Improved device for growing large-size organic single crystal by horizontal Bridgman method and preparation method thereof

Abstract

The invention belongs to the technical field of single crystal growth, and particularly discloses an improved horizontal Bridgman method large-size organic single crystal growth device and a preparation method thereof.The device comprises a horizontal tubular vacuum heating furnace, a crystal growth crucible and a horizontal moving system, and a crystal growth cavity is formed in the horizontal tubular vacuum heating furnace; the crystal growth crucible is obliquely located in the crystal growth cavity, a high-temperature heating area, a temperature gradient area and a low-temperature heating area are arranged outside the horizontal pipe type vacuum heating furnace in the axial direction at intervals, and the crystal growth crucible is designed to be of a double-layer quartz structure. According to the improved device for growing the large-size organic single crystal by the horizontal Bridgman method and the preparation method of the improved device, traditional equipment for growing the single crystal by the horizontal Bridgman method is improved, so that the problems of volatility control, thermal stress elimination and uniformity regulation and control in the growth of the organic single crystal are effectively solved; and an innovative solution is provided for industrial preparation of the photoelectric functional crystal material.

Description

Technical Field

[0001] The present invention relates to the technical field of single crystal growth, and in particular to an apparatus for growing large-size organic single crystals by an improved horizontal Bridgman method and a preparation method thereof. Background Art

[0002] Due to its unique molecular ordered arrangement characteristics, large-size organic single crystal materials exhibit important application values in the fields of radiation detection, nonlinear optical devices, microwave emitters, etc. Compared with inorganic crystals, organic crystals have intrinsic advantages such as larger carrier mobility and higher X-ray absorption coefficient. However, the weak intermolecular interaction forces lead to the crystallization process being easily disturbed, and there are common technical bottlenecks such as many lattice defects and poor mechanical properties in the process of growing large-size crystals, which seriously restrict the industrial application process.

[0003] The Bridgman method, as a single crystal growth technology based on the directional solidification of a melt, its core principle is to precisely control the temperature gradient to make the molten material solidify in a single direction to form high-quality single crystals. When this technology is applied to the field of organic crystals, it mainly adopts two implementation methods: the horizontal Bridgman method and the vertical Bridgman method. However, both face significant challenges in practical applications:

[0004] (1) The horizontal Bridgman method adopts a horizontally movable thermal field design, which has advantages such as a large heat exchange area and controllable crystal cross-sectional dimensions. However, when there are volatile components in the system, the open crucible structure easily causes the volatiles to condense uncontrollably in the furnace body; at the same time, the two-dimensional heat dissipation characteristics of the flat-bottom crucible cause anisotropic thermal stress in the crystal, resulting in obvious cleavage cracks in the finished product and affecting the quality of the single crystal.

[0005] (2) The vertical Bridgman method is to place the crucible vertically, and the thermal field is axially symmetrically distributed. The crystal grows axially by lifting the furnace body or the crucible. This method usually uses a cylindrical crucible with a conical tip, and the grown crystal is a column or a cone. However, for the growth of single crystals doped with multiple components, affected by the gravity factor, due to the difference in the diffusion coefficients between the components, a concentration boundary layer will be formed at the solidification front, resulting in a gradient distribution of the doped molecules along the growth axis, significantly deteriorating the consistency of the optoelectronic properties of the crystal.

[0006] Existing improvement technologies primarily focus on optimizing process parameters. These include optimizing the temperature gradient for the horizontal Bridgman method to reduce local thermal stress and the risk of crystal cracking; and developing a rotating crucible device for the vertical Bridgman method to generate forced convection in the melt and promote component fusion. However, these methods face two fundamental contradictions in engineering implementation: On the one hand, for the vertical Bridgman method, while enhancing melt convection can improve component uniformity, it can disrupt laminar growth conditions at the solid-liquid interface, affecting crystallization quality. On the other hand, for the horizontal Bridgman method, while reducing the temperature gradient can help reduce thermal stress, it significantly increases the probability of polycrystalline growth and fails to fundamentally resolve the issue of raw material volatilization in the open crucible. Summary of the Invention

[0007] The purpose of the present invention is to provide an improved horizontal Bridgman method for growing large-size organic single crystals and a preparation method thereof. By improving the traditional horizontal Bridgman method for growing single crystals, the difficult problems of volatility control, thermal stress elimination and uniformity regulation in the growth of organic single crystals can be effectively solved, providing an innovative solution for the industrial preparation of optoelectronic functional crystal materials.

