upper heating assembly 4a, a middle heating assembly 4b and a lower heating assembly 4c arranged from top to bottom. The area surrounded by the lower heating assembly 4c is the high temperature area 13c, the area surrounded by the middle heating assembly 4b is the middle heating area 13b, and the area surrounded by the upper heating assembly 4a is the low temperature area 13a. The crucible 3 is located in the middle temperature area 13b surrounded by the middle heating assembly 4b. The height difference between the highest point of the crucible 3 and the highest point of the upper heating assembly 4a is 6 cm, and the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating assembly 4c is 6 cm. The heating zone 13 includes a heat-insulating bottom plate 14 , a heat-insulating enclosure 15 and a heat-insulating cover plate 16 . The heat-insulating enclosure 15 surrounds the outer periphery of the heating assembly, and the heat-insulating cover plate 16 is covered on the top of the heat-insulating enclosure 15 .

[0094] The crystal growth process using the crystal device of this experimental example includes the following steps:

[0095] S1. Loading: Load the prepared bismuth trioxide and germanium dioxide into the crucible 3 , place the crucible 3 in the heating zone 13 of the furnace 1 , install the seed crystal on the seed crystal rod 5 and insert the seed crystal rod 5 into the crucible 3 .

[0096] S2. Heating: Control the heating zone 13 to heat up until the raw material is completely melted into a melt and then stop heating. The melting temperature of the raw material is 1050°C. The temperature control thermocouple of the middle heating zone 13b needs to be set at 5-10°C higher than 1050°C. At the same time, the seed rod 5 rotates at a speed of 3-5rpm.

[0097] S3, seeding: control the seed crystal rod 5 to descend, and after the seed crystal contacts the liquid surface of the melt, pull the seed crystal rod 5 upward until the diameter of the grown crystal reaches 10 mm. During this process, the rotation speed of the seed crystal rod 5 is 3-5 rpm and the pulling speed is 0.1-1 mm / h.

[0098] S4, shoulder release: the seed crystal rod 5 maintains a rotation speed of 3-5 rpm and is pulled upward at a speed of 0.1-1 mm / h until the diameter of the crystal expands to 80 mm.

[0099] S5, shoulder rotation: the seed crystal rod 5 maintains a rotation speed of 3-5 rpm and is pulled upward at a speed of 3-5 mm / h until the crystal diameter stabilizes at 80 mm.

[0100] S6, equal diameter growth: the seed crystal rod maintains a rotation speed of 3-5rpm, and stops pulling the seed crystal rod 5 upward, controls the heating zone 13 to cool down at a rate of 0.1-2℃ / h, and the melt crystallizes downward until the crystal reaches 10 kg. The cooling rate here refers to the upper heating component 4a, the middle heating component 4b and the lower heating component 4c cooling independently within this range, but the temperature gradient needs to be kept within the specified range simultaneously.

[0101] S7, tail shrinkage: the rotation speed of the seed crystal rod 5 is increased to 5-8 rpm, and the seed crystal rod 5 is pulled upward at a speed of 3-5 mm / h until the diameter of the crystal is reduced to a straight line with a length of 20 mm.

[0102] S8, cooling: control each area of ​​the heating zone 13 to cool down at a uniform cooling rate until the temperature reaches room temperature, and the cooling time is 96 hours.

[0103] In steps S2-S7, the radial temperature gradient of the heating zone 13 is 0.5-2 K / cm, and the axial temperature gradient is 0.5-1 K / cm.

[0104] The crystal obtained in this experimental example is a bismuth germanate scintillating crystal with a diameter of 80 mm. The crystal is intact without cracks, but inclusions are enriched at the bottom.

[0105] Experimental Example 2

[0106] The difference from the crystal growth device of Experimental Example 1 is that the position of the crucible 3 relative to the upper and lower parts of the heating zone 13 is changed. Specifically, the height difference between the highest point of the crucible 3 and the highest point of the upper heating assembly 4a is 8 cm, and the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating assembly 4c is 8 cm. The crystal growth method of this experimental example is different from that of Experimental Example 1 in that in steps S2-S7, the radial temperature gradient of the heating zone 13 is 0.5-2K / cm, and the axial temperature gradient is 1-1.5K / cm. The crystal grown in this experimental example is a bismuth germanate scintillating crystal with a crystal diameter of 120 mm. The crystal is intact without cracks, colorless and transparent, with no visible inclusions inside, and no light path when irradiated by a helium-neon laser pen.

