CN105987990A

CN105987990A - Simple method for representing crystalline state of graphene

Info

Publication number: CN105987990A
Application number: CN201510099583.2A
Authority: CN
Inventors: 郭磊; 陈学康; 白晓航; 王兰喜; 曹生珠
Original assignee: Lanzhou Institute of Physics of Chinese Academy of Space Technology
Current assignee: Lanzhou Institute of Physics of Chinese Academy of Space Technology
Priority date: 2015-03-06
Filing date: 2015-03-06
Publication date: 2016-10-05

Abstract

The invention discloses a simple method for representing the crystalline state of graphene. The method includes the steps that a graphene growth sample is etched through a gas etching method, and multiple hexagonal etching areas are generated on graphene; the corresponding orientations of the corners of the hexagonal etching areas are analyzed; if the corresponding orientations of the corners of the hexagonal etching areas are uniform, the growth sample is in a monocrystal state, and if the corresponding orientations of the corners of the hexagonal etching areas are not uniform, the growth sample is in a polycrystal state. According to the method, no large high-precision representation equipment is needed, cost is low, requirements can be met through a common vacuum heating furnace for graphene growth, the crystalline state of graphene can be judged by etching graphene at a high temperature with a hydrogen atmosphere, and therefore the purpose of representing the crystallization performance of graphene by etching graphene in situ directly after growth can be achieved, and the method is very simple and convenient to implement. It is not needed to prepare a special representation sample, and therefore errors generated in the representation process when a treated special representation sample is adopted are avoided.

Description

A kind of straightforward procedure characterizing Graphene crystalline state

Technical field

The invention belongs to technical field of nano material, relate to Graphene technology, be specifically related to the characterizing method of Graphene crystalline state.

Background technology

Graphene is by the former molecular alveolate texture Two-dimensional Carbon material of monolayer carbon, this material being considered impossible stable existence, after within 2004, being found by Univ Manchester UK professor An Deliehaimu, rapidly become material science and the focus of Condensed Matter Physics research field.Graphene is real close to preferable two-dimensional material, has the room temperature electron up to 400 nm to transport free path, extraordinary chemical stability, and a series of excellent performance: high intrinsic carrier mobility: 2 × 10⁵ cm²·V^-1·s^-1, SiO₂Mobility in/Si substrate: 10⁴cm²·V^-1·s^-1, resistivity is only 10^-6Ω cm, high current capacity: ~ 10⁶ A/cm², thermal conductivity is up to 5000 W m^-1·K^-1, Young's modulus: 1.0 TPa etc.).It is expected to obtain extensively application in fields such as multi-functional nanometer electronic device, nesa coating, composite, catalysis material, energy storage material, field emmision material, gas sensor and gas storages.

The crystalline state of Graphene is the important indicator of Graphene quality, and the crystalline state characterizing Graphene is the importance of Graphene research and application.The sign of current Graphene crystalline state need to use the large-scale high-accuracy sign equipment such as high-resolution-ration transmission electric-lens (HRTEM), low-energy electron diffraction (LEED), apparatus expensive, characterizes process complicated, and need to prepare Special sample.

Content of the invention

The present invention solves that the crystalline state method therefor operation characterizing Graphene is complicated, the technical problem such as accurate expensive, the sample that needs special control equipment to require of equipment, the characterizing method of the Graphene crystalline state of a kind of simple, quick, low cost is proposed.

The technical scheme is that a kind of straightforward procedure characterizing Graphene crystalline state, with hydrogen, graphene growth sample is performed etching, Graphene produces multiple hexagon etched area, analyze the corresponding orientation in corner, hexagon etched area, if the corresponding orientation in corner, hexagon etched area is consistent, growth sample is monocrystalline, if the corresponding orientation in corner, hexagon etched area is inconsistent, growth sample is polycrystalline.

Etching apparatus used is vacuum furnace, the vacuum of vacuum furnace is evacuated to base vacuum and is not less than 100 Pa, be passed through 10²Pa~10⁵Pa hydrogen, etching temperature 900 ~ 1070 DEG C.

The feature of the present invention and providing the benefit that: the present invention does not needs large-scale high-accuracy sign equipment, the vacuum furnace of general graphene growth can meet requirement, etching Graphene under hydrogen atmosphere high temperature is used i.e. to can determine whether the crystalline state of Graphene, therefore can accomplish to have grown the crystal property that rear direct in-situ etching characterizes Graphene, method is very simple and easy to do；The present invention can directly use growth sample, it is not necessary to prepare special sign sample, it is to avoid employing process after the error that produces during characterizing of Special sample；The inventive method is simple, workable, requires experiment condition simple, is a kind of simple, new method of low cost that can be commonly used.

Brief description

Fig. 1 is the hydrogen etching figure of Graphene sample 1；

Fig. 2 is hydrogen etching single crystal graphene schematic diagram；

Fig. 3 is the electronic diffraction sample multiple spot constituency schematic diagram prepared by sample 1；

Fig. 4 is the electron diffraction diagram of the electronic diffraction sample prepared by sample 1；

Fig. 5 is the hydrogen etching figure of Graphene sample 2；

Fig. 6 is hydrogen etches polycrystalline farmland Graphene schematic diagram；

Fig. 7 is the electron diffraction diagram of the electronic diffraction sample of sample 2 preparation.

