Preparation method of large-size bibenzyl organic scintillator single crystal and obtained single crystal

Abstract

The present invention discloses a method for preparing a large-sized bibenzyl organic scintillator single crystal, which relates to the technical field of organic scintillators and includes the following steps: (1) Under the protection of an inert atmosphere, pour bibenzyl into acetone, dissolve it, and heat and stir until the solvent evaporates to obtain crystals; (2) Mix the crystals in step (1) with an organic solvent, dissolve them, and add trans-1,2-distyrene; (3) Gradually lower the temperature, and use the hanging crystal method to observe and find the saturation temperature point of the current ratio; (4) Then adopt the seed crystal method for crystal growth; (5) Below the saturation point and above the avalanche point, carry out crystal growth, set the crystallization rack to rotate forward and backward alternately at a low speed, and after the solute is consumed, obtain crystals. The beneficial effects of the present invention are as follows: By using the method in the present invention, it is easy to obtain large-sized and high-quality organic scintillator single crystals, and the equipment is simple, the temperature requirement is low, it is easy to observe, and large-scale growth can be carried out.

Description

Technical Field

[0001] The present invention relates to the technical field of organic scintillators, and particularly relates to a preparation method of a large-size bibenzyl organic scintillator single crystal and the obtained single crystal. Background Art

[0002] For the inertial confinement fusion (ICF) device being built in our country, to achieve fusion ignition, it is necessary to increase the temperature and density of the fuel as much as possible. Therefore, the corresponding diagnostic technology is very important. For the implosion experiment with high fuel areal density, using the down-scattered neutron fraction to diagnose the areal density of the fuel layer is currently the most reliable method. Neutrons are electrically neutral, and their detection is mainly achieved by detecting the secondary charged particles emitted by the interaction of neutrons with atomic nuclei. The neutron time-of-flight spectrometer is a neutron detector with fast time response. It can convert the time-of-flight spectrum of neutrons into a current signal of time, so it is also called the "eye" for detecting implosion experiments.

[0003] The scintillator is the most core component used in this spectrometer. It is a luminescent material that converts the energy of ionizing radiation into light emission. There are many types of scintillators for neutron detection. From the perspective of physical form, liquid scintillators are used more, such as xylene and p-terphenyl. Although solid organic scintillation crystals only account for a small part, they are particularly suitable for detecting fast high-flux particles because of their extremely excellent fast light decay performance.

[0004] There are many criteria for measuring the performance of a scintillator. On the one hand and most fundamentally, it is required to have a low decay time (afterglow value). The decay time characterizes the response rate or counting ability of the scintillator to incident radiation. To reduce the signal blockage caused by energy pile-up in the crystal, maintain a good signal-to-noise ratio, and improve the time resolution, it is usually required that the decay time be as short as possible, so that the ghosting caused by energy accumulation can be eliminated to the greatest extent. On the other hand, the size of the scintillator should be as large as possible to receive enough signals. This requires us to adopt a suitable growth method to obtain crystals with a high decay rate and large size as much as possible.

[0005] Crystal growth methods can be classified into four categories, namely melt growth, solution growth, vapor growth, and solid-phase growth. For example, the patent application with the publication number CN114836199A discloses a perovskite single-crystal scintillator and its preparation method. With the change of specific control conditions, dozens of crystal growth techniques have evolved from these four types of crystal growth methods. Typical growth techniques include physical vapor deposition, chemical vapor deposition, Czochralski method, Bridgman method, optical floating zone method, etc. The solution method dissolves raw materials in a suitable solvent, makes it supersaturated by changing conditions at the beginning, and further makes the crystal material precipitate out in a set manner to form large single crystals. This method has a wide range of applications and is the main growth method for many crystals, such as the widely used KDP crystal, DAST crystal, and TSB crystal, etc. The advantages of growing crystals by the solution method are good uniformity, easy observation, and the ability to grow at a relatively low temperature. At the same time, a higher requirement is to screen a suitable solvent and precisely control the temperature. In the existing technology, it is not yet possible to simultaneously grow large-size benzyl biphenyl organic scintillator single crystals with a high decay rate. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing a large-size benzyl biphenyl organic scintillator single crystal and the obtained single crystal.