[0008] To achieve the above-mentioned objectives, the present invention provides an improved horizontal Bridgman method for growing large-size organic single crystals, comprising a horizontal tubular vacuum heating furnace, a crystal growth crucible and a horizontal movement system, wherein a crystal growth chamber is provided inside the horizontal tubular vacuum heating furnace, and the crystal growth crucible is tilted and located in the crystal growth chamber, and the angle between the tilt axis of the crystal growth crucible and the horizontal direction is 5°-8°; a high-temperature heating zone, a temperature gradient zone and a low-temperature heating zone are arranged axially on the outside of the horizontal tubular vacuum heating furnace; the crystal growth crucible adopts a double-layer quartz structure design, with a funnel-shaped shoulder area with a cone angle of 15° at the bottom and a cylindrical equal-diameter growth area at the top; the funnel-shaped shoulder area includes a first bending capillary channel and a second bending capillary channel, and the bending angles of the first bending capillary channel and the second bending capillary channel are both 25°.

[0009] Preferably, the high-temperature heating zone, temperature gradient zone, and low-temperature heating zone are heated by independent closed-loop controlled resistance wire heaters, and are wrapped with an alumina fiber insulation layer on the outside. The horizontal tubular vacuum heating furnace realizes dynamic air pressure control of the crystal growth chamber through the linkage of a mechanical pump and a digital pressure gauge.

[0010] Preferably, the crystal growth crucible is fixed in the crystal growth cavity, and the oblique installation of the crystal growth crucible is achieved by a high-temperature resistant alumina gasket provided at the bottom.

[0011] Preferably, the horizontal movement system includes a slide rail and a spiral stepping motor, the bottom of the horizontal tubular vacuum heating furnace is slidably connected to the slide rail, and the spiral stepping motor drives the horizontal tubular vacuum heating furnace to slide on the slide rail.

[0012] The present invention also provides a method for growing large-sized organic single crystals by an improved horizontal Bridgman method, which is realized by the above-mentioned device.

[0013] The present invention also provides a preparation method for growing large-sized organic single crystals by an improved horizontal Bridgman method, comprising the following steps:

[0014] S1 Clean the crystal growth crucible and dry it.

[0015] S2 Load the organic raw materials into the crystal growth crucible, cover it with a frosted glass stopper for preliminary sealing of the frosted opening of the crystal growth crucible, and tilt the crystal growth crucible.

[0016] S3 Transfer the loaded crystal growth crucible to the position where the high-temperature heating zone of the horizontal vacuum heating furnace is located, and simultaneously conduct vacuum treatment on the crystal growth chamber.

[0017] S4 Turn on the resistance wire heater to heat the high-temperature heating zone and the low-temperature heating zone of the crystal growth chamber, so that the raw materials in the crystal growth crucible are fully melted.

[0018] S5 Start the spiral stepping motor to gradually move the crystal growth crucible from the high-temperature heating zone to the low-temperature heating zone at a low speed until the fully melted raw material melt is completely crystallized, completing the growth of the organic single crystal.

[0019] S6 Cool the crystal growth chamber to room temperature and take out the organic single crystal.

[0020] Preferably, in step S2, at one-third of the distance from the frosted opening of the crystal growth crucible, fix the alumina gasket with a high-temperature resistant polyimide tape to stably tilt the crystal growth crucible.

[0021] Preferably, in step S4, set the temperature of the high-temperature heating zone to be 10°C to 20°C higher than the melting point temperature of the organic raw materials, set the temperature of the low-temperature heating zone to be 20°C to 30°C lower than the freezing point temperature of the organic raw materials, and keep the crystal growth crucible heated in the high-temperature heating zone for 12 hours to fully melt the organic raw materials.

[0022] Preferably, in step S5, the specific moving rate is set as follows: at the initial stage of nucleation, when the crystallization interface enters the inner layer bending position from the outer layer of the crystal growth crucible, set the crystal growth chamber to move horizontally to the right at a speed of 0.5 mm / h. When the crystallization interface moves to the funnel-shaped shoulder region, adjust the moving rate to 1 mm / h. When all the crystals are crystallized, stop moving.

[0023] Preferably, in step S6, when the temperature of the crystal growth chamber is lowered to room temperature, a stepwise cooling method is adopted for cooling: first, the high-temperature heating zone is cooled at a rate of 5 °C / h to the temperature of the low-temperature heating zone, and then both the high-temperature heating zone and the low-temperature heating zone are cooled at a rate of 10 °C / h to room temperature.

