Horizontal directional crystallization furnace apparatus and crystal growth method

Abstract

The application provides a horizontally directional crystallization furnace device and a crystal growth method, wherein the device comprises a furnace body, a crucible, a thermal field system and a transmission system arranged in the furnace body, the thermal field system comprises a first heater, a second heater and a third heater, and a first heat insulation ring arranged between the first heater and the second heater and a second heat insulation ring arranged between the second heater and the third heater, the first heater, the second heater and the third heater are all composed of a plurality of heating bodies which are parallel and symmetrically distributed on both sides of the crucible; the first heater, the first heat insulation ring, the second heater, the second heat insulation ring and the third heater correspondingly form a preheating zone, a first gradient zone, a melting zone, a second gradient zone and an annealing cooling zone; the transmission system comprises a crucible platform for placing the crucible, a plurality of supporting rods, a moving platform and a moving module, the supporting rods support the crucible platform on the moving platform, and the moving module drives the moving platform to move the crucible in the furnace body.

Description

Technical Field

[0001] This invention relates to the field of crystal growth technology, specifically to a horizontally oriented crystallization furnace apparatus and a crystal growth method. Background Technology

[0002] The horizontal directional crystallization method combines the core advantages of directional solidification and horizontal zone melting. Through a unique temperature field design and melting zone control mechanism, it achieves the growth of large-size crystals with high purity, low defects, uniform doping, and controllable shape.

[0003] Existing horizontal directional crystallization furnaces employ long cylindrical annular or four-sided heating methods, resulting in high energy consumption, complex heating element structures, and a tendency for localized deformation of the moving guide rails, leading to unstable operation or even jamming, which in turn affects crystal growth quality. Specifically, in long cylindrical annular heating, heat is uniformly input along the circumference, and the axial gradient relies on the heat dissipation difference between the two ends of the furnace body. This gradient formation is slow and the adjustment range is narrow, easily leading to an "axial temperature flat zone" and blurring the solid-liquid interface. In four-sided heating, multiple heat sources easily cause heat superposition, and the axial gradient is easily interfered with by lateral heat sources, resulting in poor directionality and difficulty in maintaining a stable solid-liquid interface propagation direction. Furthermore, the heaters are often single heaters or dual heaters including a main heater and a rear heater, which can easily lead to localized overheating or incomplete melting of the melt. After crystal solidification, the lack of a dedicated annealing temperature zone prevents the release of residual stress, resulting in an extremely high risk of cracking.

[0004] In addition, the transmission structure in the existing technology occupies a large area, the crystal furnace is long in the length direction, which leads to amplified deflection and vibration problems. Furthermore, the crucible is in direct contact with the guide rail or support platform surface, which causes the bottom of the crystal to be undercooled and the thermal conductivity mismatch effect between the melt, crystal and crucible bottom to be aggravated, thus destroying the stability of the solid-liquid interface.

[0005] To address the aforementioned issues, there is an urgent need for a horizontal directional crystallization furnace device and crystal growth method that features high heating efficiency, stable temperature field, and excellent crystal quality. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a horizontal directional crystallization furnace apparatus and crystal growth method. By symmetrically distributing heating elements on both sides and dividing the temperature zones with a heat insulation ring, each heater can be independently controlled, and the crucible support structure can be improved, thus solving the problems of high energy consumption, unstable temperature field, and numerous crystal defects in existing technologies.

[0007] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0008] According to a first aspect of the present invention, a horizontal directional crystallization furnace apparatus is provided, comprising a furnace body, a crucible, a thermal field system, and a transmission system disposed within the furnace body. The thermal field system includes a first heater, a second heater, and a third heater, as well as a first heat insulation ring disposed between the first heater and the second heater, and a second heat insulation ring disposed between the second heater and the third heater. The first heater, the second heater, and the third heater are each composed of a plurality of heating elements arranged parallel and symmetrically on both sides of the crucible. The first heater, the first heat insulation ring, the second heater, the second heat insulation ring, and the third heater respectively form a preheating zone, a first gradient zone, a melting zone, a second gradient zone, and an annealing cooling zone.

