Crystal growth methods and crystal growth apparatus

Abstract

This invention belongs to the field of multi-component crystal preparation technology, and discloses a crystal growth method and apparatus. It uses the pure melt bubble growth method to grow multi-component crystals, where the multi-component crystals are binary or higher-order oxides. The crystal growth apparatus includes a furnace chamber, a support base, a crucible, a seed crystal rod, an outlet pipe, an inlet pipe, and three sets of annular heating components. The furnace chamber includes a furnace body and a furnace cover, with the furnace cover sealing the top opening of the furnace body. The interior of the furnace body has a heating zone surrounded by insulating material. The support base and crucible are both located within the heating zone. The seed crystal rod extends into the crucible. The three sets of annular heating components are located on the inner wall of the heating zone, and are arranged from top to bottom as an upper heating component, a middle heating component, and a lower heating component. The crucible is located in the intermediate temperature zone surrounded by the middle heating component. This invention can avoid polycrystalline phenomena and internal defects, grow larger-sized, high-quality multi-component crystals, and reduce manufacturing costs.

Description

Technical Field

[0001] This invention relates to the field of multi-component crystal preparation technology, and more particularly to crystal growth methods and crystal growth apparatus. Background Technology

[0002] Multicomponent crystals such as bismuth germanate (BGO), bismuth silicate (BSO), and yttrium oxyborate (YCOB) have excellent working properties and are widely used in semiconductors, defense, aerospace and other fields. Bismuth germanate and bismuth silicate are binary oxides, while yttrium oxyborate is a ternary oxide. Currently, there are two main methods for preparing multicomponent crystals such as bismuth germanate: the falling method and the pulling method. The apparatus used in the two methods differs in structure.

[0003] An example of an apparatus employing the descending method is CN102828230B, entitled "Growth Apparatus and Method for Growing Wide-Panel Bismuth Germanate Crystals by Descending Method." This method grows crystals by controlling the vertical descent of the alumina crucible and the temperature gradient at the crystal growth interface. However, the furnace shell size of the descending method is limited, making it difficult to prepare large-sized crystals. Furthermore, the crystal growth process cannot be directly observed, and the growth cycle is relatively long.

[0004] An apparatus using the Czochralski method, such as the one published in JP2001261485A and entitled "Apparatus and Method for Manufacturing Single Crystals," involves pulling the melt at a constant pulling speed and rotation speed using a pulling mechanism after the crystal has reached the target diameter but before reaching the target length, so that the crystal can grow. However, the Czochralski method requires controlling a relatively slow pulling rate and a fast rotation speed, which is very disadvantageous for growing large-sized crystals for industrial applications.

[0005] The main difference between the Czochralski method and the Czochralski method is that the Czochralski method does not require pulling the seed crystal upwards during the constant diameter stage to achieve continuous crystallization. It is generally used for sapphire crystal growth and is more suitable for large-size crystal growth. The temperature field structure design of existing Czochralski crystal devices is not reasonable enough, making them unsuitable for the growth of multi-component crystals and prone to polycrystalline structures and internal defects. Summary of the Invention

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

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

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, a crystal growth method is provided, in which a multi-component crystal is grown using the pure melt cavitation method, 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; the heating zone is vertically spaced with independently temperature-controlled low-temperature zone, medium-temperature zone and high-temperature zone, 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, the crucible is located in the medium-temperature zone, and 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: Load the prepared raw materials into the crucible, place the crucible in the heating zone of the furnace, install the seed crystal on the seed crystal rod and insert the seed crystal rod into the crucible;

[0013] S2. Heating: Control the heating zone to heat up until the raw material is completely melted into a melt, then stop heating.