[0024] The advantages and beneficial effects of the improved horizontal Bridgman method for growing large-size organic single crystals and the preparation method thereof according to the present invention are as follows:

[0025] 1. The ultra-long crystal growth crucible designed in the present invention has an axial length of about 240 mm, and the loading area is slightly longer than the coverage range of the high-temperature zone during crystal growth, so that a dense protective film composed of growth raw materials is automatically formed at the open end of the crucible during crystal growth to prevent the volatilization of molten raw materials.

[0026] 2. The present invention adopts the method of tilting the crucible, which effectively avoids the component non-uniformity caused by the vertical placement of the crucible, and can take into account the problems of improving thermal stress and controlling uniformity.

[0027] 3. The single crystal grown by using the device of the present invention is columnar, has good crystal transparency, and the device can control the crystal growth rate by controlling the moving rate of the furnace cavity, which is beneficial to the discharge of impurities during crystal growth; adopting a slow cooling rate effectively avoids crystal cracking.

[0028] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings

[0029] Figure 1 is a schematic diagram of the device for growing large-size organic single crystals by the improved horizontal Bridgman method of the present invention;

[0030] Figure 2 Schematic diagram of the crystal growth crucible of the present invention;

[0031] Figure 3 Front view of the schematic design of the horizontal movement system used in the present invention;

[0032] Figure 4 Top view of the schematic design of the horizontal movement system used in the present invention;

[0033] Figure 5 is a schematic diagram of the single crystal grown in Example 1 of the present invention;

[0034] Figure 6 is a schematic diagram of the doped single crystal grown in Example 2 of the present invention.

[0035] Reference Numerals

[0036] 1. Thermal insulation layer; 2. High-temperature heating zone; 3. Low-temperature heating zone; 4. Temperature gradient zone; 5. Crystal growth chamber; 6. Flange; 7. Slide rail; 8. Frosted glass stopper; 9. High-temperature resistant alumina gasket; 10. Crystal growth crucible; 11. Crystal; 12. Crystal nucleus; 13. Equal-diameter growth zone; 14. Outer quartz sleeve; 15. Frosted seal; 16. Funnel-shaped shoulder region; 17. First bent capillary channel; 18. Second bent capillary channel; 19. End opening; 20. Left crystal growth chamber bracket; 21. Horizontal tube type vacuum heating furnace; 22. Right crystal growth chamber bracket; 23. Spiral stepping motor. Detailed implementation mode

[0037] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0038] Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those of ordinary skill in the art to which the present invention belongs. The "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. The terms such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms such as "connected" or "linked" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left" and "right" are only used to represent relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0039] Unless otherwise defined, the reagents, equipment and other materials used in the present invention are all obtained from conventional commercial sources.

[0040] Embodiment 1

[0041] As Figure 1 shown, the improved horizontal Bridgman method for growing large-size organic single crystals device includes a horizontal tube type vacuum heating furnace 21, a crystal growth crucible 10 and a horizontal moving system. Inside the horizontal tube type vacuum heating furnace 21, there is a crystal growth chamber 5, and the crystal growth chamber 5 is a high-temperature resistant quartz tube with an inner diameter of 60 mm, a thickness of 4 mm and a length of 1200 mm. Flanges 6 are installed at both the left and right ends of the quartz tube and are externally connected to a vacuum system (not shown in the figure). The vacuum system realizes the dynamic air pressure regulation of the growth chamber through the linkage of a mechanical pump and a digital pressure gauge. The vacuum system evacuates the air using existing technologies.

[0042] The crystal growth crucible 10 is inclined and located within the crystal growth chamber 5. The angle between the inclination axis of the crystal growth crucible 10 and the horizontal direction is 5° - 8°. This inclined configuration enables the formation of a unidirectional crystallization driving force under the combined action of gravity and surface tension, effectively inhibiting the heterogeneous nucleation at the solid-liquid interface. Meanwhile, through the precise regulation of the inclination angle, the melt flow rate and the stability of the crystallization front can be balanced.

