Crystal growth method and crystal growth device

Abstract

A crystal growth method and a crystal growth device, relating to the technical field of multi-component crystal preparation. A pure melt Kyropoulos method is used to grow multi-component crystals, and the multi-component crystals are binary and higher oxides. The crystal growth device comprises a furnace, a supporting seat, a crucible, a seed rod, an air outlet pipe, an air inlet pipe, and three annular heating assemblies, wherein the furnace comprises a furnace body and a furnace cover, the furnace cover seals a top opening of the furnace body, and a heating zone enclosed by a thermal insulation material is provided inside the furnace body; the supporting seat and the crucible are both arranged in the heating zone; the seed rod extends into the crucible; the three annular heating assemblies are arranged on the inner wall of the heating zone, the three 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 located in a medium-temperature zone surrounded by the middle heating assembly. The crystal growth method can avoid the polycrystalline phenomenon and internal defects, grow larger-size and high-quality multi-component crystals, and reduce production and manufacturing costs.

Description

Crystal growth method and crystal growth device TECHNICAL FIELD

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

[0002] Multi-component crystals such as bismuth germanate (BGO), bismuth silicate (BSO), yttrium calcium oxyborate (YCOB) and the like have good working performance and are widely used in the fields of semiconductors, national defense and military industry, aerospace and the like. Bismuth germanate and bismuth silicate are binary oxides, and yttrium calcium oxyborate is a ternary oxide. At present, the preparation methods of multi-component crystals such as bismuth germanate crystals mainly include two kinds, one is a downward method, and the other is a Czochralski method. The devices used in the two preparation methods differ in structure.

[0003] The device using the downward method, such as the growth device and method for growing wide plate-shaped bismuth germanate crystal by the downward method disclosed in CN102828230B, controls the vertical downward movement of the alumina guide crucible and the temperature gradient of the crystal growth interface to grow the crystal. However, the furnace shell size of the downward method growth device is limited, and it is difficult to prepare large-size crystals. In the crystal growth process, the crystal cannot be directly observed, and the growth cycle is also relatively long.

[0004] The device using the Czochralski method, such as the device and method for manufacturing single crystals disclosed in JP2001261485A, pulls the melt at a constant pulling speed and rotation speed by a pulling mechanism before the target diameter of the crystal is reached but before the target length is reached, so as to grow the crystal. However, the Czochralski method needs to control a slow pulling rate and a fast rotation rate, which is very unfavorable for growing large-size crystals for industrial applications.

[0005] The main difference between the Kyropoulos method and the Czochralski method is that the isodiametric stage can realize continuous crystallization of the crystal without pulling the seed crystal upward. The Kyropoulos method 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 method crystal device is not reasonable, and is not suitable for the growth of multi-component crystals, which is prone to polycrystallization and internal defects and the like. SUMMARY

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

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

[0008] To achieve the above object, the present application adopts the following technical solutions:

[0009] In a first aspect, a crystal growth method is provided for growing a multi-component crystal, which is a binary or higher oxide, using a pure melt floating zone method.

[0010] As an optional technical solution, the crystal growth is performed in a heating zone; the heating zone is provided with a low-temperature zone, a medium-temperature zone and a high-temperature zone in a vertical direction, the low-temperature zone has a lower temperature than the medium-temperature zone, and the medium-temperature zone has a lower temperature than the high-temperature zone; the crucible is located in the medium-temperature zone; the multi-zone independent temperature control makes the temperature gradient more uniform and stable, and avoids the occurrence of polycrystals and internal defects.

[0011] As an optional technical solution, the method comprises the following steps:

[0012] S1, charging: loading the prepared raw materials into a crucible, placing the crucible in a heating zone of a furnace, and installing 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 until the raw materials are completely melted into a melt, and then stopping heating;

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

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

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

[0017] S6, constant-diameter growth: stopping pulling the seed crystal rod upward, controlling the heating zone to cool at a preset cooling rate, and the melt crystallizes downward until the crystal reaches a preset weight;

[0018] S7, tail contraction: 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 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 rod is 0.1-1mm / h, the rotating speed of the seed rod is 3-5rpm, and the second target diameter of the bismuth germanate scintillation crystal is 80-210mm;

