Preparation method of boron nitride nanotubes and boron nitride nanotubes
By using carbonate, magnesium oxide and boron precursors to generate low melting point precursors under low temperature conditions, the problem of high synthesis temperature of boron nitride nanotubes is solved, and boron nitride nanotubes that reduce production costs and improve industrial production are achieved. Application.
Patent Information
- Application Number
- CN202310208969.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-07
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2043-03-07
AI Technical Summary
The synthesis temperature of boron nitride nanotubes is too high, resulting in high production costs, limiting their application in industrial production.
Carbonate, magnesium oxide and boron precursors are used to heat up under an inert atmosphere to form a low melting point precursor, and the boron nitride nanotubes are continuously reacted in an ammonia atmosphere at a lower temperature of 850 to 1200°C.
It effectively reduces the growth temperature and production cost of boron nitride nanotubes, and promotes its industrial production and wide application.
Smart Images
Figure CN116199194B_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of nanomaterials, and specifically relates to a method for preparing boron nitride nanotubes and boron nitride nanotubes. Background Art
[0002] At present, the preparation methods of boron nitride nanotubes (BNNTs) are mainly divided into ultra-high temperature preparation technology and high temperature preparation technology. Among them, the temperature of ultra-high temperature preparation technology is generally above 2000℃, and the growth temperature is extremely high, resulting in excessively high production costs and is not suitable for large-scale industrial production. The temperature of high temperature preparation technology is generally between 1100 and 1500℃. Among them, the chemical vapor deposition method (CVD) has simple equipment and is easy to control. The obtained BNNTs are of high quality and are the most popular method. In the current method of preparing BNNTs by CVD, whether the precursor is the most classic boron and metal oxide, or boron and metal compounds, or borides and nitrides, the synthesis temperature of BNNTs is above 1100℃ due to the high melting point, which greatly limits the application of CVD to prepare BNNTs in industrial production. Summary of the invention
[0003] The purpose of the present application is to provide a method for preparing boron nitride nanotubes and boron nitride nanotubes, so as to solve the technical problem in the prior art that the synthesis temperature of boron nitride nanotubes is too high, resulting in too high production cost of boron nitride nanotubes and limiting the industrial production of boron nitride nanotubes.
[0004] To achieve the above purpose, a technical solution adopted in this application is:
[0005] A method for preparing boron nitride nanotubes is provided, comprising:
[0006] Weighing raw materials into a reactor, the raw materials comprising carbonate, magnesium oxide and a boron precursor;
[0007] The reactor is heated to a reaction temperature under an inert atmosphere to generate a precursor, wherein the reaction temperature is 850 to 1200° C.;
[0008] placing the reactor under an ammonia atmosphere, maintaining the reaction temperature, and continuously reacting to generate boron nitride nanotubes;
[0009] The reactor was cooled to room temperature under an inert atmosphere to obtain boron nitride nanotubes.
[0010] In one or more embodiments, the molar ratio of carbonate, magnesium oxide and boron precursor in the raw material is 1:1:(2-6).
[0011] In one or more embodiments, the carbonate in the raw material is one or a combination of potassium carbonate and sodium carbonate.
[0012] In one or more embodiments, in the step of heating the reactor to the reaction temperature under an inert atmosphere, the heating is specifically to uniformly heat the reactor at a rate of 10 to 30° C. / min.
[0013] In one or more embodiments, in the step of heating the reactor to the reaction temperature under an inert atmosphere, the inert atmosphere is specifically argon gas with a flow rate of 20 to 100 standard cubic centimeters per minute.
[0014] In one or more embodiments, in the step of placing the reactor under an ammonia atmosphere, the ammonia atmosphere is specifically ammonia with a flow rate of 20 to 100 standard cubic centimeters per minute.
[0015] In one or more embodiments, the reaction temperature is 950-1200°C.
[0016] In one or more embodiments, in the step of continuously reacting to generate boron nitride nanotubes, the continuous reaction specifically lasts for 60 to 180 minutes.