[0009] The transmission system includes a crucible platform for placing the crucible, several support rods, a moving platform, and a moving module. The support rods support the crucible platform on the moving platform, and the moving module drives the moving platform to move the crucible within the furnace.

[0010] Preferably, the furnace body is connected to a water cooling system, a vacuum system, and a gas filling and releasing system. The water cooling system includes a circulating water cooling device to maintain the normal operation of the water-cooled electrodes and the furnace body. The vacuum system is used to create a vacuum environment inside the furnace body. The gas filling and releasing system can fill or release gas.

[0011] Preferably, the first heater, the second heater, and the third heater are each independently equipped with a temperature control thermocouple and a temperature measurement thermocouple, which enables independent heating, independent temperature measurement, and independent control of the preheating zone, the melting zone, and the annealing cooling zone.

[0012] Preferably, by adjusting the temperatures of the preheating zone, melting zone, and annealing cooling zone, as well as the thicknesses of the first and second heat insulation rings, the temperature gradient changes of the first and second gradient zones can be achieved.

[0013] Preferably, the furnace body is further provided with a U-shaped heat insulation layer, the inner and outer sides of which are made of carbon-carbon composite material, hexagonal boron nitride ceramic, mullite ceramic or alumina ceramic heat insulation screen, and the center of the heat insulation layer is carbon fiber heat insulation felt.

[0014] Preferably, the support rod is rod-shaped and arranged in a straight line or S-shape, and the support rod makes point contact with the bottom of the crucible platform.

[0015] Preferably, the moving module includes a guide rail and a ball screw, and is connected to the moving platform through a W-shaped support block. The moving module adjusts the moving speed through an external variable frequency motor, driving the moving platform to reciprocate along the guide rail.

[0016] Preferably, the mobile module is also equipped with a stainless steel dust cover and a mica heat insulation plate.

[0017] According to a second aspect of the present invention, a crystal growth method is provided, employing the horizontally oriented crystallization furnace apparatus as described above, the method comprising:

[0018] Step S1: Load the raw materials into the crucible, cover the crucible with the lid, place the crucible into the furnace, and close the furnace chamber; use the vacuum system to evacuate the vacuum degree in the furnace to below 10 Pa, turn on the thermal field system, and make the temperature of the preheating zone, melting zone and annealing cooling zone the same, within the range of 200-300ºC, and keep it at that temperature for 20 hours to remove the adsorbed water from the furnace insulation material, the adsorbed water from the raw materials and volatile impurities;

[0019] Step S2: Based on the melting point Tm (in °C) of different crystals, raise the temperature according to the preset temperature curve, set the preheating zone temperature to (0.6-0.9) Tm, and after the temperature stabilizes, hold for 20 hours to fully preheat the raw material, while controlling the interface between the raw material and the melt within the first gradient zone; set the melting zone temperature to Tm+ΔT, where ΔT≤200 °C, to ensure the raw material is completely melted in the melting zone; set the annealing cooling zone temperature to (0.5-0.8) Tm;

[0020] The first heat insulation ring between the preheating zone and the melting zone physically isolates the two temperature zones, forming a first temperature gradient zone within the first heat insulation ring interval. The second heat insulation ring between the melting zone and the annealing cooling zone physically isolates the two temperature zones, forming a second temperature gradient zone within the second heat insulation ring interval. The temperature gradient required for crystal growth is constructed within the second gradient zone.

[0021] Step S3: Using the moving module, move the crucible at a speed of 1-15 mm / h until the crystallization process is complete;

[0022] Step S4: After the crucible enters the annealing cooling zone, the raw material crystallization process ends, and the moving module is turned off; the annealing time is not less than 20 hours, and then the temperature is reduced to room temperature at a rate not exceeding 15ºC / h, the growth process ends, and crystals are obtained.