[0043] Along the axial direction outside the horizontal tube-type vacuum heating furnace 21, there are a high-temperature heating zone 2 and a low-temperature heating zone 3 with a length of 100 mm each at intervals. Each temperature section is equipped with a resistance wire heater with independent closed-loop control. A natural temperature gradient zone 4 is formed with a 50-mm interval between the two zones. The maximum working temperature of the high-temperature heating zone 2 is 900 °C, and the maximum temperature gradient of the natural temperature gradient zone 4 reaches 30 °C / cm. The periphery is wrapped with an alumina fiber insulation layer 1 to maintain the stability of the thermal field.

[0044] As Figure 2 shown, the crystal growth crucible 10 adopts a double-layer quartz structure design. There is a frosted seal 15 at the top of the left end, the outer layer quartz sleeve 14 at the bottom of the right end, a funnel-shaped shoulder release area 16 with a 15° cone angle at the bottom, and a cylindrical equal-diameter growth area 13 at the upper part. The melt is guided to the cylindrical equal-diameter growth area 13 with an inner diameter of 5 mm and a length of 220 mm through a tapered flow channel. The funnel-shaped shoulder release area 16 includes a first bent capillary channel 17 and a second bent capillary channel 18, and the bending angles of the first bent capillary channel 17 and the second bent capillary channel 18 are both 25°. After the inlet section tapers from the end of the funnel-shaped shoulder release area 16 to 2 mm, it finally converges to a 0.5-mm end opening 19 through a bent capillary pipeline with a total length of 12 mm (the single-fold angle is 25° ± 0.5°, and the length of a single capillary pipeline is 6.0 ± 0.2 mm). The bottom corner design and the end opening 19 can ensure that only one crystal nucleus 12 enters the inner layer, which can play the role of automatically screening the seed crystal.

[0045] The crystal growth crucible 10 is fixed within the crystal growth chamber 5, and the inclined installation of the crystal growth crucible 10 is achieved through the high-temperature resistant alumina gasket 9 provided at the bottom.

[0046] As Figure 3 and Figure 4 shown, the horizontal power system includes a left crystal growth chamber support 20 and a right crystal growth chamber support 22, which are used to support the crystal growth chamber 5. The cooperation and working principle of the spiral stepping motor 23, the slide rail 7, and the lead screw all adopt existing technologies.

[0047] The horizontal movement system consists of a power control device and a transmission device. The power control device uses a spiral stepper motor 23 as the power source, and its rotation speed can be precisely adjusted through the PLC control system, so as to control the moving speed of the crystal growth crucible 10 to meet the requirements of different stages of crystal growth. The transmission device uses a lead screw and a nut for transmission. The spiral stepper motor 23 drives the lead screw to rotate. The nut is connected to the crystal growth chamber 5 via a flange 6, and then drives the crystal growth chamber 5 to make a uniform and stable linear motion along the slide rail 7 in the axial direction of the lead screw. The horizontal movement system includes a slide rail 7 and a spiral stepper motor 23. The bottom of the horizontal tube type vacuum heating furnace 21 is slidably connected to the slide rail 7. The spiral stepper motor 23 drives the horizontal tube type vacuum heating furnace 21 to slide on the slide rail 7, and the crystal growth chamber 5 is translated at a super-low speed of 0.3-5 mm / h uniformly. At the same time, the furnace body including the high-temperature heating zone 2, the low-temperature heating zone 3, and the temperature gradient zone 4 remains stationary. The minimum speed is 0.3 mm / h, and the speed can be manually controlled by the PLC panel. During operation, it moves uniformly and unidirectionally. After completing the set stroke, it can return to the zero position at a speed of 10 m / h. The spiral stepper motor 23 driving the horizontal tube type vacuum heating furnace 21 to slide on the slide rail 7 adopts the existing technology. The high-temperature heating zone 2, the low-temperature heating zone 3, the temperature gradient zone 4, and the resistance wire heater adopt the existing technology.

[0048] The preparation method for growing large-size organic single crystals by the improved horizontal Bridgman method includes the following steps:

[0049] S1 Clean the crystal growth crucible 10 and dry it.

[0050] S2 Load the organic raw materials into the crystal growth crucible 10, cover it with a frosted glass stopper 8, and conduct a preliminary sealing treatment on the frosted seal 15 of the crystal growth crucible 10. The crystal growth crucible 10 is inclined. At one-third of the distance from the frosted seal 15 of the crystal growth crucible 10, fix the alumina gasket with a polyimide high-temperature resistant tape to make the crystal growth crucible 10 stably inclined.

[0051] S3 Transfer the loaded crystal growth crucible 10 to the position where the high-temperature heating zone 2 of the horizontal vacuum heating furnace is located, and at the same time conduct a vacuum treatment on the crystal growth chamber.