[0007] The present invention solves the above technical problems through the following technical means:

[0008] A method for preparing a large-size (inch-level) benzyl biphenyl organic scintillator single crystal, comprising the following steps:

[0009] (1) Under the protection of an inert atmosphere, pour benzyl biphenyl into acetone, dissolve it, and heat and stir until the solvent evaporates to obtain crystals;

[0010] (2) Mix the crystals in step (1) with an organic solvent, dissolve them, add trans-1,2-diphenylethylene, and dissolve to obtain a large-size benzyl biphenyl organic scintillator single crystal solution;

[0011] (3) Gradually lower the temperature, and use the hanging crystal method to observe and find the saturation temperature point of the current ratio;

[0012] (4) Then use the seed crystal method for crystal growth. Cut a certain shape from a part of the crystals obtained in step (2) according to the natural growth surface, place it in the middle of the bottom of the crystallization rack, and fix it with epoxy resin. Keep the entire platform in an oven at a temperature 2-5 °C higher than the saturation temperature obtained in step (3), and finally transfer it to a growth container;

[0013] (5) Grow the crystal below the saturation point and above the avalanche point. Set the crystallization rack to rotate forward and backward at a low speed. After the solute is consumed, obtain the crystal.

[0014] Beneficial effects: (1) The present invention uses trans-1,2-distyrene as a doping raw material. Compared with the matrix, the neutron attenuation performance is improved by an order of magnitude, with extremely excellent neutron attenuation performance, high application prospects, and can replace some scintillation detectors to achieve accurate detection of fast neutrons.

[0015] (2) The growth equipment of the present invention has a simple structure and is easy to build. The growth temperature requirement is low, and it is in a transparent environment, which is convenient for observing the process and controlling at any time. The preparation method is simple, safe, and efficient.

[0016] (3) In the present invention, it is easy to obtain large-size (inch-level) and high-quality organic scintillator single crystals.

[0017] The preparation method in the present invention can easily obtain large-size and high-quality organic scintillator single crystals, and the equipment is simple, the temperature requirement is low, it is easy to observe, and large-scale growth can be carried out. At the same time, through detection, compared with the matrix, the organic scintillator single crystal of bibenzyl with a certain doping amount has extremely excellent neutron attenuation performance.

[0018] The present invention selects a solution environment to grow the required crystals. At the same time, the natural flow convection in the stagnant solution is not allowed to provide sufficient and uniform crystallization raw materials to the surface of the growing crystals, resulting in a diffusion-state growth. The present invention adopts a crystallization rack that rotates forward and backward alternately at a low speed to ensure as uniform growth as possible so as not to form rough defects.

[0019] Preferably, the organic solvent includes methylene chloride, dichloroethane, cyclopentane, cyclohexane, chloroform, carbon tetrachloride, acetonitrile, acetone, or toluene.

[0020] Beneficial effects: The raw materials of the present invention, such as bibenzyl, stilbene, and organic solvents such as toluene, are convenient to synthesize, have rich reserves, and are low in price. Moreover, the raw materials have high solubility in organic solvents, are not easy to volatilize, have a wide supersaturation region, and have a high output ratio, and are expected to achieve large-scale production.

[0021] Preferably, the temperature of heating and stirring in step (1) is 50-100 °C, and the stirring rate is 0-1000 r / min.

[0022] Preferably, the mass ratio of the crystallization to the volume of the organic solvent in step (2) is 300-800 g: 30-80 mL, and the dissolution temperature is 40-50 °C.

[0023] Preferably, the mass fraction of the added trans-1,2-distyrene is 0-5%.

[0024] Preferably, the mass fraction of the added trans-1,2-distyrene is 0.5-5%.

[0025] Preferably, the cooling rate in step (5) is controlled at 0.01 - 0.03 °C / day. After 10 - 20 days, the crystals grow significantly, and the rate is adjusted to 0.04 - 0.08 °C / day. After about 40 - 60 days, the solute is basically consumed.

[0026] Preferably, when taking out the crystals after obtaining them, a syringe with a heating function is used to extract the excess solvent and solute, and finally the crystals are transferred to warm water and gradually cooled to room temperature.

[0027] Beneficial effect: Prevent the crystals from cracking due to temperature difference.

