What Is TEM Analysis?
A transmission electron microscope forms an image by passing an electron beam through a very thinly prepared sample. The interaction of electrons with the atoms in the sample gives very high-resolution images in which even atomic planes can be seen.
Purpose of TEM Analysis
The purpose is to image internal structure at a scale SEM cannot reach. Nanoparticle size distribution, thin-film layer structure, crystal defects and grain-boundary structures are examined with this technique.
Which Products Is TEM Analysis Applied To?
- Nanoparticles and nanomaterials
- Thin films and multilayer coatings
- Semiconductor structures
- Catalyst materials
- Biological thin sections
In Which Sectors Is TEM Analysis Used?
Standards Related to TEM Analysis
- ISO 21363 (nanoparticle size analysis — TEM)
- ISO 29301 (analytical TEM — magnification calibration)
TEM Analysis Conditions
- Specimen thickness
- It must be very thin for electrons to pass through; the method of preparation is selected accordingly
- acceleration voltage
- Depending on the sample and desired resolution
- display mode
- Brightfield, darkfield, high definition or STEM
- Diffraction
- Crystal structure can be determined by selected area electron diffraction
Equipment for TEM Analysis
- Transmission electron microscope
- Sample thinning systems (ion milling, ultramicrotome, FIB)
- TEM grids
- Image and diffraction analysis software
Sample Requirements for TEM Analysis
- The sample must be prepared thin enough for electrons to pass through; this is a separate and time-consuming process
- Nanoparticles are dropped onto the grid in suspension
- Preparation is destructive; the sample cannot be returned
- The sample's composition and the structure to be examined must be stated
Duration of TEM Analysis
Sample preparation often takes longer than imaging. For samples requiring FIB or ion milling, total duration reaches a few working days.
TEM Analysis Procedure
- 1The sample is prepared to an electron-transparent thickness using a suitable method.
- 2It is placed on the grid and loaded into the column.
- 3Focusing and alignment are performed.
- 4The relevant regions are imaged at different magnifications.
- 5A selected-area diffraction pattern is taken if required.
- 6Size, layer thickness and defect measurements are made.
TEM Analysis Acceptance Criteria
The acceptance criterion for nanoparticle size distribution or layer thickness comes from the product specification.
Evaluation of Results
A TEM image represents a very small volume. For statistical results such as size distribution, a sufficient number of particles and regions must be measured, and this number must be stated in the report.
TEM Analysis Report
- Specimen identification and preparation method
- Instrument conditions and imaging mode
- Scaled images
- Measurement results and the number of particles/regions examined
- Diffraction pattern and its interpretation, if any
Accreditation
EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.
Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.
Scope and authorisationsRelated Regulations
- EU recommendation on the definition of nanomaterial, and cosmetic/food nanomaterial notifications
Pages Where This Method Is Used
Analytical Methods — What Does This Group of Methods Do?
The section below describes the field that the TEM Analysis test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.
Analytical method pages are pages about a MEASUREMENT TECHNIQUE rather than about a test. The difference matters: "salt spray testing" is a test and answers one question; "ICP-MS" is a technique and is used in dozens of different tests. Sometimes the user is looking not for the test but for the technique — because the method name is what appears in their specification.
This distinction becomes decisive in choosing a laboratory. When a customer asks for "heavy metal analysis", the real question is by which technique it will be done: XRF is fast and non-destructive but does not distinguish compounds; AAS is economical for a single element; ICP-OES screens multiple elements; ICP-MS sees trace levels. The same sample gives results with different detection limits and different uncertainties across the four techniques.
Method selection is made against three criteria. DETECTION LIMIT: is the concentration sought within the range the method can see? MATRIX COMPATIBILITY: is the sample matrix (plastic, food, soil, metal) one the method can handle, and is pre-treatment required? SPECIFICATION LINK: does the product standard or legislation mandate a particular method? The third often overrides the first two — the specification binds the method.
Method pages build a CHAIN. A technique is linked to the test pages where it is used, to the standards those tests rest on, to the legislation those standards are tied to and ultimately to market access regimes. The example chain in the source document works like this: XRF → metal analysis → RoHS compliance → heavy metal restriction → coating pages. Whichever link the user enters from, they reach the others.
Sample preparation is the invisible half of the result in this family and is a greater source of error than the technique itself. The digestion method, degree of grinding, extraction solvent and dilution ratio change the result markedly. The same sample on the same instrument gives a different result with different preparation; the definition of the method therefore covers preparation too.
Calibration and verification are the third determining component. An instrument is calibrated with certified reference material, the calibration curve is verified periodically and a control sample is run in each batch. Without these steps, a number produced is not traceable even if the instrument is working correctly.
Method groups in this field
Elemental analysis
ICP-OES, ICP-MS, AAS and XRF. They differ in detection limit, matrix tolerance and multi-element capacity.
Chromatography
GC, GC-MS, HPLC, LC-MS/MS and ion chromatography. It separates a mixture into its components and measures each separately.
Spectroscopy
FTIR, Raman, UV-Vis and optical emission. For material identity, functional group identification and alloy composition.
Thermal analysis
DSC, TGA, DMA and dilatometry. Transition temperatures, composition, decomposition and dimensional behaviour.
Microscopy and imaging
Optical microscopy, SEM-EDS, radiography and tomography. Structure, defects and elemental distribution.
Classical (wet) chemistry
Titration, gravimetry and colorimetry. Used as a reference method and in confirming instrumental results.
Commonly confused in this field
- XRF is a screening tool; it sees elements and does not distinguish compounds. A decision on a restricted compound requires confirmation by wet chemistry.
- The phrase "not detected" is not proof of absence; it is read together with the detection limit of the method.
- The specification binds the method. A technically better method is not accepted if the specification calls for another.
- Sample preparation is part of the result; a report that does not state the preparation is not reproducible.
- Results obtained by different techniques cannot be compared directly; their detection limits and uncertainties differ.
- A method page is not a test page; which method applies to which test comes from the product standard.
Which decisions these results support
- Matching the method written in the specification to the laboratory's scope
- Method selection according to detection limit and matrix compatibility
- Confirming an instrumental result with a reference method
- Eliminating deviations arising from sample preparation
Related Tests
Frequently Asked Questions About TEM Analysis
How is a choice made between TEM and SEM?
SEM is used if the surface is being examined; TEM is used if internal structure or sub-nanometre detail is needed. TEM sample preparation is far more laborious.
Can every material be examined by TEM?
The sample must be able to be prepared to an electron-transparent thickness. This may not be possible for every material or may require special preparation techniques.