Differences in intensity/resolution due to differences in X-ray tubes

With the MiniFlex300/600, it is possible to select a fine focus tube (focal point size 0.4 x 8 mm²) in addition to a normal focus tube (focal point size 1 x 10 mm²) of the type generally used with powder X-ray diffractometers. Fig. 1 shows an overlay of diffraction peaks obtained by measuring with a normal focus tube and fine focus tube. Table 1 shows a comparison of intensity, and full width at half maximum (FWHM), which varies proportionally with resolution.


Table 1: Intensity ratios and full width at half maximum due to differences in focal point size
 
Fig. 1: Comparison of normal focus tube and fine focus tube

Both intensity and resolution can be improved by using a fine focus tube. Therefore, these tubes are suitable for measuring samples with many peaks, and samples containing trace components. Fig. 2 shows qualitative analysis results, and quantitative analysis results using the Rietveld method, for a cement sample (NIST 2686 standard material). In the analysis results, there was a good match, within the error range, between the content of each crystal phase, and the standard values for NIST 2686 standard material.


Fig. 2: Qualitative and quantitative analysis results for cement sample (NIST 2686 standard material)
Apparatus and Measurement conditions

Apparatus conditions:

MiniFlex600 (F.F tube), Detector: D/teX Ultra, Slit conditions: DS = 0.625°, SS = 8 mm, RS = open, Incident side and receiving side Soller slit: 5°, Incident height limiting slit = 10 mm

Measurement conditions:

Scan range: 2θ = 5 ~ 90°, Step width: 0.02°, Scan speed: 5° / min. (about 18 min.)


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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