GB/T 40066-2021.Nanotechnologies- Thickness measurement of graphene oxide-Atomic Force Microscopy (AFM).
1 Scope
GB/T 40066 specifies the sample preparation, measurement steps and result calculation for measuring the thickness of graphene oxide by atomic force microscopy (AFM).
GB/T 40066 is applicable to the measurement of the thickness of graphene oxide with a sheet size of not less than 300 nm. AFM measurement of the thickness of other two-dimensional materials can be used as a reference.
2 Normative references
The following documents are indispensable for the application of this document. For any dated referenced document, only the dated version applies to this document. For any undated referenced document, its latest version (including all amendments) applies to this document.
GB/T 27760 Method for calibrating sub-nanometer height measurements of atomic force microscopes using atomic steps on Si (111) crystal planes
GB/T 30544.13 Nanotechnology terminology Part 13: Graphene and related two-dimensional materials
JJF 1351 Specification for calibration of scanning probe microscopes
3 Terms and definitions
The terms and definitions defined in GB/T 27760, GB/T 30544.13 and JJF 1351 apply to this document. For ease of use, some terms and definitions in GB/T 30544.13 are repeated below.
3.1
Graphene oxide; GO
Chemically modified graphene obtained by oxidation and exfoliation of graphite, whose basal plane has been strongly oxidatively modified.
Note: Graphene oxide is a single-layer material with a high oxygen content, usually characterized by a carbon-oxygen atomic ratio (related to the synthesis method, generally about 2.0).
[GB/T 30544.13-2018, definition 3.1.2.13]
This standard specifies the sample preparation, measurement steps and result calculation for measuring the thickness of graphene oxide by atomic force microscopy (AFM). This standard is applicable to the measurement of the thickness of graphene oxide with a sheet size of not less than 300 nm. AFM measurement of the thickness of other two-dimensional materials can be used as a reference.

ICS17.180
National Standard of the People's Republic of China
GB/T40066—2021
Nanotechnologies
Graphene oxide thickness measurement
Atomic force microscopy
Nanotechnologies-Thickness measurement of graphene oxide-Atomic Force Microscopy (AFM)
Published on 2021-05-21
State Administration for Market Regulation
National Administration of Standardization
Implemented on 2021-12-01
GB/T 40066—2021
Normative reference documents
Terms and definitions
Original and calculation methods
Reagents and materials
Instruments and equipment
Sample preparation
Measurement steps
Result calculation
Application of graphene oxide thickness measurement·
Uncertainty
12 Test report
Appendix A (informative appendix)
Method 1 example
Appendix B (informative appendix)
Method 2 example…
Appendix ((Informative appendix) Application of xenon graphene thickness measurement Appendix 1) (Informative appendix) Method test report sample Appendix E (Informative appendix) Method 2 test report sample References
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This standard was drafted in accordance with the rules given in GB/T 1.12009. This standard is proposed by the Chinese Academy of Sciences.