[0017] In one or more embodiments, the reactor is a boron nitride boat, and the heating is specifically performed by placing the reactor in a central heating position of a tubular furnace.
[0018] To achieve the above purpose, another technical solution adopted by this application is:
[0019] Provided is a boron nitride nanotube prepared by the preparation method described in any of the above embodiments.
[0020] Different from the prior art, the beneficial effects of this application are:
[0021] The present application first uses carbonate, magnesium oxide and boron precursors to prepare a low melting point precursor during a heating process, and then continuously reacts at a lower temperature to generate boron nitride nanotubes, which can effectively reduce the growth temperature and the preparation cost of boron nitride nanotubes, and is conducive to the wide application and industrial production of boron nitride nanotubes.
[0022] The preparation method of the present application can grow boron nitride nanotubes at a relatively low temperature of 850°C, and a large number of high-quality boron nitride nanotubes can be obtained at 950°C, which effectively reduces the synthesis temperature of boron nitride nanotubes and the preparation cost of boron nitride nanotubes, and is conducive to the widespread application and industrial production of boron nitride nanotubes. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a schematic diagram of a process of an embodiment of a method for preparing boron nitride nanotubes of the present application;
[0024] Figure 2It is the XRD diffraction pattern of effect example 1 of the present application;
[0025] Figure 3 is a picture of the boron nitride nanotubes prepared in Example 3 of the present application;
[0026] Figure 4 This is the analysis diagram of effect example 2 of the present application;
[0027] Figure 5 is a transmission electron microscope image of the boron nitride nanotubes prepared in Example 3 of the present application;
[0028] Figure 6 This is a scanning electron microscope image of Effect Example 3 of the present application. DETAILED DESCRIPTION
[0029] The present application will be described in detail below in conjunction with the various embodiments shown in the accompanying drawings. However, these embodiments do not limit the present application, and any structural, methodological, or functional changes made by a person of ordinary skill in the art based on these embodiments are all within the scope of protection of the present application.
[0030] Boron nitride nanotubes (BNNTs) are one-dimensional hollow tubular nanomaterials composed of B and N through alternating covalent bonds. They have attracted much attention due to their unique physical and chemical properties. Compared with carbon nanotubes, BNNTs have similar mechanical strength and lightweight characteristics, but their high temperature resistance and oxidation resistance are better than carbon nanotubes. Due to the polar bonding between B and N, BNNTs have strong interfacial bonding with polymers and can be effectively used as a mechanical reinforcement phase for polymer materials. In addition, electrical insulation (band gap of 5.5 eV) and neutron absorption are also important characteristics of BNNTs. Therefore, BNNTs have broad application prospects in the fields of thermal interface materials, high temperature resistant materials, radiation shielding materials, deep ultraviolet emitters, etc. However, the current market price of BNNTs is very expensive, which greatly limits its application. Therefore, how to prepare BNNTs at low cost is the focus of current research.
[0031] The preparation methods of boron nitride nanotubes are mainly divided into ultra-high temperature preparation technology and high temperature preparation technology. Among them, the temperature of ultra-high temperature preparation technology is generally above 2000℃, mainly including laser ablation, thermal plasma and arc discharge methods. These three methods can produce high-quality BNNTs, but the growth temperature is extremely high, resulting in excessively high production costs and not suitable for large-scale industrial production. The temperature of high-temperature preparation technology is generally between 1100-1500℃, among which the chemical vapor deposition (CVD) method has simple equipment, is easy to control, and the obtained BNNTs are of high quality, making it the most popular method.
[0032] In the current method of preparing BNNTs by CVD, the precursors, whether they are the most classic boron and metal oxides, boron and metal compounds, or borides and nitrides, have high melting points, resulting in the synthesis temperature of BNNTs being above 1100°C, which greatly limits the application of CVD to prepare BNNTs in industrial production.
[0033] In order to solve the above problems, the applicant has developed a method for preparing boron nitride nanotubes. This preparation method can prepare high-quality boron nitride nanotubes at a lower growth temperature by preparing a low-melting-point precursor, thereby effectively reducing the production cost of boron nitride nanotubes, thereby helping to improve the application scenarios of boron nitride nanotubes.