[0052] S4 Turn on the resistance wire heater to heat the high-temperature heating zone 2 and the low-temperature heating zone 3 of the crystal growth chamber, so that the raw materials in the crystal growth crucible 10 are fully melted. Set the temperature of the high-temperature heating zone 2 to be higher than the melting point temperature of the organic raw materials by 10 °C to 20 °C, and set the temperature of the low-temperature heating zone 3 to be lower than the freezing point temperature of the organic raw materials by 20 °C to 30 °C. Keep the crystal growth crucible 10 heated in the high-temperature heating zone 2 for 12 h to fully melt the organic raw materials.

[0053] S5 activates the spiral stepper motor 23 to gradually move the crystal growth crucible 10 from the high-temperature heating zone 2 to the low-temperature heating zone 3 at a low speed until the melt is completely crystallized, completing the growth of the organic single crystal. The specific moving rate is set as follows: at the initial stage of nucleation, when the crystallization interface enters the inner layer bending position from the outer layer of the crystal growth crucible 10, the crystal growth chamber is set to move horizontally to the right at a speed of 0.5 mm / h. When the crystallization interface moves to the shoulder-forming area, the moving rate is adjusted to 1 mm / h. After all the crystals 11 are crystallized, the movement stops.

[0054] S6 cools the crystal growth chamber 5 to room temperature and takes out the organic single crystal. When the crystal growth chamber is cooled to room temperature, a step-by-step cooling method is adopted: first, the high-temperature heating zone 2 is cooled to the temperature of the low-temperature heating zone 3 at a rate of 5 °C / h, and then both the high-temperature heating zone 2 and the low-temperature heating zone 3 are cooled to room temperature at a rate of 10 °C / h.

[0055] A method for preparing large-size organic single crystals using an improved horizontal Bridgman method for growing large-size organic single crystal devices is as follows:

[0056] 1) Take 2 g of organic single crystal growth organic raw materials and place them in a mortar, grind them thoroughly into fine powders, and slowly load the raw materials into the inner tube of the crystal growth crucible 10 in a funnel shape with a clean weighing paper. For every 0.5 g of raw materials added, insert a glass rod with a diameter of 4 mm into the crystal growth crucible 10 to compact the raw materials. After the raw materials are filled, cover them with a frosted glass stopper 8 for preliminary sealing, and wind a polyimide high-temperature resistant tape around the outer layer. At one-third of the distance from the frosted seal of the crystal growth crucible 10, fix a high-temperature resistant alumina gasket 9 with a polyimide high-temperature resistant tape to make the crystal growth crucible 10 stably inclined.

[0057] 2) Transfer the loaded crystal growth crucible 10 to the position of the high-temperature heating zone 2 of the horizontal tube vacuum heating furnace 21. At the same time, the vacuum system is evacuated and maintained for 6 h, and then the vacuum system is closed.

[0058] 3) Set the temperature of the high-temperature heating zone 2 to be 10 °C - 20 °C higher than the melting point temperature of the organic raw materials, set the low-temperature heating zone 3 to be 20 °C - 30 °C lower than the solidification point temperature of the organic raw materials, and the temperature gradient zone 4 is about 6 °C / cm. Then turn on the heating switch of the horizontal tube vacuum heating furnace 21.

[0059] 4) Keep the crystal growth crucible 10 heated in the high-temperature heating zone 2 for 12 hours to fully melt the raw materials. Then start the spiral stepper motor 23, and the tip of the crystal growth crucible 10 enters the low-temperature heating zone 3, crystallizing first. The crystal 11 gradually grows as the crystal growth chamber 5 moves to the right. The specific movement rate is set as follows: in the early stage of nucleation, when the crystallization interface enters the inner corner position from the outer layer of the crystal growth crucible 10, the crystal growth chamber 5 is set to move horizontally to the right at a speed of 0.5 mm / h to screen high-quality seed crystals; when the crystallization interface moves to the funnel-shaped shoulder area 16, the movement rate is adjusted to 1 mm / h. When all the crystals 11 are crystallized, the movement stops.

[0060] 5) After all crystals 11 are crystallized, the temperature of crystal 11 is gradually lowered. First, the high temperature heating zone 2 is cooled to the temperature of the low temperature heating zone 3 at a rate of 5°C / h, and then both temperature zones are cooled to room temperature at a rate of 10°C / h.

