A Quarter Century of round Robin Tests on Xrd

This paper reports on some Round Robins conducted over the past twenty-five years. Although this review is not exhaustive, it outlines the objectives and the most frequent conclusions derived from the analysis of results. As the general follow up from these conclusions a proposal is here launched to establish an international network for the "Calibration Monitoring of the Diffractometers". INTRODUCTION X-rays were discovered in Germany more than one century ago. Since half a century Conferences are being called annually in Colorado (“The Denver X-ray Conference”) to state the art and the evolution of the many topics involving X-ray Diffraction. Round Robins tests on powder diffraction measurements have been organised in the world since a quarter of a century. It is now probably timely to promote a world-wide network for monitoring the calibration of diffractometers. Round Robins conducted in the past showed a general low comparability of data although the diffraction patterns showed high internal consistence. The general low capability of reproducing the diffraction measurements suggests a new articulation of the Round Robins where in addition to the purposes of the Round Robins the following should be taken into account: • the repeatability, reproducibility of the diffraction measurements, • the repeatability of the accurate determination of the lattice parameters of the calibrant specimen, • the traceable history of the diffractometers, • the adequacy of the evaluation of the effective values of the instrumental parameters of the diffractometers under “running conditions” and the performance of the adopted processing system. The paper presents a short not exhaustive review of some Round Robin tests and their pioneering aspects; by referring a few technical and scientific reasonings on the Calibration Monitoring of Diffractometers (Berti and D'Acunto 2001), the paper outlines the reasons why the proposal of establishing an international network is probably timely. This network should be designed mainly for reaching the following targets: (a) To monitor the calibration of diffractometers, (b) To establish protocols of use for the evaluation criteria of the quality of the diffraction measurements, (c) To set forth rules for harmonised protocols of use of diffraction measurements in various fields of applications and types of analysis. PROGRESSES AND NEW STANDARDISATION PROCESSES OF X-RAY DIFFRACTION Recent advances in currently available XRPD methods suggest the possibility of extending XRPD techniques to material diagnosis, which can be carried out without destroying the physical Copyright (c)JCPDS-International Centre for Diffraction Data 2002, Advances in X-ray Analysis, Volume 45. 60