Hydrothermal flipper for crystal growth and method for crystal growth

Abstract

The application belongs to the technical field of crystal material preparation equipment. A hydrothermal overturning device for crystal growth and a crystal growth method are provided. The device comprises a rack, a reaction kettle assembly, an electric heating furnace, an overturning mechanism, a locking mechanism and a control box. The reaction kettle assembly is rigidly connected with the electric heating furnace through an overturning shaft and is supported by a bearing seat on the rack. The electric heating furnace is divided into an upper heating section and a lower heating section with independent temperature control along the axial direction. The overturning mechanism drives the whole to overturn, and the locking mechanism realizes reliable locking at multiple angles through a locking disc and a locking pin. A seed clamping frame and a nutrient container are arranged in the reaction kettle. During use, a saturated solution is first established in the upright position, and then the whole is overturned by 180 degrees, so that the seed crystal is located in the lower mother liquor zone and the nutrient material is located in the upper condensation zone. Self-driven reflux is formed by using the inverse solubility characteristics to realize crystal growth. The whole kettle overturning is safe and reliable, the temperature field and the space structure are adapted to the reflux process, the experimental reproducibility is good, the structure is compact and convenient to move and maintain, and it is suitable for laboratories and pilot platforms.

Description

Technical Field

[0001] This invention relates to the field of crystal material preparation equipment technology, and in particular to a hydrothermal reversing device and crystal growth method for crystal growth. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Crystals exhibiting reverse solubility characteristics show decreased solubility with increasing temperature, making hydrothermal growth suitable. To obtain high-quality, large-size single crystals, it is typically necessary to arrange nutrients and seed crystals in different regions within a reactor under specific temperature and pressure conditions. Stable material transport channels are established through solvent evaporation, condensation, and reflux, achieving a "dissolution above, growth below" growth pattern. Existing reflux hydrothermal methods often rely on small-volume autoclaves, adjusting the solution flow direction by manually rotating the vessel or altering the external temperature field. While this structure can meet experimental needs at smaller volumes, direct handling or rotation poses significant safety hazards when the reactor's effective volume reaches several liters and includes an external electric heater and insulation layer. The main problems include: The large overall mass of the vessel makes it difficult for operators to stably control its rotation; the reactor is usually rigidly connected to external pipelines and cables, which can easily lead to hose entanglement, cable pulling, or loosening of interfaces during rotation; conventional high-pressure reactors are mostly installed in a fixed position and lack reliable rotation and locking mechanisms; the heating furnace is generally temperature controlled as a whole, making it difficult to form a stable and adjustable temperature gradient inside the vessel, which is not conducive to maintaining long-term reflux conditions. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing large-volume hydrothermal crystal growth devices, such as difficulty in overall rotation, difficulty in controlling the reflux temperature field, and fixed spatial positions of seed crystals and nutrients. It provides a hydrothermal rotation device and crystal growth method for crystal growth, which is simple in structure, safe and reliable, and can rotate smoothly as a whole. This allows the reactor with heating furnace and insulation layer to easily switch postures even under high temperature and high pressure operating conditions. At the same time, it forms an adjustable axial temperature gradient in the reactor, which meets the needs of industrial or scale-up experiments of inverse solubility crystals.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a hydrothermal reversing device for crystal growth.

[0006] A hydrothermal reversing apparatus for crystal growth includes: The frame has a first bearing housing and a second bearing housing arranged coaxially. The reactor assembly includes a cylindrical body, an upper flat cover, and a lower end cap. The reactor assembly is fixedly connected to the tilting shaft via a tilting sleeve set on the cylindrical body, so that the axis of the reactor assembly is coaxial with the tilting shaft and is supported by a first bearing seat and a second bearing seat, and can rotate around the tilting shaft. The electric heating furnace is wrapped around the outer periphery of the reactor cylinder and fixedly connected to the tilting shaft. It tilts synchronously with the reactor components. The electric heating furnace is divided into an upper heating section and a lower heating section that are independently controlled along the axial direction. The tilting mechanism includes an operating handle fixedly connected to the tilting shaft, used to drive the reactor assembly and the electric heating furnace to rotate around the tilting shaft; The locking mechanism includes a locking disc fixed on the tilting shaft and a locking pin set on the frame. The circumference of the locking disc is provided with locking holes corresponding to different tilting angles. The locking pin can be inserted into any locking hole to lock the reactor assembly at a predetermined angle. The control box is electrically connected to the heating elements and temperature sensors of the upper and lower heating sections, and is used to independently control the temperature of the upper and lower heating sections. Inside the reactor assembly, a seed crystal holder and a nutrient container are arranged axially. The seed crystal holder and the nutrient container are arranged at intervals. When the reactor assembly is in the first flip position, the seed crystal holder is located in the upper region of the reactor and the nutrient container is located in the lower region. When the reactor assembly is flipped 180° around the flip axis to the second flip position, the seed crystal holder is located in the lower region of the reactor and the nutrient container is located in the upper region.