[0061] 6) After cooling, air is introduced into the crystal growth chamber 5 to maintain the same air pressure inside and outside the cavity. The crystal growth crucible 10 is removed and its top is cut open using a diamond wire cutter. The crystal 11 is carefully removed from the crystal growth crucible 10 to obtain a large-sized organic single crystal.

[0062] Example 2

[0063] A method for preparing a large-sized scintillator organic single crystal by growing it using an improved horizontal Bridgman method comprises the following steps:

[0064] Step 1: Cleaning the crystal growth crucible 10.

[0065] (a) The crystal growth crucible 10 is preliminarily rinsed with deionized water.

[0066] (b) The rinsed crystal growth crucible 10 is soaked in anhydrous ethanol and ultrasonicated for 2 hours, and then rinsed with deionized water.

[0067] (c) The rinsed crystal growth crucible 10 is placed in a drying oven and kept for 12 hours to ensure complete drying.

[0068] Step 2: Loading, sealing, and tilting the crystal growth crucible 10.

[0069] (a) Place 2 g of 1,4-bis(2-methylphenyl)benzene in a mortar and grind thoroughly into a fine powder.

[0070] (b) Fold a clean weighing paper into a funnel shape and slowly load the raw materials into the inner tube of the crystal growth crucible 10. After each 0.5 g of raw materials is added, a glass rod with a diameter of 4 mm is inserted into the crucible to compact the raw materials.

[0071] (c) After the raw materials are filled, cover it with a frosted glass stopper 8 for preliminary sealing, and wind a polyimide high-temperature resistant tape around the outer layer.

[0072] (d) At one-third of the distance from the crystal growth crucible 10 to the frosted seal 15, fix a high-temperature resistant alumina gasket 9 with a polyimide high-temperature resistant tape to stably incline the crystal growth crucible 10.

[0073] Step Three: Vacuum treatment. Transfer the loaded crystal growth crucible 10 to the position of the high-temperature heating zone 2 of the horizontal tube type vacuum heating furnace 21. At the same time, turn on the vacuum system to evacuate for 6 h, and then turn off the vacuum system.

[0074] Step Four: Crystal 11 growth.

[0075] (a) Set the high-temperature heating zone 2 to heat from room temperature 25 °C to 190 °C, and the low-temperature zone to heat from 25 °C to 155 °C, with a heating time of 1 h.

[0076] (b) Keep the crystal growth crucible 10 heated in the high-temperature heating zone 2 for 6 h to fully melt the raw materials.

[0077] (c) Start the spiral stepping motor 23. The tip of the crystal growth crucible 10 enters the low-temperature heating zone 3 and starts to crystallize first. The crystal 11 gradually grows as the crystal growth chamber 5 moves to the right. The specific moving rate is set as follows: at the initial stage of nucleation, when the crystallization interface enters from the outer layer of the crystal growth crucible 10 to the inner layer corner position (a total of 4 cm), set the crystal growth chamber 5 to move horizontally to the right at a speed of 0.5 mm / h (a total of 8 h) to screen high-quality seed crystals; when the crystallization interface moves to the conical part, the moving rate is adjusted to 1 mm / h (a total of 7 cm), which takes 70 h. When the crystal 11 is completely crystallized, stop moving.

[0078] Step Five: Cooling.

[0079] (a) Cool the high-temperature heating zone 2 at a cooling rate of 3 °C / h for 12 h until the temperature drops to 155 °C;

[0080] (b) Then cool the high-temperature heating zone 2 and the low-temperature heating zone 3 simultaneously at a speed of 5 °C / h for 26 h until the temperature drops to room temperature.

[0081] Step Six: Take out the single crystal. Introduce air into the crystal growth cavity to keep the air pressure inside and outside the cavity consistent. Take out the crystal growth crucible 10 from the furnace chamber, cut its top with a diamond wire cutting machine, and carefully take out the crystal 11 from the crystal growth crucible 10 to obtain a large-size scintillator organic single crystal.

[0082] As Figure 4 shown, it is a scintillator single crystal grown by the method described in Example 2, showing a uniform yellow color.

[0083] Example 3

[0084] An improved horizontal Bridgman method for preparing large-sized pentacene doped with p-terphenyl organic single crystals, the steps are as follows:

[0085] Step 1: Clean the crystal growth crucible 10, and the specific steps are the same as those in Step 1 of Example 2.

