阅读说明：本技术 一种六方氮化硼单晶生长方法 (Hexagonal boron nitride single crystal growth method ) 是由 张相法 王大鹏 位星 王永凯 刘红伟 薛磊 于 2021-10-22 设计创作，主要内容包括：本申请属于超硬材料制造技术领域,具体涉及一种六方氮化硼单晶生长方法。该方法包括原料预处理、压制、合成等步骤。本申请所提供的六方氮化硼单晶生长方法,合成制备时,其合成压力较低、合成效果稳定、合成效率较高,且合成的六方氮化硼单晶的尺寸可控,晶粒尺寸、厚度分布范围均匀,能够有效生长出高质量大尺寸的六方氮化硼单晶,适合工业化生产应用。(The application belongs to the technical field of superhard material manufacturing, and particularly relates to a hexagonal boron nitride single crystal growth method. The method comprises the steps of raw material pretreatment, pressing, synthesis and the like. According to the hexagonal boron nitride single crystal growth method provided by the application, during synthesis and preparation, the synthesis pressure is low, the synthesis effect is stable, the synthesis efficiency is high, the size of the synthesized hexagonal boron nitride single crystal is controllable, the grain size and thickness distribution range is uniform, the high-quality large-size hexagonal boron nitride single crystal can be effectively grown, and the method is suitable for industrial production and application.)

1. A method for growing a hexagonal boron nitride single crystal, comprising the steps of:

(I) pretreatment of raw materials

Using hBN as a raw material and MxByNz flux as a catalyst, and fully mixing the raw material and the catalyst;

the MxByNz is a fusing agent, wherein M is Mg or Ca;

the raw material hBN is measured by mass ratio: the catalyst MxByNz is flux =100: 20-50;

(II) pressing

Pressing the uniformly mixed materials in the step (one) into a cylinder, then filling the cylinder into a graphite heating body, and filling the cylinder into a pyrophyllite assembly block in one step;

(III) Synthesis

Putting the assembled pyrophyllite blocks in the step (II) into a high-pressure cavity of a cubic press for synthesis, wherein the synthesis pressure is 2.0-4 GPa, the temperature is 1300-1800 ℃, and the heat preservation time is 10-60 min;

after the synthesis is finished, further purifying to obtain the hexagonal boron nitride single crystal.

2. The method for growing a hexagonal boron nitride single crystal according to claim 1, wherein the hBN raw material quality standard requirement is as follows: the granularity is less than or equal to 2 mu m, the purity is more than or equal to 98.5 percent, and the MxByNz flux catalyst requires: the granularity is less than or equal to 100 meshes.

3. The method for growing a hexagonal boron nitride single crystal according to claim 1, wherein the MxByNz-based flux is specifically: ca₃B₂N₄Or Mg₃B₂N₄。

4. A hexagonal boron nitride single crystal growth method according to claim 3, wherein in the step (one), the ratio of hBN: catalyst MxByNz is flux Mg₃B₂N₄=100:20；

In the step (III), the synthetic pressure is 2.5GPa, the temperature is 1300 ℃, and the heat preservation time is 10 min.

5. A hexagonal boron nitride single crystal growth method according to claim 3, wherein in the step (one), the ratio of hBN: catalyst MxByNz is flux Mg₃B₂N₄=100:30；

In the step (III), the synthetic pressure is 3GPa, the temperature is 1400 ℃, and the heat preservation time is 20 min.

6. A hexagonal boron nitride single crystal growth method according to claim 3, wherein in the step (one), the ratio of hBN: catalyst MxByNz is flux Ca₃B₂N₄=100:50；

In the step (III), the synthetic pressure is 4GPa, the temperature is 1700 ℃, and the heat preservation time is 50 min.

7. A hexagonal boron nitride single crystal growth method according to claim 3, wherein in the step (one), the ratio of hBN: catalyst MxByNz is flux Ca₃B₂N₄=100:50；

In the step (III), the synthetic pressure is 3GPa, the temperature is 1600 ℃, and the heat preservation time is 60 min.