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

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

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

[0026] In the 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 3-5mm / h, the rotating speed of the seed rod is 3-5rpm, and the first target diameter of the bismuth silicate crystal is 8-12mm;

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

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

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

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

[0033] In the 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 a bismuth silicate crystal;

[0035] In the step S3, the pulling speed of the seed rod is 0.5-1 mm / h, the rotating speed of the seed rod is 3-5 rpm, and the first target diameter of the yttrium calcium oxiborate 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 rotating speed of the seed rod is 3-5 rpm, and the second target diameter of the yttrium calcium oxiborate crystal is 100-130 mm;

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

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

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

[0040] In the 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] In a second aspect, a crystal growth device is provided, comprising:

[0042] A furnace chamber, comprising a furnace body and a furnace cover, the furnace cover sealing a top opening of the furnace body, and an inner portion of the furnace body being provided with a heating zone surrounded by a heat preservation material;

[0043] A bearing seat and a crucible, both being arranged in the heating zone, and the crucible being arranged above the bearing seat;

[0044] A seed rod, being vertically movable and being insertable into the heating zone and extendable into the crucible;

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

[0046] An air outlet pipe, being arranged at a first mounting opening of a side wall of the furnace body, and being used for vacuumizing the furnace chamber;

[0047] An air inlet pipe, being arranged at a second mounting opening of the side wall of the furnace body, and being used for introducing gas into the furnace chamber;

[0048] Three groups of annular heating assemblies are arranged on the inner wall of the heating zone, and the three groups of heating assemblies are an upper heating assembly, a middle heating assembly and a lower heating assembly arranged in a spaced manner from top to bottom, and the crucible is located in a middle temperature zone surrounded by the middle heating assembly.

[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 greater than 8 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.

[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] The beneficial effects of the present application are as follows:

[0053] The present application provides a crystal growth method, which uses a pure melt floating zone method to grow a multi-component crystal, instead of a flux floating zone method, the multi-component crystal is a binary and above oxide, which can avoid polycrystallization, reduce internal defects, and is beneficial to the preparation of large-size and high-quality multi-component crystals.

[0054] The present application also provides a crystal growth device, which comprises a furnace, a bearing seat, a crucible, a seed crystal rod, a gas outlet pipe, a gas inlet pipe and three groups of annular heating assemblies. The furnace comprises a furnace body and a furnace cover, the furnace cover seals the top opening of the furnace body, and the inside of the furnace body is provided with a heating zone surrounded by a heat preservation material. The bearing seat and the crucible are arranged in the heating zone, and the crucible is arranged above the bearing seat. The seed crystal rod can be lifted in a vertical direction and can be inserted into the heating zone and extended into the crucible. The furnace cover is provided with an observation port, the heating zone is provided with a first observation hole, and the observation port and the first observation hole are located on the same straight line. The gas outlet pipe is arranged in a first mounting port of the side wall of the furnace body and is used for vacuumizing the furnace. The gas inlet pipe is arranged in a second mounting port of the side wall of the furnace body and is used for introducing gas into the furnace. The three groups of annular heating assemblies are arranged on the inner wall of the heating zone, and the three groups of heating assemblies are an upper heating assembly, a middle heating assembly and a lower heating assembly arranged in a spaced manner from top to bottom, and the crucible is located in a middle temperature zone surrounded by the middle heating assembly.

[0055] The crucible is placed in the middle temperature zone surrounded by the middle heating assembly, and the existence of the upper heating assembly and the lower heating assembly is more conducive to forming a stable temperature gradient environment, greatly avoiding polycrystallization and internal defects, and being able to grow larger-size and high-quality multi-component crystals, especially crystals with a size of more than 5 inches. BRIEF DESCRIPTION OF DRAWINGS

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

[0057] Figure 2 is a magnified view of a portion of position A in Figure 1;

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

[0059] In the diagram: 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; 2. Support seat; 3. Crucible; 4a. Upper heating assembly; 4b. Middle heating assembly; 4c. Lower heating assembly; 5. Seed crystal rod; 6. Temperature control thermocouple; 7. Crucible cover; 71. Second observation port. Detailed Implementation

[0060] 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.