[0007] In one implementation of the first aspect of the present invention, the electric heating furnace is provided with an insulation layer and a metal shell, and the upper heating section and the lower heating section are respectively provided with independent heating elements and temperature sensors, and are respectively controlled by PID program through a control box.

[0008] In one implementation of the first aspect of the present invention, the tilting shaft is mounted in a bearing housing via a rolling bearing, a locking disc is fixed to one end of the tilting shaft, the locking hole includes at least two position holes corresponding to 0° and 180°, and the bottom of the frame is provided with at least three casters with braking mechanisms.

[0009] In one implementation of the first aspect of the present invention, the nutrient container is made of an inert material, and the sidewalls and bottom of the nutrient container are provided with several through holes.

[0010] In one implementation of the first aspect of the present invention, the seed crystal holder is installed on the inner side of the upper flat cover and can be detachably fixed with one or more seed crystals; the volume of the working solution in the reactor is controlled to be 50% to 60% of the total volume of the reactor cavity.

[0011] In one implementation of the first aspect of the present invention, the control box is connected to a pressure sensor installed on the reactor assembly for displaying and recording the pressure inside the reactor, and has working time display and over-temperature and over-pressure alarm functions.

[0012] In one implementation of the first aspect of the present invention, the temperature settings of the upper heating section and the lower heating section are such that an upper condensation zone and a lower mother liquor zone are formed during crystal growth, and the temperature difference between the upper heating section and the lower heating section is adjustable to a range greater than or equal to 10°C.

[0013] Secondly, the present invention provides a method for crystal growth.

[0014] A method for crystal growth, utilizing a hydrothermal inversion apparatus for crystal growth according to the first aspect of the present invention, includes the following processes: The reactor assembly is locked in the first flip position by a locking mechanism, so that the seed crystal holder is located in the upper region of the reactor and the nutrient container is located in the lower region. Hydrothermal solution is added to the reactor and solid nutrient is filled in. The upper heating section and the lower heating section are heated by the control box so that the solution reaches the saturation of the nutrient at a predetermined temperature. Stop heating, wait for the reactor to cool down, install the seed wafer on the seed wafer holder and reseal the reactor, release the locking mechanism, drive the flipping shaft through the flipping mechanism to flip the reactor assembly 180° around the flipping shaft to the second flipping position, and lock the reactor assembly through the locking mechanism; During the crystal growth stage, the temperatures of the upper heating section and the lower heating section are set separately by the control box, so that the upper region forms a condensation zone and the lower region forms a mother liquor zone. The condensate flows into the nutrient container to dissolve the nutrients and then falls back into the mother liquor zone, thus realizing crystal growth on the seed crystal. After growth is complete, the upper and lower heating sections are gradually cooled by controlling the control box. Once the pressure inside the reactor drops to a safe value, the pressure is released and the crystal product is removed.

[0015] In one implementation of the second aspect of the present invention, the hydrothermal solution is an acidic hydrothermal solution, and the crystal growth temperature and pressure are set according to the reverse solubility characteristics of the target crystal, which are high temperature and high pressure conditions in the range of tens to hundreds of degrees Celsius and several megapascals.

[0016] In one implementation of the second aspect of the present invention, during the crystal growth stage, the temperature difference between the upper heating section and the lower heating section is maintained within a predetermined range, and the growth time is controlled by a control box using programmed heating or constant temperature methods to be several days to several weeks. In the first flip position, the upper and lower heating sections of the electric heating furnace are controlled by the control box to heat the hydrothermal solution and nutrients in the reactor until the solution reaches saturation; The reactor assembly is rotated 180° to the second rotation position by a flipping mechanism that drives the flipping shaft, and then locked by a locking mechanism. In the second flip position, the temperature of the upper heating section and the lower heating section are independently controlled by the control box, so that a condensation zone is formed in the upper part of the reactor and a mother liquor zone is formed in the lower part. The condensate dissolves the nutrients in the nutrient container and then flows back to the area where the seed crystal holder is located to achieve crystal growth. After growth is complete, the temperature is controlled by the control box, the locking mechanism is released, and the crystal is removed.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention fundamentally solves the significant safety hazards associated with the traditional operation of heavy, high-temperature, and high-pressure equipment by rigidly connecting the reactor assembly, electric heating furnace, and insulation layer as a single unit to a tilting shaft, with stable support provided by high-precision bearing seats on the frame. The tilting action is driven by an operating handle, ensuring a smooth and controllable process and avoiding the risks of broken connecting pipes, seal failure, or burns caused by violent shaking. Crucially, the locking mechanism employs a purely mechanical locking disc and pin combination structure. When the reactor assembly is tilted to a predetermined position such as zero or 180 degrees, the operator simply inserts the pin into the corresponding locking hole on the locking disc to achieve absolutely reliable rigid locking. This locking method does not rely on electricity or pneumatics and remains effective even under extreme conditions, ensuring the reactor remains perfectly still during weeks of high-temperature, high-pressure operation. The entire flipping and locking process is simple, intuitive, and reliable, enabling even large-capacity (e.g., 5 liters) hydrothermal reactors with external auxiliary equipment to safely and conveniently switch positions as if operating a small instrument, greatly improving the safety and feasibility of experimental operations.

