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Introduction to powder X-ray diffractometry I. Overview

Summer 2020, Volume 36, No. 2
Keigo Nagao

Until the late 2000s, only scintillation counters (SC) were used as the detectors for general-purpose powder X-ray diffractometers. Thereafter, the core technologies that combine to create an X-ray diffractometer evolved dramatically. A one-dimensional (1D) detector—and subsequently a two-dimensional (2D) detector—came on the market, followed by new optical devices such as multilayer mirrors, in which layering technologies of super-thin film were applied. Analysis software functionality also improved remarkably. For instance, in addition to calculating crystallite size and lattice constants, programs implemented new algorithms and parameters, such as the application of whole pattern fitting, the Fundamental Parameter (FP) method, consideration of anisotropy and distribution in crystallite size.

The 1D and 2D measurement conditions described below are somewhat different from those with an SC.  The factors to which we should pay attention have changed when thinking about the optimal conditions to obtain high-quality data. Even in references in which only measurements using the focusing method and a zero-dimensional detector were described, useful hints to obtain high-quality data were rarely discussed. For this reason, in the series of articles making up this basic powder XRD course, we will explain the fundamentals of X-ray diffraction and expertise, sprinkled with the latest applications.

In this overview article, the principles and instruments used in the powder X-ray diffraction method, and what experiments can evaluate, are explained.


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