Detailed description of the invention

Embodiment 1

Sample 1 is to use the graphene growth sample that obtains at vacuum furnace of chemical vapour deposition technique, uses vacuum furnace as etching apparatus, vacuum is evacuated to base vacuum 0.01Pa(vacuum need to meet be not less than 100 Pa), be passed through 10³Pa hydrogen, is warming up to 1050 DEG C, heats 30min, etches sample 1 with hydrogen for etching gas, utilizes hydrogen atom anisotropic etching Graphene, produce multiple hexagon etch areas.Analyzing the corresponding orientation relationship in corner, multiple hexagon etched area, discovery corner, hexagon etched area only has one orientation, as shown in Figure 1.Seeing the electron diffraction diagram of electronic diffraction sample prepared by Fig. 4 sample 1 again, this tradition characterizing method characterizes this Graphene, and it is monocrystalline that multiple spot SEAD style does not deflect explanation sample 1.Fig. 2 is the corner orientation relationship deducing out corresponding single crystal graphene etched area according to the lattice structure of Graphene, provide theory analysis figure, as can be seen from Figure 2 single crystal graphene Atomic Arrangement long-range order, and there is the hexagon etched area (blank space at middle five) of serrated boundary, because of the Atomic Arrangement long-range order of single crystal graphene, and corner orientation is consistent.Therefore may determine that this etching Graphene is monocrystalline by theoretical and experimental verification.Also can determine whether that graphene domain is orientated, the orientation of hexagon etched area, i.e. single crystal graphene domain are orientated.

Embodiment 2

Sample 2 is to use the graphene growth sample that obtains at vacuum furnace of chemical vapour deposition technique, uses vacuum furnace as etching apparatus, vacuum is evacuated to base vacuum 0.01Pa((vacuum need to meet be not less than 100 Pa), be passed through 10³Pa hydrogen, is warming up to 1050 DEG C, heats 150min, etches sample 2 with hydrogen for etching gas, produces multiple hexagon etch areas.Analyzing corner, multiple hexagon etched area correspondence orientation relationship, discovery corner, hexagon etched area only has two kinds of orientations, is respectively distributed to left side and right side (such as Fig. 5, the lines of demarcation of the dotted line two kinds of orientations of signal near the upper right corner in figure).Seeing the electron diffraction diagram of electronic diffraction sample prepared by Fig. 7 sample 2 again, being that existing conventional method of electron diffraction analyzes Graphene crystalline state, SEAD style arrangement difference explanation sample 2 in crystal boundary both sides is polycrystalline.Deducing out the corner orientation relationship of corresponding polycrystalline graphite alkene etched area according to the lattice structure of Graphene, providing theory analysis figure, such as Fig. 6, middle irregular curve signal crystal boundary, two clear areas are etched area.From fig. 6 it can be seen that Atomic Arrangement is different between polycrystalline graphite alkene domain, and there is the hexagon etched area of serrated boundary, because Atomic Arrangement is different between polycrystalline graphite alkene domain, and different corner orientations occurs in crystal boundary both sides.Therefore may determine that this etching Graphene is polycrystalline from above analysis.Also can determine whether that graphene domain is orientated, the orientation of hexagon etched area, i.e. polycrystalline graphite alkene domain are orientated.

General 900 ~ 1100 DEG C of heating-up temperature, etch period is mainly determined by the air pressure size being passed through hydrogen, is typically passed through 10²Pa~10⁵Pa hydrogen, as being passed through 10²During Pa hydrogen, required etch period is long, up to several hours, if being passed through 10⁵Pa hydrogen, can have been etched by not surpassing 30 points.Can select to be passed through the hydrogen of proper air pressure according to demand.

The principle of the present invention: hydrogen etching Graphene has anisotropy.The border of Graphene has two kinds of molecular configurations to be respectively sawtooth pattern and armchair, and sawtooth pattern has higher stability than armchair.During hydrogen etching Graphene, armchair structure is easily etched, and sawtooth pattern can keep stable, therefore behaves as anisotropy, and hydrogen etching can be used to characterize the crystalline state of Graphene.

Claims

1. the straightforward procedure characterizing Graphene crystalline state, it is characterized in that: with hydrogen, graphene growth sample is performed etching, Graphene produces multiple hexagon etched area, analyze the corresponding orientation in corner, hexagon etched area, if the corresponding orientation in corner, hexagon etched area is consistent, growth sample is monocrystalline, if the corresponding orientation in corner, hexagon etched area is inconsistent, growth sample is polycrystalline.

2. the straightforward procedure characterizing Graphene crystalline state as claimed in claim 1, is characterized in that: etching apparatus is vacuum furnace, the vacuum of vacuum furnace is evacuated to base vacuum and is not less than 100 Pa, be passed through 10²Pa~10⁵Pa hydrogen, etching temperature 900 ~ 1070 DEG C.