[0061] 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.

[0062] 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.

[0063] In the description of the present embodiment, the terms "upper", "lower", "right", "left", and the like, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used to distinguish in the description, and have no special meaning.

[0064] As shown in FIG. 1 and FIG. 2, the present embodiment provides a crystal growth device, which comprises a furnace 1, a carrier seat 2, a crucible 3, a seed rod 5, a gas outlet pipe, a gas inlet pipe, and three sets of annular heating assemblies. The furnace 1 comprises a furnace body 11 and a furnace cover 12, the furnace cover 12 seals the top opening of the furnace body 11, and the inside of the furnace body 11 is provided with a heating zone 13 surrounded by a heat preservation material. The carrier seat 2 and the crucible 3 are both arranged in the heating zone 13, and the crucible 3 is placed above the carrier seat 2. The seed rod 5 can be lifted in the vertical direction and can be inserted into the heating zone 13 and extend into the crucible 3, and the seed rod 5 can also rotate while being lifted. The specific structure is consistent with the prior art, and will not be described further here. The furnace cover 12 is provided with a viewing port 121, and the heating zone 13 is provided with a first viewing hole, the midpoints of the viewing port 121 and the first viewing hole are located on the same straight line, so that the operator can check the melting state of the raw material through the viewing port 121. The gas outlet pipe is arranged at a first mounting port 17 of the side wall of the furnace body 11, and is used for vacuumizing the furnace 1; the gas inlet pipe is arranged at a second mounting port 18 of the side wall of the furnace body 11, and is used for introducing gas into the furnace 1. The three sets of annular heating assemblies are arranged on the inner wall of the heating zone 13, and the three sets of heating assemblies are an upper heating assembly 4a, a middle heating assembly 4b and a lower heating assembly 4c arranged in the order from top to bottom, and the crucible 3 is located in a middle temperature zone 13b surrounded by the middle heating assembly 4b; each set of heating assembly is provided with a temperature control thermocouple 6.

[0065] Specifically, the heating assembly is a nickel-cadmium-aluminum heating body. The area surrounded by the lower heating assembly 4c is a high temperature zone 13c, the area surrounded by the middle heating assembly 4b is a middle heating zone 13b, and the area surrounded by the upper heating assembly 4a is a low temperature zone 13a. Placing the crucible 3 in the middle temperature zone 13b surrounded by the middle heating assembly 4b is more conducive to forming a stable temperature gradient environment due to the presence of the upper heating assembly 4a and the lower heating assembly 4c, greatly avoiding the phenomenon of polycrystalline and internal defects, etc., and being able to grow larger size high quality multi-component crystals, and preparing large size crystals can reduce the production cost.

[0066] The multi-component crystals prepared by using the crystal growth device provided by the present embodiment can be applied in the fields of semiconductors, national defense and military industry, aerospace, etc.

[0067] Optionally, the furnace 1 is made of stainless steel, and the side wall of the furnace 1 is in a hollow structure, and a cooling channel 111 is arranged inside the furnace 1, and the cooling channel 111 is used for passing cooling medium to reduce the temperature of the furnace 1.

[0068] Optionally, the furnace cover 12 is provided with at least one observation port 121, and the observation port 121 is made of glass, and the glass can be used to observe the inside of the furnace 1, and the glass can prevent heat from escaping.

[0069] Optionally, the heat preservation material of the enclosed heating area 13 can be mullite, or other heat preservation materials such as alumina.

[0070] Optionally, the inside of the furnace body 11 is provided with a heat preservation bottom plate 14, a heat preservation surrounding plate 15, and a heat preservation cover plate 16, the heat preservation surrounding plate 15 is arranged around the outer periphery of the heating assembly, i.e. the heating assembly is fixed to the inner wall of the heat preservation surrounding plate 15, the heat preservation cover plate 16 is arranged on the top of the heat preservation surrounding plate 15, the heat preservation bottom plate 14, the heat preservation surrounding plate 15, and the heat preservation cover plate 16 enclose the heating area 13, the carrier seat 2 and the crucible 3 are located in the heating area 13, a through hole is arranged in the middle of the heat preservation cover plate 16 for the seed crystal rod 5 to pass through, and the first observation hole is arranged on the heat preservation cover plate 16.