Technical Field

The application belongs to the technical field of superhard material manufacturing, and particularly relates to a hexagonal boron nitride single crystal growth method.

Background

The superhard material cubic boron nitride is usually prepared by artificial synthesis of hexagonal boron nitride and a catalyst at high temperature and high pressure. Thus, hexagonal boron nitride is an essential raw material in the production of superhard materials. On the other hand, hexagonal boron nitride crystals, which are one of two-dimensional materials, have a structure similar to that of graphene, are hexagonal layered structures, and the lattices of the two-dimensional boron nitride crystals and graphene are also very similar, but the difference is that hexagonal boron nitride has a larger band gap, which is approximately 5.9 eV. In addition, hexagonal boron nitride has very excellent dielectric properties, and good insulation property of the hexagonal boron nitride has an irreplaceable effect in a semiconductor device. Therefore, the hexagonal boron nitride is also considered as an excellent choice for the two-dimensional semiconductor material insulating substrate, has important significance for the application and development of the electronic industry field, and has great development prospect in the fields of microelectronic devices and integrated circuits.

In the prior art, hexagonal boron nitride used in the electronic industry is mainly prepared by taking boron nitride as a raw material by a stripping method and a chemical vapor deposition method. Among them, the controllability of the lift-off method is poor, and a hexagonal boron nitride film with uniform size distribution and uniform layer number distribution cannot be obtained. Although chemical vapor deposition is a common method for preparing a high-quality hexagonal boron nitride film and can prepare a high-quality large-size hexagonal boron nitride film, the manufacturing process is slow, flammable and explosive gases are used in the production process, certain potential safety hazards exist, and the method is not suitable for preparing a hexagonal boron nitride single crystal with a certain thickness, so that the method has certain limitations. However, in view of the harsh growth conditions, high manufacturing cost and uneven quality level of the conventional hexagonal boron nitride single crystal, how to prepare a high-quality hexagonal boron nitride single crystal is still a technical problem to be solved in the present industry.

Disclosure of Invention

The method aims to provide the method for growing the hexagonal boron nitride single crystal with high preparation efficiency, low raw material cost, high quality and large size, thereby laying a certain technical foundation for further production and application of the hexagonal boron nitride.

The technical solution adopted in the present application is detailed as follows.

A method for growing a hexagonal boron nitride single crystal comprises the following steps:

(I) pretreatment of raw materials

Taking common commercial hBN (hexagonal boron nitride) as a raw material (the quality standard requirement is that the granularity is less than or equal to 2 mu m and the purity is more than or equal to 98.5 percent), taking MxByNz series flux (the granularity is less than or equal to 100 meshes) as a catalyst, and fully mixing the raw material and the catalyst on a three-dimensional mixer for 5-10 hours;

the MxByNz is a fusing agent, wherein M is Mg or Ca;

the raw material hBN is measured by mass ratio: the catalyst MxByNz is flux =100: 20-50;

(II) pressing

Pressing the uniformly mixed material in the step (I) into a cylinder on a hydraulic press, then filling the cylinder into a graphite heating body, and filling the cylinder into a pyrophyllite assembly block in one step;

(III) Synthesis

Putting the assembled pyrophyllite blocks in the step (II) into a high-pressure cavity of a cubic press for synthesis, wherein the synthesis pressure is 2.0-4 GPa, the temperature is 1300-1800 ℃, and the heat preservation time is 10-60 min;

after the synthesis is finished, further purifying to obtain the hexagonal boron nitride single crystal.

In the present application, the inventors believe that MxByNz-based flux has advantages such as a low synthesis pressure, a stable synthesis effect, and a high synthesis efficiency as a catalyst. Therefore, the catalyst is used for the relevant synthesis. Preliminary production and application results show that the hexagonal boron nitride single crystal growth method provided by the application has the advantages that during synthesis and preparation, the size of the synthesized hexagonal boron nitride single crystal is controllable, the grain size and thickness distribution range are uniform, the high-quality large-size hexagonal boron nitride single crystal can be effectively grown, and the method is suitable for industrial production and application.