[0107] Experimental Example 3

[0108] The difference from the crystal growth device of Experimental Example 1 is that the position of the crucible 3 relative to the upper and lower parts of the heating zone 13 is changed. Specifically, the height difference between the highest point of the crucible 3 and the highest point of the upper heating assembly 4a is 12 cm, and the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating assembly 4c is 12 cm. The crystal growth method of this experimental example is different from that of Experimental Example 1 in that in steps S2-S7, the radial temperature gradient of the heating zone 13 is 0.5-2K / cm, and the axial temperature gradient is 1.4-2K / cm. The crystal grown in this experimental example is a bismuth germanate scintillating crystal with a crystal diameter of 200 mm. The crystal is complete without cracks, colorless and transparent, with no visible inclusions inside, and no light path when irradiated by a helium-neon laser pen.

[0109] Experimental Example 4

[0110] The difference between the crystal growth device of Experimental Example 1 is that the position of the crucible 3 relative to the upper and lower parts of the heating zone 13 is changed. Specifically, the height difference between the highest point of the crucible 3 and the highest point of the upper heating assembly 4a is 15 cm, and the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating assembly 4c is 15 cm. The crystal growth method of this experimental example is different from that of Experimental Example 1 in that in steps S2-S7, the radial temperature gradient of the heating zone 13 is 0.5-2K / cm, and the axial temperature gradient is 5-6K / cm. The crystal grown in this experimental example is a bismuth germanate scintillating crystal with a diameter of 120 mm. The crystal is cracked and has cracks on the surface.

[0111] Experimental Example 5

[0112] The difference between the crystal growth device in Experimental Example 1 is that the structure design of the heating zone 13 is different, such as Figure 3 As shown, the upper heating assembly 4a and the lower heating assembly 4c are arranged from top to bottom in the heating zone 13, the area surrounded by the lower heating assembly 4c is the high temperature zone 13c, the area surrounded by the upper heating assembly 4a is the low temperature zone 13a, the upper part of the crucible 3 is located in the low temperature zone 13a, the lower part of the crucible 3 is located in the high temperature zone 13c, the height difference between the highest point of the crucible 3 and the highest point of the upper heating assembly 4a is 6cm, and the height difference between the lowest point of the crucible 3 and the lower heating assembly 4c is 6cm. The growth method of the crystal in this experimental example is different from that in Experimental Example 1 in that, in steps S2-S7, the radial temperature gradient of the heating zone 13 is 0.5-2K / cm, and the axial temperature gradient is 0.2-0.4K / cm. The crystal grown in this experimental example is a bismuth germanate scintillating crystal with a diameter of 80mm. The crystal has a complete appearance, bubbles and layered polycrystalline structure inside, black inclusions at the bottom, and an obvious light path under the irradiation of a helium-neon laser pen.

[0113] Experimental Example 6

[0114] The crystal growth device is the same as that in Experimental Example 1. The difference is that this experimental example is used for the growth of bismuth silicate crystals, and the raw materials are replaced with bismuth silicate crystal raw materials. In the heating stage, the temperature control thermocouple of the middle heating zone 13b is set 5-10°C higher than 1030°C; in steps S2-S7, the radial temperature gradient of the heating zone 13 is 0.5-2K / cm, and the axial temperature gradient is 0.75-1.2K / cm; in the equal-diameter growth of step S6, the preset cooling rate is 0.1-1°C / h. The crystal grown in this experimental example is a bismuth silicate crystal with a diameter of 100mm. The crystal is intact without cracks. There are bubbles in the equal-diameter part of the crystal diameter and inclusions are enriched in the tail part. There is no obvious light path under the irradiation of the helium-neon laser pen.

[0115] Experimental Example 7

[0116] The crystal growth device is the same as that in Experimental Example 2. The difference is that this experimental example is used for the growth of bismuth silicate crystals. In steps S2-S7, the radial temperature gradient of the heating zone 13 is 0.5-2K / cm, and the axial temperature gradient is 1.3-2K / cm. In the equal-diameter growth of step S6, the preset cooling rate is 0.1-1℃ / h. The crystal grown in this experimental example is a bismuth silicate crystal with a diameter of 120mm. The crystal is intact without cracks, there are no visible inclusions inside, and there is no obvious light path under the irradiation of the helium-neon laser pen.