[0014] S3, Crystal introduction: Control the seed crystal rod to descend, and after the seed crystal contacts the liquid surface of the melt, pull the seed crystal rod upward until the diameter of the grown crystal reaches the first target diameter;

[0015] S4. Shoulder Release: Reduce the pulling speed of the seed crystal rod to increase the diameter of the crystal to the second target diameter;

[0016] S5. Shoulder Rotation: Increase the pulling speed of the seed crystal rod to stabilize the crystal diameter at the second target diameter;

[0017] S6. Constant Diameter Growth: Stop pulling the seed crystal rod upward, control the heating zone to cool down at a preset cooling rate, and let the melt crystallize downward until the crystal reaches the preset weight.

[0018] S7. Tail Reduction: Pull the seed crystal rod upward to reduce the diameter of the crystal to the third target diameter;

[0019] S8. Cooling: Control the heating zone to cool down until room temperature.

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

[0021] In 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 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 crystal rod is 3-5 rpm, and the preset cooling rate is 0.1-2℃ / h;

[0025] 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 diameter of the third target is 0-20 mm.

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

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

[0028] In 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 silicate crystal is 8-12 mm.

[0029] In 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 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 crystal rod is 3-5 rpm, and the preset cooling rate is 0.1-1℃ / 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 diameter of the third target is 0-20 mm.

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

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

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

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

[0037] In 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 seed crystal rod rotates at a speed of 3-5 rpm, and the preset cooling rate is 5-8℃ / h.

[0039] 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 diameter of the third target is 0-20 mm.

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

[0041] Secondly, a crystal growth apparatus is provided, comprising:

[0042] The furnace chamber includes a furnace body and a furnace cover, the furnace cover sealing the top opening of the furnace body, and the interior of the furnace body having a heating zone surrounded by insulation material;

[0043] Both the support and the crucible are disposed within the heating zone, with the crucible positioned above the support.

[0044] The seed crystal rod can be raised and lowered vertically and can be inserted into the heating zone and extended into the crucible;

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

[0046] An exhaust pipe, located at the first mounting port on the side wall of the furnace body, is used to evacuate the furnace chamber;

[0047] An air inlet pipe, located at the second mounting port on the side wall of the furnace body, is used to introduce gas into the furnace chamber;

[0048] Three sets of annular heating components are disposed on the inner wall of the heating zone. The three sets of heating components are an upper heating component, a middle heating component, and a lower heating component 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 component is more than 8 cm, and the height difference between the lowest point of the crucible and the lowest point of the lower heating component 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 component is more than 8cm and less than 12cm, and the height difference between the lowest point of the crucible and the lowest point of the lower heating component is more than 8cm and less than 12cm.

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

[0052] The beneficial effects of this invention are:

[0053] This invention provides a crystal growth method that uses pure melt cavitation to grow multicomponent crystals, rather than flux cavitation. The multicomponent crystals are binary or higher oxides, which can avoid polymorphism, reduce internal defects, and facilitate the preparation of large-size and high-quality multicomponent crystals.

[0054] The present invention also provides a crystal growth apparatus, which includes a furnace chamber, a support base, a crucible, a seed crystal rod, a gas outlet pipe, a gas inlet pipe, and three sets 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. The interior of the furnace body is provided with a heating zone surrounded by insulation material. The support base and the crucible are both located in the heating zone, with the crucible positioned above the support base. The seed crystal rod can be raised and lowered vertically 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. The observation port and the first observation hole are located on the same straight line. The gas outlet pipe is located at a first mounting port on the side wall of the furnace body for evacuating the furnace chamber. The gas inlet pipe is located at a second mounting port on the side wall of the furnace body for introducing gas into the furnace chamber. The three sets of annular heating components are arranged on the inner wall of the heating zone. The three sets of heating components are 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 middle temperature zone surrounded by the middle heating component.