Drawings

FIG. 1 is a measurement result of the size of the hexagonal boron nitride single crystal prepared in example 4, which shows that the size of the single crystal can reach about 120 μm;

FIG. 2 is an electron microscope Scanning (SEM) image of the thickness of the hexagonal boron nitride single crystal prepared in example 4; as can be seen, the thickness data is better;

FIG. 3 is an XRD pattern of a hexagonal boron nitride single crystal prepared in example 4.

Detailed Description

The present application is further illustrated by the following examples.

Example 1

The outline of the specific operation steps of the method for growing a hexagonal boron nitride single crystal provided in this example is as follows.

(I) pretreatment of raw materials

Using ordinary commercial hBN (hexagonal boron nitride) as raw material (quality standard requirement is that its grain size is less than or equal to 2 micrometers and purity is greater than or equal to 98.5%) and using Mg₃B₂N₄The flux (the granularity is less than or equal to 100 meshes) is used as a catalyst, and the raw materials and the catalyst are fully mixed for 5 hours on a three-dimensional mixer (the rotating speed is 24 r/min);

the raw material hBN is measured by mass ratio: catalyst MxByNz is flux Mg₃B₂N₄=100:20；

(II) pressing

Pressing the uniformly mixed material in the step (I) into a cylinder on a hydraulic press (when pressing, boosting the pressure to 15MPa, maintaining the pressure for 1s, then decompressing, repeating for 3 times, pressing into a cylinder with the height of phi 35mm and the height of 13 mm), then loading into a graphite heating body, and loading into a pyrophyllite assembly block in one step;

(III) Synthesis

Putting the pyrophyllite block assembled in the step (II) into a high-pressure cavity of a cubic press for synthesis, wherein the synthesis pressure condition is 2.5GPa, the temperature is 1300 ℃, and the heat preservation time is 10 min;

after the synthesis is finished, further purifying by washing with shaking table water, boiling acid and the like to obtain the hexagonal boron nitride single crystal.

The detection result shows that the size of the prepared hexagonal boron nitride single crystal is 30 μm.

Example 2

The preparation method of the hexagonal boron nitride single crystal growth method provided by this embodiment is substantially the same as that of embodiment 1, and only some process parameters are adjusted as follows:

in the step (one), the raw material hBN: catalyst MxByNz is flux Mg₃B₂N₄=100:30；

In the step (III), the synthetic pressure is 3GPa, the temperature is 1400 ℃, and the heat preservation time is 20 min.

The detection result shows that the size of the prepared hexagonal boron nitride single crystal is 50 μm.

Example 3

The preparation method of the hexagonal boron nitride single crystal growth method provided by this embodiment is substantially the same as that of embodiment 1, and only some process parameters are adjusted as follows:

in the step (one), Ca is used₃B₂N₄The flux (the granularity is less than or equal to 100 meshes) is used as a catalyst, and the raw material hBN: catalyst MxByNz is flux Ca₃B₂N₄=100:50；

In the step (III), the synthetic pressure is 4GPa, the temperature is 1700 ℃, and the heat preservation time is 50 min.

The detection result shows that the size of the prepared hexagonal boron nitride single crystal is 80 μm.

Example 4

The preparation method of the hexagonal boron nitride single crystal growth method provided by this embodiment is substantially the same as that of embodiment 1, and only some process parameters are adjusted as follows:

in the step (one), Ca is used₃B₂N₄The flux (the granularity is less than or equal to 100 meshes) is used as a catalyst, and the raw material hBN: catalyst MxByNz is flux Ca₃B₂N₄=100:50；

In the step (III), the synthetic pressure is 3GPa, the temperature is 1600 ℃, and the heat preservation time is 60 min.

The hexagonal boron nitride single crystal prepared in this example was examined and measured, and the results are shown in fig. 1, 2, and 3. The result shows that the prepared hexagonal boron nitride single crystal has larger size (up to 120 mu m), better thickness and purer structure, and shows higher product quality effect.