Bulk boron arsenide and methods of making and using the same

Abstract

The application provides a boron arsenide bulk body and a preparation method and application thereof, and the method comprises the following steps: pre-activating arsenic powder and boron powder to obtain a pre-activated product; mixing the pre-activated product with an iodine agent to obtain a mixed product; and performing high-temperature and high-pressure sintering treatment on the mixed product to obtain the boron arsenide bulk body; wherein the pressure of the high-temperature and high-pressure sintering treatment is 1-6 GPa, the temperature is 800-900 DEG C, and the time length is 5-60 minutes. The application improves the arsenic-boron reactivity through ball milling pre-activation, uses the iodine agent as an active mineralizer, generates gaseous iodides from the iodine agent under high temperature and high pressure to promote the reaction and optimize the selective inhibition of the side phase, simultaneously, the high-pressure environment makes the arsenic in a liquid state as a reaction medium, and the reaction activation energy is greatly reduced. The application realizes the rapid preparation of the boron arsenide bulk body, the obtained product has high phase purity, uniform microstructure and excellent crystal quality.

Description

Technical Field

[0001] This invention belongs to the field of boron arsenide preparation technology, specifically relating to a boron arsenide bulk, its preparation method, and its application. Background Technology

[0002] Boron arsenide (BAs), as a novel wide-bandgap semiconductor material, possesses ultra-high thermal conductivity, excellent carrier mobility, and good radiation resistance, showing broad application prospects in high-temperature semiconductor fields such as thermoelectric conversion, optoelectronic devices, nuclear protection, and aerospace. Currently, the main methods for preparing boron arsenide include chemical vapor transport (CVT) and melt methods. The CVT involves sealing elemental arsenic, elemental boron, and a transport agent in a specific ratio within a quartz tube. Under vacuum conditions, a temperature gradient is established to achieve mass transport, thereby growing boron arsenide crystals. The melt method involves sealing excess arsenic and boron within a quartz tube. The volatilization of excess arsenic generates self-generated pressure, causing some arsenic to exist in a liquid state, thus growing cubic boron arsenide crystals through a solution mechanism.

[0003] However, existing methods for preparing boron arsenide generally suffer from the easy formation of secondary phases (such as boron dodecyl diarsenide, B) in the product. 12 The technical challenges of As2 synthesis are significant. Due to the vast differences in the physicochemical properties of arsenic (sublimation point approximately 613℃) and boron (melting point approximately 2076℃), and the complexity of the reaction pathways, boron atoms tend to preferentially form stable boron atoms during high-temperature synthesis if the reaction kinetics are not properly controlled. 12 The icosahedral structure leads to the generation of B. 12 As2 is the secondary phase, not the target BAs phase. While chemical vapor transport can yield some BAs crystals, the reaction time is long (2-6 days), and parameters such as temperature gradient and transport agent dosage are difficult to control precisely. The product often contains contaminants of B. 12 As2 and other secondary phases result in poor product purity and uniformity. Although the melt method utilizes excess arsenic to provide self-generated pressure, its pressure control capability is limited (typically below 10 MPa), making it difficult to effectively suppress the aggregation of boron atoms into boron (B). 12 The icosahedron still presents a significant problem with the secondary phase, and the quartz tube is at risk of bursting under high temperature and pressure, resulting in poor operational safety.

[0004] Therefore, there is an urgent need in the field to develop a method for rapidly and controllably preparing pure boron arsenide bulk without secondary phases. Summary of the Invention

[0005] To address the technical problems of long preparation cycles and the tendency of products to contain secondary phases (such as boron dodecyl arsenide) in the aforementioned commonly used techniques, this invention provides a method for preparing boron arsenide bulk, comprising the following steps: Arsenic powder and boron powder are pre-activated to obtain a pre-activated product; The pre-activated product is mixed with an iodine agent to obtain a mixed product; The mixed product is subjected to high-temperature and high-pressure sintering to obtain boron arsenide bulk material; the sintering pressure during the high-temperature and high-pressure sintering process is 1-6 GPa, the temperature is 800-900℃, and the duration is 5-60 minutes.

[0006] Furthermore, the molar ratio of the arsenic powder to the boron powder is 1:0.5-6.

[0007] Furthermore, the pre-activation treatment includes ball milling, wherein the ball milling speed is 200-800 r / min, the ball milling time is 12-36 h, and the ball-to-material ratio is 1:15-40.

[0008] Furthermore, the purity of the arsenic powder is not less than 99.999%, and the purity of the boron powder is not less than 99.9%. The particle size of the arsenic powder and the boron powder is 0.5-20 μm.

[0009] Furthermore, the iodine agent in the mixture accounts for 1-5 wt% of the total mass.