[0018] The core advantage of this device lies in its unique "segmented temperature control + physical flipping" synergistic mechanism. The electric heating furnace is clearly divided into an upper heating section and a lower heating section along the axial direction of the reactor. These two sections are controlled independently via a control box, allowing for complete temperature setting and closed-loop control, precisely creating a stable axial temperature gradient within the reactor. Furthermore, a flipping mechanism rotates the entire reactor 180 degrees, cleverly achieving spatial interchange between the seed crystal holder and the nutrient container. During the crystal growth stage, the upper region can be designated as a low-temperature condensation zone, and the lower region as a high-temperature mother liquor zone. After the condensate drips into the upper nutrient container to dissolve the nutrients, it naturally flows back to the seed crystal surface due to gravity. For crystals with reverse solubility characteristics, the high-temperature mother liquor region is precisely the ideal location for supersaturated precipitation, perfectly aligning with the "upper dissolution, lower growth" reflux growth mechanism. This self-driven convection mass transfer mode, guaranteed by hardware structure, is not only highly efficient but also has a stable flow field. It can effectively suppress stray nucleation and significantly improve the integrity, uniformity, and size of the obtained crystals. It is particularly suitable for the high-quality preparation of important functional crystals such as quartz and aluminum phosphate.

[0019] This invention ensures extremely high process reproducibility through a standardized and mechanically controlled design. The reactor assembly uses a uniformly sized high-pressure vessel (e.g., 5L), with its internal geometry and the relative positions of the seed crystal holder and nutrient container strictly fixed. The flipping posture for each experiment is not determined by the operator's visual inspection or experience, but is rigidly constrained by precisely machined locking holes on the locking plate, ensuring absolute consistency in installation regardless of whether the position is zero or 180 degrees. Simultaneously, the independent temperature control systems for the upper and lower heating sections accurately reproduce the preset temperature curves and temperature differences (e.g., ≥10℃). This high degree of repeatability at the hardware level means that the initial conditions, temperature field distribution, and fluid dynamics environment of each experiment are almost identical, resulting in highly comparable and reliable experimental results. This lays a solid foundation for systematically optimizing growth parameters (such as temperature, temperature difference, and growth time). More importantly, the design concept has good scalability. When it is necessary to transition from laboratory scale to pilot scale, only the size of the reactor and heating furnace needs to be scaled up proportionally, while the core "flipping + segmented temperature control" architecture does not need to be changed, which greatly reduces the technical risks and costs of process scale-up.

[0020] This device is designed with user convenience in mind. All core components, including the reactor assembly, electric heater, insulation layer, and related electrical connections, are integrated and fixed on a single motion unit centered on the tilting axis, which is then securely mounted on a frame. This integrated layout makes the entire device exceptionally compact, occupying minimal floor space, making it ideal for space-constrained laboratory environments. Braked casters at the bottom of the frame provide excellent mobility, allowing researchers to easily move it to power sources, water sources, or fume hoods, or flexibly transfer it between different workbenches. Maintenance, such as replacing heating elements, inspecting temperature sensors, or cleaning the reactor, is also extremely simple: just move the device to an open area, release the tilting lock, and all components can be accessed and operated without obstruction. The electrical control system is centrally located in a control box, with neat wiring and clear fault diagnosis. This compact design, combining safety, functionality, and convenience, not only improves daily operational efficiency but also reduces long-term maintenance costs, making it an ideal platform connecting laboratory research and pilot production.

[0021] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 A front view of the structure of a hydrothermal reversing device for crystal growth provided in an exemplary embodiment of the present invention; Figure 2 Left view of the structure of a hydrothermal flipping device for crystal growth provided as an exemplary embodiment of the present invention; Figure 3 A top view of the structure of a hydrothermal flipping device for crystal growth provided in an exemplary embodiment of the present invention; The components include: 1. Frame; 2. Reactor body; 3. Upper flat cover; 4. Lower end cap; 5. Electric heating furnace shell; 6. Upper heating section; 7. Lower heating section; 8. Tilting shaft; 9. Operating handle; 10. Locking plate; 11. Temperature sensor; 12. Casters; 13. Seed crystal holder; 14. Nutrient container; 15. Mother liquor area; 16. Condensation area. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] This invention innovatively proposes a hydrothermal reversing device for crystal growth, the specific structure and operation of which are as follows. Figure 1 , Figure 2 and Figure 3 As shown, the overall frame of the device consists of a frame 1, which is a rectangular frame structure welded from high-strength steel. Its main function is to provide a stable mounting base and support for all other components. To facilitate flexible movement and precise positioning in the laboratory or pilot plant, casters 12 with braking mechanisms are installed at the four corners of the bottom of the frame 1. These casters 12 allow operators to easily push the entire device to the desired position and secure it firmly during operation using the braking mechanism to prevent any accidental slippage.