[0055] Placing the crucible in the intermediate temperature zone surrounded by the intermediate heating components, the presence of the upper and lower heating components is more conducive to forming a stable temperature gradient environment, which greatly avoids polycrystalline phenomena and internal defects, and can grow larger-sized, high-quality multi-component crystals, especially crystals larger than 5 inches. Attached Figure Description

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

[0057] Figure 2 yes Figure 1 A magnified view of a portion of position A in the middle;

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

[0059] In the picture:

[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 base plate; 15. Insulation enclosure plate; 16. Insulation cover plate; 17. First mounting port; 18. Second mounting port;

[0061] 2. Support base;

[0062] 3. Crucible;

[0063] 4a. Upper heating element; 4b. Middle heating element; 4c. Lower heating element;

[0064] 5. Seed crystal rod;

[0065] 6. Temperature-controlled thermocouple;

[0066] 7. Crucible lid; 71. Second observation hole. Detailed Implementation

[0067] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0068] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0069] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0070] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0071] like Figure 1 and Figure 2 As shown, this embodiment provides a crystal growth apparatus, which includes a furnace chamber 1, a support base 2, a crucible 3, a seed crystal rod 5, an exhaust pipe, an inlet pipe, and three sets of annular heating components. The furnace chamber 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 insulation material. The support base 2 and the crucible 3 are both located within the heating zone 13, with the crucible 3 positioned above the support base 2. The seed crystal rod 5 can be raised and lowered vertically and can be inserted into the heating zone 13 and extended 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 on the same straight line, so that the operator can observe the melting state of the raw material through the observation port 121. An exhaust pipe is located at the first mounting port 17 on the side wall of the furnace body 11 for evacuating the furnace chamber 1; an intake pipe is located at the second mounting port 18 on the side wall of the furnace body 11 for introducing gas into the furnace chamber 1. Three sets of annular heating components are arranged on the inner wall of the heating zone 13. The three sets of heating components are 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; each set of heating components is equipped with a temperature-controlled thermocouple 6.

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

[0073] The multi-component crystals prepared using the crystal growth apparatus provided in this embodiment can be applied in the fields of semiconductors, defense, and aerospace.

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

[0075] Optionally, the furnace cover 12 is provided with at least one observation port 121, which is made of glass, allowing the interior of the furnace chamber 1 to be observed through the glass, while the glass prevents heat from escaping.

[0076] Optionally, the insulation material for the enclosed heating zone 13 can be mullite or alumina, etc.

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

[0078] Optionally, the support base 2 can be made of alumina. The crucible 3 is a platinum crucible with an open top, which is sealed by a crucible lid 7. The crucible lid 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 on the same straight line. 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] Furthermore, the height difference between the highest point of the crucible 3 and the highest point of the upper heating component 4a is 8 cm or more, for example, 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, or 13 cm. Preferably, the height difference between the highest point of the crucible 3 and the highest point of the upper heating component 4a is 8 cm or more and less than 12 cm. Similarly, the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating component 4c is 8 cm or more, for example, 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, or 13 cm. Preferably, the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating component 4c is 8 cm or more and less than 12 cm. Here, the highest point of the crucible 3 is not considered part of the crucible lid 7; that is, the highest point of the crucible lid 7 is not used as the standard.

[0080] This embodiment provides a crystal growth method that uses the pure melt chemiluminescence method to grow multi-component crystals, where the multi-component crystals are binary or higher-order oxides. Specifically, they can be bismuth germanate scintillation crystals, bismuth silicate crystals, yttrium oxyborate crystals, or other multi-component crystals. The heating zone 13 for crystal growth consists of three independently temperature-controlled sections. Specifically, the heating zone 13 is vertically spaced with independently temperature-controlled low-temperature zone 13a, medium-temperature zone 13b, and high-temperature zone 13c. The temperature of the low-temperature zone 13a is lower than that of the medium-temperature zone 13b, and the temperature of the medium-temperature zone 13b is lower than that of the high-temperature zone 13c. The crucible 3 containing the raw materials is located within the medium-temperature zone 13b.

[0081] Using the pure melt zoning method to grow multicomponent crystals can avoid polymorphism, reduce internal defects, and is beneficial for preparing large-size and high-quality multicomponent crystals.

[0082] The crystal growth method includes 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 chamber 1 can be evacuated and oxygen can be introduced.

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

[0086] S3, Crystal introduction: Control the seed crystal rod 5 to descend. 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 the first target diameter.