[0117] Experimental Example 8

[0118] The crystal growth device is the same as that in Experiment 4. The difference is that this experimental example is used for the growth of bismuth silicate crystals; in steps S2-S7, the radial temperature gradient of the heating zone 13 is 0.5-2K / cm, and the axial temperature gradient is 3-4.5K / cm. In the equal-diameter growth of step S6, the preset cooling rate is 0.1-1℃ / h. The crystal grown in this experimental example is a bismuth silicate crystal with a diameter of 120mm. The crystal has cracks, and there are multiple cracks in the shoulder to equal-diameter part.

[0119] Experimental Example 9

[0120] The crystal growth device structure design and method steps used in this experimental example are the same as those in Experimental Example 1, except that this experimental example is used to grow calcium yttrium oxyborate crystals, which belong to borate system crystals. The specific steps are as follows:

[0121] S1. Loading: Load the prepared calcium yttrium oxyborate crystal raw material into the crucible 3 , place the crucible 3 in the heating zone 13 of the furnace 1 , install the seed crystal on the seed crystal rod 5 and insert the seed crystal rod 5 into the crucible 3 .

[0122] S2. Heating: The seed crystal rod 5 rotates at a speed of 3-5 rpm, and the heating zone 13 is heated until the raw material is completely melted into a melt and then the heating is stopped. Generally, the temperature control thermocouple of the middle heating zone 13b is set at 1520°C.

[0123] S3, seeding: control the seed crystal rod 5 to descend, and after the seed crystal contacts the liquid surface of the melt, pull the seed crystal rod 5 upward until the diameter of the grown crystal reaches 10 mm. The rotation speed of the seed crystal rod 5 is 3-5 rpm and the pulling speed is 0.5-1 mm / h.

[0124] S4, shoulder release: the seed crystal rod 5 maintains a rotation speed of 3-5 rpm and is pulled upward at a speed of 0.2-0.5 mm / h until the diameter of the crystal expands to 120 mm.

[0125] S5, shoulder rotation: the seed crystal rod 5 maintains a rotation speed of 3-5 rpm and is pulled upward at a speed of 0.5-0.8 mm / h until the crystal diameter stabilizes at 75 mm.

[0126] S6, equal diameter growth: maintain the rotation speed of the seed crystal rod at 3-5 rpm, stop pulling the seed crystal rod 5 upward, control the heating zone 13 to cool at a rate of 5-8°C / h, and allow the melt to crystallize downward until the crystal reaches 4 kg.

[0127] S7, tail shrinkage: pull the seed crystal rod 5 upward at a speed of 3-5 mm / h to reduce the diameter of the crystal to a point.

[0128] S8, cooling: control each area of ​​the heating zone 13 to cool down at a uniform cooling rate until the temperature reaches room temperature, and the cooling time is 96 hours.

[0129] In steps S2-S7, the radial temperature gradient of the heating zone 13 is 1-10 K / cm, and the axial temperature gradient is 2-3 K / cm.

[0130] The crystal obtained in this experimental example is yttrium calcium oxyborate crystal, with a diameter of 75 mm. The crystal has no cracks, is colorless and transparent, and there are bubbles visible to the naked eye in the equal diameter part.

[0131] Experimental Example 10

[0132] The difference from the crystal growth device of Experimental Example 9 is that the position of the crucible 3 relative to the upper and lower parts of the heating zone 13 is changed. Specifically, the height difference between the highest point of the crucible 3 and the highest point of the upper heating assembly 4a is 8 cm, and the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating assembly 4c is 8 cm. The crystal growth method of this experimental example is different from that of Experimental Example 9 in that in steps S2-S7, the radial temperature gradient of the heating zone 13 is 1-10K / cm, and the axial temperature gradient is 4-5.5K / cm. The crystal obtained in this experimental example is yttrium calcium oxyborate crystal with a diameter of 120 mm. The crystal is intact without cracks, and there are no visible inclusions inside, and the overall quality is good.

[0133] Experimental Example 11

[0134] The difference from the crystal growth device of Experimental Example 9 is that the position of the crucible 3 relative to the upper and lower parts of the heating zone 13 is changed. Specifically, the height difference between the highest point of the crucible 3 and the highest point of the upper heating component 4a is 12 cm, and the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating component 4c is 10 cm. The crystal growth method of this experimental example is different from that of Experimental Example 1 in that in steps S2-S7, the radial temperature gradient of the heating zone 13 is 1-10K / cm, and the axial temperature gradient is 6-7K / cm. The crystal obtained in this experimental example is yttrium calcium oxyborate crystal with a diameter of 120 mm. The crystal is intact without cracks, and there is no visible inclusion in the equal diameter part. After natural cooling and taking out the crystal, the crystal self-cracks at room temperature.