[0027] On the upper crossbeam of frame 1, bearing seats (including a first bearing seat and a second bearing seat) are fixedly mounted coaxially in the horizontal direction. These two bearing seats constitute the rotation fulcrum of the entire tilting mechanism. Their coaxiality has been precisely adjusted to ensure the smoothness and reliability of subsequent tilting actions. The design of frame 1 fully considers the balance of the overall center of gravity. Its height and width have been optimized and calculated so that even when the reactor assembly 2 is full of material and in a tilting state, the entire device can still maintain extremely high stability and will not tip over.

[0028] The reactor assembly 2, as the core working unit of this device, is rotatably supported between the aforementioned first and second bearing seats. Specifically, the reactor assembly 2 consists of a reactor body 2, an upper flat cover 3, and a lower end cap 4, forming a sealed high-pressure vessel. In this embodiment, the reactor assembly 2 is designed as a standard high-pressure hydrothermal reactor with an effective volume of approximately 5 liters, a design pressure of not less than 5 MPa, and a design temperature of not less than 280 degrees Celsius, fully meeting the stringent conditions of most hydrothermal crystal growth processes. To resist the erosion of internal acidic or other corrosive hydrothermal solutions, all parts of the reactor assembly 2 that come into direct contact with the working medium, including the reactor body 2, the upper flat cover 3, and the inner surface of the lower end cap 4, are made of corrosion-resistant alloy materials (such as Hastelloy C-276, Inconel 625, or high-purity titanium).

[0029] The reactor vessel body 2 is a cylinder made of thick-walled seamless steel tubing. Its upper end is connected to the upper flat cover 3 via a flange. The upper flat cover 3 is securely sealed to the upper flange of the reactor vessel body 2 by a ring of evenly distributed high-pressure bolts, forming a detachable sealing structure. The upper flat cover 3 also integrates multiple standard interfaces, including a safety relief port, a pressure gauge port for connecting a pressure gauge, and inlets and outlets for initial loading and final sampling, to meet the safety operation specifications and process requirements of high-pressure vessels. A rupture disc or safety valve is typically installed inside the safety relief port as a final safety barrier in case of overpressure. The lower head 4 is a standard elliptical or hemispherical head, its edge permanently welded to the lower end of the reactor vessel body 2, forming the sealed bottom of the reactor assembly 2. This welded connection method ensures the structural integrity of the vessel body under high-temperature and high-pressure cycling, avoiding the risk of seal failure due to repeated disassembly.

[0030] To achieve the overall tilting function of the reactor assembly 2, robust tilting sleeves are symmetrically welded to both ends of the outer wall of the reactor body 2. The central holes of these two tilting sleeves are securely fixed to a tilting shaft 8 that runs through the entire reactor assembly 2 using various methods such as interference fit, key connection, and end lock nuts, ensuring that the geometric center axis of the reactor assembly 2 is strictly coincident with the rotation axis of the tilting shaft 8. The left and right ends of the tilting shaft 8 pass through and are precisely supported inside the aforementioned first and second bearing seats, respectively. High-load-capacity rolling bearings (e.g., self-aligning roller bearings) are installed in the inner holes of each bearing seat. The journal portion of the tilting shaft 8 is precisely press-fitted into the inner rings of these rolling bearings, allowing the tilting shaft 8 to rotate with low friction and high stability around its own axis within the bearing seat, thereby driving the entire reactor assembly 2, which is rigidly connected to it, to rotate synchronously. The tilting shaft 8 itself is made of high-strength alloy steel and undergoes heat treatment to obtain excellent comprehensive mechanical properties, capable of withstanding the enormous inertial torque and static load of the reactor assembly 2 and its auxiliary equipment during the tilting process. The length and diameter of the flip shaft 8 have been rigorously calculated to ensure that its deflection and stress are within safe limits under maximum load conditions.

[0031] Within the internal cavity of the reactor assembly 2, two key functional components are arranged axially: a seed crystal holder 13 and a nutrient container 14. The seed crystal holder 13 is fixedly installed at the center of the inner side of the upper flat cover 3. Its structure is designed to quickly and detachably secure one or more precision-cut and polished seed crystal wafers via threaded connections, snap-fits, or spring clips. The seed crystal holder 13 is also made of a corrosion-resistant alloy, such as platinum, titanium, or the aforementioned Hastelloy alloy, to prevent the introduction of impurities that contaminate the crystals in a high-temperature, high-pressure hydrothermal environment.

[0032] In this embodiment, when the reactor assembly 2 is in its initial upright position (i.e., the first flipped position), the seed crystal holder 13 is located in the upper region inside the reactor. Correspondingly, the nutrient container 14 is fixedly installed at the inner center of the lower head 4. Its preferred structure is a perforated basket-like structure made of an inert material (such as polytetrafluoroethylene, quartz glass, or high-purity alumina ceramic), with several through-holes evenly distributed on its sidewalls and bottom to facilitate free flow of solution and condensate. The dimensions of these through-holes are carefully designed to ensure smooth liquid flow while effectively preventing leakage of fine nutrient powder.