[0087] S4. Shoulder Formation: Reduce the pulling speed of the seed crystal rod 5 to expand the crystal diameter to the second target diameter.

[0088] S5, Shoulder Rotation: Increase the pulling speed of the seed crystal rod 5 to stabilize the crystal diameter at the second target diameter.

[0089] S6. Constant Diameter Growth: Stop pulling the seed crystal rod 5 upwards, control the heating zone 13 to cool down at the preset cooling rate, and let the melt crystallize downwards until the crystal reaches the preset weight.

[0090] S7, Tail Reduction: Pull the seed crystal rod 5 upward to reduce the diameter of the crystal to the third target diameter.

[0091] S8. Cooling: Control the heating zone 13 to cool down until room temperature.

[0092] Experimental Example 1

[0093] like Figure 1 and 2As shown, the crystal growth apparatus includes a furnace chamber 1, a support base 2, a crucible 3, a seed crystal rod 5, an exhaust pipe, an inlet pipe, and three sets of annular heating components. The furnace chamber 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 contains a heating zone 13 surrounded by mullite. The support base 2 and the crucible 3 are both located within the heating zone 13, with the crucible 3 positioned above the support base 2. The seed crystal rod 5 can be raised and lowered vertically and can be inserted into the heating zone 13 and extend into the crucible 3. The furnace cover... The furnace body 12 has an observation port 121, and the heating zone 13 has a first observation hole. The midpoints of the observation port 121 and the first observation hole are on the same straight line. The exhaust pipe is located at the first mounting port 17 on the side wall of the furnace body 11, and the intake pipe is located at the second mounting port 18 on the side wall of the furnace body 11. The heating element is a nickel-cadmium-aluminum heating element. Three sets of annular heating elements are arranged on the inner wall of the heating zone 13. The three sets of heating elements are an upper heating element 4a, a middle heating element 4b, and a lower heating element 4c, which are arranged from top to bottom at intervals. The area surrounded by the lower heating element 4c is the high-temperature zone 13c, the area surrounded by the middle heating element 4b is the middle heating zone 13b, and the area surrounded by the upper heating element 4a is the low-temperature zone 13a. The crucible 3 is located in the middle-temperature zone 13b surrounded by the middle heating element 4b. The height difference between the highest point of the crucible 3 and the highest point of the upper heating element 4a is 6 cm, and the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating element 4c is 6 cm. The heating zone 13 includes an insulation base plate 14, an insulation enclosure plate 15, and an insulation cover plate 16. The insulation enclosure plate 15 surrounds the outer periphery of the heating component, and the insulation cover plate 16 covers the top of the insulation enclosure plate 15.

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

[0095] S1. Loading: The prepared bismuth trioxide and germanium dioxide are loaded into crucible 3. The crucible 3 is placed in the heating zone 13 of the furnace chamber 1. The seed crystal is installed on the seed crystal rod 5 and the seed crystal rod 5 is inserted 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℃. The temperature control thermocouple of the middle heating zone 13b needs to be set 5-10℃ higher than 1050℃. At the same time, the seed crystal rod 5 rotates at a speed of 3-5 rpm.

[0097] S3, Crystal introduction: Control the seed crystal rod 5 to descend. 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 10mm. During this process, the rotation speed of the seed crystal rod 5 is 3-5rpm and the pulling speed is 0.1-1mm / h.

[0098] S4. Shoulder Formation: Keep the seed crystal rod 5 rotating at 3-5 rpm and pull it upward at a speed of 0.1-1 mm / h until the crystal diameter expands to 80 mm.

[0099] S5, Shoulder Rotation: Keep the seed crystal rod 5 rotating at a speed of 3-5 rpm and pull it upward at a speed of 3-5 mm / h until the crystal diameter is stable at 80 mm.

[0100] S6. Constant Diameter Growth: The seed crystal rod is kept at a rotation speed of 3-5 rpm, and the upward pulling of the seed crystal rod 5 is stopped. The heating zone 13 is controlled 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 independent cooling of the upper heating component 4a, the middle heating component 4b, and the lower heating component 4c within this range, but the temperature gradient needs to be kept within the specified range synchronously.

