Differences in resolution due to differences in Soller slits

The width of the standard incident and receiving Soller slits of the MiniFlex300/600 is 5°, but to obtain high-resolution it is possible to select a width of 2.5° (incident/receiving Soller slits) or a width of 0.5° (receiving Soller slit only). Fig. 1 shows a comparison of the X-ray diffraction profiles of LaB₆ powder when the Soller slit is changed, and Table 1 shows the intensity ratios, and the full width at half maximum (FWHM), which varies proportionally with resolution.


Table 1: Differences in intensity ratio and full width at half maximum due to differences in
Soller slits
 
Fig. 1: Comparison of diffraction patterns due to different Soller slits

The axial divergence or umbrella effect can be suppressed by using a Soller slit with a narrow width angle. Low angle reflections become more symmetrical, and resolution improves as a result. This is suitable for measuring samples with many peaks in the low-angle region, and samples with overlapping peaks. Fig. 2 shows the X-ray diffraction profile of mixed powder comprised of anhydrous gypsum (CaSO₄) and anatase (TiO₂). Resolution was improved by narrowing the width of the Soller slit, and the trace amount of anatase was detected due to improved of peaks. 


Fig. 2: X-ray diffraction profile of mixed powder comprised of
anhydrous gypsum (CaSO₄) and anatase (TiO₂)

Apparatus conditions:

MiniFlex600 (F.F tube 40 kV, 15 mA), Detector: D/teX Ultra, Scan range: 2θ = 23.5 ~ 27.5°, Step width: 0.02°

Measurement conditions:

(A) Scan speed: 60° / min., Slit conditions: DS = 1.25°, SS = 8 mm, RS = 13 mm, Soller slit: 5°, DHL = 10 mm (B) Scan speed: 15° / min., Slit conditions: DS = 0.625°, SS = 8 mm, RS = 13 mm, Soller slit: 5°, DHL = 10 mm (C) Scan speed: 0.2° / min., Slit conditions: DS = 0.1 mm, SS = 8 mm, RS = 13 mm, Incident side Soller slit: 2.5°, Receiving side Soller slit: 0.5°, DHL = 2 mm


The fifth generation MiniFlex is a general purpose X-ray diffractometer that can perform qualitative and quantitative analysis of polycrystalline materials. The MiniFlex is available in two variations. Operating at 600 watts (X-ray tube), the MiniFlex 600 is twice as powerful as other benchtop models, enabling faster analysis and improved overall throughput. Running at 300 watts (X-ray tube), the new MiniFlex 300 does not require an external heat exchanger. Each model is engineered to maximize flexibility in a benchtop package. Read more...

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