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Getting more from less, and sometimes taking it along
A “walk” along the electromagnetic spectrum—heading toward smaller wavelengths—leads from the visible red to violet, through the ultraviolet and then to X-rays. With wavelengths of 0.1–10 nanometers, even atoms can diffract X-rays. So, aiming X-rays at a material produces interference patterns. Consequently, X-ray diffraction (XRD) can be used to analyze fluids, powders, and crystals, all without damaging a sample. Analysis of the interference patterns reveals a sample’s molecular structure.
The range of ways to use XRD—from basic research to industrial processes—drives a varied market of instruments. (For an overview of some of the available instruments, see:https://www.labcompare.com/Spectroscopy/178-X-Ray-Diffractometer-XRD-Instruments/.) Given the need to generate the X-rays, collect the diffraction pattern, and analyze the results, XRD devices tend to take up some room, but that doesn’t have to be the case.
Scientists can even take XRD into the field, but not with many options on the market. The options expand if a benchtop instrument is all that’s needed.
Into the wild
At Canada-based 911 Metallurgy, metallurgist consultant and plant metallurgist David Michaud knows a lot about XRD. As the CEO and managing director of 911 Metallurgy since 1993 and with a background in mining engineering, he’s used XRD for various tasks. When asked about the latest advance in portable X-ray diffraction, he says there are “not too many recent changes other than the Olympus XRD systems.”
At Olympus Scientific Solutions Americas (Waltham, MA), scientists keep improving portable XRD technology. “Our latest-generation XRD instruments have a higher count detector, which can dramatically improve detection limits,” says Jose Brum—XRD scientist, analytical instruments at Olympus Scientific Solutions Americas. “For geoscience applications, such as mineral exploration and mining, or oil exploration, minerals in low concentrations can have large impacts on the economic viability of a project.” Brum adds, “By improving our detection limits with the new high-count rate detector, our customers can make more informed decisions.”
To get better results, Olympus takes a different approach. “Unlike more traditional goniometer-based systems, Olympus uses a transmission approach—in effect—allowing Olympus instruments to use a very minimal amount of sample,” Brum explains. “This variation on XRD technique greatly diminishes the peak-broadening issues associated with the older technology that the traditional systems use.”
Portable X-ray diffraction equipment can even analyze samples in the field. (Image courtesy of Olympus Scientific Solutions Americas.)
In addition, goniometer-based systems usually use a step-scan method, which can extend the testing time. “Olympus analyzes the entire practical two theta range simultaneously,” Brum points out. “This is done through the use of an area detector.”
The sample preparation also depends on the XRD technology. In goniometer-based systems, powders must be ground to sizes less than 20 micrometers. That is required to get the needed level of random orientation for analyses. “Olympus uses a convective technique that completely randomizes each and every particle contained within the sample chamber,” as Brum describes it. “Within 30 seconds of analysis time, every single particle within the chamber will have crossed the X-ray beam in every possible orientation.” He adds, “We can claim 100% randomization.” Consequently, the Olympus portable XRD only needs the sample coarsely ground to sizes of about 120 micrometers. “This can easily be done in the field with just manual crushing tools,” Brum explains.
With the Olympus approach, samples like clays and micas can be analyzed more accurately, says Michaud. He adds, the samples “can actually be analyzed with a larger degree of confidence—less bias to lying flat—and also less moving parts in the machines—big benefit for maintenance.”
Other companies also make portable XRD options. For example, Bruker (Billerica, MA) describes its D2 PHASER as “XRD for everyone, everywhere, and everything.” In combination with the Bruker DIFFRAC.SUITE software platform, this XRD instrument “allows users the flexibility to create automated push-button methods for maximum ease of use and the ability to customize measurement conditions and configurations to obtain optimum data quality for every sample,” says product literature. This XRD is portable—requiring no water cooling or special power.
Still pretty small
Not all XRD devices can go to the field or measurement site, but some still don’t need much room. Scientists can consider a variety of XRD instruments that sit on a benchtop.
In addition to portable instruments, Olympus makes benchtop XRD instruments. For example, its BTX II Compact Benchtop X-ray Diffraction System is described as “a fast, low-cost, small-footprint, benchtop XRD for full-phase ID of major, minor, and trace components.” This instrument also provides X-ray fluorescence. Olympus adds that this instrument’s “unique, minimal sample prep technique and sample chamber allow for fast, benchtop analysis rivaling the performance of large, costly lab units.”
Olympus developed this benchtop XRD instrument for many uses, from educational applications in academics to quality control in industrial settings. For example, sample handling is quick and easy. As product literature notes: “With the BTX II patented sample handling system, not only is sample preparation time minimized, but accuracy in peak identification previously only available using large and expensive laboratory-based systems can now be achieved.”
As another example, Rigaku (Tokyo, Japan) is on the sixth generation of its MiniFlex benchtop X-ray diffractometer, which it calls “a multipurpose powder diffraction analytical instrument.” Rigaku recommends this XRD instrument for basic research, especially studies in materials science or chemistry, as well as industrial research and quality control. According to Rigaku, the “MiniFlex XRD system delivers speed and sensitivity through innovative technology advances, including the HyPix-400 MF 2D hybrid pixel array detector (HPAD) together with an available 600-W X-ray source and new eight-position automatic sample changer.” Consequently, the company notes that this device “is versatile enough to perform challenging qualitative and quantitative analyses of a broad range of samples, whether performing research or routine quality control.”
Other manufacturers also offer benchtop XRDs. For instance, the ARL EQUINOX 100 X-ray Diffractometer from Thermo Fisher Scientific (Waltham, MA) is “designed for QA/QC, academic, and routine X-ray diffraction applications.” As the company adds, “This instrument simplifies operation without sacrificing speed or performance.”
As the instruments mentioned here indicate, there’s a trend in this market segment: Being small cannot be an excuse for less power. Even if an XRD can go into the field, it must provide lab-like potential. Then, scientists can analyze materials inside the lab and beyond.
Mike May is a freelance writer and editor living in Texas. He can be reached at [email protected]