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JY/T 011-1996 English PDF (JYT011-1996)

JY/T 011-1996 English PDF (JYT011-1996)

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JY/T 011-1996: General rules for transmission electron microscopy

This General Rules specify the conventional analytical method of transmission electron microscopy; it is are applicable to high-voltage transmission electron microscopy, high-resolution transmission electron microscopy, ordinary transmission electron microscopy AND simple transmission electron microscopy.
JY/T 011-1996
JY
INDUSTRY STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
General rules for transmission electron microscopy
ISSUED ON. JANUARY 22, 1997
IMPLEMENTED ON. APRIL 1, 1997
Approved by. State Education Commission
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Definitions ... 4
3 Principle... 4
4 Instruments ... 6
5 Specimen ... 8
6 Analytical procedures ... 8
7 Expression of analysis results ... 14
8 Safety precautions ... 14
Foreword
The drafting format and method of this Standard complies with the requirements of GB/T 1.1-1993 "Directives for the work of standardization - Unit 1. Drafting and presentation of standards - Part 1. General rules for drafting standards" and GB/T 1.4-88 "Directives for the work of standardization - rules for drafting chemical analysis standards".
The drafting organization of this Standard. The State Education Commission. Main drafters of this Standard. Zhang Datong and Wang Yongrui.
Participating drafters of this Standard. Wan Derui, Lin Chengyi and Zhou Shanyuan.
General rules for transmission electron microscopy
1 Scope
This General Rules specify the conventional analytical method of transmission electron microscopy; it is are applicable to high-voltage transmission electron microscopy, high-resolution transmission electron microscopy, ordinary
transmission electron microscopy AND simple transmission electron
microscopy (hereinafter referred to as TEM).
2 Definitions
This Standard adopts the following definitions.
2.1 Resolution
TEM's capability that can clearly distinguish the minimum distance between two object points and crystal faces.
2.2 Astigmatism
An image blurring that is caused by non-rotational symmetry of electromagnetic lenses' magnetic field, in which the lenses have different focusing ability in mutually perpendicular directions.
2.3 Electron diffraction
The effect whereby electron beams are scattered in crystals; only in the direction of satisfying the Bragg's Law, are there emitting of diffracted beams that are mutually reinforced.
3 Principle
The determinant of TEM imaging is the specimen scattering to incident electron, including elastic scattering and inelastic scattering. When thin-specimen is imaging, the un-scattered electrons shall constitute the background. However, the image contrast depends on different scattering characteristics of each part of the specimen to the electrons. Different experimental conditions shall produce different image contrasts.
TEM can not only show the microstructure morphology of the specimen, but 3.2 Diffraction modality
If the specimen is crystal, its electron diffraction pattern shall be presented on the focal plane of the objective lens. Change the current of intermediate lens to make the image formed on the focal plane of the objective lens. The electron diffraction pattern on the plane is enlarged by the intermediate lens and the projector lens. Then the enlarged image of electron diffraction pattern shall be obtained on the phosphor screen.
4 Instruments
4.1 Instrument structure
4.1.1 Lighting system
It is composed of electron gun and condenser. Electron gun provides stable electron source of small size and emits high-brightness electron beams. Condenser converges electron beams and irradiates the specimen.
4.1.2 Specimen room and imaging system
The specimen room is under the lighting system. Placed on the specimen holder, the specimen can move or tilt within the specified range. Composed of objective lens, intermediate lens and projector lens, the imaging system enlarges the image and presents it on the phosphor screen.
4.1.3 Observing and recording system
The observing room is under the projector lens. The image on the phosphor screen can be observed through windows. The photographic plate is placed under the phosphor screen. When phosphor screen is erected, it shall expose and record the image.
4.1.4 Other systems and accessories
Other systems and accessories include vacuum system, power system,
security system and cooling system. Some are equipped with scanning
accessories, micro diffraction apparatus, electron energy loss spectrometer (EELS) and X-ray energy dispersive spectrometer (EDS), etc.