[0010] Furthermore, the iodine agent includes at least one of elemental iodine and boron iodide.

[0011] Furthermore, the mixing of the pre-activated product with the iodine agent includes: mixing the pre-activated product and the iodine agent by tumbling and shaking at a speed of 15-50 r / min for 10-30 h.

[0012] Furthermore, the high-temperature and high-pressure sintering process is carried out using a six-sided top press.

[0013] The present invention provides a boron arsenide bulk material, wherein the phase is boron arsenide.

[0014] This invention provides a boron arsenide bulk prepared by the method described above, or the application of the boron arsenide bulk prepared as described above in the preparation of high thermal conductivity materials or semiconductor devices.

[0015] Compared with the prior art, the present invention has at least the following advantages: This invention introduces iodine into a high-temperature, high-pressure system. Unlike chemical vapor transport methods where iodine acts merely as a gaseous transport medium (achieving spatial transfer of matter through reversible iodides), the iodine in this invention functions as an active mineralizer within a closed, high-pressure chamber: on one hand, iodine reacts with boron to generate gaseous boron iodide, significantly enhancing the reactivity of boron and promoting its reaction kinetics with molten arsenic; on the other hand, the iodine effectively inhibits the reaction of boron with molten arsenic. 12 The nucleation and growth of As2 and other secondary phases are optimized by improving the reaction pathway, thereby selectively shifting the product towards the target BAs phase.

[0016] Experimental comparisons show that, without iodine (as in Comparative Examples 2-3), even with the same pre-activation and high-pressure sintering conditions, the product still predominates in the form of B. 12 The As2 secondary phase was dominant; however, when iodine was introduced at the same temperature (800℃) (as shown in the comparison between Comparative Example 1 and Example 1), not only was the secondary phase suppressed, but the microstructure of the product was also significantly improved. Furthermore, although Comparative Example 4 (800℃, without iodine) avoided secondary phase formation due to the low temperature, the resulting BAs grains were small, had poor crystallinity, and uneven morphology; while in Example 1, with the assistance of iodine, the product had well-developed grains, a uniform and dense structure, and significantly better crystal quality. This indicates that iodine not only participates in the reaction but also regulates the nucleation density and grain growth behavior of the product.

[0017] This invention utilizes the physicochemical behavior of arsenic under high temperature and pressure. Under a high-pressure environment of 1-6 GPa, the high-temperature volatilization of arsenic is effectively suppressed, while arsenic transforms into a molten liquid state at 800-900℃. This liquid arsenic directly participates in the reaction as a reactant and also acts as a liquid-phase reaction medium (flux), significantly reducing the dissolution and diffusion energy barriers of boron. The dissolution-precipitation mechanism of boron atoms in liquid arsenic transforms the traditional solid-solid reaction into a liquid-phase solid-liquid reaction, significantly reducing the reaction activation energy. This shortens the reaction process, which originally required several days (2-6 days for chemical vapor transport method), to 5-60 minutes, achieving ultra-fast preparation of boron arsenide bulk materials.

[0018] In summary, this invention, through the synergistic effect of ball milling pre-activation, iodine mineralization, and high-temperature, high-pressure liquid-phase reaction, achieves the following results: the synthesis cycle from raw materials to dense bulk material is shortened to the minute level, far superior to the several-day cycle of traditional chemical vapor transport methods; the product has a single phase, being pure boron arsenide (BAs), and contains no boron. 12 As2 and other impurity phases are present; the resulting bulk crystals are well-developed, with uniform microstructure and high density. This invention successfully solves the technical problems of long preparation cycle, easy inclusion of secondary phases in products, and difficulty in controlling microstructure in the prior art of boron arsenide preparation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart of the method for rapidly preparing boron arsenide bulk material by six-sided top pressing in this invention; Figure 2 This is a schematic diagram of the assembly of the high-pressure synthesis block in this invention; Figure 3 This is a physical image of the product obtained in Example 1 of the present invention; Figure 4 The image shows the X-ray diffraction (XRD) pattern of the product obtained in Example 1 of this invention. Figure 5 Here is an electron microscope image of the product obtained in Example 1 of the present invention, wherein, Figure 5 (a) is a microscopic morphology image in secondary electron (SE) imaging mode. Figure 5 (b) Compositional contrast map in backscattered electron (BSE) imaging mode; Figure 6 Here is an electron microscope image of the product obtained in Comparative Example 4 of the present invention, wherein, Figure 6 (a) is a microscopic morphology image in secondary electron (SE) imaging mode. Figure 6 (b) is a compositional contrast map in backscattered electron (BSE) imaging mode. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0023] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of the invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to the methods, devices, and materials in the embodiments of the present invention.