[0034] Specifically, see Figure 1 , Figure 1 It is a schematic flow chart of an embodiment of a method for preparing boron nitride nanotubes of the present application.
[0035] The preparation method comprises:
[0036] S100, weighing raw materials into a reactor, the raw materials including carbonate, magnesium oxide and a boron precursor.
[0037] S200, heating the reactor to a reaction temperature under an inert atmosphere to generate a precursor.
[0038] The reaction temperature is 850-1200° C. Preferably, the reaction temperature may be 950-1200° C.
[0039] Firstly, carbonate, magnesium oxide and boron precursors may be used as raw materials. In the process of heating to a reaction temperature, the carbonate, magnesium oxide and boron precursors may react to generate a low melting point precursor.
[0040] In one embodiment, the molar ratio of carbonate, magnesium oxide and boron precursor in the raw material may be 1:1:(2-6).
[0041] Preferably, the molar ratio of carbonate, magnesium oxide and boron precursor may be 1:1:4.
[0042] Specifically, in one embodiment, the boron precursor may be boron powder, and in other embodiments, the boron precursor may also be other materials containing boron elements, such as sodium tetraborate, etc., which can achieve the effect of this embodiment.
[0043] In one embodiment, the carbonate may be potassium carbonate. During the heating process, potassium carbonate, magnesium oxide and a boron precursor may react to generate a KMgBO3 precursor, which contains both a boron source and a catalyst metal and has a low melting point. Based on this precursor, a boron nitride precursor can be prepared at a relatively low temperature.
[0044] In another embodiment, the carbonate may also be sodium carbonate. During the heating process, sodium carbonate, magnesium oxide and a boron precursor may react to generate a NaMgBO3 precursor, which has a lower melting point and can also prepare a boron nitride precursor at a lower temperature.
[0045] In other embodiments, the carbonate may also be other types of metal salts, and any low-melting-point precursor that can be prepared and synthesized to include both a boron source and a catalyst metal can achieve the effect of this embodiment.
[0046] In one embodiment, the reactor may be a boron nitride boat, and the reactor may be placed in the central heating area of a tube furnace, and the reactor may be heated to the reaction temperature by the tube furnace.
[0047] In other embodiments, other types of reactors, such as ceramic reactors, crucibles, etc., may also be used, and other heating devices may be used. The effect of this embodiment can be achieved by heating the reaction temperature to 850 to 1200°C.
[0048] In one embodiment, in order to ensure the stable reaction of carbonate, magnesium oxide and boron precursor, the temperature can be raised by uniformly raising the temperature of the reactor at a rate of 10 to 30° C. / min. Preferably, the temperature of the reactor can be uniformly raised at a rate of 20° C. / min.
[0049] In one embodiment, the inert atmosphere may be argon gas with a flow rate of 20 to 100 standard cubic centimeters per minute. In other embodiments, other types of inert gases, such as nitrogen, helium, etc., may also be used.
[0050] S300, placing the reactor under an ammonia atmosphere, maintaining the reaction temperature, and continuing the reaction to generate boron nitride nanotubes.
[0051] After a low-melting-point precursor is generated in the reactor, the inert gas can be replaced by ammonia, thereby placing the reactor under an ammonia atmosphere, so that the precursor continuously reacts with ammonia at a reaction temperature to generate boron nitride nanotubes.
[0052] In one embodiment, the ammonia atmosphere may be ammonia gas with a flow rate of 20 to 100 standard cubic centimeters per minute.
[0053] In one embodiment, the continuous reaction may specifically be a reaction time of 60 to 180 minutes. Preferably, the continuous reaction may specifically be a reaction time of 120 minutes.
[0054] S400, cooling the reactor to room temperature under an inert atmosphere to obtain boron nitride nanotubes.
[0055] Specifically, the inert atmosphere may be the same as the inert atmosphere in step S200, or other inert gases may be used as long as they can fully protect the boron nitride nanotubes at high temperatures.