4.2 Technical indicators
6.2 Test preparation
6.2.1 Centering adjustment
Increase high voltage and filament current. After light spot appears on the phosphor screen, center the lighting system and imaging system. Adjustment of ?€?current center?€? or ?€?voltage center?€? shall be strictly in accordance with the instructions for use.
6.2.2 Astigmatism calibration
Use the well-known specimens, for example, micro sieve. Observe the hole at high magnification. Alternately adjust the focus of the objective lens and the anastigmator. When the objective lens is under-focused or over-focused, the uniform and clear Fresnel Fringes image shall be obtained at the edge of the hole.
6.2.3 Magnification calibration
Because of hysteresis effect of electromagnetic lens, there are 5%~10% error between the actual magnification and the reading value. If the magnification is less than 50,000 times, use grating replica (2000 pcs/mm) with 50 nm fringe space to calibrate. For greater magnification, use thin crystal with well-known grating space to calibrate. Shoot photos of different magnifications and obtain the calibration curve by calculation.
6.2.4 Camera constant calibration
Camera constant is the product of diffraction camera length L and wavelength of the incident electron beams k. Because of uncertainty of the length of TEM camera, it needs to use a gold polycrystalline thin film to calibrate.
6.2.5 Magnetic rotation calibration
In the selective-area, when diffraction modality is switched to imaging modality, the change on excitation conditions of intermediate lens shall make the image and the diffraction pattern rotate at different angles, comparing to the actual orientation of specimen crystal. If the magnetic rotation of the image is ??i and the magnetic rotation of the pattern is ??d. then the magnetic rotation of the image to the pattern shall be ??=??i?????d. Usually, it utilizes external features to directly reflect the calibrated magnetic rotation of MOO3 thin crystal. Therefore, it shall only need the calibration value of crystal rotation represented by the diffraction pattern to represent the actual rotation of the crystal.
6.2.6 Specimen height calibration
During magnification calibration and selective-area diffraction, in order to them coincide. Switch to diffraction modality. Pull out objective lens aperture. The electron diffraction pattern, which reflects the crystallographic
characteristics of specimen in micro-area, can be obtained on phosphor screen. For electron diffraction in selective-area, the size of selective-area is limited by the effect of spherical aberration of objective lens and image focus error. For high-resolution TEM, the diameter of minimum selective-area is about 1 ??. In order to obtain smaller selective-area, it uses micro-diffraction techniques (?? diffraction). In experiment, use scanning transmission operation mode, the beam-spot diameter is reduced to less than 100 nm. The scope of micro-area of specimen that participates in diffraction is limited by the beam-spot diameter. 6.4.3 Bright-field image and dark-field image of diffraction contrast
Usually, the analysis on bright-field imaging and dark-field imaging is always combined with electron diffraction of selective-area, so as to determine the phase's microscopic morphology, lattice type and parameters. If objective lens aperture is used to block diffraction beams, and only transmission beams are allowed to go through the aperture hole to imaging, then, the image obtained shall be called bright-field image of diffraction contrast. If objective lens aperture is used to block transmission beams and most of diffraction beams, and only some diffraction beams are allowed to go through the aperture hole to imaging, obviously, the area contributed to the diffraction beams of specimen or the bright contrast represented by phase in dark field shall be called the dark-field image of diffraction contrast.
Generally speaking, central dark field imaging produces small aberration. Make selective-area diffraction of specimen first. Tilt the specimen to make some diffraction spot to be the brightest (dual-beam conditions) except the
transmission spot. Adjust the lighting electron beam to tilt. Move the
transmission beam to the original bright diffraction spot. Then the weak spot which is symmetrical to the original bright spot is moved to optical axis and shall get brighter. Allow only this diffraction beam to get through the aperture hole of objective lens to form the central dark-field image. Use specific diffraction beams to form the central dark-field image of diffraction contrast is one of the effective methods to analyze complicating diffrac...

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