[0071] Optionally, the material of the carrier seat 2 can be alumina. The crucible 3 is made of platinum gold, and the top of the crucible 3 is open and is 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 on the same straight line, and the operator or the visual equipment can observe the melting and growth of the raw materials in the inside of the crucible 3 through the observation port 121, the first observation hole, and the second observation hole 71.

[0072] 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, for example, 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, or 13 cm, and 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, 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 or more, for example, 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, or 13 cm, and 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. Here, the highest point of the crucible 3 does not include the crucible cover 7 as a part of the crucible 3, i.e. the highest point of the crucible cover 7 is not taken as a standard.

[0073] The embodiment provides a crystal growth method, which grows a multi-component crystal by using a pure melt Czochralski method, and the multi-component crystal is a binary oxide or the like. Specifically, the multi-component crystal can be a bismuth germanate scintillation crystal, a bismuth silicate crystal, a calcium yttrium oxysulfate crystal, or another multi-component crystal. The heating zone 13 for crystal growth is composed of three independently temperature-controlled sections. Specifically, the independently temperature-controlled low-temperature zone 13a, the independently temperature-controlled medium-temperature zone 13b, and the independently temperature-controlled high-temperature zone 13c are arranged in the vertical direction in the heating zone 13 at intervals. 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 raw materials is located in the medium-temperature zone 13b.

[0074] The multi-component crystal is grown by using the pure melt Czochralski method, so that the polycrystal can be avoided, internal defects can be reduced, and a large-size and high-quality multi-component crystal can be prepared.

[0075] The crystal growth method comprises the following steps.

[0076] S1, charging: raw materials prepared are loaded into the crucible 3, the crucible 3 is placed in the heating zone 13 of the furnace chamber 1, a seed crystal is installed on the seed crystal rod 5, and the seed crystal rod 5 is inserted into the crucible 3.

[0077] Before the raw materials are loaded, the furnace chamber 1 can be vacuumized and oxygen can be introduced.

[0078] S2, temperature rising: the heating zone 13 is controlled to rise in temperature until the raw materials are completely melted into a melt, and then the temperature rising is stopped.

[0079] S3, crystal pulling: the seed crystal rod 5 is controlled to descend, and after the seed crystal contacts the liquid surface of the melt, the seed crystal rod 5 is pulled upward until the diameter of the grown crystal reaches a first target diameter.

[0080] S4, shoulder growth: the pulling speed of the seed crystal rod 5 is reduced, so that the diameter of the crystal is expanded to a second target diameter.

[0081] S5, shoulder turning: the pulling speed of the seed crystal rod 5 is increased, so that the diameter of the crystal is stabilized at the second target diameter.

[0082] S6, constant-diameter growth: the seed crystal rod 5 is stopped from being pulled upward, the heating zone 13 is controlled to be cooled at a preset cooling rate, the melt is crystallized downward until the crystal reaches a preset weight.

[0083] S7, tail shrinking: the seed crystal rod 5 is pulled upward, so that the diameter of the crystal is reduced to a third target diameter.

[0084] S8, temperature lowering: the heating zone 13 is controlled to be cooled to room temperature.