[0056] It can be understood that by adopting the above-mentioned preparation method, a low-melting-point precursor is first prepared by using carbonate, magnesium oxide and boron precursors during a heating process, and then the boron nitride nanotubes are generated by continuous reaction at a relatively low temperature. This can effectively reduce the growth temperature and the preparation cost of the boron nitride nanotubes, which is conducive to the widespread application and industrial production of boron nitride nanotubes.
[0057] The technical solution of the present application is further explained in detail below with specific implementation methods.
[0058] Embodiment 1:
[0059] A boron nitride nanotube is prepared by the following steps:
[0060] Weigh potassium carbonate, magnesium oxide and boron powder in a molar ratio of 1:1:4, place them in a boron nitride boat, and place the boron nitride boat in the center of the tube furnace. Introduce 50 standard cubic centimeters per minute (sccm) of argon into the tube furnace, and control the tube furnace to heat up to a center temperature of 850°C at 20°C / min. During the heating process, the boron nitride boat reacts to generate KMgBO3 precursor.
[0061] Then, 50 sccm of ammonia gas was introduced into the tube furnace to replace argon gas, and the temperature was maintained at 850°C for 120 minutes to grow boron nitride nanotubes. After the reaction was completed, 50 sccm of argon gas was introduced into the tube furnace, and the sample was taken out after cooling to room temperature to obtain boron nitride nanotubes.
[0062] Embodiment 2:
[0063] A boron nitride nanotube is prepared by the following steps:
[0064] Weigh potassium carbonate, magnesium oxide and boron powder in a molar ratio of 1:1:2, place them in a boron nitride boat, and place the boron nitride boat in the central heating position of a tube furnace. Introduce 20 standard cubic centimeters per minute (sccm) of argon gas into the tube furnace, and control the tube furnace to heat up to a central temperature of 950°C at 10°C / min. During the heating process, the boron nitride boat reacts to generate a KMgBO3 precursor.
[0065] Then, 100 sccm of ammonia gas was introduced into the tube furnace to replace argon gas, and the temperature was maintained at 950°C for 60 minutes to grow boron nitride nanotubes. After the reaction was completed, 20 sccm of argon gas was introduced into the tube furnace, and the sample was taken out after cooling to room temperature to obtain boron nitride nanotubes.
[0066] Embodiment 3:
[0067] A boron nitride nanotube is prepared by the following steps:
[0068] Sodium carbonate, magnesium oxide and boron powder were weighed in a molar ratio of 1:1:6 and placed in a boron nitride boat, which was then placed in the central heating position of a tube furnace. 100 standard cubic centimeters per minute (sccm) of argon gas was introduced into the tube furnace, and the tube furnace was controlled to heat up to a central temperature of 1000°C at 30°C / min. During the heating process, the boron nitride boat reacted to generate a NaMgBO3 precursor.
[0069] Then, 20 sccm of ammonia gas was introduced into the tube furnace to replace argon gas, and the temperature was maintained at 1000°C for 180 minutes to grow boron nitride nanotubes. After the reaction was completed, 20 sccm of argon gas was introduced into the tube furnace, and the sample was taken out after cooling to room temperature to obtain boron nitride nanotubes.
[0070] Embodiment 4:
[0071] A boron nitride nanotube is prepared by the following steps:
[0072] Weigh potassium carbonate, magnesium oxide and boron powder in a molar ratio of 1:1:4, place them in a boron nitride boat, and place the boron nitride boat in the center of the tube furnace. Introduce 50 standard cubic centimeters per minute (sccm) of argon into the tube furnace, and control the tube furnace to heat up to the center temperature of 1100°C at 20°C / min. During the heating process, the boron nitride boat reacts to generate KMgBO3 precursor.
[0073] Then, 50 sccm of ammonia gas was introduced into the tube furnace to replace argon gas, and the temperature was maintained at 1100°C for 120 minutes to grow boron nitride nanotubes. After the reaction was completed, 50 sccm of argon gas was introduced into the tube furnace, and the sample was taken out after cooling to room temperature to obtain boron nitride nanotubes.
