It’s easy to forget how much of our scientific work hinges upon comparative data. The entire field of metrology is concerned with the verification and maintenance of “standard reference materials” (SRMs). Creating a perfect reference standard essentially involves proving a negative. In the XRD world, we need to prove that there are no impurities, no crystalline defects, no unaccounted for thermal variations, no stress/strain effects present, and above all, that the first unit produced is effectively identical to the last
Plastic sample holders have been the default option XRD for decades. They’re inexpensive to make, good enough for most purposes, and very resistant to a wide range of chemicals. Seems like a “win” all around right? As long as they’re made correctly and from the proper materials, these work just fine. Spoiler alert: 3D printed thermoplastics have a distinct structure so if you try making your own, be sure they’re well out of the irradiated area. Comparison of the same powder
We’ve been experimenting with better ways to quantify the quality of XRD tubes in the shop. We use these tests on new and used tubes to monitor performance in two key areas. 1) Intensity 2) Spectral purity. What we’ve settled on is a test that involves a wavelength-dispersive approach which gives us a lot of intensity to work with while eliminating background scatter and fluorescence effects. Basically, we’re able to extract more information from the data because the “noise” is almost
Another fully-rebuilt, digital autosampler out in the wild. This one is on a system that already has one of our Si-Drift Detectors and an awesome ICDD Jade Pro/PDF-4+ software package. We’ve got all the fancy new hardware at our in-house lab, but when we need the absolute best data, this is our goto configuration.
Energy-dispersive detectors have been in use on XRD systems for decades, but have always come with caveats. Low energy resolution, Liquid nitrogen cooling, slow start-up and tedious/cryptic tuning controls have limited their popularity in many applications. Silicon Drift technology solves most of these issues and modern electronics covers the rest. The new KSA-SDD system for X-ray diffraction utilizes a full spectrum EDXRF detector which is fully software tuned. The result is a detection system with high enough energy resolution to