[0033] In its initial state, the nutrient container 14 is located in the lower region of the reactor. During operation, the volume of the hydrothermal solution added to reactor assembly 2 is strictly controlled between 50% and 60% of the total volume of the reactor cavity. This ensures sufficient top gas phase space for the solvent to evaporate during heating and condense during cooling, a necessary condition for forming a reflux circulation. This filling ratio is the optimal value obtained through extensive experimental verification; too high a ratio will result in excessive liquid impact during inversion, while too low a ratio will prevent effective convection.

[0034] Enclosing the outer periphery of the reactor vessel 2 is an electric heating furnace 5. This electric heating furnace 5 is not an independent, stationary component, but is rigidly connected to the aforementioned tilting shaft 8 via a support or flange, thus forming an inseparable whole with the reactor vessel assembly 2. Therefore, when the tilting shaft 8 drives the reactor vessel assembly 2 to rotate, the electric heating furnace 5 also tilts synchronously. The outermost layer of the electric heating furnace 5 is a metal shell, namely the electric heating furnace shell 5, which is filled with a high-efficiency heat-insulating material (such as ceramic fiber). Inside the heat-insulating layer is the heating element.

[0035] Crucially, the electric heating furnace 5 is clearly divided along the axial direction of the reactor vessel 2 into two independent heating sections: an upper heating section 6 and a lower heating section 7. The upper heating section 6 corresponds to the upper half of the reactor vessel assembly 2, while the lower heating section 7 corresponds to its lower half. Inside the upper heating section 6 and the lower heating section 7, each section contains its own independently arranged heating elements (such as resistance wires, silicon carbide rods, or heating tubes) and temperature sensors 11 for real-time temperature monitoring. The lead wires of these heating elements and temperature sensors 11 are routed from the fixed junction box of the electric heating furnace 5 via high-temperature resistant and bend-resistant dedicated cables. The outer shell 5 of the electric heating furnace not only protects the internal heating elements and insulation layer but also provides a clean and safe external profile for the entire furnace, preventing burns to operators during operation. The thickness of the insulation layer is calculated thermally to minimize heat loss, improve energy efficiency, and ensure that the temperature of the furnace's outer surface remains within a safe range.

[0036] The flipping mechanism for driving the entire flipping motion mainly includes an operating handle 9 fixedly connected to one end (e.g., the right end) of the flipping shaft 8. In this embodiment, the operating handle 9 is directly welded or bolted to the extended end of the flipping shaft 8 via a flange. The operator only needs to manually crank the operating handle 9 to smoothly and effortlessly rotate the flipping shaft 8, the reactor assembly 2, and the electric heating furnace 5 fixed thereto around the axis of the flipping shaft 8. The length of the operating handle 9 is ergonomically optimized, allowing even a lighter operator to easily complete the entire flipping motion using the lever principle. The flipping angle range includes at least two key positions: 0° (upright posture) and 180° (inverted posture). In some more advanced embodiments, the operating handle 9 can also be replaced by an electric transmission component consisting of a motor, reducer, and coupling, achieving automated and precise flipping through commands issued from the control box, but this does not depart from the basic concept of the invention.

[0037] To ensure the absolute safety and stability of the reactor assembly 2 in a specific working posture, this device is equipped with a dedicated locking mechanism. This locking mechanism consists of a locking disc 10 fixed to the same end of the tilting shaft 8 (i.e., the end where the operating handle 9 is installed), and a locking pin fixed to the frame 1 at a position adjacent to the locking disc 10. The locking disc 10 is a disc-shaped metal piece with multiple locking holes precisely machined on its circumference. The positions of these locking holes correspond to different tilting angles. In this embodiment, there are at least two locking holes, one corresponding to the first tilting position at 0° and the other to the second tilting position at 180°. The locking pin typically consists of a pin with a handle and a return spring. When it is necessary to lock the reactor assembly 2, the operator pulls the locking pin out of the guide hole on the frame 1 and inserts it into the corresponding locking hole on the locking disc 10, thus mechanically locking the entire reactor assembly 2 in the predetermined posture. When it is necessary to tilt, simply pull out the locking pin to release the lock. This purely mechanical locking method offers extremely high reliability, ensuring that the reactor assembly 2 remains firmly secured even in the event of a power outage or control system malfunction, thus preventing any safety accidents caused by accidental rotation. The connection between the locking disc 10 and the tilting shaft 8 must be rigid to ensure effective transmission of the locking force.