[0101] S7. Tail Reduction: Increase the rotation speed of the seed crystal rod 5 to 5-8 rpm, and pull the seed crystal rod 5 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 ​​heating zone 13 to cool down at a uniform rate until room temperature, with a cooling time of 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 experiment is a bismuth germanate scintillation crystal with a diameter of 80 mm. The crystal is intact and without cracks, but there are inclusions enriched at the bottom.

[0105] Experimental Example 2

[0106] The difference between this experimental example and the crystal growth apparatus in Example 1 is that the position of the crucible 3 relative to the upper and lower parts of the heating zone 13 has changed. Specifically, the height difference between the highest point of the crucible 3 and the highest point of the upper heating component 4a is 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 8 cm. The crystal growth method in this example differs from that in Example 1 in that, 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 1-1.5 K / cm. The crystal grown in this example is a bismuth germanate scintillation crystal with a diameter of 120 mm. The crystal is intact, crack-free, colorless, transparent, and has no visible inclusions. It shows no light path when illuminated with a helium-neon laser.

[0107] Experimental Example 3

[0108] The difference between this experimental example and the crystal growth apparatus in Example 1 lies in the change of the position of the crucible 3 relative to the upper and lower parts of the heating zone 13. 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 12 cm. The crystal growth method in this example differs from that in Example 1 in that, 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 1.4-2 K / cm. The crystal grown in this example is a bismuth germanate scintillation crystal with a diameter of 200 mm. The crystal is intact, crack-free, colorless, transparent, and has no visible inclusions. It shows no light path when illuminated with a helium-neon laser.

[0109] Experiment Example 4

[0110] The difference between this experimental example and the crystal growth apparatus in Example 1 lies in the change of the position of the crucible 3 relative to the upper and lower parts of the heating zone 13. Specifically, the height difference between the highest point of the crucible 3 and the highest point of the upper heating component 4a is 15 cm, and the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating component 4c is 15 cm. The crystal growth method in this example differs from that in Example 1 in that, 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 5-6 K / cm. The crystal grown in this example is a bismuth germanate scintillation crystal with a diameter of 120 mm. The crystal is cracked, and there are cracks on the surface.

[0111] Experimental Example 5

[0112] The difference between this apparatus and the crystal growth apparatus in Example 1 lies in the different structural design of heating zone 13, such as... Figure 3 As shown, the heating zone 13 has an upper heating component 4a and a lower heating component 4c arranged from top to bottom. The area surrounded by the lower heating component 4c is the high-temperature zone 13c, and the area surrounded by the upper heating component 4a is the low-temperature zone 13a. The upper part of the crucible 3 is located in the low-temperature zone 13a, and 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 component 4a is 6 cm, and the height difference between the lowest point of the crucible 3 and the lower heating component 4c is 6 cm. The crystal growth method in this experimental example differs from that in Experimental Example 1 in that, 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 0.2-0.4 K / cm. The crystal grown in this experimental example is a bismuth germanate scintillation crystal with a diameter of 80 mm. The crystal has a complete shape, contains bubbles and a layered polycrystalline structure, has black inclusions at the bottom, and exhibits a clear light path under helium-neon laser illumination.

[0113] Experimental Example 6

[0114] The crystal growth apparatus is the same as in Example 1. The difference is that this example is used for the growth of bismuth silicate crystals, and the raw material is changed to bismuth silicate crystal raw material. During the heating stage, the temperature control thermocouple of the heating zone 13b is set 5-10℃ higher than 1030℃. 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 constant diameter growth in step S6, the preset cooling rate is 0.1-1℃ / h. The crystal obtained in this example is a bismuth silicate crystal with a diameter of 100mm. The crystal is intact and crack-free. Bubbles are present in the constant diameter portion of the crystal, and inclusions are enriched in the terminal portion. No obvious light path is observed under helium-neon laser illumination.