[0085] Experimental Example 1

[0086] As shown in FIG. 1 and 2, the crystal growth device comprises a furnace 1, a support seat 2, a crucible 3, a seed rod 5, an exhaust pipe, an air inlet pipe and three sets of annular heating assemblies. The furnace 1 comprises a furnace body 11 and a furnace cover 12, the furnace cover 12 seals the top opening of the furnace body 11, and the furnace body 11 is internally provided with a heating zone 13 surrounded by mullite; the support seat 2 and the crucible 3 are both arranged in the heating zone 13, and the crucible 3 is arranged above the support seat 2; the seed rod 5 can be lifted in the vertical direction and can be inserted into the heating zone 13 and extended 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; the exhaust pipe is arranged at a first mounting port 17 of the side wall of the furnace body 11; the air inlet pipe is arranged at a second mounting port 18 of the side wall of the furnace body 11; the heating assembly is a nickel-cadmium-aluminum heating body, and the three sets of annular heating assemblies are arranged on the inner wall of the heating zone 13, and the three sets of heating assemblies are an upper heating assembly 4a, a middle heating assembly 4b and a lower heating assembly 4c arranged in the vertical direction from top to bottom. The area surrounded by the lower heating assembly 4c is a high-temperature zone 13c, the area surrounded by the middle heating assembly 4b is a middle heating zone 13b, and the area surrounded by the upper heating assembly 4a is a low-temperature zone 13a. The crucible 3 is located in the middle-temperature zone 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 comprises a heat preservation bottom plate 14, a heat preservation surrounding plate 15 and a heat preservation cover plate 16, the heat preservation surrounding plate 15 surrounds the outer periphery of the heating assembly, and the heat preservation cover plate 16 is arranged on the top of the heat preservation surrounding plate 15.

[0087] The crystal device of the present experimental example is used for growth, comprising the following steps:

[0088] S1, charging: the prepared bismuth trioxide and germanium dioxide are charged into the crucible 3, the crucible 3 is placed in the heating zone 13 of the furnace 1, the seed crystal is installed on the seed rod 5, and the seed rod 5 is inserted into the crucible 3.

[0089] S2, heating: the temperature of the heating zone 13 is controlled to be raised until the raw material is completely melted into a melt, and then the temperature rising is stopped, the raw material melting temperature is 1050℃, the temperature control thermocouple of the middle heating zone 13b needs to be set at 5-10℃ higher than 1050℃, and at the same time, the seed rod 5 is rotated at a speed of 3-5 rpm.

[0090] S3, seeding: the seed rod 5 is controlled to be lowered, and after the seed crystal contacts the liquid surface of the melt, the seed rod 5 is pulled up until the diameter of the grown crystal reaches 10 mm, in the process, the rotation speed of the seed rod 5 is 3-5 rpm, and the pulling speed is 0.1-1 mm / h.

[0091] S4, shoulder: the seed rod 5 is kept rotating at a speed of 3-5 rpm, and the pulling speed is 0.1-1 mm / h, until the diameter of the crystal is expanded to 80 mm.

[0092] S5, Rotating shoulder: the seed rod 5 is kept rotating at a speed of 3-5 rpm and is pulled up at a speed of 3-5 mm / h until the diameter of the crystal is stabilized at 80 mm.

[0093] S6, Equal diameter growth: the seed rod 5 is kept rotating at a speed of 3-5 rpm and is stopped to be pulled up, the heating zone 13 is controlled to be cooled down at a rate of 0.1-2 ℃ / h, the melt is crystallized down until the crystal reaches 10 kg. Here, the cooling rate refers to that the upper heating assembly 4a, the middle heating assembly 4b and the lower heating assembly 4c are independently cooled down within the range, but need to be kept in the specified temperature gradient range synchronously.

[0094] S7, Tail contraction: the rotating speed of the seed rod 5 is increased to 5-8 rpm and the seed rod 5 is pulled up 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.

[0095] S8, Cooling down: the heating zone 13 is controlled to be cooled down at a uniform rate until room temperature, and the cooling time is 96 hours.

[0096] 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.

[0097] The crystal obtained in the experimental example is a bismuth germanate scintillation crystal with a diameter of 80 mm, which is complete without cracking, but there is an enrichment of inclusions at the bottom.

[0098] Experimental Example 2

[0099] The difference between the crystal growth device of the experimental example 1 and the experimental example 2 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 difference between the crystal growth method of the experimental example and the experimental example 1 is 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 obtained in the experimental example is a bismuth germanate scintillation crystal, the diameter of the crystal reaches 120 mm, the crystal is complete without cracking, colorless and transparent, there is no inclusion visible to the naked eye inside, and there is no light path when irradiated by a helium-neon laser pen.

[0100] Experimental Example 3

[0101] 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 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 0.5-2 K / cm, and the axial temperature gradient is 1.4-2 K / cm. The crystal grown in this experimental example is a bismuth germanate scintillation crystal, with a diameter of 200 mm. The crystal is complete and has no cracks, is colorless and transparent, has no visible inclusions inside, and has no light path when irradiated with a helium-neon laser pen.