[0028] Large-sized bibenzyl organic scintillator single crystals prepared by the above preparation method.

[0029] Beneficial effect: After testing, the bibenzyl organic scintillator single crystals with a certain doping amount prepared by the method of the present invention have extremely excellent neutron attenuation performance compared with the matrix.

[0030] The present invention has the following advantages over the prior art:

[0031] (1) The present invention uses trans-1,2-distyrene as the doping raw material. Compared with the matrix, the neutron attenuation performance is improved by an order of magnitude, with extremely excellent neutron attenuation performance, high application prospects, and can replace some scintillator detectors to achieve accurate detection of fast neutrons.

[0032] (2) The growth equipment of the present invention has a simple structure and is easy to build. The growth temperature requirement is low, and it is in a transparent environment, which is convenient for observing the process and controlling at any time. The preparation method is simple, safe, and efficient.

[0033] (3) Large-sized (inch-level) and high-quality organic scintillator single crystals can be easily obtained in the present invention.

[0034] (4) The present invention selects a solution environment to grow the required crystals. At the same time, the natural flow convection in the stagnant solution is not allowed to provide sufficient and uniform crystallization raw materials to the surface of the growing crystals, resulting in diffusive growth. The present invention adopts a crystallization rack that rotates forward and backward alternately at a low speed to ensure as uniform growth as possible and avoid forming rough defects.

[0035] (5) The raw materials of the present invention, such as bibenzyl, stilbene, and organic solvents such as toluene, are convenient to synthesize, have rich reserves, and are inexpensive. Moreover, the raw materials have high solubility in organic solvents, are not easy to volatilize, have a wide supersaturated region, and have a high output ratio, and are expected to achieve large-scale production. Description of the Drawings

[0036] Figure 1 It is a physical diagram of the bibenzyl organic scintillator single crystal prepared in Example 1 of the present invention;

[0037] Figure 2 XRD patterns of the single crystal and ground polycrystal of bibenzyl organic scintillator prepared in Example 1 of the present invention;

[0038] Figure 3 Test results of the decay performance of bibenzyl organic scintillators with different doping concentrations prepared in the examples of the present invention. Detailed implementation mode

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0040] The test materials and reagents used in the following embodiments can be obtained from commercial channels without special instructions.

[0041] For those not specifying specific technologies or conditions in the embodiments, they can all be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications.

[0042] The bibenzyl material used in the following embodiments has the English name Bibenzyl, the chemical name 1,2-diphenylethane, and the molecular formula C 14 H 14 . The doping material used is another organic compound Stilbene, the chemical name trans-1,2-distyrene, and the molecular formula C 14 H 12 .

[0043] Example 1

[0044] A bibenzyl single crystal doped with 1% by mass of stilbene, and the specific preparation method includes the following steps:

[0045] (1) Inside a glove box protected by argon, pour more than 500 g of bibenzyl raw material powder into 50 mL of acetone solution;

[0046] (2) Place the mixed solution obtained in step (1) on a magnetic stirrer, set the temperature to 80 °C, and the stirring rate to 500 r / min. After 2 hours, a lot of white crystals are obtained at the bottom of the beaker;

[0047] (3) Weigh 500 g of the crystals obtained in step (2) and place them in a flat-bottomed glass cup. Pour 50 mL of toluene into it, and place the entire container in a silicone oil bath pot with an initial temperature set to 50 °C. At the same time, weigh 5 g of stilbene and add it to the beaker. After keeping warm for 1 day, it can be seen that it is completely dissolved;

[0048] (4) Gradually lower the temperature. Every 0.5 °C, continuously use the hanging crystal method, that is, hang a seed crystal to observe the eddy current and dissolution on the surface, and finally determine that the saturation point at this solubility is 48 °C;

[0049] (5) Select crystals with appropriate sizes and certain natural growth surfaces from the partial crystallization obtained in step (2), place them in the middle at the bottom of the crystallization rack, and fix them with epoxy resin. Then keep the entire platform at 50 °C in an oven. After 3 hours, quickly transfer it to the growth container; in this embodiment, the shape and structure of the crystallization rack are prior arts, and the crystallization rack can rotate forward or backward.

