Proficiency Testing of Instruments - a Key Element for Quality Assurance in X-Ray Powder Diffraction Part 1: Matching the Effort to the Actual Needs

摘要

Certified reference materials (CRM), phosphor grade CaF_2 micron powder and a finegrained indialite powder synthesized at BAM were used for proficiency testing of an X-ray powder diffraction instrument which is operated in Bragg-Brentano geometry and equipped with stepper motor driven variable slit systems both for the aperture and for the anti-scatter slits. Relative intensity corretion functions (ICF's) were determined for a wide range of diffraction angles (10 deg - 140 deg ) with estimated standard deviations (esd's) smaller 1percnet. For two direct--dependant deviations of the integrated intensities of diffraction lines from the simple sindirect--law were detected. It is concluded that regular monitoring of the refined temperature factors or of the ICF's measured on standard samples should be part of proficiency testing of XRPD instruments used in connection with Rietveld refinements.