A new high-performance, precision-manufactured germanium diffraction crystal design for wavelength-dispersive spectrometers has received this award for its contribution to the efficiency and accuracy of microscopy.
When it comes to microanalysis, precision and accuracy are of paramount importance. The development of new high-performance precision germanium diffraction crystals specifically designed for wavelength-dispersive spectrometers represents a major advance in this field. High-precision germanium diffraction crystals jointly developed by Concord University, Rigaku Innovative Technologies, and Advanced MicroBeam, Inc. are expected to enhance microanalysis capabilities and improve accuracy and efficiency in a variety of analytical studies. Following successful field test results, the potential of this crystal is clear and has now been recognized as one of the 10 Best Microscopy Innovations at the 2025 Microscopy Today Awards.
Ge <111> Introduction to crystals
Rigaku Innovative Technologies (RIT) Ge Crystals offer high-performance single-crystal Johansson diffraction elements designed for wavelength-dispersive X-ray spectrometers (WDS) commonly used in electron probe microscopy (EPMA) and X-ray fluorescence (XRF) instruments.
Manufactured from high-purity, semiconductor-grade germanium (Ge), these crystals are created using a proprietary manufacturing process that includes:
a. Elastic bending is used to eliminate lattice distortions typically caused by traditional bending crystal manufacturing techniques. and
b.Produces very high quality crystal surfaces.
These properties significantly improve X-ray focusing accuracy and increase X-ray spectral resolution and intensity for end-user applications.
Ge designed for EPMA <111> The crystals offer a similar spectral range as PET crystals, but with a slight shift to shorter X-ray wavelengths and higher energies. They offer superior analytical performance compared to LiF and PET crystals in important aspects such as intensity, peak-to-background ratio, predicted detection limits, peak width, and ability to separate dense X-ray lines. Furthermore, Ge <111> The crystal suppresses higher order diffraction and minimizes spectral interferences.
High-performance Si produced using similar methods <111> and Si <222> Crystals are also available and other crystal orientations and materials can be provided by RIT upon request.
Client Field Testing: LIF Comparison
In field tests performed with the ARL SEMQ electron microprobe, additional masks were placed on either side of the detector slit, increasing resolution but decreasing intensity. In another evaluation of V-metal, removing the mask significantly increased the intensity by about 70%, but the resolution decreased slightly. It is important to note that cobalt (Co) is the last element in the range of germanium (Ge) in the ARL geometry. In this position, the physical spectrometer is closest to the sample and is not ideal in terms of resolution, but most advantageous in terms of intensity.
Advantages compared to previous methods
Traditional WDS analysis often involves a trade-off between intensity and resolution when multiple diffractometer options are available for a given element. You can prioritize either stronger signal strength or better peak width and peak-to-background ratio, but it is usually not possible to achieve both at the same time. This trade-off is evident when comparing commonly used PET and LIF diffractometers. PET has higher intensity and LIF has better resolution.
However, Rigaku Innovative Technologies (RIT)’s high-precision Ge <111> The crystal simultaneously increases both intensity and resolution compared to LIF. Using the same EPMA test conditions, Ge <111> The crystals produced more than twice the strength of iron (Fe) and cobalt (Co) LIFs, while also having narrower linewidths.
Test analysis of trace amounts of barium (Ba) using the La line <111> The detection limit for crystals was nearly three times lower than that obtained with LIF under the same acquisition parameters. Furthermore, Ge <111> The crystals significantly reduce potential interference from nearby titanium (Ti) Kα radiation.
EPMA testing for thorium (Th) and uranium (U) in monazite did not allow LIF analysis, but Ge <111> effectively removed the higher-order interference from the L-line of rare earth elements (REE). Otherwise, accurate measurement of the X-ray background could be complicated.
Solutions to REE challenges
Over the past few decades, trace element analysis has become a more popular application for EPMA instruments. This change was primarily driven by advances in system stability, software enhancements, and the introduction of larger crystals and detectors in EPMA, in parallel with advances in SEM-EDS for major element analysis. However, many EPMA instruments still rely on the same set of TAP, PET, and LIF diffraction elements that were commonly used in the 1970s and 1980s. Ge <111> Crystals and similar alternatives have the potential to improve the analytical performance of these instruments, especially as demand for trace element applications continues to grow.
Furthermore, the importance of REEs is increasing due to their important role in various high-tech applications, and at the same time concerns about their availability and supply chain security are also increasing. Natural rare earth materials generally consist of mixtures of these elements, and the L-rays typically used for analysis in X-ray spectroscopy are complex and closely spaced. This can lead to spectral interferences and make accurate quantification difficult. Ge <111> The use of crystals may alleviate these challenges, thereby supporting both the development of REE materials and the exploration of new REE resources.
Potential uses
Most applications involving X-ray-based analysis of elemental abundances may utilize instruments such as EPMA, benchtop X-ray fluorescence (XRF), and synchrotron XRF. In these situations, germanium <111> outperforms more commonly used diffractive elements such as PET and LIF. This advantage is particularly useful in situations where overlapping X-ray spectra are a challenge, such as trace element quantification, rare earth elements, and barium titanium (Ba-Ti) materials. Furthermore, germanium <111> serves as an alternative to PET or LIF in a suitable spectral range and allows observation of finer scale patterns in the X-ray spectrum.
Ge <111> Crystals are not just an upgrade to existing technology, but a transformative leap forward that promises to redefine analytical possibilities in elemental analysis.
This article will also be published in the quarterly magazine issue 24.
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