[0050] (6) The growth of the crystal should be in the supersaturated region. Initially, control the cooling rate at 0.02 °C / day. After 2 weeks, the crystal grows significantly. At this time, adjust the rate to 0.05 °C / day, and the crystal continues to grow stably. After about 60 days, the solute in it is consumed, and then stop cooling;

[0051] (7) Prepare warm water in advance. Use a syringe with a heating function to extract the excess solvent and solute, then promptly transfer the crystal to the warm water, wait for it to cool to room temperature, and finally transfer it from the crystallization rack to a vacuum drying dish for storage.

[0052] Figure 1 This is a physical picture of the dibenzyl organic scintillator single crystal prepared in this embodiment. The dimensions in its three directions all exceed 3 cm, belonging to a large single crystal of inch level. It is transparent as a whole, and there are a few hole-type defects locally.

[0053] Figure 2 This is the XRD pattern of the single crystal prepared in this embodiment and the polycrystal obtained after grinding. The fitting shows that its space group is P21 / n, belonging to the monoclinic system, and the natural growth surface is the (1 0 -1) plane.

[0054] Figure 3 These are the test results of the decay performance of organic scintillators with different doping concentrations. It can be seen that compared with the parent body, the neutron decay performance of the doped dibenzyl single crystal has an order of magnitude improvement, and the performance of the single crystal sample in this embodiment is the best, and the decay rate per nanosecond can reach one ten-thousandth.

[0055] Example 2

[0056] A dibenzyl single crystal (parent body) doped with 0.0% mass fraction of stilbene, and the specific preparation method includes the following steps:

[0057] (1) In a glove box protected by argon, pour more than 500 g of dibenzyl raw material powder into 50 mL of acetone solution;

[0058] (2) Place the mixed solution obtained in step (1) on a magnetic stirrer, set the temperature at 80 °C, and the stirring rate at 500 r / min. After 2 hours, a lot of white crystals are obtained at the bottom of the beaker;

[0059] (3) Weigh 500 g of the crystals obtained in step (2) and place them in a flat-bottomed glass cup. Pour 50 mL of toluene into it, and place the whole container in a silicone oil bath pot with an initial temperature set at 50 °C. After keeping warm for 1 day, it can be seen that it is completely dissolved;

[0060] (4) Gradually cool down. Every 0.5 °C, continuously use the hanging crystal method, that is, hang a seed crystal and observe the eddy current and dissolution on the surface. Finally, it is determined that the saturation point at this solubility is 48 °C;

[0061] (5) Select crystals of appropriate size with a certain natural growth surface from the crystals obtained in step (2), place them in the middle at the bottom of the crystallization rack, and fix them with epoxy resin. Then keep the whole platform at 50 °C in an oven. After 3 hours, quickly transfer it to a growth container; in this embodiment, the shape and structure of the crystallization rack are prior art, and the crystallization rack can rotate forward or backward.

[0062] (6) The growth of the crystal should be in the supersaturated region. In the initial stage, the cooling rate is controlled at 0.02 °C / day. After 2 weeks, the crystal grows significantly. At this time, adjust the speed to 0.05 °C / day, and the crystal continues to grow stably. After about 60 days, the solute in it is consumed, and at this time, stop cooling;

[0063] (7) Prepare warm water in advance. Use a syringe with a heating function to extract the excess solvent and solute, then quickly transfer the crystal to the warm water, wait for it to cool to room temperature, and finally transfer it from the crystallization rack to a vacuum drying dish for storage.

[0064] Figure 3 For the test results of the decay performance of organic scintillators with different doping concentrations, it can be seen that the neutron decay performance of undoped bibenzyl single crystals can reach one-thousandth within nanoseconds.

