International
Tables for
Crystallography
Volume H
Powder diffraction
Edited by C. J. Gilmore, J. A. Kaduk and H. Schenk

International Tables for Crystallography (2018). Vol. H, ch. 2.9, p. 189

Section 2.9.3.1. Introduction

W. van Beeka* and P. Pattisona,b

aSwiss–Norwegian Beamlines at ESRF, CS 40220, 38043 Grenoble CEDEX 9, France, and bLaboratory for Quantum Magnetism, Institute of Physics, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland
Correspondence e-mail:  wouter@esrf.fr

2.9.3.1. Introduction

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Powder-diffraction experiments can be performed either in transmission or reflection geometries. The diffraction signals can be collected in angular- or energy-dispersive mode with parallel or focused X-ray or neutron beams. Dedicated reaction cells have been developed for all possible permutations of the above variables. Each setup has its own trade-off in terms of time, angular and crystallographic resolution, and intrinsic limitations in data quality. In the last two decades, enormous progress has been made in instrumentation for diffraction experiments. A good example is the development of X-ray detectors where, as a direct consequence of the use of linear or area detectors, a time resolution of seconds or even shorter is now feasible in angular-dispersive mode. These and many other developments, such as more intense laboratory X-ray sources, have redefined the ways in which one can best perform in situ experiments. Energy-dispersive systems have lost some of their early advantages with respect to angular-dispersive geometries; nevertheless, there are still good grounds for selecting the energy-dispersive technique for some applications. Similarly, reflection-geometry flat-plate reactors have lost a lot of their early popularity because of well known problems with the diffraction geometry during heating. On the other hand, flat-plate strip heaters can reach thermal ramp rates that are hard to obtain otherwise. Flat-plate reflection-geometry reactors remain the main workhorses in academic and industrial home laboratories (mainly because of the good diffraction intensities which they provide) and several commercial vendors sell these units. Commercial and home-laboratory-developed cells, such as that from Moury et al. (2015[link]) for high-pressure hydrogenation experiments, often provide the basis for further studies at central facilities. In this chapter, we intend rather to focus on new types of cells and their use with modern linear and area detectors, also indicating the level of information that can obtained. Microreactors in the form of capillary cells are popular for many different kinds of in situ diffraction experiments, and we therefore will review their use in some detail.

References

Moury, R., Hauschild, K., Kersten, W., Ternieden, J., Felderhoff, M. & Weidenthaler, C. (2015). An in situ powder diffraction cell for high-pressure hydrogenation experiments using laboratory X-ray diffractometers. J. Appl. Cryst. 48, 79–84.Google Scholar








































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