GB/T40066—2021
This standard is under the jurisdiction of the National Technical Committee for Nanotechnology Standardization, Nanomaterials Subcommittee (SAC/TC279/SC1): Drafting units of this standard: Jiangnan Graphene Research Institute, China Institute of Metrology, Changzhou Guocheng New Materials Technology Co., Ltd., Harbin Wanxin Graphite Valley Technology Co., Ltd., Tsinghua University of Science and Technology, Changzhou Institute of Standards and Metrology Technology Information, Taizhou Juna New Energy Co., Ltd., Metallurgical Industry Information General Standard Research Institute, Hefei Guoxuan High-tech Power Energy Co., Ltd., Jiangsu Special Equipment Safety Supervision and Inspection Institute National Graphene Product Quality Supervision and Inspection Center (Jiangsu). The main drafters of this standard: Dong Guocai, Ren Lingling, Zhang Xiaomin, Xia Dajia, Liang Feng, Ai Guohui, Hou Huiyu, Yao Yaxuan, Wang Lili, Yang Yuhua, Liang Zheng, Yu Xiaojun, Yan Guoping, Wang Lenniu, Yang Yongqiang, Li Xiaojun, Yang Xulai. rrKaeerkAca-
GB/T40066—2021
Graphene oxide is a new type of carbon material with excellent performance. It has a high specific surface area and rich functional groups on the surface, and has high application value in engineering materials, energy and environment and other fields. Simple and accurate measurement of the thickness of graphene oxide is of great significance: among the common thickness characterization methods, the resolution of atomic force microscopy can reach the atomic level. The thickness of graphene oxide is directly determined by measuring the height difference between graphene oxide and the substrate. This standard uses atomic force microscopy scanning technology. Through the two-number analysis method, the thickness of xenonized graphene is measured, and the consistency measurement method of xenonized graphene thickness measured by atomic force microscopy is established. This method can effectively avoid the influence of pollution, noise and other factors on thickness measurement, and is practical. r kaeerkAca
1 Scope
Nanotechnology Graphene oxide thickness measurement
Atomic force microscopy
GB/T 40066—2021
This standard specifies the sample preparation, measurement steps and result calculation for the atomic force microscopy (AFM) method for measuring the thickness of graphene oxide. This standard is applicable to the measurement of the thickness of graphene oxide with a sheet diameter of not less than 300 nm. The AFM measurement of the thickness of other two-dimensional materials can be used as a reference
2 Normative references
The following documents are essential for the application of this document. For all referenced documents with a date, only the version with the date is applicable to this document. For any undated referenced documents, the latest version (including all amendments) shall apply to this document. GB/T27760 Method for calibrating atomic force microscope nanometer height measurement using atomic steps on Si (111) samples G3/T30511.13 Nanotechnology Terminology Part 13: Graphene and related two-dimensional materials JJI F1351 Scanning probe microscope calibration specification 3 Terms and definitions
The terms and definitions defined in GB/T27760, G3/T30511.13 and JJF1351 apply to this document. For ease of use, some terms and definitions in GB/T30544.13 are repeated below. 3.1
grapheneoxide:Gobzxz.net
Graphene oxide
Chemically modified graphene obtained by oxidation and exfoliation of graphite, which is basically flat and has been strongly oxidized and modified. Note: Graphene oxide is a single-layer material with a high oxygen content, usually characterized by the oxygen atom to carbon ratio (related to the synthesis method, generally about 2.0) [GB/T30544.13-2018, definition 3.1.2.13] 4 Principle and calculation method
4.1 Principle
Spread the graphene oxide sample on the substrate. Use AFM to characterize the surface morphology of graphene oxide and substrate. Then use software to perform background subtraction to obtain the contour line. Measure the height difference between the upper step and the lower step, which is the graphene oxide sample. Thickness: There are two methods for measuring height difference: 4.2 and 4.3.
4.2 Calculation method 1
Use the least squares method to linearly fit the coordinates of each point on the upper and small steps of the contour line to obtain two fitting straight lines (see Figure 1) and the corresponding fitting parameters αbab. The height difference I of the upper and lower steps is measured by formula (1), that is, the distance between the upper and lower straight lines at points,
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GB/T40066—2021
Where:
Y+=a,+b,xx
yr=d,lb,xx
Schematic diagram of calculation method 1
H=(aibXar)-(aa
Sample thickness value, unit is nanometers (nm); the coordinates of the center positions of the adjacent endpoints of the two fitting lines; ab.——the parameter value corresponding to the upper step fitting line; a..b.
the parameter value formed by the lower step fitting line. 4.3 Calculation method 2
The corresponding data on both sides of the step formed by graphene oxide and the substrate are converted into a height probability distribution histogram (see Figure 2), and the normal distribution curve is obtained by Gaussian fitting. The difference in coordinates between the height peaks on both sides is the sample thickness, and its thickness value is calculated using formula (2). er
W yuan/2
height/am
Figure 2 Schematic diagram of the principle of calculation method 2
Note: Probability distribution histogram of height data, where the black-enclosed histogram represents the height probability distribution of graphene oxide on the right side. Blue The histogram represents the probability distribution of substrate height, and the red line is the Gaussian fitting line obtained according to the formula in the figure. Also: and are the maximum values ​​of the height probability distribution obtained by Gaussian fitting of graphene oxide and substrate respectively: and the difference is the sample thickness value. 2
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Where:
H=aI-r
Sample thickness value, in nanometers (nm): GB/T40066—2021
The maximum value of the height probability distribution obtained by fitting the Gaussian function (formula in Figure 2) on the upper surface of the step formed by graphene oxide and the substrate:
The maximum value of the height probability distribution obtained by fitting the Gaussian function (formula in Figure 2) on the lower surface of the step formed by graphene oxide and the substrate.