[0102] Experimental Example 4

[0103] 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 0.5-2 K / cm, and the axial temperature gradient is 5-6 K / cm. The crystal grown in this experimental example is a bismuth germanate scintillation crystal, with a diameter of 120 mm. The crystal is cracked and has cracks on the surface.

[0104] Experimental Example 5

[0105] The difference between the crystal growth device of Experimental Example 1 is that the structure of the heating zone 13 is designed differently. As shown in FIG. 3, the heating zone 13 is provided with an upper heating assembly 4a and a lower heating assembly 4c from top to bottom. The area surrounded by the lower heating assembly 4c is a high-temperature zone 13c, and the area surrounded by the upper heating assembly 4a is a 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 assembly 4a is 6 cm, and the height difference between the lowest point of the crucible 3 and the lower heating assembly 4c is 6 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 0.5-2 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 is complete in shape, has bubbles and layered polycrystalline structures inside, has black inclusions at the bottom, and has a clear light path when irradiated with a helium-neon laser pen.

[0106] Experimental Example 6

[0107] The crystal growth device used in this experimental example 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 material is changed to bismuth silicate crystal raw material. In the temperature rising stage, the temperature control thermocouple of the middle heating zone 13b is set to be 5-10°C higher than 1030°C. 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 0.75-1.2 K / cm. In the isodiametric 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 100 mm. The crystal is complete without cracking. There are bubbles in the isodiametric part of the crystal, and there are inclusions enriched in the tailing part. There is no obvious light path under the irradiation of a helium-neon laser pen.

[0108] Experimental Example 7

[0109] The crystal growth device used in this experimental example 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 0.5-2 K / cm, and the axial temperature gradient is 1.3-2 K / cm. In the isodiametric 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 120 mm. The crystal is complete without cracking. There are no inclusions visible to the naked eye inside the crystal. There is no obvious light path under the irradiation of a helium-neon laser pen.

[0110] Experimental Example 8

[0111] The crystal growth device used in this experimental example is the same as that in experimental example 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 0.5-2 K / cm, and the axial temperature gradient is 3-4.5 K / cm. In the isodiametric 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 120 mm. The crystal has cracks, and there are multiple cracks from the shoulder to the isodiametric part.

[0112] Experimental Example 9

[0113] The crystal growth device used in this experimental example is the same as that in experimental example 1, and the difference is that this experimental example is used for the growth of yttrium calcium oxoborate crystals, which belong to borate system crystals. The specific steps are as follows:

[0114] S1, loading: load the prepared yttrium calcium oxoborate crystal raw material into the crucible 3, place the crucible 3 in the heating zone 13 of the furnace chamber 1, install the seed crystal on the seed crystal rod 5 and insert the seed crystal rod 5 into the crucible 3.

[0115] S2, temperature rising: rotate the seed crystal rod 5 at a speed of 3-5 rpm, heat the heating zone 13 until the raw material is completely melted into a melt, and then stop heating. Generally, the temperature control thermocouple of the middle heating zone 13b is set at 1520°C.

[0116] S3, seeding: control the seed rod 5 to descend, after the seed contacts the liquid surface of the melt, pull up the seed rod 5 until the diameter of the grown crystal reaches 10mm, the rotation speed of the seed rod 5 is 3-5rpm, and the pulling speed is 0.5-1mm / h.

[0117] S4, shoulder growth: the seed rod 5 keeps the rotation speed of 3-5rpm, and the upward pulling speed is 0.2-0.5mm / h, until the diameter of the crystal expands to 120mm.

[0118] S5, shoulder rotation: the seed rod 5 keeps the rotation speed of 3-5rpm, and the upward pulling speed is 0.5-0.8mm / h, until the diameter of the crystal stabilizes at 75mm.

[0119] S6, equal-diameter growth: keep the rotation speed of 3-5rpm of the seed rod 3, and stop pulling up the seed rod 5, control the heating area 13 to decrease at the rate of 5-8℃ / h, the melt crystallizes downward until the crystal reaches 4Kg.

