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Method for preparing van der Waals two-dimensional layered single crystal

A two-dimensional layered, single crystal technology, applied in the direction of single crystal growth, single crystal growth, chemical instruments and methods, etc., can solve the problems of crystal thermal defects increase, difficult to control, uncontrollable nucleation density, etc., to accelerate the momentum and mass transport, reducing the effect of thermal defects

Active Publication Date: 2022-04-22
INST OF PHYSICS - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional CVT has the following disadvantages: on the one hand, too high growth temperature will increase crystal thermal defects; on the other hand, too large temperature difference will make the nucleation points dense and difficult to control, and the crystals near the nucleation points will be connected into one piece
Moreover, an excessively high growth temperature will increase the number of thermal defects in the crystal.
Blindly increasing the temperature difference will lead to uncontrollable nucleation density and make the crystal morphology worse

Method used

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  • Method for preparing van der Waals two-dimensional layered single crystal
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  • Method for preparing van der Waals two-dimensional layered single crystal

Examples

Experimental program
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Effect test

Embodiment 1

[0065] Preparation of NbSe 2 single crystal

[0066] (1) Use acetone and absolute ethanol to ultrasonically clean the inner wall of a quartz tube with an inner diameter of 16mm x a length of 200mm for 10 minutes, rinse it twice with deionized water, and finally dry it in a blast drying oven.

[0067] (2) Mix 1 g of Nb and Se powder (purity above 4N) in a ratio of 1:2 in a glove box, and 5 mg / cm 3 iodine (purity 3N or more) mixed into a quartz tube and sealed.

[0068] (3) Put the open end of the quartz tube into the quartz fiber cotton, connect it to the busbar of the vacuum system and then evacuate it. When the vacuum degree reaches 10 -4 At Pa, heat and seal the quartz tube with a flame gun at a height (10 cm) from the bottom of the quartz tube.

[0069] (4) Put the sealed quartz tube into a horizontal double-temperature zone tube furnace with pre-calibrated temperature distribution, such as Figure 3a shown.

[0070] (5) Electric tube furnace, at a rate of 8°C / min, hea...

Embodiment 2

[0080] The parameters of the technical characteristics of all steps are all the same as in Example 1, except changing the synchronous cooling rate in step (6) in Example 1, that is, modifying step (6) in Example 1 to: rate, control the temperature at the raw material end to 600°C, and the temperature near the nucleation end to drop to 550°C. After the temperature stabilized for 2 hours, the two temperature zones were simultaneously lowered by 12°C at a rate of 3°C / hour, then raised to 24°C at a rate of 12°C / hour, and then lowered by 24°C at a rate of 3°C / hour. Repeat the process of "increasing the temperature by 24°C at a rate of 12°C / hour, and then decreasing the temperature by 24°C at a rate of 3°C / hour", so that the temperature of the raw material end and the nucleation end oscillates at 550°C.

[0081] Figure 4a The single crystal diagram prepared in this example is shown.

Embodiment 3

[0083] The parameters of the technical characteristics of all steps are all the same as in Example 1, except changing the synchronous cooling rate in step (6) in Example 1, that is, modifying step (6) in Example 1 to: rate, control the temperature at the raw material end to 600°C, and the temperature near the nucleation end to drop to 550°C. After the temperature stabilized for 2 hours, the two temperature zones were simultaneously lowered by 12°C at a rate of 4°C / hour, then raised to 24°C at a rate of 12°C / hour, and then lowered by 24°C at a rate of 4°C / hour. Repeat the process of "increasing the temperature by 24°C at a rate of 12°C / hour, and then decreasing the temperature by 24°C at a rate of 4°C / hour", so that the temperature of the raw material end and the nucleation end oscillates at 550°C.

[0084] Figure 4a The single crystal diagram prepared in this example is shown.

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Abstract

The invention provides a method for preparing van der Waals two-dimensional layered single crystal, which includes the following steps: (1) placing raw materials and transmission media at one end of the quartz tube, and then vacuumizing; wherein, the end where the raw materials and transmission media are placed is called The raw material end, the other end of the quartz tube is called the nucleation end; (2) Make the temperature of the raw material end of the quartz tube T2, the temperature of the nucleation end is the growth temperature T1 of the material, and make the raw material end temperature T2 higher than the nucleation end temperature T1, and control the temperature difference ΔT between the raw material end temperature T2 and the nucleation end temperature T1 21 30-100°C; (3) With the same cooling rate and heating rate, synchronously adjust the raw material end temperature T2 and the nucleation end temperature T1, so as to realize the temperature drop and temperature rise in the range of 1-30°C, thereby preparing van der Waals two-dimensional layered single crystal. The method of the invention solves the technical problems of slow single crystal growth, many growth defects and unstable quality in the traditional CVT technology, and realizes single crystal growth with controllable morphology and quality at a relatively low temperature.

Description

technical field [0001] The invention belongs to the technical field of single crystal preparation of intermetallic compounds. In particular, the present invention relates to methods for preparing van der Waals two-dimensional layered single crystals. More specifically, the present invention relates to a method for preparing single crystals of transition metal chalcogenides and transition metal halides using an oscillating temperature field based on the principle of chemical vapor transport (CVT). Background technique [0002] The layered compounds of transition metal chalcogenides or transition metal halides have a layered structure similar to graphite, and the atomic layers in the crystal are bonded by van der Waals force. Single-layer or few-layer thin films of such materials have attracted extensive attention in the fields of materials science and physics in recent years due to their excellent magnetic, magnetoelectric transport and optical properties. It is worth point...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C30B25/00C30B29/12C30B29/46
CPCC30B25/00C30B29/12C30B29/46
Inventor 李泽方郗学奎王文洪
Owner INST OF PHYSICS - CHINESE ACAD OF SCI