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


New sixth generation MiniFlex X-ray diffractometer (XRD) is a multipurpose analytical instrument that can determine: phase identification and quantification, percent (%) crystallinity, crystallite size and strain, lattice parameter refinement, Rietveld refinement, and molecular structure. It is widely used in research, especially in material science and chemistry, as well as in industry for research and quality control. It is the newest addition to MiniFlex series of benchtop X-ray diffraction analyzers from Rigaku, which began with the introduction of the original MiniFlex system decades ago. Read more...

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