[0024] like Figure 1 As shown, the present invention provides a method for preparing boron arsenide bulk material, comprising the following steps: S1. Arsenic powder and boron powder are pre-activated to obtain a pre-activated product.

[0025] In some embodiments, the molar ratio of arsenic powder to boron powder is 1:0.5-6. If the proportion of arsenic is too high (molar ratio less than 1:0.5, i.e., boron is relatively insufficient), although the excess arsenic can provide a more sufficient liquid phase medium under high temperature and pressure, the free arsenic remaining after the reaction is easily oxidized to form highly toxic arsenic oxide, affecting the purity of the product. If the proportion of boron is too high (molar ratio greater than 1:6, i.e., boron is severely excessive), since boron is still in a solid phase at 800-900℃, the excess boron cannot participate in the reaction and will remain in the product as unreacted elemental boron, resulting in an impure bulk phase.

[0026] For example, the molar ratio of arsenic powder to boron powder can be 1:0.5, 1:0.8, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:5, 1:6, and any value between these ratios or any range of any two ratios.

[0027] In some embodiments, the pre-activation treatment includes ball milling, wherein the ball milling speed is 200-800 r / min, the ball milling time is 12-36 h, and the ball-to-material ratio is 1:15-40.

[0028] This invention employs ball milling to pre-activate arsenic and boron powders. During ball milling, the powder particles repeatedly deform, break, and cold-weld under high-energy mechanical force, generating numerous lattice defects, dislocations, and fresh surfaces. This significantly reduces the activation energy of the reaction, making it easier for arsenic and boron, which would otherwise be difficult to react directly due to their large melting point differences, to combine during subsequent high-temperature and high-pressure sintering. Comparative Example 1, without ball milling pre-activation and only using tumbling and shaking mixing, even under the same high-temperature and high-pressure conditions (6 GPa, 800 °C), produced products with extremely uneven morphology and distribution. Boron arsenide existed only on the surface of the arsenic particles and did not form a uniform phase. This fully demonstrates that ball milling pre-activation is a crucial preliminary step in this invention to ensure uniform reaction and obtain a dense bulk material.

[0029] For example, the ball mill speed can be 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min, 600 r / min, 650 r / min, 700 r / min, 750 r / min, 800 r / min, and any value between these speeds or a range of any two values.

[0030] In some embodiments, the purity of the arsenic powder is not less than 99.999%, and the purity of the boron powder is not less than 99.9%. The particle size of the arsenic powder and the boron powder is 0.5-20 μm. In this invention, the particle size of the arsenic powder and the boron powder are each independently 0.5-20 μm. If the particle size is too large (>20 μm), it will reduce the specific surface area of ​​the powder and the reaction contact interface, leading to slower reaction kinetics and difficulty in complete reaction within the 5-60 minute holding time, potentially leaving unreacted core areas inside the block. If the particle size is too small (<0.5 μm), the powder surface activity will be too high, easily leading to agglomeration or oxidation during ball milling and mixing, thus reducing the effective contact area. Furthermore, the fine powder has a lower density when pre-pressed into cylindrical blocks, affecting the density of the sintered block. Using a particle size range of 0.5-20 μm, especially the use of 0.5-2 μm or 10-20 μm amorphous boron powder in the examples, ensures both good reactivity and good powder workability and sintering performance.

[0031] S2. The pre-activated product is mixed with iodine to obtain a mixed product.

[0032] In some embodiments, the iodine agent in the mixture comprises 1-5 wt% by mass.

[0033] In this invention, the amount of iodine added is controlled to be 1-5 wt% of the total mass of the mixed product. The iodine acts as an active mineralizer in this system: iodine reacts with boron to generate gaseous boron iodide, increasing the reactivity of boron and optimizing the reaction selectivity to inhibit B. 12 As2 secondary phase. If the amount of iodine added is less than 1 wt%, the mineralization effect is insufficient, and the improvement in reactivity is limited. For example, Comparative Examples 2 and 3 (without iodine) did not form the target BAs phase under conditions of 6 GPa and 900℃ or 1 GPa and 800℃, and the product was B. 12 As2 secondary phase, it can be seen that insufficient iodine cannot effectively suppress the secondary phase.

[0034] If the amount of iodine added exceeds 5 wt%, the excess iodine will generate excessively high gas phase partial pressure under high temperature and pressure, which may lead to excessively high pressure in the reaction chamber and even cause the boron nitride encapsulation tube to rupture. At the same time, excess iodine will cause porosity in the boron arsenide block, affecting the product quality. In Examples 1-4, a good effect was obtained with an iodine addition of 1 wt%. Therefore, 1-5 wt% is the preferred range that balances mineralization efficiency and product quality.

[0035] For example, the mass fraction of the iodine can be 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, and any range of these percentages or any two of these percentages.

