A 10-minute read
At first glance, building a custom-made diffractometer for a lab seems like an exotic adventure – reserved for technology aficionados, specific applications, extensive budgets, and exhausting procedures. So, why would anyone undertake such a project?
In this article, Dr. Semën Gorfman looks back on his experiences with building a customized X-ray diffraction machine and says that, maybe, the most difficult part was making the decision to begin. The keys to his success were good collaborations and a clear vision, underpinned by his experience with X-ray diffractometers in laboratories and at synchrotron sources.
Similar to the experiences of many other scientists, Dr. Semën Gorfman’s research took him to several institutes and through many collaborations in crystallography and solid-state physics. So, when he took a position as a senior lecturer at Tel Aviv University, he was well aware that setting up a research lab comes with a challenge. “It is difficult to predict what is going to be needed in ten years or more, so one needs flexibility”, Semën begins the story. “For me, flexibility meant designing a custom-made diffractometer that could be used for independent research and as a teaching platform.”
Of course, such a big project does not come completely unexpectedly. Based on his previous experiences with various diffraction instruments, he had realized that many commercial diffractometers are optimized for rather specific tasks. “Also, I had long been dreaming about making a diffractometer that would resemble a multi-purpose beamline: an upgradeable diffractometer, which would fit current research interests and future needs in general”, he comments.
Indeed, Semën’s research interests are broad, spanning advanced materials and X-ray techniques. “In order to ensure flexibility of the research program, we aimed for a diffractometer that allows for quick and easy switching between different single-crystal X-ray diffraction configurations and setups. The different configurations cover, for instance, finding crystal orientation, measurement of diffucse scattering, high-resolution reciprocal space mapping, investigating thin films, and performing in-situ measurements. In addition to the fast switching between configurations, the possibility of upgrades and modifications is important for adding further configurations in the future”, he explains.
Building such a diffractometer relies on two basic tasks: picking each component individually, and then ensuring that all of them are integrated into a unit that can fully support materials research. So, Semën teamed up with Dr. Youli Li, who is the technical director of the X-ray facility at UC Santa Barbara and also runs Forvis Technologies, a company that provides consultancy and design services for custom X-ray instruments. “Youli’s experience with building X-ray diffractometers, and his extensive knowledge of engineering, mechanics, and software made him the perfect partner for this project. Separated by half a globe and nearly a dozen time zones, we worked together to pick each and every component of the system”, comments Semën.
The project started with a four-circle Huber goniometer, which gave Semën and Youli their much-needed flexibility. This allowed them to cover a variety of experimental setups, while also giving them the freedom to choose other components without restrictions. These components included a microfocus, Cu-based X-ray source (from Xenocs); collimating X-ray optics; a four-bounce monochromator (from INTEGRATDS); an analyzer crystal; a DECTRIS PILATUS3 R 1M detector; and a scintillation counter. Control of the diffractometer is facilitated through SPEC, while data analysis is performed using in-house scripts. The resulting diffractometer design was published in 2021, and the summary definitely includes one keyword: flexibility!
The monochromators that Semën and Youli selected for the diffractometer allow them to use it in two ways: in a very high flux mode, or in a high-resolution mode that suppresses Kß radiation while keeping the optimal flux. The DECTRIS PILATUS3 R 1M detector’s large area and pixel size further support the idea of experimental flexibility: angular coverage and resolution can be optimized for each sample. A scintillation counter, combined with a crystal analyzer, can be used to achieve an extremely high resolution, and the crystal can be moved in and out of the setup. As a final touch, Youli designed an interlock system to make the diffractometer complete and user-ready.
“Sometimes I joke that we have a million and one detectors. But, jokes aside, a large detector area was one of the main requirements for the diffractometer’s design. With a million hybrid pixels, the triggering capabilities of the DECTRIS PILATUS3, and the SPEC communication we implemented, we can do a lot, like a small multi-purpose beamline”, comments Semën.
Eventually, the diffractometer ended up being a true cosmopolitan: using German mechanics, a Slovakian monochromator, a French source, and a Swiss detector. Data processing, meanwhile, relies on in-house scripts using Matlab. “That makes it a bit harder on students, but this is also very good training, as it requires a deeper understanding of crystallography”, comments Semën.
Now that the diffractometer is up and running, Semën and his group are planning to focus on materials, particularly ferroelectrics and piezoelectrics, and on applied crystallography. This effort has already resulted in some publications, such as a study on twinning, which uses reciprocal space mapping. “However, we are also keeping our eyes and minds open for instrumentation and methodologies; the diffractometer is flexible, so there is room to play”, concludes Semën.
Once again, we congratulate Semën, Youli, and everyone involved on this successful project, and we wish Semën and his group all the best in their future projects. This year, Semën will be joining the European Crystallographic Meeting in Paris, so we are looking forward to having more exchanges with him soon.
S. Gorfman, D. Spirito, N. Cohen, P. Siffalovic, P. Nadazdy, and Y. Li, “Multi-purpose Diffractometer for In-Situ X-Ray Crystallography of Functional Materials”, J. Appl. Crystallogr. 54, 914 (2021).
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