5 Reagents and materials
5.1 Cloud sheet: The surface flatness is atomic level. 5.2 Ultrapure water: conductivity not higher than 0.1us/cm5.3
Ethanol: analytical grade.
6 Instruments and equipment
Atomic force microscope: vertical resolution better than 0.1nm. The number of scanning lines in a single image is not less than 500. Ultrasonic dispersion instrument: power not more than 300W. 6.2
6.3 Others: analytical flatbed, pipette, glass culture blood, tape, etc. 7 Sample preparation
The sample preparation environment conditions are 20℃~30℃ and the relative humidity is not higher than 65%. 7.1
During the sample preparation process, the environment and utensils should be kept clean and pollutants should be avoided as much as possible. 7.2
Ensure that the prepared samples can be dispersed independently. Stacking of sheets: See Appendix A for sample preparation method: 8 Measurement steps
8.1 The calibration of the atomic force microscope should comply with the provisions of JJIF1351. 8.2 The AFM scanning parameters are set to the tapping mode, and the number of traces is greater than 500, such as 512 or 1024. The scanning range is generally selected within 10 μm×10 μm.
8.3 Select a clear test image and save its original test data. In order to ensure the representativeness of the sample, at least xenonized graphene in different effective areas should be selected on the mica surface for testing. A total of at least 0 (m) independent samples are selected for thickness measurement, and at least 3 (n) contour lines are tested for each sample.
Note: m, n apply to formula (3) in 11.1.
9 Result calculation
9.1 Background subtraction
Perform background subtraction on the AFM original image of the selected sample (see Appendix A), and an image with consistent substrate baseline height on both sides of the measured area can be obtained (see Figure 3).
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GB/T40066—2021
2) AFM original measurement image of graphene oxide 0.8um
b) a) Image after background subtraction
Figure 3 Comparison before and after background subtraction
Select contour line
Select the contour line at the single-sided step of graphene oxide. The selected contour line is parallel to the AFM fast scanning direction (see Figure 4a) and then the height curve L of the contour line is automatically generated (see Figure 4b) Note: When selecting the contour line, try to choose a position with clear boundaries to ensure that the upper and lower steps of the contour line are located on the sample and the substrate. .
|||Single-sided step contour line of graphene oxide sheet
Select a single-sided step contour line a on the graphene oxide surface
h) Height curve of the contour line
Figure 4 Select a single-sided step contour line
9.3 Thickness calculation
Method 1
Use the least squares method to make linear fits for the coordinates of each point on the upper step and the lower step in Figure 4b), and obtain the upper step fitting line 3up—.一h,×.: and the lower step fitting straight line ynexta＋h,×. (see Figure 5). The two fitted straight lines should have the same length and number of points, with a length of not less than 14 nm and a number of points of not less than 20. The absolute values ​​of the slopes bl and b of the two straight lines should be less than 0.1, otherwise the KaeerkAca-
GB/T 40066—2021
contour line is discarded: the step height of the contour line in Figure 5 is calculated using the single-sided step algorithm as shown in formula (1), and (n3) different wheel lines are selected on the same sample. The calculated arithmetic mean is the thickness of the sample, see Appendix A. 1.2-
9.3.2 Method 2
Length 1.2mm, 60 points
Parameters of the fitting line of the lower step
=a+h,xx
hecept.60.738
Parameters of the fitting line of the upper step
Center position of the step height transition zone
P=,lbgxx
Length 1.2um, 60 points
Figure 5 Linear fit is made to the height curve of Figure 4h). The Gaussian fit is used to obtain the maximum value of the height probability distribution of the substrate and the xenonized graphene. The thickness of the measured xenonized graphene is calculated by subtraction (see Figure 2, formula (2), see Appendix 1310 Application of graphene oxide thickness measurement
Application of graphene oxide thickness measurement see Appendix C11 Uncertainty
11.1 Class A uncertainty
Class A The uncertainty is the uncertainty introduced by sample uniformity and the standard uncertainty introduced by measurement repeatability. a) Uncertainty ul introduced by sample uniformity The uncertainty u1 introduced by sample uniformity is calculated by formula (3): ur = s (r) =
Where:
Combined sample standard deviation:
Number of groups (number of test samples), 1, 2..….. m (m[0]): number of measurements per group (number of round lines), -1, 2 (n): the th measurement value of the th group;
The average value of the th group measurement,
Standard uncertainty introduced by measurement repeatability b2
Standard uncertainty introduced by measurement repeatability is calculated by formula (4): u: = MAXLs (r,) J = MAX
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Zas-r)
(4)
GB/T 40066—2021
Formula:
MAX[s(r)-
The maximum value of the single red measurement standard deviation in the single red measurement experiment: The number of measurements when the single red measurement experiment standard deviation occurs (the number of contour line tests): - the th/th measurement value of the group; the average value of the 1st group of measurements.