[0115] Experimental Example 7

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

[0117] Experimental Example 8

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

[0119] Experimental Example 9

[0120] The crystal growth apparatus structure and method used in this experiment are the same as in Experiment 1. The difference is that this experiment is used for the growth of oxy-calcium yttrium borate crystals, which belong to the borate system. The specific steps are as follows:

[0121] S1. Loading: Load the prepared calcium oxy borate crystal raw material into crucible 3, place crucible 3 in heating zone 13 of furnace 1, install seed crystal on seed crystal rod 5 and insert seed crystal rod 5 into 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 heating zone 13b is set at 1520℃.

[0123] S3, Crystal introduction: Control the seed crystal rod 5 to descend. 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 10mm. The rotation speed of the seed crystal rod 5 is 3-5rpm and the pulling speed is 0.5-1mm / h.

[0124] S4. Shoulder Formation: Keep the seed crystal rod 5 rotating at 3-5 rpm and pull it upward at a speed of 0.2-0.5 mm / h until the crystal diameter is expanded to 120 mm.

[0125] S5, Shoulder Rotation: Keep the seed crystal rod 5 rotating at a speed of 3-5 rpm and pull it upward at a speed of 0.5-0.8 mm / h until the crystal diameter stabilizes at 75 mm.

[0126] S6. Constant diameter growth: Maintain the rotation speed of the seed crystal rod at 3-5 rpm and stop pulling the seed crystal rod 5 upward. Control the heating zone 13 to cool down at a rate of 5-8℃ / h. The melt crystallizes downward until the crystal reaches 4Kg.

[0127] S7. Tail Reduction: Pull the seed crystal rod 5 upward at a speed of 3-5 mm / h to reduce the diameter of the crystal to a single point.

[0128] S8. Cooling: Control each area of ​​heating zone 13 to cool down at a uniform rate until room temperature, with a cooling time of 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 experiment is yttrium oxyborate crystal with a diameter of 75 mm. The crystal is free of cracks, colorless and transparent, and contains visible bubbles in the constant diameter portion.

[0131] Experimental Example 10

[0132] The difference between this experimental example and the crystal growth apparatus in Example 9 lies in the change of the position of the crucible 3 relative to the upper and lower parts of the heating zone 13. Specifically, the height difference between the highest point of the crucible 3 and the highest point of the upper heating component 4a is 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 8 cm. The crystal growth method in this example differs from that in Example 9 in that, in steps S2-S7, the radial temperature gradient of the heating zone 13 is 1-10 K / cm, and the axial temperature gradient is 4-5.5 K / cm. The crystal obtained in this example is yttrium oxyborate crystal with a diameter of 120 mm. The crystal is intact without cracks, has no visible inclusions, and exhibits good overall quality.

[0133] Experimental Example 11

[0134] The difference between this experimental example and the crystal growth apparatus in Example 9 lies in the position of the crucible 3 relative to the upper and lower parts of the heating zone 13. 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 in this example differs from that in Example 1 in that, in steps S2-S7, the radial temperature gradient of the heating zone 13 is 1-10 K / cm, and the axial temperature gradient is 6-7 K / cm. The crystal obtained in this example is yttrium oxyborate crystal with a diameter of 120 mm. The crystal is intact without cracks, and there are no visible inclusions in the constant-diameter portion. After natural cooling and removal of the crystal, it spontaneously cracked at room temperature.

