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Large platforms limit where a scientist can perform many measurements, including X-ray diffraction (XRD). But, that’s not the case with a portable XRD device. With this nondestructive technique that can be used to analyze powdered crystalline materials, it really helps to take the technology to the samples. Portable devices let scientists take XRD into the field, and beyond.
When asked where portable XRD can be used, Jose Brum—XRD Scientist at Olympus (Tokyo, Japan)—says, “Portable XRD is used in a variety of settings from Mars to right here on planet Earth.” In fact, Olympus XRD technology is onboard the Mars Curiosity rover to test the mineralogical characteristics of the Martian surface. “Here on Earth, it’s used for geochemical exploration, petroleum exploration, mine grade control, mineralogical process analysis, and various inspection applications,” Brum says. “XRD is also used in a variety of industries, including mining, petrochemical, hazardous-material identification, and pharmaceutical applications.”
NASA’s Curiosity rover carries X-ray diffraction to Mars to analyze the surface. (Image courtesy of NASA/Paul E. Alers.)Across those industries, XRD gets used in a broad range of jobs. For mining iron ore, for example, engineers use XRD to “quickly analyze iron-rich ore and automatically generate quantitative compositions of the samples even when certain phases are completely absent, such as quartz, hematite, goethite, and magnetite,” Brum explains. In mining coal, scientists quantify the calcite (CaCO3). This “mineral reduces the efficiency of the raw material fuel in a coal-fired power plant,” Brum says, and it’s quantified “to improve efficiency and reduce carbon emissions.”
For limestone and cement, XRD can also be used for quality control. With XRD on these materials, scientists can “easily perform quantitative analysis of common minerals associated with limestone, like alpha-quartz, asbestos minerals, calcite, and dolomite,” says Brum. “In cases where the quarry contains various levels of dolomite, the TERRA portable XRD analyzer can quickly determine this mineral in the range of 0.50 to 9.0% with an error of only 0.02%.”
The TERRA also makes it possible to perform analysis in the field for petrochemical applications, like pipelines. Here, says Brum, “The TERRA analyzer’s smart sense feature enables optimum peak-to-background performance to identify and quantify corrosion materials on pipelines.”
It also helps to carry XRD to sites to identify hazardous materials. Portable XRD can be used to rapidly identify suspected dangerous and hazardous materials on-site for local and global security,” Brum explains, “or to identify explosives, fusing materials, and accelerants on location.”
The size of a small suitcase, the Olympus TERRA XRD analyzer is easy to take into the field. (Image courtesy of Olympus.) Law enforcement can even put XRD to work with pharmaceuticals. For instance, it can be used to identify counterfeit pharmaceuticals. For drug efficacy and safety, portable XRD also comes in handy. This testing fingerprints drug formulations, which can reveal the quantity of active and inactive components, or even foreign or substituted ingredients. Plus, Brum points out that “fast XRD screening helps ensure patient safety and safeguards legitimate pharmaceutical manufacturers’ branding.”
Even that wide-ranging tour of XRD’s potential applications only discusses a small proportion of the possibilities. By carrying this technology where needed, XRD gets even more useful.
Improving the XRD options
“Olympus is committed to continuous improvement,” Brum explains. “As such, the electronics of our XRD instruments are now faster on boot-up and detector cool down.” In addition, the detectors on the Olympus XRD devices provide enhanced data-processing capabilities that deliver faster data acquisition. The instruments have been optimized to minimize power consumption—“The TERRA analyzer can now operate in the field on battery power for 5 hours,” Brum states.
The TERRA is about the size of a suitcase. It “can be used in the back of a pickup truck or in a trailer on a mine site,” Brum notes. Plus, no external cooling is required.
Brum adds that the TERRA analyzer makes it easier to collect data. “Typically, a sample must be finely ground and pressed into a pellet to ensure a sufficiently random orientation of the crystals,” as Brum describes the process. “Olympus’s patented vibrating sample chamber eliminates this issue.” Instead, “Olympus XRD instruments require a mere 15-milligram sample ground to 140 microns or less,” Brum says.
Other features of the TERRA analyzer set it off from other devices. “Rather than moving the detector like a traditional XRD instrument, the vibration chamber causes convection in the sample, presenting all orientations of the crystalline structure,” Brum explains. “The detector captures the entire angular range of the diffractogram at the same time.” Consequently, the TERRA quickly creates an X-ray diffraction pattern that is virtually free of the preferred-orientation effects encountered with traditional XRD instruments.
As Brum sums it up: “Due to its unique powder-handling system, lack of mechanical goniometers, and lack of complicated moving parts, the TERRA analyzer is well suited for those applications where field portability, speed, and ease of use are essential.”
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Other manufacturers also simplify taking XRD to the field. For example, the PLANET from Germany-based xplorex is described as a “portable powder diffractometer with sufficient attainable resolution to identify even the most complex mixtures of minerals.” As an example, the company discusses the identification of phases in soil samples for geology and mineralogy.
Many features make the PLANET field-worthy. Beyond its size, it runs for at least four hours on lithium-ion batteries. The company also notes that the PLANET includes an “ultra-sensitive linear detector.”
The iXRD platform from PROTO Manufacturing (Taylor, MI) is described as lightweight and fast. “PROTO’s proprietary position sensitive scintillation detectors (PSSD) provide unsurpassed speed [and] stability,” the company claims. “Unlike other X-ray detectors, they do not deteriorate with exposure to X-rays.”
If a scientist can’t find just the right portable XRD device, some make their own. That’s what Graeme Hansford of the UK-based University of Leicester’s Space Research Centre did.1 At least, he developed what he called a conceptual design for a handheld XRD device. As he noted: “[The] insensitivity of the technique to sample morphology and the precise instrument-to-sample distance implies that a handheld instrument will be tolerant to minor operator movements relative to the sample during data acquisition.” He added: “The lack of a sample preparation requirement in many cases also saves considerable time and is highly convenient.”
So, from outside to outer space, portable XRD can be applied to samples of many, many sorts. The collected data can quickly be analyzed, and the results can save time and money, sometimes even lives.
Reference
- Hansford, G. A prototype handheld X-ray diffraction instrument. J. Appl. Crystallogr. 2018, 51(Pt 6), 1571–85; doi:10.1107/S1600576718012943.
Mike May is a freelance writer and editor living in Texas. He can be reached at [email protected]