[0086] Step 2: Loading, sealing, and tilting the crystal growth crucible 10.

[0087] (a) Take 2 g of p-terphenyl powder and 0.0002 g of pentacene powder and place them in a mortar, add 2 ml of ethanol, and grind thoroughly until the ethanol completely evaporates.

[0088] (b) Place the mortar in an oven and keep it for 1 h.

[0089] (c) Fold a clean weighing paper into a funnel shape and slowly pour the raw materials into the inner tube of the crystal growth crucible 10. For every 0.5 g of raw materials added, insert a glass rod with a diameter of 4 mm into the crystal growth crucible 10 to compact the raw materials.

[0090] (d) After the raw materials are filled, cover with a frosted glass stopper 8 for preliminary sealing, and wind a high-temperature resistant polyimide tape on the outer layer.

[0091] (e) At one-third of the frosted seal 15 of the crystal growth crucible 10, fix a high-temperature resistant alumina gasket 9 with a high-temperature resistant polyimide tape to make the crystal growth crucible 10 stably tilted.

[0092] Step 3: Vacuum treatment. Transfer the loaded crystal growth crucible 10 to the position of the high-temperature heating zone 2 of the horizontal tube vacuum heating furnace 21, and at the same time turn on the vacuum system to evacuate for 6 h, and then turn off the vacuum system.

[0093] Step 4: Crystal 11 growth.

[0094] (a) Set the high-temperature heating zone 2 to heat from room temperature 25 °C to 220 °C, and the low-temperature heating zone 3 to heat from 25 °C to 180 °C, and the heating time is 1 h.

[0095] (b) Keep the crystal growth crucible 10 in the high-temperature heating zone 2 for heating for 6 h to fully melt the raw materials.

[0096] (c) Start the spiral stepper motor 23, and the tip of the crystal growth crucible 10 enters the low-temperature heating zone 3 and starts to crystallize first. The crystal 11 gradually grows as the crystal growth chamber 5 moves to the right. The specific moving rate is set as follows: at the initial stage of nucleation, when the crystallization interface enters from the outer layer to the inner corner position of the crystal growth crucible 10 (a total of 4 cm), set the crystal growth chamber 5 to move horizontally to the right at a speed of 0.5 mm / h (a total of 8 h) to screen high-quality seed crystals; when the crystallization interface moves to the conical part, the moving rate is adjusted to 1 mm / h (a total of 7 cm), which takes 70 h. When the entire crystal 11 has crystallized, stop moving.

[0097] Step Five: Cooling.

[0098] (a) Cool the high-temperature heating zone 2 at a cooling rate of 3 °C / h for 13 h, and the temperature drops to 180 °C;

[0099] (b) Then cool the high-temperature heating zone 2 and the low-temperature heating zone 3 simultaneously at a speed of 5 °C / h for 31 h until the room temperature is reached.

[0100] Step Six: Take out the single crystal. Inject air into the crystal growth chamber 5 to keep the air pressure inside and outside the cavity consistent. Take out the crystal growth crucible 10 from the furnace chamber, cut its top with a wire saw, and carefully take out the crystal 11 from the crystal growth crucible 10 to obtain a large-sized pentacene doped with p-terphenyl organic single crystal.

[0101] As Figure 5 shown, it is a pentacene doped with p-terphenyl single crystal grown by the method described in Example 3, showing a uniform purplish red color.

[0102] Therefore, the present invention adopts the above improved horizontal Bridgman method for growing large-sized organic single crystals and its preparation method. By improving the traditional single crystal growth equipment of the horizontal Bridgman method, it can effectively solve the problems of volatile control, thermal stress elimination and uniformity regulation in the growth of organic single crystals, and provides an innovative solution for the industrial preparation of optoelectronic functional crystal materials.

[0103] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An apparatus for growing large-sized organic single crystals by an improved horizontal Bridgman method, comprising a horizontal tubular vacuum heating furnace, a crystal growth crucible, and a horizontal moving system, characterized in that: The horizontal tube type vacuum heating furnace is internally provided with a crystal growth chamber. The crystal growth crucible is inclined and located in the crystal growth chamber. The inclination axis of the crystal growth crucible forms an angle of 5° - 8° with the horizontal direction. Externally along the axis of the horizontal tube type vacuum heating furnace, a high-temperature heating zone, a temperature gradient zone, and a low-temperature heating zone are arranged at intervals. The crystal growth crucible adopts a double-layer quartz structure design. The bottom is a funnel-shaped shoulder discharging area with a 15° taper angle, and the upper part is a cylindrical equal-diameter growth area. The funnel-shaped shoulder discharging area includes a first bent capillary channel and a second bent capillary channel, and the bending angles of the first bent capillary channel and the second bent capillary channel are both 25°.

