CN-121992504-A - Method for remarkably improving yield of high-quality hexagonal boron nitride monocrystal at high temperature and high pressure

Abstract

The invention belongs to the technical field of single crystal material preparation, and provides a barium-magnesium bimetallic boron nitrogen compound-based solvent (Ba-Mg DMB), which remarkably improves the yield of hexagonal boron nitride (h-BN) single crystals under high temperature and High Pressure (HPHT) conditions and further improves the crystal quality. The Ba-Mg DMB solvent improved the yield by 4.8 times, reaching a stable yield of about 57.3%, compared to the yield of about 12% of the barium-based solvent. It was found that magnesium element in Ba-Mg DMB can effectively remove carbon and oxygen impurities under HPHT conditions, which has a key promoting effect on obtaining excellent quality of h-BN single crystal. The high quality characteristics are verified by detailed characterization of raman spectra, X-ray diffraction, X-ray photoelectron spectroscopy, and the like, and are particularly reflected on photoluminescence and cathodoluminescence characteristics. Through the high carrier mobility exhibited in the single-layer graphene, the h-BN single crystal derived from Ba-Mg DMB can be directly proved to be an ideal packaging material of a two-dimensional device.

Inventors

• WAN NENG
• TIAN MING
• CHENG JINGUANG
• WANG NINGNING

Assignees

• 东南大学
• 中国科学院物理研究所

Dates

Publication Date

20260508

Application Date

20251231

Claims (10)

1. 1. The method for remarkably improving the yield of the high-quality hexagonal boron nitride monocrystal at high temperature and high pressure is characterized by comprising the following steps of: the barium-magnesium bimetallic boron nitride compound solvent and the deoxidized hexagonal boron nitride powder are heated and pressurized to prepare the high-quality hexagonal boron nitride monocrystal.
2. 2. The method of claim 1, wherein the oxygen content of the deoxidized hexagonal boron nitride powder is 0.1 wt% or less.
3. 3. The method according to claim 1, wherein the barium-magnesium bimetallic boron nitride solvent is prepared by a process comprising the steps of: Heating the barium nitride powder and the deoxidized hexagonal boron nitride powder to prepare a barium-based cosolvent, and then fully grinding and uniformly mixing the barium-based cosolvent and the magnesium nitride powder to obtain the barium-magnesium bimetallic boron nitride compound solvent.
4. 4. The method of claim 1, wherein the deoxidized hexagonal boron nitride powder is produced by a process comprising the steps of: and (3) treating the hexagonal boron nitride powder for 2-8 hours at the temperature of 2000-2100 ℃ in a protective atmosphere.
5. 5. The method according to claim 3, wherein the temperature of the heating treatment is 1000 ℃ to 1100 ℃, the time of the heating treatment is 12h to 48h, and the heating treatment is performed under a protective atmosphere.
6. 6. The method according to claim 3, wherein the mass ratio of the barium-based cosolvent to the magnesium nitride powder is 1:3, the grinding time is 1-2 hours, and the whole process is operated in a glove box.
7. 7. The method according to claim 4 or 5, wherein the protective atmosphere is selected from one or more of nitrogen, hydrogen and argon, and the flow rate of the protective atmosphere is 100 sccm~200 sccm.
8. 8. The method according to claim 1, wherein the mass ratio of the barium-magnesium bimetallic boron nitride compound solvent to the deoxidized hexagonal boron nitride powder is (3-5): 1.
9. 9. The method according to claim 1, wherein the heating and pressurizing treatment is performed under the conditions that the pressure of the heating and pressurizing treatment is 4 GPa-5 GPa, the temperature of the heating and pressurizing treatment is 1450 ℃ to 1500 ℃, and the time of the heating and pressurizing treatment is 20h to 30h.
10. 10. Use of the method according to any one of claims 1 to 9 for the preparation of substrates, packaging materials, thermally conductive materials, solar blind detectors and deep ultraviolet light sources.