[0135] Experimental Example 12

[0136] The difference between this experimental example and the crystal growth apparatus in Example 9 lies in the change of position of the crucible 3 relative to the upper and lower parts of the heating zone 13. Specifically, the height difference between the highest point of the crucible 3 and the highest point of the upper heating component 4a is 15 cm, and the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating component 4c is 8 cm. The crystal growth method in this example differs from that in Example 1 in that, in steps S2-S7, the radial temperature gradient of the heating zone 13 is 1-10 K / cm, and the axial temperature gradient is 7-8 K / cm. In this embodiment, spiral twisting occurred during the growth process, and after two remelting-shoulder-equal-diameter growth cycles, a complete crystal was still not 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 implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A crystal growth method, characterized in that, Multicomponent crystals are grown using the pure melt sculpting method, wherein the multicomponent crystals are binary or higher-component oxides. The crystal growth is carried out in the heating zone (13); the heating zone (13) is vertically spaced with independently temperature-controlled low temperature zone (13a), medium temperature zone (13b) and high temperature zone (13c), the temperature of the low temperature zone (13a) is lower than the temperature of the medium temperature zone (13b), the temperature of the medium temperature zone (13b) is lower than the temperature of the high temperature zone (13c), and the crucible (3) holding the raw material is located in the medium temperature zone (13b).

2. The crystal growth method according to claim 1, characterized in that, Includes the following steps: 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 extend the seed crystal rod (5) into the crucible (3); S2, Heating: Control the heating zone (13) to heat up until the raw material is completely melted into a melt and then stop heating; S3, Crystal introduction: 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 the first target diameter; S4, Shoulder Release: Reduce the pulling speed of the seed crystal rod (5) to increase the diameter of the crystal to the second target diameter; S5, Shoulder Rotation: Increase the pulling speed of the seed crystal rod (5) to stabilize the crystal diameter 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 let the melt crystallize downward until the crystal reaches the preset weight; S7, Tail Reduction: Pull the seed crystal rod (5) upward to reduce the diameter of the crystal to the third target diameter; S8. Cooling: Control the heating zone (13) to cool down until room temperature.

3. The crystal growth method according to claim 2, characterized in that, The multi-component crystal is a bismuth germanate scintillation 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 germanate scintillation crystal is 8-12 mm. In 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 scintillation 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 crystal rod (5) is 3-5 rpm, and the preset cooling rate is 0.1-2℃ / 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 diameter of the third target is 0-20 mm. In steps S2-S7, the radial temperature gradient of the heating zone (13) is 0.5-2K / cm, and the axial temperature gradient is 0.5-2K / cm.

4. The crystal growth method according to claim 2, characterized in that, The multi-component crystal is 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 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 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 crystal rod (5) is 3-5 rpm, and the preset cooling rate is 0.1-1℃ / 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 diameter of the third target is 0-20 mm. In steps S2-S7, the radial temperature gradient of the heating zone (13) is 0.5-2K / cm, and the axial temperature gradient is 0.5-2K / cm.

5. The crystal growth method according to claim 2, characterized in that, The multi-component crystal is 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 calcium oxyborate yttrium crystal is 8-12 mm. In 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 calcium oxyborate yttrium 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℃ / 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 diameter of the third target is 0-20 mm. In steps S2-S7, the radial temperature gradient of the heating zone (13) is 1-10 K / cm, and the axial temperature gradient is 2-5 K / cm.

6. A crystal growth apparatus, characterized in that, include: The furnace chamber (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 insulation material. The support base (2) and the crucible (3) are both located in the heating zone (13), with the crucible (3) positioned above the support base (2); The seed crystal rod (5) can be raised and lowered vertically 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), 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 on the same straight line. An exhaust pipe is provided at the first mounting port (17) on the side wall of the furnace body (11) for evacuating the furnace chamber (1); An air inlet pipe, located at the second mounting port (18) on the side wall of the furnace body (11), is used to introduce gas into the furnace chamber (1); Three sets of annular heating components are disposed on the inner wall of the heating zone (13). The three sets of heating components are an upper heating component (4a), a middle heating component (4b) and a lower heating component (4c) arranged from top to bottom. The crucible (3) is located in the medium temperature zone (13b) surrounded by the middle heating component (4b).

7. The crystal growth apparatus according to claim 6, 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 8cm, 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 8cm.

8. The crystal growth apparatus according to claim 6, 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 8cm and less than 12cm, 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 8cm and less than 12cm.

9. The crystal growth apparatus according to any one of claims 6-8, characterized in that, The observation port (121) is made of glass.

Images