Extreme Sample Environments Research Articles

Neutron powder diffraction of minerals at high pressures and temperatures: some recent technical developments and scientific applications

The application of neutron powder diffraction to the study of mineral behaviour at high temperature and high pressure is reviewed. The characteristics of neutrons that make them particularly amenable to such studies are outlined, and recent techno- logical developments in the attainment of extreme sample environments are discussed. These developments include the design of new high-pressure cells, hydrothermal cells, and furnaces that allow in situ diffraction under extreme conditions. The application of this technology to problems of order-disorder in minerals is illustrated in a series of recent examples.

A multiple-crystal data-collection method in time-of-flight neutron Laue diffraction

A novel multiple-crystal data-collection method has been employed to obtain neutron diffraction data simultaneously from several randomly oriented crystals of a low-symmetry molecular material. The method exploits the ability of time-of-flight neutron Laue diffraction to resolve the overlapping diffraction patterns from the multiple-crystal sample. The method has been applied to acetylcholine bromide, yielding a good-quality structure refinement. This opens up the possibility for wider exploitation of the method in collecting data sets more rapidly, under more extreme sample environment conditions and from smaller single-crystal samples.