2. The large-size organic single crystal growth device by the improved horizontal Bridgman method according to claim 1, wherein: The high-temperature heating zone, the temperature gradient zone, and the low-temperature heating zone are respectively heated by resistance wire heaters with independent closed-loop control, and are wrapped with alumina fiber heat insulation layers on the periphery. The horizontal tube type vacuum heating furnace realizes dynamic air pressure regulation of the crystal growth chamber through the linkage of a mechanical pump and a digital pressure gauge.

3. The large-size organic single crystal growth device by the improved horizontal Bridgman method according to claim 1, characterized in that: The crystal growth crucible is fixed in the crystal growth cavity, and the inclined installation of the crystal growth crucible is realized by a high-temperature resistant alumina gasket arranged at the bottom.

4. The large-size organic single crystal growth device by the improved horizontal Bridgman method according to claim 1, characterized in that: The horizontal movement system includes a slide rail and a spiral stepping motor. The bottom of the horizontal tube type vacuum heating furnace is slidably connected to the slide rail, and the spiral stepping motor drives the horizontal tube type vacuum heating furnace to slide on the slide rail.

5. The improved horizontal Bridgman method for growing large-sized organic single crystals is characterized in that It is realized by using the device according to any one of claims 1 - 4.

6. The preparation method of growing large-sized organic single crystals by the improved horizontal Bridgman method according to claim 5, characterized in that It includes the following steps: S1 Clean and dry the crystal growth crucible; S2 Load the organic raw material into the crystal growth crucible, cover the ground glass stopper to conduct preliminary sealing treatment on the ground opening of the crystal growth crucible, and incline the crystal growth crucible; S3 Transfer the loaded crystal growth crucible to the position where the high-temperature heating zone of the horizontal vacuum heating furnace is located, and simultaneously conduct vacuum treatment on the crystal growth chamber; S4 Turn on the resistance wire heater to heat the high-temperature heating zone and the low-temperature heating zone of the crystal growth chamber, so that the raw material in the crystal growth crucible is fully melted; S5 Start the spiral stepping motor, and gradually move the crystal growth crucible from the high-temperature heating zone to the low-temperature heating zone at a low speed until the fully melted raw material melt is completely crystallized, and complete the growth of organic single crystals; S6 Cool the crystal growth chamber to room temperature, and take out the organic single crystal.

7. The preparation method for growing large-sized organic single crystals by the improved horizontal Bridgman method according to claim 6, characterized in that, In step S2, at one-third of the distance from the ground opening of the crystal growth crucible, fix the alumina gasket with a polyimide high-temperature resistant tape to make the crystal growth crucible stably inclined.

8. The preparation method of growing large-sized organic single crystals by the improved horizontal Bridgman method according to claim 6, characterized in that, In step S4, set the temperature of the high-temperature heating zone to be 10°C - 20°C higher than the melting point temperature of the organic raw material, set the temperature of the low-temperature heating zone to be 20°C - 30°C lower than the solidification point temperature of the organic raw material, and keep the crystal growth crucible heated in the high-temperature heating zone for 12h to fully melt the organic raw material.

9. The preparation method of growing large-sized organic single crystals by the improved horizontal Bridgman method according to claim 6, characterized in that In step S5, the specific moving rate is set as follows: in the initial stage of nucleation, when the crystallization interface enters from the outer layer to the inner layer bending position of the crystal growth crucible, set the crystal growth chamber to horizontally move to the right at a speed of 0.5 mm / h. When the crystallization interface moves to the funnel-shaped shoulder discharging area, the moving rate is adjusted to 1 mm / h. When all the crystals are crystallized, stop moving.

10. The preparation method of growing large-sized organic single crystals by the improved horizontal Bridgman method according to claim 6, characterized in that, In step S6, when the crystal growth chamber is cooled to room temperature, a stepwise cooling method is adopted for cooling: First, the high-temperature heating zone is cooled to the temperature of the low-temperature heating zone at a rate of 5 °C / h, and then both the high-temperature heating zone and the low-temperature heating zone are cooled to room temperature at a rate of 10 °C / h.

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