[0023] Preferably, in step S3, the crucible containing the raw material is moved horizontally, so that the crucible passes through the preheating zone, the first gradient zone, the melting zone, the second gradient zone, and the annealing cooling zone in sequence; the raw material exists in solid form in the preheating zone, and completes the transformation to the molten state in the first gradient zone; the raw material is in the molten state in the melting zone, and completes the transformation to the single crystal state in the second gradient zone, and during the crystal growth process, the solid-liquid interface between the raw material and the melt, and between the melt and the crystal, are located in the first gradient zone and the second gradient zone, respectively.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The horizontal directional crystallization furnace device and crystal growth method provided by the present invention adopts several heating elements that are parallel and symmetrically distributed on both sides of the crucible to form three independent heaters, which directly radiate heat to the crucible, resulting in high energy efficiency, convenient installation and debugging, and reduced influence of high temperature radiation on the moving guide rail; and a heat insulation ring is added between the three heaters on both sides of the crucible to divide the preheating zone, melting zone and annealing cooling zone. Each heater is equipped with an independent temperature control thermocouple and a temperature measuring thermocouple, that is, each temperature zone is independently heated, independently measured and independently controlled.

[0026] 2. The horizontal directional crystallization furnace device and crystal growth method provided by the present invention form a first gradient region and a second gradient region respectively by a first heat insulation ring and a second heat insulation ring. The presence of the heat insulation ring avoids heat crosstalk between different temperature zones. By precisely controlling the temperature of different temperature zones and adjusting the thickness of the heat insulation ring, the first gradient region and the second gradient region can be made to have different temperature gradients, thereby achieving precise control of the crystal growth process.

[0027] 3. The horizontal directional crystallization furnace device and crystal growth method provided by the present invention include a preheating zone for initially heating the crystallization raw material, a first gradient zone for isolating the preheating zone from the melting zone, a melting zone for providing the high-temperature environment required for complete melting of the crystallization raw material, a second gradient zone for forming a stable crystal growth temperature gradient, and an annealing cooling zone for slowly cooling and stress relief of the crystal.

[0028] 4. The horizontal directional crystallization furnace device and crystal growth method provided by the present invention adopt multi-point contact support rods to avoid surface contact between the crucible platform and the bottom moving platform, which can effectively reduce the heat conduction interference at the bottom of the crucible, thereby reducing melt convection disturbance and solid-liquid interface fluctuation caused by uneven heat conduction of the crucible, and ensuring the stability of the crystal growth interface.

[0029] 5. The horizontal directional crystallization furnace device and crystal growth method provided by the present invention adopt a moving module including a ball screw to replace the traditional servo motor driven push rod, crystal pulling rod or seed crystal rod transmission method. Precision speed regulation is achieved through an external variable frequency motor, realizing the linear reciprocating motion of the moving platform, improving the stability and accuracy of crucible movement, and effectively solving the problems of easy deformation and unstable operation of existing moving supports in high temperature environment and large footprint. Attached Figure Description

[0030] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0031] Figure 1 This is a schematic diagram of the horizontal directional crystallization furnace apparatus in Example 1;

[0032] Figure 2This is a side view of the horizontal directional crystallization furnace apparatus in Example 1;

[0033] Figure 3 This is a diagram showing the internal structure of the horizontal directional crystallization furnace apparatus in Example 1;

[0034] Figure 4 This is a structural diagram of the transmission system of the horizontal directional crystallization furnace device in Example 1;

[0035] Figure 5 This is a structural diagram of the moving module of the horizontal directional crystallization furnace device in Example 1;

[0036] Figure 6 This is a structural diagram of the thermal field system of the horizontal directional crystallization furnace apparatus in Example 1;

[0037] Explanation of reference numerals in the attached figures:

[0038] 1-Furnace body; 11-U-shaped insulation layer;

[0039] 2-Crucible;

[0040] 3-Thermal field system; 31-First heater; 32-Second heater; 33-Third heater; 34-First insulation ring; 35-Second insulation ring; 36-Temperature control thermocouple; 37-Temperature measuring thermocouple; 38-Heating element;

[0041] 4-Transmission system; 41-Crucible platform; 42-Support rod; 43-Moving platform; 44-Moving module; 45-Guide rail; 46-Ball screw; 47-W-type support block;

[0042] 5-Water cooling system;

[0043] 6-Vacuum system;

[0044] 7-Inflation / Depression System. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0047] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, all directional indications (such as up, down, left, right, front, back, bottom, etc.) in this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indication will also change accordingly. Furthermore, descriptions involving "first," "second," etc., in this application are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0048] Example 1

