XRD Sample Prep: Pulverization w/o Affecting Crystallinity?

In summary, the conversation discusses the methods for analyzing precipitate samples for XRD. The individual mentions that the collected samples are not in powdered form, which is ideal for XRD analysis, and asks for suggestions on how to achieve pulverization without affecting the crystallinity. The idea of evaporating off the carrier fluid as an alternative method is also mentioned. However, the individual expresses concerns about the practicality and the need to collect the filtrate for analysis.
  • #1
Baho Ilok
47
5
I have some precipitate samples that I wish to analyze for XRD. I collected them by filtration of a slurry. Through the filtration, the precipitates "cemented" on the surface of the filter pad so the samples I collected are not exactly in powdered form, which I believe is the ideal form to do XRD analysis.

I have read that in such cases, pulverization can be achieved using mortar and pestle. However, I worry that this might affect the crystallinity of the precipitates, which is the most important characteristic that I wish to analyze.

Can somebody suggest a method to achieve pulverization without affecting (or at least minimizing) the effect on crystallinity? Or if I am to use mortar and pestle, is there an additional step that should be taken to avoid errors?

Thank you so much!
 
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  • #2
Can you evaporate off the carrier fluid instead of using filtering for separation ?
 
  • #3
Nidum said:
Can you evaporate off the carrier fluid instead of using filtering for separation ?
I have thought of that but my slurry volume is 1 L so it may be a bit impractical to evaporate off the solvent. And I also have to collect the filtrate for analysis.
 

1. What is the purpose of pulverization in XRD sample preparation?

Pulverization is used to create a homogeneous sample for XRD analysis. It breaks down large particles into smaller, more uniform particles, making it easier for X-rays to penetrate and interact with the sample.

2. How can I prevent the pulverization process from affecting the crystallinity of my sample?

To minimize the impact on the crystallinity of your sample, it is important to use a gentle grinding method, such as a mortar and pestle or a ball mill with low energy input. It is also crucial to avoid excessive grinding time and to keep the sample cool during the process.

3. Can I use liquid nitrogen to cool my sample during pulverization?

Yes, liquid nitrogen can be used to cool the sample during pulverization. It can help to prevent thermal damage and maintain the crystallinity of the sample. However, it is important to be cautious and use proper safety measures when handling liquid nitrogen.

4. Are there any alternative methods for sample pulverization that do not affect crystallinity?

Yes, there are alternative methods such as cryomilling, which involves freezing the sample in liquid nitrogen and then grinding it in a ball mill. This method is often used for samples that are sensitive to heat or have low melting points.

5. How can I determine if the pulverization process has affected the crystallinity of my sample?

The most common way to determine the impact of pulverization on the crystallinity of a sample is by performing XRD analysis before and after the grinding process. This will allow you to compare the diffraction patterns and look for any changes or shifts in the peaks, which could indicate a change in crystallinity.

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