11.2 B Class uncertainty
The uncertainty component u introduced by the error of the instrument's own test parameters is the uncertainty introduced by the calibration of the original force microscope equipment. 11.3 Synthetic standard uncertainty of measurement results The uncertainty components are unrelated or have little correlation. The relative standard uncertainty \ is synthesized according to formula (5): ue=Vui+uu!
11.4 Evaluation of expanded uncertainty
For normal distribution. When the confidence level is 95※, the corresponding one is 2, then the expanded uncertainty is calculated according to formula (6): U-kXue-2Xue
12 Test report
The test report should include but not limited to the following contents: This standard number:
Test date;
Test environment;
Instrument and equipment;
Sample name;
Experimental results:
Test personnel and units.
12.2 Methods For the test report format of Method 2, please refer to Appendix D and Appendix E6
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.. (6)
A.1 Experimental content
Appendix A
(Informative Appendix)
Method 1 Example
GB/T40066—2021
Example 1 of graphene oxide thickness measurement. The example process mainly includes sample preparation, measurement steps, and result calculation. A.2 Sample preparation
Add 1.5 mg of graphene oxide sample into 10 ml of deionized water and ultrasonically disperse it for 2 h to obtain a uniform xenonized graphene water dispersion solution. Take 1 ml of the water dispersion solution and dilute it 4 times with deionized water. Mark it as sample A. Ultrasonicate for 20 min: Take 0.5 ml of sample A and dilute it 8 times with deionized water, and mark it as sample B for later use. First, use tape to crack a fresh mica surface and place it in a glass culture medium. Then transfer 7 l of sample B and apply it to the mica surface. Then cover the glass culture medium with a lid. Transfer the mica sheet with the sample to an oven and dry it at 60℃ for 2h to remove the water from the mica surface. After drying, remove the instrument for inspection. Note: Ultrasonication for 2 hours will cause the water temperature in the ultrasonic disperser to rise. Change the water in the ultrasonic disperser every half an hour. A.3 Measurement steps Refer to Chapter 8. A.4 Background subtraction Import the AFM original measurement file using the software WSxM4.0Beta8.5. Do not select Plane, Flatten, EqualizeA.4.1 in the import process. Derivative and Reverse options. The file type is all formats (see Figure Al). 40066—2021
Use the software to perform background subtraction on the selected sample, and you can get an image with consistent substrate baseline height on both sides of the measured area. The specific operation is as follows: click the Flatten icon. In the Flattendiscarclingregions operation interface, select the Substracttype type as Line. Then create a Newregion, select all the areas protruding from the substrate surface, click Applyflatteningrcgions and confirm (see Figure A.2). After confirming, the software automatically generates an image after background subtraction (see Figure A.3). Product RT3CO··国国4
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Figure A.3 Image after background subtraction
A.5 Contour line selection
Use the software's contour function to select the contour line at the single-side step of the sample. The software will automatically generate a height curve of the contour line (see Figure A.4). The selected contour line should be parallel to the AFM fast scanning direction. 8
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