[0065] Example 3

[0066] Bibenzyl single crystal doped with 0.5% by mass fraction of stilbene, and the specific preparation method includes the following steps:

[0067] (1) Inside a glove box protected by argon, pour more than 500 g of bibenzyl raw material powder into 50 mL of acetone solution;

[0068] (2) Place the mixed solution obtained in step (1) on a magnetic stirrer, set the temperature at 80 °C, and the stirring rate at 500 r / min. After 2 hours, a lot of white crystals are obtained at the bottom of the beaker;

[0069] (3) Weigh 500 g of the crystals obtained in step (2) and place them in a flat-bottomed glass cup. Pour 50 mL of toluene into it, and place the whole container in a silicone oil bath pot with an initial temperature set at 50°C. Meanwhile, weigh 2.5 g of stilbene and add it to the beaker. After keeping it warm for 1 day, it can be seen that it is completely dissolved;

[0070] (4) Gradually lower the temperature. Every 0.5°C, continuously use the hanging crystal method, that is, hang a seed crystal to observe the eddy current and dissolution on the surface, and finally determine that the saturation point at this solubility is 48°C;

[0071] (5) Select crystals of appropriate size with a certain natural growth surface from the crystals obtained in step (2), place them in the middle at the bottom of the crystallization rack, and fix them with epoxy resin. Then keep the whole platform warm at 50°C in an oven. After 3 hours, quickly transfer it to the growth container; in this embodiment, the shape and structure of the crystallization rack are prior art, and the crystallization rack can rotate forward or backward.

[0072] (6) The growth of the crystals should be in the supersaturated region. In the initial stage, the cooling rate is controlled at 0.02°C / day. After 2 weeks, the crystals grow significantly. At this time, adjust the rate to 0.05°C / day, and the crystals continue to grow stably. After about 60 days, the solute in them is consumed, and then stop cooling;

[0073] (7) Prepare warm water in advance. Use a syringe with a heating function to extract the excess solvent and solute, then promptly transfer the crystals to the warm water, wait for them to cool to room temperature, and finally transfer them from the crystallization rack to a vacuum drying dish for storage.

[0074] Figure 3 The results of the decay performance test of organic scintillators with different doping concentrations are shown. It can be seen that the neutron decay performance of the 0.5% doped bibenzyl single crystal is between that of the matrix and the 1% doped one, and can reach one ten-thousandth within nanoseconds.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a large-sized bibenzyl organic scintillator single crystal, characterized in that: It includes the following steps: (1) Under the protection of an inert atmosphere, pour bibenzyl into acetone. After dissolution, heat and stir until the solvent evaporates to obtain crystals; (2) Mix the crystals in step (1) with an organic solvent. After dissolution, add trans-1,2-diphenylethylene. After dissolution, obtain a large-sized single crystal solution of bibenzyl organic scintillator; the mass fraction of trans-1,2-diphenylethylene added is 0.5% - 5%; (3) Gradually cool down and use the hanging crystal method to observe and find the saturation temperature point of the current ratio; (4) Adopt the seed crystal method for crystal growth. Cut a certain shape from a part of the crystals obtained in step (2) according to the natural growth surface, place it in the middle of the bottom of the crystallization rack, and fix it with epoxy resin. Keep the whole platform in an oven at a temperature 2 - 5 °C higher than the saturation temperature obtained in step (3), and finally transfer it to the growth container; (5) Grow the crystals below the saturation point and above the avalanche point. Set the crystallization rack to rotate forward and backward at a low speed alternately. After the solute is consumed, obtain the crystals; control the cooling rate at 0.01 - 0.03 °C / day. After 10 - 20 days, the crystals grow significantly, and the speed is adjusted to 0.04 - 0.08 °C / day. After 40 - 60 days, the solute is consumed. The obtained crystals are large single crystals of inch size and belong to the monoclinic crystal system with the space group of P21 / n.

2. The preparation method of the large-sized bibenzyl organic scintillator single crystal according to claim 1, characterized in that: The organic solvent includes methylene chloride, dichloroethane, cyclopentane, cyclohexane, chloroform, carbon tetrachloride, acetonitrile, acetone or toluene.

3. The preparation method of the large-sized bibenzyl organic scintillator single crystal according to claim 2, characterized in that: The organic solvent is toluene.

4. The preparation method of the large-size bibenzyl organic scintillator single crystal according to claim 1, wherein: In step (1), the temperature of heating and stirring is 50 - 100 °C, and the stirring rate is 0 - 1000 r / min.

5. The preparation method of the large-sized bibenzyl organic scintillator single crystal according to claim 1, characterized in that: In step (2), the ratio of the mass of the crystals to the volume of the organic solvent is 300 - 800 g: 30 - 80 mL, and the dissolution temperature is 40 - 50 °C.

Images