A new data collection method, ‘multiframes’, was presented which produced high-quality data, suitable for Rietveld refinement, using micro X-ray diffractometry. Thus 91 frames of two-dimensional X-ray diffraction data were collected for powdered NIST SRM 660 standard material, using a general area-detector diffraction system at intervals of 0.8° 2θ. For each frame, only the central 1° 2θ was integrated and merged to produce a diffraction profile from 17 to 90° 2θ. Rietveld refinement of this data yielded a unit-cell parameter (ao) and boron atomic position of 4.1549Å and 0.1991, respectively (Rwp = 4.26, RBragg = 3.21). The corresponding La-B bond length was calculated to be 3.0522Å.

These parameters were in good agreement with literature values. These results suggested that Rietveld-quality micro X-ray diffraction data could be collected by diffractometry, provided that the detector was stepped in small increments, that for each frame only the central 1° 2θ was integrated at constant arc length and that the counting time was sufficient to yield an adequate intensity (∼10000 counts).

Rietveld Refinement of LaB6: Data from μXRD. Ning, G., Flemming, R.L.: Journal of Applied Crystallography, 2005, 38[5], 757-9

Table 3

Bulk Force Constants