[0049] like Figure 1-6 As shown, this embodiment provides a horizontal directional crystallization furnace apparatus, including a furnace body, a crucible, a heating system, and a transmission system disposed within the furnace body. The furnace body is supported by a furnace body support frame and also includes a furnace shell and a furnace chamber within the shell. An upper furnace door is provided at the top of the furnace body, with a furnace door at the opening. The furnace body is externally connected to a water cooling system, a vacuum system, and a gas filling / expanding system. The water cooling system includes a circulating water cooling device to maintain the normal operation of the water-cooled electrodes and the furnace body. The vacuum system is used to create a vacuum environment within the furnace body, and the gas filling / expanding system can fill or release inert gases.

[0050] The thermal field system includes a first heater, a second heater, and a third heater, as well as a first heat insulation ring disposed between the first and second heaters, and a second heat insulation ring disposed between the second and third heaters. During crystal growth, the three heaters directly radiate heat to the crucible, and each heater consists of several heating elements arranged parallel and symmetrically on both sides of the crucible. The first heater, the first heat insulation ring, the second heater, the second heat insulation ring, and the third heater respectively form the preheating zone, the first gradient zone, the melting zone, the second gradient zone, and the annealing cooling zone. The presence of the heat insulation rings prevents heat crosstalk between the different temperature zones. The first heater, the second heater, and the third heater are each independently equipped with a temperature-controlling thermocouple and a temperature-measuring thermocouple, enabling independent heating, independent temperature measurement, and independent control of the preheating zone, the melting zone, and the annealing cooling zone.

[0051] Specifically, a first heat-insulating ring between the preheating zone and the melting zone physically isolates the two temperature zones, limiting the axial heat conduction path through thermal barrier, thus forming a first gradient zone within the first heat-insulating ring section. Similarly, a second heat-insulating ring between the melting zone and the annealing cooling zone physically isolates the two temperature zones, limiting the axial heat conduction path through thermal barrier, thus forming a second gradient zone within the second heat-insulating ring section. Different temperature gradients can be controlled by adjusting the temperatures of the temperature zones on both sides of the heat-insulating ring and changing the thickness of the heat-insulating ring. For example, if the preheating zone temperature is 500℃, the melting zone temperature is 800℃, and the first heat-insulating ring thickness is 50mm, then the theoretical linear gradient is (800-500) / 50 = 6℃ / mm. If the second heat-insulating ring thickness is 100mm and the annealing zone temperature is 400℃, then the temperature gradient of the second gradient zone is (800-400) / 100 = 4℃ / mm.

[0052] The transmission system includes a crucible platform for placing the crucible, several support rods, a moving platform, and a moving module. The support rods support the crucible platform on the moving platform, and the moving module drives the moving platform to move the crucible within the furnace. The support rods are rod-shaped and arranged in a straight line or S-shape. The support rods make point contact with the bottom of the crucible platform, avoiding surface contact between the crucible platform and the moving platform, thereby reducing the downward conduction of heat from the bottom of the crucible.

[0053] The moving module includes guide rails and ball screws, and is connected to the moving platform via W-shaped support blocks. The moving module adjusts its speed via an external variable frequency motor, driving the moving platform to reciprocate along the guide rails. The platform's moving speed ranges from 0.1mm / h to 7200mm / h, allowing precise control of the crucible's step distance and position. It enables complex motion modes such as uniform speed movement, segmented speed changes, and fixed-point stops, accurately adapting to the crystal growth movement requirements at each stage of melting, growth, and annealing. Located at the bottom of the crucible, the moving module replaces the traditional servo motor-driven push rod, crystal puller, and seed crystal rod transmission traction method, reducing the equipment length and improving the stability and accuracy of crucible movement. Movement of several meters can be achieved through ball screw splicing or the selection of long ball screws, and the guiding effect of the guide rails effectively suppresses the deflection deformation of long screws.

