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The D2 Phaser 6-position autosampler uses a completely different sample holder that their other systems. We’ve just completed our first production run of these blanks so they’ll be ready for custom orders. Contact KSA for more information.

XRD patterns are complicated by a variety of undesirable effects. Some of which are easy to deal with, others are unavoidable. One of the issues we see often is scattering and diffraction effects that are actually being caused by the sample holder itself. These effects can usually be modeled out, but simply knowing which artifacts are being generated from scatter off the sample holder vs amorphous content or phases present in the sample itself can make the difference between an easy analysis and a grinding, iterative march toward a final result. One of the most common effect we see is scatter from plastic sample holders. Most of the sample holders we produce are either Aluminum or PMMA plastic, but either way, one of the easiest ways to avoid undesirable scatter is to simply enlarge the sample well. We’ve been doing this for decades on the standard, non-rotating sample holders by cutting a large, rectangular well rather than the standard, 25mm circular well.

This week we did a little experiment to see just how much larger our sample well needed to be to eliminate the common PMMA hump at ~13 degrees 2Theta (Cu energy). It turns out that an increase of only 5mm in diameter made a huge difference in the total scatter even with very “wide-open” optics. See the scan images below for a real-world picture of the difference we saw. This may not seem like a significant problem until you’re looking for phases with D-spacings down in that region near the hump. Analysis of clay minerals can become particularly complicated. This is a great example of why we love talking to clients and XRD users around the world.

We often receive requests for small powder wells to be ground into our zero-background sample holder plates. I usually try to talk the requestor out of this as it has limited usefulness for most applications, but there are some reasons one might benefit from this type of holder. It’s for these special cases that we’ve always offered custom ground wells in our ZBH plates and we continually improve our process to give our clients exactly what they want and need to get their work done.

There are three reasons I try to avoid this.

  1. It adds cost. The very small grinding tools required for this cut very slowly. This is partially to avoid building up heat in the plate which will shatter if it goes too far. In the foolishness of my youth I once tried to score large wafers with a CO2 laser. After two passes it would explode leaving about 50% waste material, but it got the job done. Heat is your enemy when it comes to very hard materials like this. We also don’t use pre-ground plates. Each one is machined from a flat plate after it’s been mounted in the sample holder to ensure perfect alignment with the plane of diffraction while also giving us the freedom to cut any shape/depth we could want. I.e. if one wanted a square or oval shaped pocket, we could machine that. All this flexibility adds up to additional work/time which adds to the cost of each holder.
  2. It’s often unnecessary. If you have enough material to fill most wells, it probably won’t be transparent to x-rays anyway. I find that many users of sample holders with wells could get by without them by simply using a smaller well in a standard sample holder. The additional scatter from PMMA plastic may or may not be a problem, but if the user can live with it, it’s a huge cost saver.
  3. As soon as we break the surface, we’re no longer dealing with a monocrystalline material. I’ve never seen any practical evidence that this causes a problem, but it’s always concerned me that grinding these plates essentially creates a polycrystalline material at the surface of the well. I would love to hear from anyone who’s ever seen a weak Si pattern superimposed on their data.

One alternative I often recommend is recessing the entire plate by some number of microns to accommodate different particle sizes if that’s a concern. I believe that many XRD users are asking for sample wells in their ZBH simply to avoid the displacement error inherent in mounting their powder on top of a plate which has already been fixed at the plane of diffraction. Recessing the plate allows us to retain the polished surface of the ZBH and allows us to mount it with at least the same degree of precision that a well would provide. Precision mounting adds about as the same cost as grinding, but it definitely has benefits. To my knowledge, KSA is the only company offering this type of mounting.

So that was an awful lot of reasons to avoid this, but there is one very big benefit of using a ZBH with a ground well. This allows you to run very small volumes of sample material while maintaining a very consistent irradiated area. Imagine the same volume of powder spread across a flat plate. Each time this is done, a slightly (if not significantly) different surface area of the plate is likely to be presented. The end result of this will be variations in intensity and perhaps preferred-orientation. Particle statistics change with varying numbers of crystallites in the plane of diffraction as well. This is all complicated by the changes in the irradiated area throughout a normal scan with divergent-beam optics.