[0036] In some embodiments, the iodine agent includes at least one of elemental iodine and boron iodide.

[0037] In some embodiments, the mixing of the pre-activated product with the iodine agent includes: mixing the pre-activated product and the iodine agent by tumbling and shaking at a speed of 15-50 r / min for a duration of 10-30 h.

[0038] S3. The mixed product is subjected to high temperature and high pressure sintering to obtain boron arsenide bulk material; the sintering pressure during the high temperature and high pressure sintering process is 1-6 GPa, the temperature is 800-900℃, and the duration is 5-60 minutes.

[0039] The high-temperature and high-pressure sintering temperature of the present invention is controlled at 800-900℃. For example, the high-temperature and high-pressure sintering temperature can be 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃, 890℃, 900℃, and any value between these temperatures or a range of any two values.

[0040] Below 800℃, although the melting point of elemental arsenic decreases under high pressure, it is still difficult to fully melt into a continuous liquid phase. The solid-solid reaction kinetics between solid arsenic and boron are extremely slow, and the atomic diffusion capacity is severely insufficient. As shown in Comparative Example 8, at 700℃ with an iodine addition of 1 wt%, the product is only elemental arsenic. As shown in Comparative Example 5, even when the iodine addition is increased to 2.5 wt%, although trace amounts of BAs can be detected at 700℃, the reaction degree is extremely low, and the product is still mainly elemental arsenic, far from achieving the reaction efficiency and product purity at temperatures above 800℃. This indicates that the reaction kinetics are severely limited at 700℃.

[0041] At temperatures above 900℃, although reaction kinetics accelerate, thermodynamically B 12 The formation tendency of the As2 secondary phase was significantly enhanced. The product of Comparative Example 7 (1000℃, without iodine) was B. 12 As2 secondary phase, no target BAs were formed. The experimental results for Comparative Example 6 (1000℃, iodine addition) showed As and B... 12 As2 secondary phase, no target BAs were generated. In addition, excessively high temperatures can cause arsenic to be released again, resulting in excessively high local arsenic vapor pressure, affecting the uniformity of the pressure field in the high-pressure synthesis chamber, and even causing corrosion to the encapsulation material (boron nitride).

[0042] In both Example 1 (800℃) and Example 2 (900℃), pure-phase BAs bulk materials were successfully obtained. However, in Comparative Example 2 (900℃, without iodine), a secondary phase was generated. This indicates that even at the preferred temperature range of 800-900℃, the target pure phase cannot be obtained without the participation of iodine. Iodine is key to achieving selective synthesis and suppressing secondary phases. Furthermore, although no secondary phase was generated in Comparative Example 4 (800℃, without iodine), the product had small grains, poor crystallinity, and uneven morphology, which contrasted sharply with the bulk material with complete grains and uniform structure obtained in Example 1 (800℃, with iodine). This shows that iodine not only suppresses secondary phases but also significantly promotes grain growth and optimizes microstructure. On the other hand, no boron arsenide phase was generated in Comparative Examples 8-9 (700℃, with or without iodine), indicating that even in the presence of iodine, the reaction cannot be initiated unless the temperature reaches above 800℃. Comparative Examples 6-7 (1000℃, with and without iodine, both generated secondary phases) showed that excessively high temperatures significantly increase the risk of secondary phase formation and may even weaken the selective control effect of iodine.

[0043] Therefore, the 800-900℃ temperature window and the addition of iodine are both indispensable and work synergistically: below 800℃, the reaction kinetics are insufficient, and the iodine cannot exert its mineralization effect; above 900℃, the thermodynamic tendency of the secondary phase is too strong, and the iodine is difficult to effectively suppress; even at a suitable temperature, without iodine, the reaction pathway is still prone to bias towards the secondary phase, and the crystal morphology of the product deteriorates. Only under the combined conditions of 800-900℃ and the addition of iodine can the iodine promote arsenic liquefaction, accelerate the reaction, and simultaneously optimize phase selectivity and product crystal morphology.

[0044] Therefore, the combination of 800-900℃ with 1-5wt% iodine is an essential technical feature of this invention to ensure the full liquefaction of arsenic, rapid reaction, effective suppression of the secondary phase, and good crystal growth. The two are synergistic and indispensable.

[0045] This invention employs high-pressure sintering conditions of 1-6 GPa. Below 1 GPa, the inhibitory effect on arsenic volatilization is limited; arsenic still undergoes significant sublimation loss at 800-900℃, leading to a deviation in the As / B stoichiometric ratio. Furthermore, the melting point of arsenic decreases only slightly under low pressure, making it difficult to form a continuous liquid phase medium; the reaction remains predominantly a solid-solid reaction, resulting in low efficiency. Comparative Example 3 (1 GPa, without iodine) produced product B. 12 As2 secondary phase, no BAs formed. At pressures above 6 GPa, although it is more beneficial for suppressing volatilization and promoting densification, it exceeds the normal safe operating range of the six-sided press, increases equipment wear, and excessive pressure may excessively suppress atomic mobility, which is not conducive to grain growth.