[0038] The control box is used for centralized management and control of the entire unit's operation. It is securely mounted on one side of the frame 1 and integrates a temperature control module, power supply module, data logging module, and alarm circuit. The control box is electrically connected to the heating elements and temperature sensors 11 inside the upper heating section 6 and lower heating section 7 via a multi-core high-temperature resistant cable, enabling completely independent closed-loop temperature control of these sections. For example, a PID control algorithm can be used to precisely set and maintain their respective temperatures. Furthermore, the control box is connected to a pressure sensor mounted on the reactor assembly 2 via a signal line for real-time display and recording of the pressure values ​​inside the reactor assembly 2. The control box panel has a display screen that simultaneously displays key parameters such as the temperature of the upper heating section 6, the temperature of the lower heating section 7, the pressure inside the reactor, and the operating time. It also features over-temperature and over-pressure alarms and automatic power cut-off safety protection functions. The control box's circuit design complies with relevant electrical safety standards, and all high-voltage and low-voltage lines are effectively isolated and shielded to prevent electromagnetic interference from affecting the accuracy of temperature and pressure signals. The control box is not only the operating interface, but also the brain of the entire device, coordinating all functions such as heating, temperature measurement, pressure measurement, and safety protection.

[0039] During actual operation of the device, two distinct functional zones are formed internally: the mother liquor zone 15 and the condensation zone 16. The mother liquor zone 15 refers to the area within reactor assembly 2 where the solution, containing a large amount of dissolved nutrients, is at a higher temperature; while the condensation zone 16 is the area with a lower temperature, primarily used for solvent vapor condensation. By independently setting the temperatures of the upper heating section 6 and the lower heating section 7 through the control box, the position and temperature difference between these two zones can be flexibly adjusted. During the crystal growth stage, the temperature difference between the upper heating section 6 and the lower heating section 7 can be adjusted within a range of at least ten degrees Celsius to ensure a sufficiently strong driving force to maintain a stable reflux mass transfer process. This temperature difference is specifically optimized for crystal growth with reverse solubility characteristics, directly determining the reflux rate and crystal growth speed.

[0040] The specific method of using the device of the present invention includes the following process: During the solution saturation stage, the reactor assembly 2 is locked in the first flip position by a locking mechanism. At this time, the seed crystal holder 13 is located in the upper region of the reactor, and the nutrient container 14 is located in the lower region. A hydrothermal solution suitable for the target crystal is added to the reactor assembly 2, and solid nutrients are filled into the nutrient container 14. At this time, the seed crystal holder 13 can be temporarily left unattached. The temperature of the lower heating section 7 is set to the target growth temperature through the control box. The temperature of the upper heating section 6 can be slightly higher or slightly lower than that of the lower heating section 7, depending on the reverse solubility characteristics of the target crystal. The purpose is to ensure that the hydrothermal solution in the reactor reaches saturation of the nutrient at the predetermined temperature. During this stage, since the seed crystal holder 13 is located in the upper gas phase space or the low-temperature zone near the liquid surface, crystallization will not occur on the seed crystal even if the solution is saturated, thus avoiding disordered nucleation and ensuring the purity of subsequent growth.

[0041] After the solution reaches the predetermined saturation state, heating is stopped and the reactor assembly 2 is allowed to cool naturally to a safe temperature suitable for opening the lid. The upper flat cover 3 is opened, and one or more seed crystals are installed onto the seed crystal holder 13. The upper flat cover 3 is then resealed and tightened to the reactor body 2 using high-pressure bolts. Next, the locking mechanism is released by pulling out the locking pin. The operator then slowly and steadily rotates the reactor assembly 2 and the electric heating furnace 5 connected to it 180° around the rotating axis 8 by cranking the operating handle 9, until the second rotation position is reached. In this position, the seed crystal holder 13, originally located at the top, is now moved to the lower area inside the reactor, while the nutrient container 14, originally located at the bottom, is moved to the upper area. After confirming the correct position, the locking pin is reinserted into the locking hole on the locking plate 10 corresponding to the 180° position, achieving mechanical locking of the rotated posture and ensuring safe operation under high temperature and high pressure. This step is the core innovation of the invention. It cleverly uses physical flipping to realize the interchange of the roles of seed crystal and nutrient, without the need for any complex internal mechanical structure.

[0042] After entering the crystal growth stage, the temperatures of the upper heating section 6 and the lower heating section 7 are set separately via the control box. Typically, the lower heating section 7 is set to a higher temperature, creating a mother liquor region 15 below it; the upper heating section 6 is set to a lower temperature, creating a condensation region 16 above it. Under this temperature field, the solvent in the reactor evaporates upon heating, and the vapor rises to the upper condensation region 16, where it condenses into liquid water. This condensate drips and flows into the nutrient container 14 located above, dissolving the solid nutrients and forming a solution rich in solute. Due to gravity, this solution then falls back to the mother liquor region 15 below and flows over the surface of the seed crystal holder 13 located there. Because the crystal has reverse solubility characteristics, in the relatively high-temperature mother liquor region 15, the solution is in a supersaturated state, and the solute will orderly precipitate and crystallize on the surface of the seed crystal, thus achieving directional and controllable crystal growth. This backflow mass transfer process continues, and the growth time, depending on the required crystal size, can be set from several days to several weeks via the control box. Throughout the growth process, the control box continuously monitors the signal fed back by the temperature sensor 11 and dynamically adjusts the heating power to maintain the set temperature gradient and ensure the stability of the growth environment.