[0074] Embodiment 5:
[0075] A boron nitride nanotube is prepared by the following steps:
[0076] Weigh potassium carbonate, magnesium oxide and boron powder in a molar ratio of 1:1:4, place them in a boron nitride boat, and place the boron nitride boat in the center of the tube furnace. Introduce 50 standard cubic centimeters per minute (sccm) of argon gas into the tube furnace, and control the tube furnace to heat up to the center temperature of 1200°C at 20°C / min. During the heating process, the boron nitride boat reacts to generate KMgBO3 precursor.
[0077] Then, 50 sccm of ammonia gas was introduced into the tube furnace to replace argon gas, and the temperature was maintained at 1200°C for 120 minutes to grow boron nitride nanotubes. After the reaction was completed, 50 sccm of argon gas was introduced into the tube furnace, and the sample was taken out after cooling to room temperature to obtain boron nitride nanotubes.
[0078] Effect example 1:
[0079] The precursor prepared in Example 2 was subjected to XRD diffraction analysis, and control experiments 1 and 2 were designed. Control experiment 1 used magnesium oxide and boron powder in a molar ratio of 1:2 as raw materials, and the precursor was prepared in the same steps as in Example 2. Control experiment 2 used potassium carbonate and boron powder in a molar ratio of 1:2 as raw materials, and the precursor was prepared in the same steps as in Example 2. The precursors of control experiments 1 and 2 were subjected to XRD diffraction analysis, and the results were obtained. Figure 2 .
[0080] See also Figure 2 , Figure 2 It is the XRD diffraction pattern of Example 1 of the present application, wherein a, b, and c are the XRD diffraction patterns of the precursors prepared in Control Experiment 1, Control Experiment 2, and Example 2, respectively.
[0081] As shown in Figure a, the peak with number 4 corresponds to Mg2B2O5, which means that magnesium oxide and boron react to generate Mg2B2O5 (JCPDS Card No. 73-2232) with a melting point of about 1400°C; as shown in Figure b, the peak with number 5 corresponds to K2B4O7 (JCPDS Card No. 70-1494), which means that potassium carbonate and boron powder react to generate potassium borate with a melting point of about 780°C; as shown in Figure c, the peak with number 6 corresponds to KMgBO3 (.JCPDS Card No. 174336), and the peak with number 7 corresponds to Mg3(BO3)2 (JCPDS Card No. 33-0858).
[0082] The above experiments can verify that the main product of the reaction of potassium carbonate, magnesium oxide and boron is potassium magnesium borate, and the melting point of potassium magnesium borate is between magnesium borate and potassium borate.
[0083] Effect example 2:
[0084] See also Figure 3 , Figure 3 This is a picture of the boron nitride nanotubes prepared in Example 3 of the present application. As shown in the figure, it is in the form of white powder.
[0085] The boron nitride nanotubes prepared in Example 3 were subjected to XRD diffraction analysis, Raman spectroscopy analysis, and infrared spectroscopy analysis, respectively, to obtain Figure 4 .
[0086] See also Figure 4 , Figure 4 This is the analysis spectrum of Effect Example 2 of the present application, in which a is the XRD diffraction spectrum, b is the Raman spectrum, and c is the FTIR spectrum.
[0087] As shown in the figure, the XRD diffraction pattern shows that the five peaks of (002), (100), (101), (102) and (110) planes are the characteristic signals of h-BN, which correspond to the characteristic signals of h-BN in the JCPDS card (No. 73-2095), proving that the grown sample has a pure h-BN structure.
[0088] Raman spectrum showed that at 1368 cm -1 There is a strong absorption band at , which is related to the E2g in-plane vibration mode of h-BN.
[0089] Furthermore, the FTIR spectrum showed that at 1520 cm -1 、1365cm -1 and 806cm -1 Three absorption regions were obtained near 806cm -1 The absorption peak at 1365 cm is the BNb bending vibration parallel to the c-axis. -1 The absorption peak at 1520cm is the BN stretching vibration perpendicular to the c-axis, which is a characteristic of BN. -1 The absorption peak at belongs to the vibration of the BN skeleton along the tangent direction of the nanotube and is only observed in high-purity and high-crystallinity BNNTs.