[0046] For example, the high-temperature and high-pressure sintering pressure can be 1 GPa, 1.5 GPa, 2 GPa, 2.5 GPa, 3 GPa, 3.5 GPa, 4 GPa, 4.5 GPa, 5 GPa, 5.5 GPa, 6 GPa, and any value between these pressure values ​​or any range of any two values.

[0047] For example, the high-temperature and high-pressure sintering holding time can be 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, and any value between these time points or any range of two values.

[0048] In some more specific embodiments, the mixture can be pre-compressed into cylindrical blocks and placed in a high-pressure synthesis block.

[0049] For example, the mixed product can be pre-pressed into a cylindrical block and placed inside a boron nitride tube. The tube is then sealed from top to bottom with boron nitride ceramic sheets before being placed into the high-pressure synthesis block. A schematic diagram of the assembly of the high-pressure synthesis block is shown below. Figure 2 As shown.

[0050] In some embodiments, the high-temperature and high-pressure sintering process is carried out using a six-sided top press.

[0051] It should be noted that in this invention, the entire process, from mixing the pre-activated product with the iodine agent to pre-pressing it into cylindrical blocks and encapsulating it in a high-pressure synthesis block, is carried out under an inert atmosphere. The inert atmosphere is selected from at least one of nitrogen and argon. Since arsenic powder, boron powder, and iodine agent are all highly reactive substances, especially the powder after ball milling and pre-activation which has a large amount of fresh surface area, they readily adsorb oxygen and moisture in the air, leading to surface oxidation or the formation of an oxide film, thereby inhibiting the subsequent arsenic-boron reaction under high temperature and pressure. Furthermore, iodine agent is prone to sublimation in air and may absorb moisture. Therefore, mixing, loading, and encapsulating under an inert atmosphere (such as an argon glove box) can effectively prevent raw material oxidation and contamination, ensuring the cleanliness and high activity of the reaction interface, which is an important prerequisite for obtaining high-purity, high-quality boron arsenide blocks.

[0052] It should be noted that after high-temperature and high-pressure sintering, the surface and interior of the resulting bulk product may contain a small amount of unreacted free arsenic, iodides (such as arsenic iodide), and possible arsenic-containing impurities.

[0053] Therefore, in some embodiments, the present invention uses aqua regia to clean and remove impurities from the sintered products.

[0054] Aqua regia (concentrated hydrochloric acid to concentrated nitric acid in a volume ratio of approximately 3:1) has strong oxidizing and coordinating abilities, and can effectively dissolve elemental arsenic, arsenic oxide, and various iodides, but does not react significantly with boron arsenide (BAs). Therefore, it can selectively remove impurity phases without destroying the target product.

[0055] In some more specific embodiments, the sintered block is soaked in aqua regia for an appropriate time (e.g., 10-30 minutes), then rinsed repeatedly with deionized water and dried to obtain a boron arsenide block with a clean surface and improved purity.

[0056] The present invention provides a boron arsenide bulk material, wherein the phase is boron arsenide.

[0057] This invention provides a boron arsenide bulk prepared by the method described in any of the preceding claims, or the application of the boron arsenide bulk as described above in the preparation of high thermal conductivity materials or semiconductor devices.

[0058] To facilitate a further understanding of the present invention by those skilled in the art, the following examples are provided: Example 1 S1. Arsenic powder and boron powder are pre-activated to obtain a pre-activated product: Arsenic metal ingots with a purity of 99.9999% were ball-milled, and the milled product was sieved to obtain arsenic metal powder. The obtained arsenic metal powder was then ball-milled with high-purity boron powder (10-20 μm particle size) for pre-activation. The molar ratio of arsenic metal powder to high-purity boron powder was 1:1. The ball milling speed was 200 r / min, the milling time was 24 h, and the ball-to-material ratio was 1:25.

[0059] S2. The pre-activated product is mixed with iodine to obtain a mixed product: The activated product after ball milling was mixed with elemental iodine by tumbling and shaking. The amount of iodine added was 1 wt%, the rotation speed was 30 r / min, and the mixing time was 24 h.

[0060] S3. The mixed product is subjected to high-temperature and high-pressure sintering to obtain boron arsenide bulk material: The mixed product was loaded into a container under an inert argon atmosphere, pre-compressed into a cylindrical block, placed into a boron nitride tube, sealed from top to bottom with boron nitride ceramic sheets, and then placed into a high-pressure synthesis block.

