X-ray fluorescence analysis (XRF)
X-ray fluorescence analysis (XRF) enables the chemical composition of a material or coating system to be determined quickly and precisely. The method is completely non-destructive, which makes it particularly valuable for quality control and research.
Table of contents
- What is X-ray fluorescence analysis?
- How does X-ray fluorescence analysis work?
- X-ray fluorescence analysis at Quality Analysis
- Advantages of XRF
- The X-ray fluorescence spectrometer
- What is measured using X-ray fluorescence analysis?
- Applications for X-ray fluorescence analysis
- X-ray fluorescence analysis in summary
What is X-ray fluorescence analysis?
X-ray fluorescence analysis is an analytical method that uses X-rays to determine the chemical composition of a material. The high-energy rays excite the atoms in the sample to emit characteristic fluorescence rays, which are then acquired by a detector. The XRF method is precise, fast and permits the testing of solids, powders or liquids.
How does X-ray fluorescence analysis work?
X-ray fluorescence analysis is based on the interaction of X-rays with a sample. The following steps are necessary and can be undertaken automatically:
1
Sample preparation
Solid materials such as metals, powders, jewellery or finished components and coatings can be analysed directly, i.e. non-destructively.
2
Generation of the X-rays
X-rays are generated in an X-ray tube by accelerating electrons in the direction of a target (e.g. tungsten or rhodium). These rays have a high energy and are incident on the sample to be analysed.
3
Emission of the rays
As electrons move within their orbitals, energy is emitted in the form of characteristic fluorescence rays. These rays are uniquely specific to each element, comparable to a "fingerprint".
4
Detection of the rays
A detector, often a silicon drift detector (SDD), acquires the energy and intensity of the rays emitted. The energy indicates which element is involved, while the intensity indicates the quantity of the related element.
5
Analysis of the data
The data measured are processed by a software application permitting precise elemental analysis. The result is an overview of the chemical composition of the sample.
X-ray fluorescence analysis
at Quality Analysis
At Quality Analysis, we offer a wide range of analytical methods for the determination of the chemical composition of materials. With the aid of a Spectro Midex XRO spectrometer, with its high-resolution detectors and automated control system, we can achieve fast, precise results with small, complex samples.
In addition to X-ray fluorescence analysis, we also use EDX and spark emission spectroscopy to determine the elemental composition of various materials.
- Analysis of the smallest samples, particles or fibres using the Spectro Midex
- Layer thickness measurement and layer analysis
- Analysis of alloys, solids, liquids and powders
- Detection and quantification of heavy metals and other harmful substances in soils, sediments and plastics
- Analysis of electronic assemblies for harmful residues
Advantages of XRF
XRF is fast, cost-effective and generally non-destructive, which means that samples can be analysed without loss. It offers high precision during the determination of the chemical composition and can detect a wide range of elements. The method is ideal for applications in quality assurance, environmental analytics and material inspection.
The X-ray fluorescence spectrometer
An XRF analysis is undertaken in an X-ray fluorescence spectrometer such as the Spectro Midex. Essentially, every XRF spectrometer consists of two main components. Firstly, there is the primary radiation source, which in most cases is an X-ray tube. This tube generates the high-energy X-rays required to excite the atoms in the sample to emit characteristic fluorescence radiation.
The second key component is the spectrometer's detector, as it determines the type of detection and therefore the precision and accuracy of the analysis. Two different types of detectors are used in X-ray fluorescence analysis: energy-dispersive and wavelength-dispersive detectors. The difference between these types is in the way the X-rays emitted are analysed.
Energy-dispersive X-ray fluorescence analysis
Energy-dispersive X-ray fluorescence analysis (ED-XRF) is a special form of X-ray fluorescence analysis in which the characteristic X-rays emitted by the atoms in a sample are analysed based on their energy. In this method, the sample is excited with X-rays, causing the atoms in the sample to emit X-rays with specific energies. Similar to EDX, an energy-dispersive detector measures these energies and identifies the elements in the sample as well as their concentrations.
Wavelength-dispersive X-ray fluorescence analysis in comparison
In contrast, wavelength-dispersive X-ray fluorescence analysis (WD-XRF) is characterised by its greater precision and sensitivity. Instead of measuring the energy of the X-rays directly, WD-XRF separates the rays by wavelength using a crystal monochromator. This method permits finer differentiation of the elements with similar radiation energy and provides more precise quantitative results. However, it requires more complex equipment and is slower than ED-XRF.
What is measured using X-ray fluorescence analysis?
X-ray fluorescence analysis (XRF) is used to identify chemical elements in a material and measure their concentrations. The method provides qualitative and quantitative information about the elemental composition. Among other aspects, the following materials and elements can be analysed:
Detection of heavy metals
Using XRF, harmful heavy metals such as lead, cadmium or arsenic can be identified in various materials and components, e.g. in electronic devices, toys, consumer goods and jewellery.
Determination of the gold content
XRF is often used to quickly and precisely determine the purity and authenticity of gold (carat-content) in precious metals and jewellery. Gold coatings on electronic components such as printed circuit boards, connectors and contacts can also be analysed. This analysis is used for quality control and ensures that the coating is sufficiently thick, corrosion-resistant and conductive.
Analysis of alloys
XRF is used to analyse the exact composition of alloys. The metals contained in steel or bronze and their percentages, for example, can be precisely identified. This information is crucial for quality control in metal processing.
Applications for X-ray fluorescence analysis
Due to its non-destructive method and high precision, X-ray fluorescence analysis is an indispensable tool in numerous sectors:
Environmental analytics
XRF is used to analyse soil samples, water samples and recycling fractions to detect heavy metals such as lead, cadmium or arsenic. This analysis is crucial for environmental monitoring and compliance with safety regulations.
Electronics manufacturing
X-ray fluorescence analysis can be used to analyse electronic components and printed circuit boards for contamination (e.g. heavy metals such as lead, cadmium and mercury) and determine the thickness of metallic coatings (e.g. layers of gold or nickel).
Automotive
In the automotive industry, XRF is used to check the chemical composition of metals, plastics and coatings in various components for quality assurance. This analysis assists with the control of the quality and characteristics of alloys and therefore contributes to material optimisation and quality assurance.
Plastics analytics
XRF is used to determine the chemical composition of additives, filler materials or flame retardants in plastics and for the analysis of coatings on plastics. This information is important for quality control and compliance with legal requirements.
X-ray fluorescence analysis in summary
X-ray fluorescence analysis (XRF) is an analytical method for materials in which a sample is irradiated with X-rays. The resulting fluorescence radiation is characteristic for the chemical elements in the material. In this way, these elements can be identified and their proportions determined. This method is frequently used in industry and research because it is quick, non-destructive and precise.