[0054] The mobile module is also equipped with a stainless steel dust cover, which can isolate the high-temperature radiation, raw material dust and corrosive atmosphere inside the furnace. The stainless steel dust cover is lined with a 5mm thick mica sheet, which can reflect the heat of the temperature field back, reduce heat loss of the temperature field, and prevent the temperature of the mobile module from becoming too high, thus protecting the module.

[0055] The horizontal directional crystallization furnace apparatus provided in this embodiment can achieve temperature gradient changes in the first gradient region and the second gradient region by adjusting the temperatures of the preheating zone, the melting zone and the annealing cooling zone, as well as the thicknesses of the first heat insulation ring and the second heat insulation ring, thereby achieving precise control of the crystal growth process.

[0056] The horizontal directional crystallization furnace apparatus provided in this embodiment also includes a U-shaped insulation layer inside the furnace. This insulation layer employs a "sandwich" structure, with 5-10mm thick heat shields on both the inner and outer sides. These heat shields are made of carbon-carbon composite materials, hexagonal boron nitride ceramics, mullite ceramics, or alumina ceramics. The center of the insulation layer uses inexpensive carbon fiber insulation felt with lower thermal conductivity, effectively isolating heat transfer, increasing insulation performance, and reducing energy consumption. The interior of the insulation layer forms a space for placing the crucible and a moving platform, with a narrow opening at the bottom allowing for linear movement of the moving platform.

[0057] The horizontal directional crystallization furnace device provided in this embodiment employs several heating elements arranged parallel and symmetrically on both sides of the crucible to form three independent heaters, directly radiating heat to the crucible. This results in high energy efficiency, convenient installation and debugging, and reduced impact of high-temperature radiation on the moving guide rail. A heat insulation ring is added between the three heaters on both sides of the crucible to divide the area into a preheating zone, a melting zone, and an annealing cooling zone. Each heater is equipped with an independent temperature-controlling thermocouple and a temperature-measuring thermocouple, meaning each temperature zone is independently heated, measured, and controlled. The first and second heat insulation rings form the first and second gradient zones, respectively. The presence of the heat insulation rings prevents heat crosstalk between temperature zones. Through precise temperature control of different temperature zones and adjustment of the thickness of the heat insulation rings, different temperature gradients can be achieved between the first and second gradient zones, thereby enabling precise control of the crystal growth process. The preheating zone is used for preliminary heating of the crystallization raw materials. The temperature gradient zone isolates the preheating zone from the melting zone, while the melting zone provides the high-temperature environment required for complete crystallization of the raw material. The second gradient zone forms a stable crystal growth temperature gradient, and the annealing cooling zone achieves slow cooling and stress relief of the crystal. Simultaneously, multi-point contact support rods are used to avoid surface contact between the crucible platform and the bottom moving platform, effectively reducing heat conduction interference at the bottom of the crucible. This reduces melt convection disturbances and solid-liquid interface fluctuations caused by uneven crucible heat conduction, ensuring the stability of the crystal growth interface. Furthermore, a moving module including a ball screw replaces the traditional servo motor-driven push rod, crystal puller, or seed crystal rod transmission method. Precise speed regulation is achieved through an external frequency converter motor, realizing linear reciprocating motion of the moving platform. This improves the stability and accuracy of crucible movement and effectively solves the problems of deformation, unstable operation, and large footprint of existing moving supports under high-temperature environments.

[0058] Example 2

[0059] This embodiment provides a crystal growth method using the horizontally oriented crystallization furnace apparatus as described in Embodiment 1. The method includes:

[0060] Step S1: Load the raw materials into the crucible, cover the crucible with the lid, place the crucible into the furnace, and close the furnace chamber; use the vacuum system to evacuate the vacuum degree in the furnace to below 10 Pa, turn on the thermal field system, and make the temperature of the preheating zone, melting zone and annealing cooling zone the same, within the range of 200-300ºC, and keep it at that temperature for 20 hours to remove the adsorbed water from the furnace insulation material, the adsorbed water from the raw materials and volatile impurities;