Description

Method for remarkably improving yield of high-quality hexagonal boron nitride monocrystal at high temperature and high pressure Technical Field The invention belongs to the technical field of monocrystalline material preparation. In particular, the invention relates to a method for remarkably improving the yield of high-quality hexagonal boron nitride single crystals at high temperature and high pressure. Background Hexagonal boron nitride (h-BN) belongs to a wide band gap III-V compound semiconductor, is recognized as a high-performance layered van der waals crystal, and is widely used in various fields. By virtue of their chemically inert and atomically smooth surface (no dangling bonds) properties, h-BN has become an ideal dielectric and protective layer for two-dimensional (2D) materials. In fact, encapsulation of two-dimensional materials in h-BN has proven to be an effective strategy to improve its performance, which method makes it possible to delve into many novel phenomena, including fractional quantum hall effect, huo Fushi tatter butterfly effect in moire superlattice, and superconducting phenomenon in twisted bilayer graphene, etc. In addition, by virtue of the ultra-wide band gap (5.9 eV) and high quantum yield characteristics, the h-BN becomes a material with great prospect in manufacturing a vacuum ultraviolet light-emitting device and a high-performance solar blind detector. In addition, the h-BN has low-loss phonon polaron characteristics as a natural hyperbolic material, so that the h-BN becomes an ideal candidate material in the front application fields of negative refraction, nano lithography, thermal radiation enhancement and the like. In all these applications, the performance of the device or material is highly dependent on the quality of the h-BN material used. At present, the h-BN film prepared by chemical vapor deposition, molecular beam epitaxy, sputter deposition and other technologies has high-density grain boundaries and defects, and is difficult to meet quality standards required by high-performance application. Nowadays, high quality h-BN single crystals are mainly produced by the normal pressure high temperature metal flux method (APHT), high pressure high temperature method (HPHT) or polymer derivative crystal method (PDC), characterized by extremely narrow full width at half maximum (FWHM) of the E 2g raman vibrational mode (< 9 cm -1). In the HPHT synthesis route, T.taniguchi and J.Cheng et al have achieved significant results in the synthesis of h-BN single crystals, with crystals of about 2 mm in size, high purity and low defect density being successfully prepared. Sodium-based, magnesium-based, barium-based, and strontium-based solvents have all been successfully used to obtain high quality HPHT h-BN single crystals. HPHT h-BN single crystals prepared by the National Institute of Material Science (NIMS) from T.taniguchi and K.Watanabe using barium-based solvents have been put into use in more than 200 research institutions worldwide. In fact, the throughput of HPHT processes is severely limited by the size and yield of the high pressure, high temperature reaction chamber. When a cubic anvil high-pressure device is adopted, the typical yield of the barium-based solvent is about 12% -17% (by mass of h-BN single crystal/h-BN precursor), so that the production cost of the h-BN single crystal is extremely high. One of the most critical challenges at present is to develop a manufacturing technique that combines high yield with high quality, thereby providing a powerful support for the growing demand for two-dimensional material research. Disclosure of Invention In view of the above problems, an object of the present invention is to provide a method for significantly improving the yield of a high-quality hexagonal boron nitride single crystal at high temperature and high pressure. Compared with the traditional scheme, the method improves the yield of the h-BN monocrystal by 4.8 times, achieves stable yield of about 57.3 percent, greatly reduces the cost and can prepare high-quality h-BN monocrystal. The above object of the present invention is achieved by the following technical solutions: in the context of the present invention, the term "heat and pressure treatment" refers to the simultaneous application of temperature and pressure in a reactor. In the context of the present invention, the term "heat treatment" refers to the application of temperature in a reactor. In the context of the present invention, the term "oxygen content" refers to the weight percentage of elemental oxygen in the hexagonal boron nitride powder. The invention provides a method for remarkably improving the yield of high-quality hexagonal boron nitride monocrystal at high temperature and high pressure, which comprises the following steps: Heating and pressurizing the barium-magnesium bimetallic boron nitride compound solvent and the deoxidized hexagonal boron nitride powder to prepare the dominant hex