[0135] Experimental Example 12

[0136] The difference from the crystal growth device of Experimental Example 9 is that the position of the crucible 3 relative to the upper and lower parts of the heating zone 13 is changed. Specifically, the height difference between the highest point of the crucible 3 and the highest point of the upper heating assembly 4a is 15 cm, and the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating assembly 4c is 8 cm. The crystal growth method of this experimental example is different from that of Experimental Example 1 in that, in steps S2-S7, the radial temperature gradient of the heating zone 13 is 1-10K / cm, and the axial temperature gradient is 7-8K / cm. Spiral distortion occurred during the growth process of this embodiment, and after two times of re-melting-shoulder release-equal diameter growth, no complete crystal was obtained.

[0137] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A crystal growth method, characterized in that: A pure melt-growing method is used to grow multi-component crystals, wherein the multi-component crystals are binary or higher oxides.

2. The crystal growth method according to claim 1, characterized in that: The crystal growth is carried out in a heating zone (13); a low temperature zone (13a), a medium temperature zone (13b) and a high temperature zone (13c) with independent temperature control are arranged at intervals in a vertical direction in the heating zone (13); the temperature of the low temperature zone (13a) is lower than the temperature of the medium temperature zone (13b), and the temperature of the medium temperature zone (13b) is lower than the temperature of the high temperature zone (13c); and a crucible (3) for holding raw materials is located in the medium temperature zone (13b).

3. The crystal growth method according to claim 1, characterized in that: The following steps are involved: S1. Loading: loading the prepared raw materials into a crucible (3), placing the crucible (3) in a heating zone (13) of a furnace (1), mounting a seed crystal on a seed crystal rod (5), and extending the seed crystal rod (5) into the crucible (3); S2, heating: controlling the heating zone (13) to heat up until the raw material is completely melted into a melt and then stopping the heating; S3, seeding: controlling the seed crystal rod (5) to descend, and pulling the seed crystal rod (5) upward after the seed crystal contacts the liquid surface of the melt until the diameter of the grown crystal reaches a first target diameter; S4, shoulder release: reducing the pulling speed of the seed crystal rod (5) so as to expand the diameter of the crystal to a second target diameter; S5, shoulder rotation: increasing the pulling speed of the seed crystal rod (5) so that the crystal diameter is stabilized at the second target diameter; S6, equal diameter growth: stop pulling the seed crystal rod (5) upward, control the heating zone (13) to cool down at a preset cooling rate, and allow the melt to crystallize downward until the crystal reaches a preset weight; S7, shrinking the tail: pulling the seed crystal rod (5) upward to reduce the diameter of the crystal to a third target diameter; S8, cooling: controlling the heating zone (13) to cool down to room temperature.

4. The crystal growth method according to claim 3, characterized in that: The multi-component crystal is a bismuth germanate scintillation crystal; In the step S3, the pulling speed of the seed crystal rod (5) is 3-5 mm / h, the rotation speed of the seed crystal rod (5) is 3-5 rpm, and the first target diameter of the bismuth germanate scintillator crystal is 8-12 mm; In the step S4, the pulling speed of the seed crystal rod (5) is 0.1-1 mm / h, the rotation speed of the seed crystal rod (5) is 3-5 rpm, and the second target diameter of the bismuth germanate scintillator crystal is 80-210 mm; In step S5, the pulling speed of the seed crystal rod (5) is 1-3 mm / h, and the rotation speed of the seed crystal rod (5) is 3-5 rpm; In step S6, the rotation speed of the seed rod (5) is 3-5 rpm, and the preset cooling rate is 0.1-2° C. / h; In step S7, the pulling speed of the seed crystal rod (5) is 3-5 mm / h, the rotation speed of the seed crystal rod (5) is 5-8 rpm, and the third target diameter is 0-20 mm; In steps S2-S7, the radial temperature gradient of the heating zone (13) is 0.5-2 K / cm, and the axial temperature gradient is 0.5-2 K / cm.