[0061] Step S2: Based on the melting point Tm (in °C) of different crystals, raise the temperature according to the preset temperature curve. Set the preheating zone temperature to (0.6-0.9)Tm. After the temperature stabilizes, keep it at that temperature for 20 hours to fully preheat the raw material. At the same time, control the interface between the raw material and the melt within the first gradient zone. Set the melting zone temperature to Tm+ΔT, where ΔT≤200 °C, so that the raw material is completely melted in the melting zone. Set the annealing cooling zone temperature to (0.5-0.8)Tm. The first heat insulation ring between the preheating zone and the melting zone physically isolates the two temperature zones, forming the first temperature gradient zone between the first heat insulation rings. The second heat insulation ring between the melting zone and the annealing cooling zone physically isolates the two temperature zones, forming the second temperature gradient zone between the second heat insulation rings. Construct the temperature gradient required for crystal growth within the second gradient zone.

[0062] Step S3: Using the moving module, move the crucible at a speed of 3-15 mm / h until the crystallization process is complete;

[0063] Step S4: After the crucible enters the annealing cooling zone, the raw material crystallization process ends, and the moving module is turned off; the annealing time is not less than 20 hours, and then the temperature is reduced to room temperature at a rate not exceeding 15ºC / h, the growth process ends, and crystals are obtained.

[0064] Example 3

[0065] This embodiment details the crystal growth process to aid in further understanding of the invention. This embodiment employs the horizontal directional crystallization furnace apparatus described in Embodiment 1 and the crystal growth method described in Embodiment 2. Tl-doped NaI (Tm=651℃) powder is loaded into a graphite boat-shaped crucible with equal width dimensions of 250mm×100mm×100mm and a shoulder angle, and the crucible is covered with a graphite crucible cover. The crucible is then placed in a horizontal growth furnace, and the furnace chamber is closed. The vacuum pump is turned on, and the vacuum level inside the furnace is evacuated to 0.1Pa. The heating power is turned on, and the preheating zone, melting zone, and annealing cooling zone are maintained at 300℃ for 20 hours. After the holding period, the temperature is further increased: the preheating zone temperature is 500ºC, the melting zone temperature is 700ºC, and the annealing cooling zone temperature is 350ºC, with a heating time of 10 hours. After the temperature stabilizes, it is held for another 20 hours until the temperature field stabilizes. The crucible moving mechanism is then activated. The crucible was moved at a speed of 5 mm / h. The entire raw material crystallization process ended when the end of the crucible entered the annealing cooling zone. The moving mechanism was then shut off. The crucible was annealed in the annealing cooling zone for 20 hours, and then slowly cooled to room temperature at a rate of 15ºC / h. The growth process was completed, yielding a pristine boat-shaped crystal. This crystal was then processed to obtain a 1L (200mm × 100mm × 50mm) plate-shaped Tl-doped NaI crystal. Scintillation performance testing showed excellent energy resolution, as shown in Table 1.

[0066] Table 1. Energy resolution test results of NaI(Tl) crystals prepared in Example 1

[0067] <![CDATA[ 137 Cs source location]]> Energy resolution Horizontal: 50 mm; Height: 0 mm 7.88% Horizontal: 100 mm; Height: 0 mm 7.01% Horizontal: 150 mm; Height: 0 mm 6.82% Horizontal: 100 mm; Height: 600 mm 7.82%

[0068] Example 4

[0069] This embodiment details the crystal growth process to aid in further understanding of the invention. This embodiment employs the horizontal directional crystallization furnace apparatus described in Embodiment 1 and the crystal growth method described in Embodiment 2. BaF2 (Tm=1280℃) raw material is placed in a crucible, covered, and then placed in a horizontal growth furnace, which is then closed. The vacuum pump is turned on, and the vacuum level inside the furnace is evacuated to 0.01 Pa. The heating power is turned on, and the temperatures of the preheating zone, melting zone, and annealing cooling zone are maintained at 500℃ for 20 hours. After the holding period, the preheating zone temperature is increased to 1150℃, the melting zone temperature to 1400℃, and the annealing cooling zone temperature to 1000℃, with a heating time of 15 hours. After the temperature stabilizes, it is held for another 20 hours. The crucible moving mechanism is then activated, allowing the crucible to move at a speed of 5 mm / h until the crystallization process is complete. After the crucible enters the annealing cooling zone at the end, the raw material crystallization process ends, and the crucible moving mechanism is shut off; the annealing time is 20h, and then it is cooled to room temperature at a rate of 15℃ / h, the growth process ends, and crystals are obtained.

