Provision, Suitability and Stability of Standards for Quantitative Powder Diffractometry

Abstract

Standards required for quantitative powder diffractometry are essentially of three types as shown in Table 1 - external instrument standards for the initial and long term check of instrument alignment (i.e., an “instrument” standard), external analytical standards, which are similar in composition to the specimens to be analysed, for the preparation of calibration curves for “in-type“ analysis; and internal analytical standards for the minimization of problems due to variations in specimen absorption.The ideal equipment alignment standard should be free from preferred orientation, stable and available in large quantities, since it should serve the dual role of providing a continuing indication of the performance of a given diffractometer, as well as allowing absolute intensity comparisons to be made between different diffractometers.