Neutron Powder Diffraction

Abstract

AbstractThe first powder diffraction studies on simple materials such as iron metal using x‐rays were done independently by Debye and Scherrer in Germany and by Hull in the United States. For a long time x‐ray powder diffraction was primarily used for qualitative purposes such as phase identification and the assessment of crystalline quality. The earliest structure determinations using only x‐ray powder diffraction data were done by Zachariasen in 1949, who solved the structures of α‐ and β‐UF5 by an intuitive trial‐and‐error approach. An important subsequent step was taken when Zachariasen and Ellinger solved the monoclinic structure of β‐plutonium using manual direct‐method procedures. The use of neutrons to determine structures using powder diffraction has advanced significantly over the past 60 years. Neutron powder diffraction is complementary to both x‐ray and electron powder diffraction. The greater penetration depth of neutrons, due to the fact that the neutron‐nucleus interaction is a point scattering process implying no variation of the nuclear scattering length with the scattering angle, the independence of the scattering cross‐section from the atomic number (Z) of an element, and therefore the stronger interaction of neutrons with “light” elements such as oxygen and hydrogen, and its isotope specificity as well as its interaction with unpaired electrons (“magnetic scattering”) make neutrons a unique and indispensable probe for structural condensed matter physics and chemistry.