[0061] The high-pressure synthesized block was placed in the synthesis chamber of a domestically produced six-sided top press for high-temperature and high-pressure sintering. The high-temperature and high-pressure sintering pressure was 6 GPa; the temperature was 800℃; and the holding time was 60 minutes. The heating time for high-temperature and high-pressure sintering was 6 minutes; and the cooling time was 20 minutes. After sintering, the temperature was reduced and the pressure was released. The boron arsenide block with a diameter of 10 mm was removed, and the product was cleaned with aqua regia to remove impurities.

[0062] Result: The product of this embodiment is boron arsenide.

[0063] Figure 3 This is a photograph of the product obtained in this embodiment; Figure 4 The X-ray diffraction (XRD) pattern of the product obtained in this embodiment shows that the product is boron arsenide. The electron microscope image of the boron arsenide product prepared in this embodiment is shown below. Figure 5 As shown.

[0064] Example 2 S1. Arsenic powder and boron powder are pre-activated to obtain a pre-activated product: Arsenic metal ingots with a purity of 99.9999% were ball-milled and the milled product was sieved to obtain arsenic metal powder.

[0065] The obtained metallic arsenic powder was pre-activated by ball milling with high-purity boron powder with a particle size of 10-20 μm. The molar ratio of metallic arsenic powder to high-purity boron powder was 1:1. The ball milling speed was 200 r / min, the ball milling time was 24 h, and the ball-to-particle ratio was 1:25.

[0066] S2. The pre-activated product is mixed with iodine to obtain a mixed product: The activated product after ball milling was mixed with elemental iodine by tumbling and shaking. The amount of iodine added was 1 wt%, the rotation speed was 30 r / min, and the mixing time was 24 h.

[0067] S3. The mixed product is subjected to high-temperature and high-pressure sintering to obtain boron arsenide bulk material: The mixed product was loaded into a container under an inert argon atmosphere, pre-compressed into a cylindrical block, placed into a boron nitride tube, sealed from top to bottom with boron nitride ceramic sheets, and then placed into a high-pressure synthesis block.

[0068] The high-pressure synthesized block was placed in the synthesis chamber of a domestically produced six-sided top press for high-temperature and high-pressure sintering. The high-temperature and high-pressure sintering pressure was 6 GPa; the temperature was 900℃; and the holding time was 60 minutes. The heating time for high-temperature and high-pressure sintering was 6 minutes; and the cooling time was 20 minutes. After sintering, the temperature was reduced and the pressure was released. The boron arsenide block with a diameter of 10 mm was removed, and the product was cleaned with aqua regia to remove impurities.

[0069] The product obtained in this embodiment was determined by XRD to be boron arsenide.

[0070] Example 3 Compared to Example 1, this embodiment differs only in that the high-temperature and high-pressure sintering pressure is 1 GPa, while other conditions remain unchanged.

[0071] The product obtained in this embodiment was determined by XRD to be boron arsenide.

[0072] Example 4 Compared to Example 1, this embodiment only adjusts the high-temperature and high-pressure sintering holding time to 5 minutes, while keeping other conditions unchanged.

[0073] The product obtained in this embodiment was determined by XRD to be boron arsenide.

[0074] Example 5 Compared with Example 1, the rest of the steps remain the same in this embodiment, except that the amount of iodine added is adjusted to 2.5 wt%.

[0075] Result: The product of this embodiment is boron arsenide.

[0076] Comparative Example 1 Compared to Example 1, the other conditions remain unchanged in this comparative example, except that the ball milling pre-activation treatment in step S1 is cancelled, and the tumbling and oscillating mixing in step S2 is directly used as the raw material mixing method.

[0077] S1. The arsenic metal ingot with a purity of 99.9999% is ball-milled and pulverized. The ball-milled product is then sieved to obtain arsenic metal powder.

[0078] The obtained metallic arsenic powder was mixed with high-purity boron powder with a particle size of 10-20 μm by tumbling and shaking. The molar ratio of metallic arsenic powder to high-purity boron powder was 1:1. The tumbling and shaking speed was 30 r / min, and the tumbling and shaking time was 24 h.

[0079] S2. The mixture after tumbling and shaking is placed into a container under an argon inert gas atmosphere, pre-pressed into a cylindrical block, placed into a boron nitride tube, sealed at the top and bottom with boron nitride ceramic sheets, and then placed into a high-pressure synthesis block.

