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The DECTRIS MYTHEN 1K strip detector has recently been incorporated into the STOE STADI P powder diffractometer and software. The following examples demonstrate the capabilities of this combination of outstanding instruments for powder diffraction experiments.
Due to the increased sensitivity of the MYTHEN 1K detector, high resolution and extremely fast measurements of typical powder samples are now possible. It is possible to record a complete pattern from 0° to 120° 2Θ in 60s with a good signal to noise ratio, as seen in Figure 1.
Figure 1. Measurement of the NIST Silicon standard (NIST SRM 660). STOE StadiP, DECTRIS MYTHEN 1K, Cu-Kα1 radiation, transmission sample.
High resolution measurements are easily performed using this instrumentation. A complete pattern of a combination of three standard materials Silicon, Lanthanum Hexaboride and Quartz recorded from 0° to 120° 2Θ is seen in Figure 2.
Figure 2. Measurement of a mixture of Silicon, Lanthanum Hexaboride and Quartz. STOE StadiP, DECTRIS MYTHEN 1K, Cu- Kα1 radiation, transmission sample.
The inlay shows a detail of the recorded pattern from 66° to 83° 2Θ. The (300) reflection of Lanthanum Hexaboride (LaB6) at 67.56° and the (212) reflection of Quartz (SiO2) at 67.74° 2Θ are as well resolved as the (311) reflection (LaB6) at 75.85° and the (302) reflection (SiO2) at 75.76° 2Θ.
It is also possible to obtain high quality data for Rietveld refinement.
Figure 3 shows a pattern recorded from a sample of Potassium Tartrate (C4H5O6K, powder ground from single crystals) recorded from 10° to 80° 2Θ. The overlay shows the simulated pattern obtained from single crystal structure analysis of the same material.
Figure 3. Measurement of Potassium Tartrate; blue: powder diffraction data; magenta: calculated reflection pattern from single crystal structure analysis (scaled to 50 % intensity for full pattern).
Figure 4 shows detail of the recorded pattern from 40° to 45° 2Θ. The operation mode of the MYTHEN 1K detector enables the setting of an energy threshold. This allows radiation suppression of lower energy radiation. The powder pattern of a 20/80 mixture of Quartz and Iron Oxide with and without the setting of this threshold is shown as an example below.
Figure 4. Measurement of a mixture of Quartz and Iron Oxide; blue: data without the setting of an energy threshold; magenta: data with the setting of an energy threshold; turquoise: ICDD 46-1045 /silicon Oxide / Quartz, syn; unindexed reflections: Iron Oxide. STOEStadiP, DECTRIS MYTHEN 1K, Cu-Kα1 radiation, transmission sample.
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Both the measurements were done with the same sampling parameters and can be directly compared. The iron oxide fluorescence with used copper Kα1 radiation can be suppressed almost totally while reflection pattern intensity of iron oxide and quartz decreases 60%. It is possible to index both components.
This information has been sourced, reviewed and adapted from materials provided by STOE.
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