[0070] Example 5

[0071] This embodiment details the crystal growth process to aid in further understanding of the invention. This embodiment employs the horizontal directional crystallization furnace apparatus described in Embodiment 1 and the crystal growth method described in Embodiment 2. CeBr3 (Tm=730℃) raw material is placed in a crucible, covered, and then placed in a horizontal growth furnace, which is then closed. A vacuum pump is turned on to evacuate the furnace to 0.1 Pa. The heating power is turned on, and the temperatures of the preheating zone, melting zone, and annealing cooling zone are maintained at 300℃ for 20 hours. After the holding period, the preheating zone temperature is increased to 650℃, the melting zone temperature to 830℃, and the annealing cooling zone temperature to 550℃ for 10 hours. After the temperature stabilizes, it is held for another 20 hours. A first temperature gradient zone naturally forms between the preheating zone and the melting zone, and a second temperature gradient zone naturally forms between the melting zone and the annealing cooling zone. The crucible moving mechanism is activated, allowing the crucible to move at a speed of 3 mm / h until the crystallization process is complete. After the crucible enters the annealing cooling zone at the end, the raw material crystallization process ends, and the crucible moving mechanism is shut off; the annealing time is 20h, and then it is cooled to room temperature at a rate of 10℃ / h, the growth process ends, and crystals are obtained.

[0072] Example 6

[0073] This embodiment details the crystal growth process to aid in further understanding of the invention. This embodiment employs the horizontal directional crystallization furnace apparatus described in Embodiment 1 and the crystal growth method described in Embodiment 2. CsI (Tm=621℃) raw material is placed in a crucible, covered, and then placed in the horizontal growth furnace, which is then closed. The vacuum pump is turned on, and the vacuum level inside the furnace is evacuated to 0.1 Pa. The heating power is turned on, and the temperatures of the preheating zone, melting zone, and annealing cooling zone are maintained at 200℃ for 20 hours. After the holding period, the preheating zone temperature is increased to 500℃, the melting zone temperature to 750℃, and the annealing cooling zone temperature to 400℃, with a heating time of 10 hours. After the temperature stabilizes, it is held for another 20 hours. A first temperature gradient zone naturally forms between the preheating zone and the melting zone, and a second temperature gradient zone naturally forms between the melting zone and the annealing cooling zone. The crucible moving mechanism is activated, allowing the crucible to move at a speed of 3 mm / h until the crystallization process is complete. After the crucible enters the annealing cooling zone at the end, the raw material crystallization process ends, and the crucible moving mechanism is shut off; the annealing time is 20h, and then it is cooled to room temperature at a rate of 15℃ / h, the growth process ends, and crystals are obtained.

[0074] The specific embodiments of the present invention have been described above. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of the present invention.

Claims

1. A horizontal directional crystallization furnace apparatus, characterized in that, The system includes a furnace body, within which a crucible, a heating system, and a transmission system are disposed. The heating system includes a first heater, a second heater, and a third heater, as well as a first heat insulation ring disposed between the first and second heaters, and a second heat insulation ring disposed between the second and third heaters. Each of the first, second, and third heaters consists of several heating elements arranged parallel and symmetrically on both sides of the crucible. The first heater, first heat insulation ring, second heater, second heat insulation ring, and third heater respectively form a preheating zone, a first gradient zone, a melting zone, a second gradient zone, and an annealing cooling zone. The transmission system includes a crucible platform for placing the crucible, several support rods, a moving platform, and a moving module. The support rods support the crucible platform on the moving platform, and the moving module drives the moving platform to move the crucible within the furnace.

2. The horizontal directional crystallization furnace apparatus according to claim 1, characterized in that, The furnace body is externally connected to a water cooling system, a vacuum system, and a gas filling and releasing system. The water cooling system includes a circulating water cooling device to maintain the normal operation of the water-cooled electrodes and the furnace body. The vacuum system is used to create a vacuum environment inside the furnace body. The gas filling and releasing system can fill or release gas.

