KS ANALYTICAL SYSTEMS

Tag: diffraction

  • Rigaku D-Max zero background sample holders

    Rigaku D-Max zero background sample holders

    This project started with a phone call several months ago from a Canadian government lab. They had a very specific application so the design was driven much more by their requirements than most zero-background holder designs. A 1mm deep well with a zero-background plate at the bottom was a key specification. We tried several options for creating this, but settled on a two-part design with a solid “floor” plate and a ring above it. As it turns out, cutting a ring out of monocrystalline Si was more challenging than I’d expected.

    It took a few months of experimenting with various fixtures to settle on a design that had a low failure rate and excellent cut quality, but with that done, the sample holders came out beautifully. Making these with a traditional, solid, plate would certainly be much easier, but this kind of project is always an opportunity to try something new.

  • NIST 1976c custom mount

    NIST 1976c custom mount

    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 and all between.

    There really isn’t any one material that checks all the boxes, but the NIST gets very close thanks to the efforts of Mr. Jim Cline and his associates. The hardware they’re using is completely custom to the point that it bares no resemblance to the instrumentation we normally work with. There’s a great page on their divergent-beam lab here.

    Image of DBD

    The NIST 1976 material has been a mainstay in regular monitoring and certification of XRD system performance for many years and is now on its third (c) generation. With this most recent revision the shape of the standard has been changed from a flat plate to a round disk. This allows for much greater compatibility across the range of sample holders in the market.

    This week we made a custom mount for a company using a Siemens D5005 with a 40-position autosampler. It’s common to mount these, but this is the first time I can recall doing so for this particular autosampler so I thought it was worth sharing a little about the material and a picture of the finished product.

  • Mystery crystals

    Mystery crystals

    Curiosity may have killed the cat, but it’s the lifeblood of a well-functioning analytical lab. A few days ago, Todd was preparing a water chiller for shipping and washed out some corrosion products with acetic acid. The resulting solution was left in a beaker over the weekend and when we returned, he noticed that it had formed rather large crystals. So he did what any curious person with a lab full of XRD instrumentation would do. He ground it up into a fine powder and ran it through a D4 Endeavor. The resulting pattern was definitive and made complete sense given the brass metals involved in the corrosion product and the acetic acid solution. 

    The data was imported into MDI Jade Pro for phase identification. Jade makes it very easy to take the analysis all the way through whole pattern fitting (WPF/Rietveld) when paired with the COD or ICDD PDF-4 databases. I generated a full report even though the data was not nearly the quality we would usually require for this type of analysis for a client.

  • What’s really coming out of my XRD tube?

    What’s really coming out of my XRD tube?

    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 zero.

    We used Jade Pro to evaluate the scans, but they’re not D-spacing vs intensity as one would normally expect. This scan represents Wavelength vs intensity more like one would see in a WDXRF spectrometer. Cu KA1 and 2 are obvious, as is Cu KB1. Many of the current generation of XRD users have never seen a W LA1 peak in their data, but it’s clearly visible here as this is an older tube. What I’ve never been able to see before is the W La2 peak in the green scan. You’re looking at a peak that is ~62eV separated from W La1. No XRD detector on the market has energy resolution like that so these would always be lumped together so you’d see a series of additional peaks from every d-spacing in the sample in the diffractogram. Only a handful of detectors (our SDD-150 for example) could even separate the W La from the Cu K lines. That’s the power of wavelength-dispersive techniques. Incidentally, the most common device for cleaning up superfluous energy emissions in XRD data is a diffracted-beam monochromator and they eliminate all the W La through a secondary diffraction event much like what we’re doing.

    Characterizing emissions is nothing new. In fact, I started wanting to improve this after listening to a talk at DXC about Jim Cline’s famous XRD system which is used at NIST to perform the primary data collection on the CRMs we all use. To paraphrase Sir Arthur Conan Doyle, “When you explain every extraneous data point, the remaining information is the pure truth of the sample”.

  • Bruker D2 Phaser Sample Holders

    Bruker D2 Phaser Sample Holders

    KS Analytical Systems now offers custom sample holders for the Bruker D2 Phaser 6-position autosampler. These can be finished to order with any depth and diameter of well or a zero-background plate (ZBH) with or without a well ground in the surface.

  • Sample holders for Rigaku Miniflex systems

    Sample holders for Rigaku Miniflex systems

    KS Analytical Systems now offers custom sample holders for Rigaku Miniflex systems. The 6-position autosamplers and rotation stages (and even some fixed stages) make use of the magnetic disk design for holding powder without taking up much extra room in the diminutive benchtop.

    • Top-loading
    • Rear-loading
    • Zero-background

  • KS Analytical Systems now offers new Bruker XRD and XRF hardware

  • Energy-dispersive detector systems for XRD applications

    Energy-dispersive detector systems for XRD applications

    Energy resolution

    • 140eV under ideal conditions.
    • All KB peaks eliminated electronically.
    • W LA1 (8.40 KeV) lines eliminated from Cu KA1,2 (8.04 KeV) scans even with thoroughly contaminated tubes.
    • Common fluorescence energies (i.e. Fe when Cu tube anodes are used) are greatly reduced. (Brehmstralung effects are impossible to remove completely)
    • Most PSD detectors offer no better than 650eV. This allows for a great deal of fluorescence energy to pass as well as W LA1 from older Cu tubes.

    Low angle scatter

    • The detector mounts in place of the traditional scintillation counter allowing for use of automated variable (motorized) or interchangeable aperture slits to control angular resolution. Scans starting from 0.5 degrees 2? are possible with the proper slit arrangement just as they are with the scintillation counter. The user controls the intensity vs angular resolution of the scan based upon the ideal conditions for their work rather than the limitations of the hardware.
    • Position sensitive detectors are wide open by design which necessitates knife edges over the sample and additional mechanical aperture plates to block air scatter at low angles. Closing off the detector limits the useable channels and reduces the benefit of these detectors dramatically.

    Truly zero maintenance design

    • No delays – The detector is ready to collect data almost as soon as power is applied.
    • No external cooling – Air backed Peltier cooling eliminates the need for water circulation and/or liquid nitrogen.
    • Zero maintenance vacuum design eliminates reliance on an ion pump/backup battery.
    • 12-month warranty against hardware failure under normal use.

    Versatility

    • The Digital Pulse Processor (DPP) includes a usb interface allowing for adjustment and refinement should they be necessary for a particular application. With optional software, full quantitative EDXRF analysis can be performed.

    The detector can be set for any common XRD anode (energy) easily. Multiple energies may even be configured to allow for use with various anodes without the need for additional hardware. We specialize in Siemens (now Bruker) XRD and WD-XRF instrumentation and have installation kits ready for the D500, D5000 and D5005. The output is a standard BNC cable with a 5V square pulse output which is standard across every manufacturer we’ve worked with. Kevex and Thermo Si(Li) detectors used this same output.

    Please contact KS Analytical Systems for a quote.