[0120] S7, tail contraction: pull up the seed rod 5 at the speed of 3-5mm / h, so that the diameter of the crystal is reduced to a point.

[0121] S8, temperature decrease: control each area of the heating area 13 to decrease at a uniform rate until room temperature, and the temperature decrease time is 96 hours.

[0122] In steps S2-S7, the radial temperature gradient of the heating area 13 is 1-10K / cm, and the axial temperature gradient is 2-3K / cm.

[0123] The crystal obtained in the experimental example is a calcium yttrium oxoborate crystal with a diameter of 75mm, and the crystal is colorless and transparent without cracking, and there are bubbles visible to the naked eye in the equal-diameter part.

[0124] Experimental Example 10

[0125] The difference between the crystal growth device of the experimental example 9 and the crystal growth device of the experimental example 10 is that the position of the crucible 3 relative to the upper and lower parts of the heating area 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 8cm, and the height difference between the lowest point of the crucible 3 and the lowest point of the lower heating assembly 4c is 8cm. The crystal growth method of the experimental example is different from that of the experimental example 9 in that, in steps S2-S7, the radial temperature gradient of the heating area 13 is 1-10K / cm, and the axial temperature gradient is 4-5.5K / cm. The crystal obtained in the experimental example is a calcium yttrium oxoborate crystal with a diameter of 120mm, and the crystal is complete without cracking, and there are no inclusions visible to the naked eye in the interior, and the overall quality is good.

[0126] Experimental Example 11

[0127] The difference between 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 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 10 cm. The crystal growth method of the present 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 1-10 K / cm, and the axial temperature gradient is 6-7 K / cm. The crystal obtained in the present experimental example is a calcium yttrium oxoborate crystal with a diameter of 120 mm, and the crystal is complete without cracking. The equiaxial part has no visible inclusions, and after natural cooling and removal of the crystal, the crystal self-cracks at room temperature.

[0128] Experimental example 12

[0129] The difference between 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 the present 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 1-10 K / cm, and the axial temperature gradient is 7-8 K / cm. During the growth of the present embodiment, spiral twisting occurs, and after 2 times of remelting-shoulder removal-equiaxial growth, a complete crystal is not obtained.

[0130] Obviously, the above embodiments of the present application are only examples for clarity, and are not intended to limit the embodiments of the present application. Those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the scope of the present application. It is not necessary or possible to exhaust all embodiments here. Any modification, equivalent substitution and improvement within the spirit and principles of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method of crystal growth, characterized by, Multi-component crystals, which are binary and above binary oxides, are grown using a pure melt floating zone method.

2. The crystal growth method according to claim 1, wherein The crystal growth is performed in a heating zone (13); the heating zone (13) is provided with low-temperature, medium-temperature and high-temperature zones (13a, 13b and 13c) with independent temperature control in a vertical direction, 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), and a crucible (3) containing raw materials is located in the medium-temperature zone (13b).

3. The crystal growth method according to claim 1, wherein The method comprises the following steps: S1, charging: raw materials are charged into a crucible (3), the crucible (3) is placed in a heating zone (13) of a furnace chamber (1), a seed crystal is installed on a seed crystal rod (5) and the seed crystal rod (5) is inserted into the crucible (3); S2, heating: the heating zone (13) is controlled to heat until the raw materials are completely melted into a melt, and then the heating is stopped; S3, seeding: the seed crystal rod (5) is controlled to descend, and after the seed crystal contacts the liquid surface of the melt, the seed crystal rod (5) is pulled up until the diameter of the grown crystal reaches a first target diameter; S4, shoulder growth: the pulling speed of the seed crystal rod (5) is reduced so that the diameter of the crystal is expanded to a second target diameter; S5, shoulder turning: the pulling speed of the seed crystal rod (5) is increased so that the diameter of the crystal is stabilized at the second target diameter; S6, equal-diameter growth: the seed crystal rod (5) is stopped to be pulled up, the heating zone (13) is controlled to be cooled at a preset cooling rate, and the melt is crystallized downward until the crystal reaches a preset weight; S7, tail shrinking: the seed crystal rod (5) is pulled up so that the diameter of the crystal is reduced to a third target diameter; S8, cooling: the heating zone (13) is controlled to be cooled to room temperature.