3. The horizontal directional crystallization furnace apparatus according to claim 1, characterized in that, The first heater, the second heater, and the third heater are each independently equipped with a temperature control thermocouple and a temperature measurement thermocouple, which enables independent heating, independent temperature measurement, and independent control of the preheating zone, the melting zone, and the annealing cooling zone.

4. The horizontal directional crystallization furnace apparatus according to claim 1, characterized in that, By adjusting the temperatures of the preheating zone, melting zone, and annealing cooling zone, as well as the thicknesses of the first and second heat insulation rings, temperature gradient changes in the first and second gradient zones can be achieved.

5. The horizontal directional crystallization furnace apparatus according to claim 1, characterized in that, The furnace body is also provided with a U-shaped heat insulation layer. The inner and outer sides of the heat insulation layer are made of carbon-carbon composite material, hexagonal boron nitride ceramic, mullite ceramic or alumina ceramic heat insulation screen, and the center of the heat insulation layer is carbon fiber heat insulation felt.

6. The horizontal directional crystallization furnace apparatus according to claim 1, characterized in that, The support rod is rod-shaped and arranged in a straight line or S-shape, and the support rod makes point contact with the bottom of the crucible platform.

7. The horizontal directional crystallization furnace apparatus according to claim 1, characterized in that, The moving module includes a guide rail and a ball screw, and is connected to the moving platform through a W-shaped support block. The moving module adjusts the moving speed through an external variable frequency motor, driving the moving platform to reciprocate along the guide rail.

8. The horizontal directional crystallization furnace apparatus according to claim 1, characterized in that, The mobile module is also equipped with a stainless steel dust cover and a mica heat insulation plate.

9. A crystal growth method, characterized in that, The method, employing the horizontal directional crystallization furnace apparatus as described in any one of claims 1-8, comprises: Step S1: Load the raw materials into the crucible, cover the crucible with the lid, place the crucible into the furnace, and close the furnace chamber; use the vacuum system to evacuate the vacuum degree in the furnace to below 10 Pa, turn on the thermal field system, and make the temperature of the preheating zone, melting zone and annealing cooling zone the same, within the range of 200-300ºC, and keep it at that temperature for 20 hours to remove the adsorbed water from the furnace insulation material, the adsorbed water from the raw materials and volatile impurities; Step S2: Based on the melting point Tm of different crystals, raise the temperature according to the preset temperature curve, set the preheating zone temperature to (0.6-0.9)Tm, and after the temperature stabilizes, hold for 20 hours to fully preheat the raw material, while controlling the interface between the raw material and the melt within the first gradient zone; set the melting zone temperature to Tm+ΔT, where ΔT≤200℃, to ensure the raw material is completely melted in the melting zone; set the annealing cooling zone temperature to (0.5-0.8)Tm; The first heat insulation ring between the preheating zone and the melting zone physically isolates the two temperature zones, forming a first temperature gradient zone within the first heat insulation ring interval. The second heat insulation ring between the melting zone and the annealing cooling zone physically isolates the two temperature zones, forming a second temperature gradient zone within the second heat insulation ring interval. The temperature gradient required for crystal growth is constructed within the second gradient zone. Step S3: Using the moving module, move the crucible at a speed of 1-15 mm / h until the crystallization process is complete; Step S4: After the crucible enters the annealing cooling zone, the raw material crystallization process ends, and the moving module is turned off; the annealing time is not less than 20 hours, and then the temperature is reduced to room temperature at a rate not exceeding 15ºC / h, the growth process ends, and crystals are obtained.

10. The crystal growth method according to claim 9, characterized in that, In step S3, the crucible containing the raw material is moved horizontally, so that the crucible passes through the preheating zone, the first gradient zone, the melting zone, the second gradient zone, and the annealing cooling zone in sequence. The raw material exists in solid form in the preheating zone and completes the transformation to the molten state in the first gradient zone. The raw material is in the molten state in the melting zone and completes the transformation to the single crystal state in the second gradient zone. During the crystal growth process, the solid-liquid interface between the raw material and the melt, and between the melt and the crystal, are located in the first gradient zone and the second gradient zone, respectively.

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