5. The crystal growth method according to claim 3, characterized in that: The multi-component crystal is a bismuth silicate crystal; In step S3, the pulling speed of the seed crystal rod (5) is 3-5 mm / h, the rotation speed of the seed crystal rod (5) is 3-5 rpm, and the first target diameter of the bismuth silicate crystal is 8-12 mm; In the step S4, the pulling speed of the seed rod (5) is 0.1-1 mm / h, the rotation speed of the seed rod (5) is 3-5 rpm, and the second target diameter of the bismuth silicate crystal is 70-130 mm; In step S5, the pulling speed of the seed crystal rod (5) is 1-3 mm / h, and the rotation speed of the seed crystal rod (5) is 3-5 rpm; In step S6, the rotation speed of the seed rod (5) is 3-5 rpm, and the preset cooling rate is 0.1-1° C. / h; In step S7, the pulling speed of the seed crystal rod (5) is 3-5 mm / h, the rotation speed of the seed crystal rod (5) is 5-8 rpm, and the third target diameter is 0-20 mm; In steps S2-S7, the radial temperature gradient of the heating zone (13) is 0.5-2 K / cm, and the axial temperature gradient is 0.5-2 K / cm.

6. The crystal growth method according to claim 3, characterized in that: The multi-component crystal is calcium yttrium oxyborate crystal; In step S3, the pulling speed of the seed crystal rod (5) is 0.5-1 mm / h, the rotation speed of the seed crystal rod (5) is 3-5 rpm, and the first target diameter of the yttrium calcium oxyborate crystal is 8-12 mm; In the step S4, the pulling speed of the seed crystal rod (5) is 0.2-0.5 mm / h, the rotation speed of the seed crystal rod (5) is 3-5 rpm, and the second target diameter of the yttrium calcium oxyborate crystal is 100-130 mm; In step S5, the pulling speed of the seed crystal rod (5) is 0.5-0.8 mm / h, and the rotation speed of the seed crystal rod (5) is 3-5 rpm; In step S6, the rotation speed is 3-5 rpm, and the preset cooling rate is 5-8°C / h; In step S7, the pulling speed of the seed crystal rod (5) is 3-5 mm / h, the rotation speed of the seed crystal rod (5) is 5-8 rpm, and the third target diameter is 0-20 mm; In steps S2-S7, the radial temperature gradient of the heating zone (13) is 1-10K / cm, and the axial temperature gradient is 2-5K / cm.

7. A crystal growth device, characterized in that: include: A furnace (1), the furnace (1) comprising a furnace body (11) and a furnace cover (12), the furnace cover (12) sealing a top opening of the furnace body (11), and a heating zone (13) surrounded by a heat-insulating material is provided inside the furnace body (11); The support seat (2) and the crucible (3) are both arranged in the heating zone (13), and the crucible (3) is placed above the support seat (2); A seed crystal rod (5) which can be raised and lowered in a vertical direction and can be inserted into the heating zone (13) and extend into the crucible (3); The furnace cover (12) is provided with an observation port (121), the heating zone (13) is provided with a first observation hole, and the midpoints of the observation port (121) and the first observation hole are located on the same straight line; An air outlet pipe, arranged at a first mounting opening (17) on a side wall of the furnace body (11), and used for evacuating the furnace chamber (1); an air inlet pipe, located at a second mounting opening (18) on the side wall of the furnace body (11), and used for introducing gas into the furnace (1); Three groups of annular heating components are arranged on the inner wall of the heating zone (13), and the three groups of heating components are respectively an upper heating component (4a), a middle heating component (4b) and a lower heating component (4c) arranged at intervals from top to bottom. The crucible (3) is located in the medium temperature zone (13b) surrounded by the middle heating component (4b).

8. The crystal growth device according to claim 7, characterized in that: The height difference between the highest point of the crucible (3) and the highest point of the upper heating component (4a) is more than 8 cm, and the height difference between the lowest point of the crucible (3) and the lowest point of the lower heating component (4c) is more than 8 cm.

9. The crystal growth device according to claim 7, characterized in that: The height difference between the highest point of the crucible (3) and the highest point of the upper heating component (4a) is greater than 8 cm and less than 12 cm, and the height difference between the lowest point of the crucible (3) and the lowest point of the lower heating component (4c) is greater than 8 cm and less than 12 cm.

10. The crystal growth device according to any one of claims 7 to 9, characterized in that: The observation port (121) is made of glass.

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