[0043] After growth is complete, the cooling and crystal removal stage begins. The output power of the upper heating section 6 and lower heating section 7 is gradually reduced via the control box, allowing the temperature and pressure inside the reactor assembly 2 to slowly and evenly decrease to a safe range according to a preset program, preventing the crystals from cracking due to thermal stress. Once the internal pressure has completely dropped to atmospheric pressure, the locking mechanism is released, and the reactor assembly 2 is flipped back to its initial 0° position using the operating handle 9. Finally, the upper flat cover 3 is opened, and the grown crystal product is removed from the seed crystal holder 13. The removed crystals typically require post-processing steps such as cleaning and drying to obtain the final product.

[0044] This device is designed not only for the reflux hydrothermal growth of crystals with reverse solubility characteristics, but also for other types of hydrothermal crystal preparation processes, such as conventional temperature gradient hydrothermal methods. In such applications, the operator only needs to flexibly adjust the initial arrangement of the seed crystal and nutrient material in the reactor, as well as the temperature setting strategy of the upper heating section 6 and the lower heating section 7, according to specific process requirements. This allows for the completion of growth experiments for different crystal systems on the same equipment, greatly improving the versatility and efficiency of the equipment. Through the precise coordination of the flipping shaft 8, bearing seat, and locking mechanism (locking disc 10 and locking pin), this device successfully solves the industry problem of the difficulty and danger of overall flipping of large-volume hydrothermal reactors with external heating furnaces and insulation layers. At the same time, by dividing the electric heating furnace 5 axially into upper heating section 6 and lower heating section 7 and controlling their independent temperatures, and by interchangering the spatial positions of the seed crystal clamping frame 13 and the nutrient container 14 before and after flipping, this device can accurately construct an ideal reflux environment of "dissolution above and growth below," providing a reliable technical guarantee for the preparation of high-quality, large-size single crystals. The entire device has a compact structure, and the casters 12 at the bottom of the frame 1 make it extremely convenient to move and maintain, making it very suitable for use in laboratories with limited space and pilot-scale platform environments that require process scale-up.

[0045] All components, including the frame 1, reactor body 2, upper flat cover 3, lower end cap 4, electric heating furnace shell 5, upper heating section 6, lower heating section 7, tilting shaft 8, bearing seat, operating handle 9, locking plate 10, locking pin, control box, temperature sensor 11, caster wheel 12, seed crystal holder 13, nutrient container 14, mother liquor area 15, and condensation area 16, are interconnected and work together as described in detail above, together constituting the complete technical solution of the hydrothermal tilting device for crystal growth proposed in this invention. The frame 1 serves as the basic platform, supporting the bearing housing and control box. The bearing housing supports the tilting shaft 8 via rolling bearings. The tilting shaft 8 rigidly connects the reactor assembly 2 and the electric heating furnace 5. The operating handle 9 and locking disc 10 are fixed to the end of the tilting shaft 8, used for driving and locking respectively. The locking pin is installed on the frame 1 and cooperates with the locking disc 10. The control box is connected to the heating elements and temperature sensors 11 in the upper heating section 6 and lower heating section 7 via cables to achieve independent temperature control. The positions of the seed crystal holder 13 and the nutrient container 14 inside the reactor assembly 2 are interchanged during tilting, thereby establishing an efficient material circulation between the mother liquor area 15 and the condensation area 16. The shape, size, material, and connection method of each component are mutually adapted to ensure that the entire system can maintain excellent performance and reliability under long-term, repeated high-temperature and high-pressure cycling conditions. This design concept, which organically combines mechanical tilting, segmented temperature control, and internal component layout, is the fundamental difference between this invention and the prior art, providing a new, safe, and efficient solution for the field of hydrothermal crystal growth.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hydrothermal reversing device for crystal growth, characterized in that, include: A frame, on which a first bearing housing and a second bearing housing are arranged coaxially; The reactor assembly includes a cylindrical body, an upper flat cover, and a lower end cap. The reactor assembly is fixedly connected to a rotating shaft via a rotating sleeve mounted on the cylindrical body, so that the axis of the reactor assembly is coaxial with the rotating shaft. It is supported by the first bearing seat and the second bearing seat and can rotate around the rotating shaft. An electric heating furnace is wrapped around the outer periphery of the reactor cylinder and fixedly connected to the tilting shaft. It tilts synchronously with the reactor assembly. The electric heating furnace is divided into an upper heating section and a lower heating section that are independently controlled along the axial direction. The tilting mechanism includes an operating handle fixedly connected to the tilting shaft, used to drive the reactor assembly and the electric heating furnace to rotate around the tilting shaft; The locking mechanism includes a locking disc fixed on the rotating shaft and a locking pin set on the frame. The circumference of the locking disc is provided with locking holes corresponding to different rotating angles. The locking pin can be inserted into any locking hole to lock the reactor assembly at a predetermined angle. The control box is electrically connected to the heating elements and temperature sensors of the upper and lower heating sections, and is used to independently control the temperature of the upper and lower heating sections. The reactor assembly is provided with a seed crystal holder and a nutrient container arranged axially inside. The seed crystal holder and the nutrient container are arranged at intervals. When the reactor assembly is in the first flip position, the seed crystal holder is located in the upper region of the reactor and the nutrient container is located in the lower region. When the reactor assembly is flipped 180° around the flip axis to the second flip position, the seed crystal holder is located in the lower region of the reactor and the nutrient container is located in the upper region.

