What Does Transmission Electron Microscopy Mean?
1. General morphology observation
Visual observation of the appearance of the sample can provide basic information for subsequent research.
2. Phase analysis utilizes techniques such as electron diffraction, micro area electron diffraction, and convergent beam electron diffraction to determine the phase, crystal system, and even space group of materials, thereby gaining a deeper understanding of their crystal structure and composition.
3. Determination of crystal structure
With the help of high-resolution electron microscopy, it is possible to directly observe the structural projection of atoms or atomic clusters in a specific direction within a crystal. For objects of different sizes, the appropriate type of electron microscope can be selected based on their size: objects larger than 100 nanometers can be observed using low-pressure, low resolution electron microscopy; Objects between 100 nanometers and 10 nanometers are barely visible using high-pressure, low resolution electron microscopy; Objects smaller than 10 nanometers must be observed using high-pressure, high-resolution electron microscopy.
4. Observation of structural defects
By using diffraction contrast imaging and high-resolution electron microscopy techniques, structural defects present in the crystal can be observed, the types of defects can be determined, and defect density can be estimated.
For the observation of different types of defects, different types of electron microscopes can be selected: low-pressure and low resolution electron microscopes are used for interface observation; High voltage and low resolution electron microscopy can be used for dislocation observation, and using high voltage and high resolution electron microscopy yields better results; High voltage and high-resolution electron microscopy are required for the observation of stacking faults. The traditional method for observing dislocations is metallographic corrosion, which forms "pits" by exposing dislocations through corrosion. However, this method is indirect observation and has poor effectiveness. In contrast, high-pressure and low resolution transmission electron microscopy can directly observe dislocations with better results; The observation effect of high-pressure and high-resolution transmission electron microscopy is better.
5. Micro area chemical composition analysis
The use of energy dispersive X-ray spectrometer or electron energy loss spectrometer attached to transmission electron microscopy can accurately analyze the micro chemical composition of samples, providing important basis for studying the composition distribution and chemical properties of materials.
6. Analysis of Element Distribution
By using transmission electron microscopy with scanning attachments and energy dispersive X-ray spectrometer, or transmission electron microscopy with image filters, the distribution of elements in the sample can be analyzed to determine whether there is component segregation in the sample. This is of great significance for studying the relationship between the microstructure and properties of materials.
