Reducing the Particle Size Effect in XRF Measurements

Undertaking X-ray fluorescence (XRF) is an excellent way of ascertaining a material’s elemental make-up. Not only is XRF a non-destructive technique, meaning that the analyzed sample remains undamaged, but it can identify a variety of elements, starting with sodium (Na) and ending with uranium (U). Its ability to decipher the elements within a sample works through the application of X-rays. These X-rays can excite a material’s atoms, generating characteristic X-rays that have a specific energy that relates to an element, which can be deciphered through a detector. Unfortunately, there is something that can affect the accuracy of XRF measurements: the particle size effect.

The Particle Size Effect And Its Consequences

There are times when particle size can impact XRF measurements, causing the gathered results to be inaccurate. Larger particles can have more of an effect than the smaller ones and influence the reliability of the results.

X-rays may be more scattered with larger particles, heightening background signals and concealing lower fluorescence signals that’re emitted by the elements. This scattering effect can also heighten relative errors from measurements. Moreover, larger particles can cause issues with the sample’s uniformity. Particles with an increased size tend to possess an irregular distribution of elements. The lack of uniform distribution can alter the lengths of X-ray paths and influence the accuracy and intensity of the fluorescence signals that’re identified.

Managing The Particle Size Effect in XRF

The particle size effect can have negative repercussions on XRF measurements. Particles with a larger size can cause relative errors and issues with accuracy. That’s why it’s crucial to know the best steps to take to prevent the particle size effect from causing issues with XRF measurements.

1. Preparing The Sample

Controlling the particle size effect begins with how well a sample is prepared. There are a number of methods that can be implemented to ensure XRF measurements are both reproducible and accurate. These include:

• Grinding and Sieving: The sample is ground down to create more uniform and finer sizes of particles through grinding tools or a ball mill. From there, the sample can be sieved to take away any particles with increased sizes and provide uniformity. Utilizing grinding to form particles with smaller sizes can lessen X-ray scattering, something which can cause issues with XRF measurements.
• Forming Pellets: Once grinding has been completed, pellet creation can be undertaken to enhance the accuracy of XRF measurements. A sample can be pressed to create a pellet through the use of a hydraulic press. The pellet will be smooth and flat, ensuring the surface of the sample is more homogenous. This helps make sure the interactions between X-rays are consistent throughout the full area of the sample, delivering a better representative measurement and understanding of its bulk composition.

2. Algorithms

The application of correction algorithms is another way to enhance XRF measurements. These algorithms include:

• The Fundamental Parameters Approach: Its theoretical calculations consider the physics behind the interactions between matter and the X-rays. That way it can rectify the impact that particle size may have.
• Compton Scattering Normalization: Fluorescence intensities can be normalized with the inclusion of the Compton scattering peak in the XRF spectrum. It can be utilized as a reference to amend elemental peaks as it’s less likely to be influenced by the effects of particle sizes.

3. Calibration

Calibration can also lower the impact that the particle size effect can have on XRF measurements. Incorporating a standard, one that reflects the sample’s composition or size, helps with any matrix effects that occur due to particle size. As a result of using a matrix-matched standard, it’s possible to enhance the accuracy of XRF measurements. This is because it can compensate for the impact of particle sizes, including any absorption effects.

4. Additional Techniques

Other XRF techniques exist that can manage particle size and, thus, deliver accurate XRF measurements. For instance, micro-XRF is a technique that focuses on smaller sections of the sample. This means it’s less likely to be impacted due to the sample’s full particle size distribution. Additionally, there’s total reflection XRF, a technique that hones in on extremely thin layers of the sample. Its focus on thinner layers means it’s unlikely to be influenced by particle size.

Remain Diligent Against The Effects of Particle Size On XRF Measurements

XRF is a technique that can be applied to so many different areas, including geology, environmental analysis, and pharmaceutics. Therefore it’s crucial that its measurements remain accurate and unaffected by the impact of particle size. Particle size can cause a number of problems for XRF, from altering uniformity to causing X-ray scattering issues. To protect XRF measurements and retain their accuracy, try the methods we have discussed. These techniques and tools can help you generate reliable results.

We, XRF Scientific, have various products related to XRF analysis and information about XRF spectrometers on our website. Contact us now and we’ll be there to help you understand which of our products is the right fit for establishing robust XRF measurements.