The well pictured here is 12mm in diameter and 0.2mm in depth and a good example of the kind of custom work that is most common for us.

The majority of the samples we receive come in volumes high enough to completely fill the well in any of our standard sample holders. Some are too large or oddly shaped which calls for a special holding solution like those listed here, but many are simply very small quantities of powder. Placing these in a standard holder would leave them well outside the plane of diffraction and provide terrible data, not to mention substantial scatter
or diffracted background from whatever the powder is placed on. The answer is a zero background sample holder (ZBH). Most our users at KS Analytical Systems run the original Siemens/Bruker plates, but others are using Si(100) and even glass substrates. We’re very happy to say that
we’re able to offer a direct replacement for these with our new ZBH-32 holders. These fit most Siemens XRD systems and can be customized for use in most any other system. Contact us for more information on this. The scan below shows the data collected from a single mg of Silicon 640B standard powder spread across a ZBH.

Off Planar Quartz ZBH w-1mg 640B

Full scan of 1mg Silicon 640B standard spread across a ZBH


ZBH-32 sample holders mounted for Siemens and Bruker single sample stages.


Some users report acceptable results using simple glass plates. While there are serious caveats here, it may be a reasonable solution for some users. The issue with amorphous glass is not diffracted peaks in the background, but rather, scatter off the surface. X-ray scattering off a surface is inversely proportional to the average atomic number of that material. That is to say, the lighter the matrix, the more efficiently it will scatter X-rays. This is why we use a pure Graphite sample to characterize the emission spectra of our XRF instrumentation. The glass sample shows the expected scatter “hump” starting at a very low angle and it doesn’t flatten until nearly 100°2Θ. While some of this can be modeled and subtracted with good profile fitting software like Jade 2010, it can be challenging to match the data quality of a good ZBH. We’re working on a series of videos to guide new users through some of these features, but on-site training classes are also available.


Glass plate

Amorphous glass empty

Glass-Qtz-Si510 overlay

Glass, ZBH-32 and off-planar quartz scans overlayed for comparison









Several of our customers in the geological industry use standard Si(100) wafers. These can be a great solution, but again have serious drawbacks for some applications. The Si(100) material creates diffracted peaks which are very sharp and therefore easier to model out sometimes, but also very high as the material is monocrystalline. The scan below shows what happens when one tries to run a normal scan across a bare plate. The largest peaks are actually only one or two which have over loaded the detector and caused it to drop out. All of these scans were collected with our SDD-150 which can handle up to 1×10^6 cps, but for the sake of good comparison, we left it tuned as it would be for a standard pattern. The monocrystalline nature of this material causes big problems, but it also allows for a creative solution. See the second scan for the results of the same measurement with the plate angled 1 degree off of theoretical. With this geometry, it’s unlikely this would affect the data quality dramatically, but the offending peaks are drastically diminished.


Si-100 wafer

Si-100 empty

Si-100 locked vs unlocked

Si-100 standard vs skewed scan











Off-planar Quartz holders have been the industry standard for decades. Historically, these have been made from solid, monocrystalline quartz material cut at a specific angle (6° off the C axis if I’m not mistaken). While these work well, they can be inconsistent. Even some of the OEM holders we’ve tested have shown some peaks which we can’t explain. Talking to some very experienced crystallographers, we find that they’ve had similar experiences.



Off Planar Quartz ZBH

Off-planar Quartz empty

ZBH-32 empty

ZBH-32 empty









We’ve been looking for a better answer for several years, but there are few off-the-shelf materials which work as well as off-planar quartz. The ideal answer was to cut solid Si(100) oriented billets such that the face presented to the diffractometer had no d-spacings which would diffract in the normal range of these machines. This is not unlike the off-planar Quartz method, but the starting material is much more consistent and durable. Si(510) offers very low background as well as the consistency of a manufactured product. The new ZBH-32 sample holders from KSA come in two versions, ZBH-25 and ZBH-32 with the latter being ideally suited for rotating stages and low angle work.