[0090] Therefore, based on the above spectra, it is proved that high-purity boron nitride is prepared in Example 3.
[0091] The boron nitride nanotubes prepared in Example 3 were analyzed by transmission electron microscopy, and the results were Figure 5 , Figure 5 This is a transmission electron microscope image of the boron nitride nanotubes prepared in Example 3 of the present application.
[0092] As shown in the figure, the prepared boron nitride nanotubes have a hollow tubular structure.
[0093] Based on the above analysis, it can be seen that Example 3 prepares high-purity boron nitride nanotubes.
[0094] Effect Example 3: Characterization Analysis
[0095] The boron nitride nanotubes prepared in Examples 1 to 5 were analyzed by scanning electron microscopy to obtain Figure 6 .
[0096] See also Figure 6 , Figure 6 1 is a scanning electron microscope image of Example 3 of the present application, in which a, b, c, d, and e are SEM images of boron nitride nanotubes prepared in Examples 1, 2, 3, 4, and 5, respectively.
[0097] As shown in the figure, some boron nitride nanotubes have grown at 850°C in Example 1, but the number is small. A large number of high-quality boron nitride nanotubes can be grown at 950°C in Example 2; and a large number of high-quality boron nitride nanotubes can be grown in Examples 3 to 5.
[0098] Therefore, it can be seen from the above that the present application can grow boron nitride nanotubes at a relatively low temperature of 850°C, and a large number of high-quality boron nitride nanotubes can be obtained at 950°C.
[0099] The above description of the present disclosure is provided to enable any person of ordinary skill in the art to implement or use the present disclosure. Various modifications to the present disclosure will be apparent to those of ordinary skill in the art, and the general principles corresponding to the present disclosure may be applied to other variations without departing from the scope of protection of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but is consistent with the widest range of principles and novel features disclosed herein.
Claims
1. A method for preparing boron nitride nanotubes, characterized in that: include: Weighing raw materials into a reactor, the raw materials comprising carbonate, magnesium oxide and a boron precursor; The reactor is heated to a reaction temperature under an inert atmosphere to generate a precursor, wherein the reaction temperature is 850-1200° C.; Placing the reactor under an ammonia atmosphere, maintaining the reaction temperature, and continuously reacting to generate boron nitride nanotubes; Cooling the reactor to room temperature under an inert atmosphere to obtain boron nitride nanotubes; Wherein, the carbonate in the raw material is one or a combination of potassium carbonate and sodium carbonate.
2. The preparation method according to claim 1, characterized in that: The molar ratio of carbonate, magnesium oxide and boron precursor in the raw material is 1:1:(2-6).
3. The preparation method according to claim 1, characterized in that: In the step of heating the reactor to the reaction temperature under an inert atmosphere, the heating is specifically to uniformly heat the reactor at a rate of 10-30° C. / min.
4. The preparation method according to claim 1, characterized in that: In the step of heating the reactor to the reaction temperature under an inert atmosphere, the inert atmosphere is specifically argon gas with a flow rate of 20 to 100 standard cubic centimeters per minute.
5. The preparation method according to claim 1, characterized in that: In the step of placing the reactor under an ammonia atmosphere, the ammonia atmosphere is specifically ammonia with a flow rate of 20 to 100 standard cubic centimeters per minute.
6. The preparation method according to claim 1, characterized in that: The reaction temperature is 950-1200°C.
7. The preparation method according to claim 1, characterized in that: In the step of continuously reacting to generate boron nitride nanotubes, the continuous reaction specifically lasts for 60 to 180 minutes.
8. The preparation method according to claim 1, characterized in that: The reactor is a boron nitride boat, and the heating is specifically performed by placing the reactor in the central heating position of a tubular furnace.
9. A boron nitride nanotube prepared by the preparation method according to any one of claims 1 to 8.