4. The crystal growth method according to claim 3, wherein 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 rotating 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 the step S4, the pulling speed of the seed crystal rod (5) is 0.1-1 mm / h, the rotating 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 the step S5, the pulling speed of the seed crystal rod (5) is 1-3 mm / h, and the rotating speed of the seed crystal rod (5) is 3-5 rpm; In the step S6, the rotating speed of the seed crystal rod (5) is 3-5 rpm, and the preset cooling rate is 0.1-2 ℃ / h; In the step S7, the pulling speed of the seed crystal rod (5) is 3-5 mm / h, the rotating speed of the seed crystal rod (5) is 5-8 rpm, and the third target diameter is 0-20 mm; In the 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, wherein The multi-component crystal is a bismuth silicate crystal; In the step S3, the pulling speed of the seed rod (5) is 3-5 mm / h, the rotating speed of the seed 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 rotating 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 the step S5, the pulling speed of the seed rod (5) is 1-3 mm / h, and the rotating speed of the seed rod (5) is 3-5 rpm; In the step S6, the rotating speed of the seed rod (5) is 3-5 rpm, and the preset cooling rate is 0.1-1 ℃ / h; In the step S7, the pulling speed of the seed rod (5) is 3-5 mm / h, the rotating speed of the seed rod (5) is 5-8 rpm, and the third target diameter is 0-20 mm; In the 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, wherein The multi-component crystal is yttrium calcium oxiborate crystal; In the step S3, the pulling speed of the seed rod (5) is 0.5-1 mm / h, the rotating speed of the seed rod (5) is 3-5 rpm, and the first target diameter of the yttrium calcium oxiborate crystal is 8-12 mm; In the step S4, the pulling speed of the seed rod (5) is 0.2-0.5 mm / h, the rotating speed of the seed rod (5) is 3-5 rpm, and the second target diameter of the yttrium calcium oxiborate crystal is 100-130 mm; In the step S5, the pulling speed of the seed rod (5) is 0.5-0.8 mm / h, and the rotating speed of the seed rod (5) is 3-5 rpm; In the step S6, the rotating speed is 3-5 rpm, and the preset cooling rate is 5-8 ℃ / h; In the step S7, the pulling speed of the seed rod (5) is 3-5 mm / h, the rotating speed of the seed rod (5) is 5-8 rpm, and the third target diameter is 0-20 mm; In the 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.

7. A crystal growing apparatus, characterized by comprising: It comprises: a furnace chamber (1) comprising a furnace body (11) and a furnace cover (12), the furnace cover (12) sealing the top opening of the furnace body (11), the inside of the furnace body (11) being provided with a heating zone (13) surrounded by a heat preservation material; a bearing seat (2) and a crucible (3) both arranged in the heating zone (13), the crucible (3) being placed above the bearing seat (2); a seed rod (5) which can be lifted in the vertical direction and can be inserted into the heating zone (13) and extend into the crucible (3); the furnace cover (12) is provided with a viewing port (121), the heating zone (13) is provided with a first viewing hole, and the midpoints of the viewing port (121) and the first viewing hole are located on the same straight line; An air outlet pipe is arranged at a first installation opening (17) in the side wall of the furnace body (11) and used for vacuumizing the furnace chamber (1); An air inlet pipe is arranged at a second installation opening (18) in the side wall of the furnace body (11) and used for introducing gas into the furnace chamber (1); 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 an upper heating assembly (4a), a middle heating assembly (4b) and a lower heating assembly (4c) arranged in sequence from top to bottom, and the crucible (3) is located in a middle temperature zone (13b) surrounded by the middle heating assembly (4b).

8. The crystal growing apparatus of claim 7 wherein, The height difference between the highest point of the crucible (3) and the highest point of the upper heating assembly (4a) is greater than 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 greater than 8 cm.

9. The crystal growing apparatus of claim 7 wherein, The height difference between the highest point of the crucible (3) and the highest point of the upper heating assembly (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 assembly (4c) is greater than 8 cm and less than 12 cm.

10. The crystal growing apparatus according to any one of claims 7 to 9, wherein The observation window (121) is made of glass.

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