[0080] The high-pressure synthesized block was placed in the synthesis chamber of a domestically produced six-sided top press for high-temperature and high-pressure sintering. The high-temperature and high-pressure sintering pressure was 6 GPa; the temperature was 800℃; and the holding time was 60 minutes. The heating time for high-temperature and high-pressure sintering was 6 minutes; and the cooling time was 20 minutes. After sintering, the temperature was reduced and the pressure was released. The boron arsenide block with a diameter of 10 mm was removed, and the product was cleaned with aqua regia to remove impurities.

[0081] Results: The size and morphology of the products obtained in this comparative example were not uniform, and boron arsenide existed on the arsenic surface, failing to form the uniform phase distribution seen in Example 1.

[0082] Comparative Example 2 Compared to Example 2, all other conditions remain unchanged in this comparative example, except that step S2 is omitted.

[0083] S1. The arsenic metal ingot with a purity of 99.9999% is ball-milled and pulverized. The ball-milled product is then sieved to obtain arsenic metal powder.

[0084] The obtained metallic arsenic powder was pre-activated by ball milling with high-purity boron powder with a particle size of 10-20 μm. The molar ratio of metallic arsenic powder to high-purity boron powder was 1:1. The ball milling speed was 200 r / min, the ball milling time was 24 h, and the ball-to-particle ratio was 1:25.

[0085] S2. The activated product after ball milling is loaded into a container under an argon inert gas atmosphere, pre-pressed into a cylindrical block, placed into a boron nitride tube, sealed at the top and bottom with boron nitride ceramic sheets, and then placed into a high-pressure synthesis block.

[0086] The high-pressure synthesized block was placed in the synthesis chamber of a domestically produced six-sided top press for high-temperature and high-pressure sintering. The high-temperature and high-pressure sintering pressure was 6 GPa; the temperature was 900℃; and the holding time was 60 minutes. The heating time for high-temperature and high-pressure sintering was 6 minutes; and the cooling time was 20 minutes. After sintering, the temperature was reduced and the pressure was released. The boron arsenide block with a diameter of 10 mm was removed, and the product was cleaned with aqua regia to remove impurities.

[0087] Results: X-ray diffraction (XRD) analysis showed that the product obtained in this comparative example was boron dodecyl arsenide phase, and did not form the boron monoarsenide phase in Example 2.

[0088] Comparative Example 3 Compared to Example 3, the other conditions in this comparative example remain unchanged, except that step S2 is omitted.

[0089] S1. The arsenic metal ingot with a purity of 99.9999% is ball-milled and pulverized. The ball-milled product is then sieved to obtain arsenic metal powder.

[0090] The obtained metallic arsenic powder was pre-activated by ball milling with high-purity boron powder with a particle size of 10-20 μm. The molar ratio of metallic arsenic powder to high-purity boron powder was 1:1. The ball milling speed was 200 r / min, the ball milling time was 24 h, and the ball-to-particle ratio was 1:25.

[0091] S2. The activated product after ball milling is loaded into a container under an argon inert gas atmosphere, pre-pressed into a cylindrical block, placed into a boron nitride tube, sealed at the top and bottom with boron nitride ceramic sheets, and then placed into a high-pressure synthesis block.

[0092] The high-pressure synthesized block was placed in the synthesis chamber of a domestically produced six-sided top press for high-temperature and high-pressure sintering. The high-temperature and high-pressure sintering pressure was 1 GPa; the temperature was 800℃; and the holding time was 60 minutes. The heating time for high-temperature and high-pressure sintering was 6 minutes; and the cooling time was 20 minutes. After sintering, the temperature was reduced and the pressure was released. The boron arsenide block with a diameter of 10 mm was removed, and the product was cleaned with aqua regia to remove impurities.

[0093] Results: The product obtained in this comparative example was determined by XRD to be elemental arsenic and boron arsenide diarsenide phases, and did not form the boron monoarsenide phase in Example 3.

[0094] Comparative Example 4 Compared to Example 1, all other conditions remain the same in this comparative example, except that step S2 is omitted.

[0095] S1. Arsenic powder and boron powder are pre-activated to obtain a pre-activated product: Arsenic metal ingots with a purity of 99.9999% were ball-milled, and the milled product was sieved to obtain arsenic metal powder. The obtained arsenic metal powder was then ball-milled with high-purity boron powder (10-20 μm particle size) for pre-activation. The molar ratio of arsenic metal powder to high-purity boron powder was 1:1. The ball milling speed was 200 r / min, the milling time was 24 h, and the ball-to-material ratio was 1:25.

[0096] S2. The pre-activated product is subjected to high-temperature and high-pressure sintering to obtain boron arsenide bulk: The pre-activated product was loaded into a container under an inert argon atmosphere, pre-pressed into a cylindrical block, placed into a boron nitride tube, sealed from top to bottom with boron nitride ceramic sheets, and then placed into a high-pressure synthesis block.