2. The hydrothermal reversing apparatus for crystal growth as described in claim 1, characterized in that, The electric heating furnace is equipped with an insulation layer and a metal shell. The upper heating section and the lower heating section are each equipped with independent heating elements and temperature sensors, and are controlled by PID programs through a control box.

3. The hydrothermal reversing apparatus for crystal growth as described in claim 1, characterized in that, The tilting shaft is mounted in the bearing housing via rolling bearings, the locking disc is fixed to one end of the tilting shaft, the locking hole includes at least two position holes corresponding to 0° and 180°, and the bottom of the frame is provided with at least three casters with braking mechanisms.

4. The hydrothermal reversing apparatus for crystal growth as described in claim 1, characterized in that, The nutrient container is made of inert material, and the side walls and bottom of the nutrient container are provided with several through holes.

5. The hydrothermal reversing apparatus for crystal growth as described in claim 1, characterized in that, The seed crystal holder is installed on the inside of the upper flat cover and can be detachably fixed with one or more seed crystals; the volume of the working solution in the reactor is controlled at 50% to 60% of the total volume of the reactor cavity.

6. The hydrothermal reversing apparatus for crystal growth as described in claim 1, characterized in that, The control box is connected to a pressure sensor installed on the reactor assembly to display and record the pressure inside the reactor, and has working time display and over-temperature and over-pressure alarm functions.

7. The hydrothermal reversing apparatus for crystal growth as described in claim 1, characterized in that, The temperature settings of the upper heating section and the lower heating section enable the formation of an upper condensation zone and a lower mother liquor zone during crystal growth, and the temperature difference between the upper heating section and the lower heating section is adjustable within a range greater than or equal to 10°C.

8. A method for crystal growth, characterized in that, Using the hydrothermal reversing apparatus for crystal growth as described in any one of claims 1-7, Includes the following processes: The reactor assembly is locked in the first flip position by a locking mechanism, so that the seed crystal holder is located in the upper region of the reactor and the nutrient container is located in the lower region. Hydrothermal solution is added to the reactor and solid nutrient is filled in. The upper heating section and the lower heating section are heated by the control box so that the solution reaches the saturation of the nutrient at a predetermined temperature. Stop heating, wait for the reactor to cool down, install the seed wafer on the seed wafer holder and reseal the reactor, release the locking mechanism, drive the flipping shaft through the flipping mechanism to flip the reactor assembly 180° around the flipping shaft to the second flipping position, and lock the reactor assembly through the locking mechanism; During the crystal growth stage, the temperatures of the upper heating section and the lower heating section are set separately by the control box, so that the upper region forms a condensation zone and the lower region forms a mother liquor zone. The condensate flows into the nutrient container to dissolve the nutrients and then falls back into the mother liquor zone, thus realizing crystal growth on the seed crystal. After growth is complete, the upper and lower heating sections are gradually cooled by controlling the control box. Once the pressure inside the reactor drops to a safe value, the pressure is released and the crystal product is removed.

9. The crystal growth method as described in claim 8, characterized in that, The hydrothermal solution is an acidic hydrothermal solution, and the crystal growth temperature and pressure are set according to the reverse solubility characteristics of the target crystal, which are high temperature and high pressure conditions in the range of tens to hundreds of degrees Celsius and several megapascals.

10. The crystal growth method as described in claim 8 or 9, characterized in that, During the crystal growth stage, the temperature difference between the upper heating section and the lower heating section is maintained within a predetermined range, and the growth time is controlled by a control box using programmed heating or constant temperature methods, ranging from several days to several weeks. In the first flip position, the upper and lower heating sections of the electric heating furnace are controlled by the control box to heat the hydrothermal solution and nutrients in the reactor until the solution reaches saturation; The reactor assembly is rotated 180° to the second rotation position by a flipping mechanism that drives the flipping shaft, and then locked by a locking mechanism. In the second flip position, the temperature of the upper heating section and the lower heating section are independently controlled by the control box, so that a condensation zone is formed in the upper part of the reactor and a mother liquor zone is formed in the lower part. The condensate dissolves the nutrients in the nutrient container and then flows back to the area where the seed crystal holder is located to achieve crystal growth. After growth is complete, the temperature is controlled by the control box, the locking mechanism is released, and the crystal is removed.

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