[0097] The high-pressure synthesized block was placed in the synthesis chamber of a domestically produced six-sided top press for high-temperature and high-pressure sintering. The high-temperature and high-pressure sintering pressure was 6 GPa; the temperature was 800℃; and the holding time was 60 minutes. The heating time for high-temperature and high-pressure sintering was 6 minutes; and the cooling time was 20 minutes. After sintering, the temperature was reduced and the pressure was released. The boron arsenide block with a diameter of 10 mm was removed, and the product was cleaned with aqua regia to remove impurities.

[0098] Results: The product obtained in this comparative example was identified by XRD as a boron arsenide phase. However, the boron arsenide product had poor crystal structure. The electron micrograph of the boron arsenide phase product prepared in this comparative example is shown below. Figure 6 As shown.

[0099] Comparative Example 5 Compared to Example 5, all other conditions in this comparative example remain unchanged, except that the sintering temperature is adjusted to below 800°C, specifically 700°C.

[0100] Results: X-ray diffraction (XRD) analysis of the products obtained in this comparative example showed that the products were elemental arsenic and boron arsenide phases.

[0101] Comparative Example 6 Compared to Example 1, all other conditions in this comparative example remain unchanged, except that the sintering temperature is adjusted to above 900°C, specifically 1000°C.

[0102] Results: X-ray diffraction (XRD) analysis of the products obtained in this comparative example showed that the products were elemental arsenic and boron arsenide, and did not form the boron arsenide phase in Example 1.

[0103] Comparative Example 7 Compared to Comparative Example 4, all other conditions in this comparative example remain unchanged, except that the sintering temperature is adjusted to above 900℃, specifically 1000℃.

[0104] Results: X-ray diffraction (XRD) analysis of the product obtained in this comparative example showed that the product was boron dodecyl arsenide phase, and boron monoarsenide phase was not formed.

[0105] Comparative Example 8 Compared to Example 1, all other conditions remain the same in this comparative example, except that the sintering temperature is adjusted to below 800°C, specifically 700°C.

[0106] Results: X-ray diffraction (XRD) analysis showed that the product obtained in this comparative example was an elemental arsenic phase, and did not form the boron arsenide phase in Example 1.

[0107] Comparative Example 9 Compared to Comparative Example 4, all other conditions in this comparative example remain unchanged, except that the sintering temperature is adjusted to below 800℃, specifically 700℃.

[0108] Results: X-ray diffraction (XRD) analysis of the product obtained in this comparative example showed that the product was an elemental arsenic phase and no boron arsenide phase was formed.

[0109] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing boron arsenide bulk, characterized in that, Including the following steps: Arsenic powder and boron powder are pre-activated to obtain a pre-activated product; The pre-activated product is mixed with an iodine agent to obtain a mixed product; The mixed product is subjected to high-temperature and high-pressure sintering to obtain boron arsenide bulk material; the sintering pressure during the high-temperature and high-pressure sintering process is 1-6 GPa, the temperature is 800-900℃, and the duration is 5-60 minutes.

2. The method for preparing boron arsenide bulk material according to claim 1, characterized in that, The molar ratio of the arsenic powder to the boron powder is 1:0.5-6.

3. The method for preparing boron arsenide bulk material according to claim 1, characterized in that, The pre-activation treatment includes ball milling, wherein the ball milling speed is 200-800 r / min, the ball milling time is 12-36 h, and the ball-to-material ratio is 1:15-40.

4. The method for preparing boron arsenide bulk material according to claim 1, characterized in that, The purity of the arsenic powder is not less than 99.999%, and the purity of the boron powder is not less than 99.9%. The particle size of the arsenic powder and the boron powder is 0.5-20 μm.

5. The method for preparing boron arsenide bulk material according to claim 1, characterized in that, The iodine agent in the mixture accounts for 1-5 wt% of the total mass.

6. The method for preparing boron arsenide bulk material according to claim 1, characterized in that, The iodine agent includes at least one of elemental iodine and boron iodide.

7. The method for preparing boron arsenide bulk material according to claim 1, characterized in that, The mixing of the pre-activated product with the iodine agent includes: mixing the pre-activated product and the iodine agent by tumbling and shaking at a speed of 15-50 r / min for 10-30 h.

8. The method for preparing boron arsenide bulk material according to claim 1, characterized in that, The high-temperature and high-pressure sintering process is carried out using a six-sided top press.

9. A boron arsenide bulk material, characterized in that, It is prepared by the preparation method according to any one of claims 1-8, and the phase is boron arsenide.

10. The use of a boron arsenide bulk obtained by the preparation method of boron arsenide bulk as described in any one of claims 1-8, or the boron arsenide bulk as described in claim 9, in the preparation of high thermal conductivity materials or semiconductor devices.

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