An Introduction to Neutron Scattering

Abstract

It has been stated that the neutron is the most versatile probe of condensed matter systems. While some may dispute this, it is clear that the unique properties of the neutron make it an extremely important, and in many instances, unique probe of interstitial alloy systems. Neutron scattering can not only examine the structure of the alloys, including unambiguous determination of the location and occupancy of the interstitial species, but can measure the diffusion of the interstitial species and determine the shape and depth of the potential in which the interstitial atom is found. Furthermore, neutron scattering can follow, in detail, the changes in magnetic ordering and coupling which accompany the insertion of interstitial species into magnetic phases. Since the neutron is a neutral, weakly interacting probe, it allows investigation of the bulk versus near surface properties and the easy study of alloys in low and high temperature environments (mK-2000°C) and in high pressure environments of several kbar. While some of the information determined from neutron measurements may be extracted from other methods, including x-ray scattering, Mossbauer spectroscopy, NMR and other techniques, none provide the breadth and microscopic detail of neutron scattering. In order to appreciate the vast range of opportunity afforded by neutron scattering, it is useful to review the fundamentals of neutron scattering and then to consider, in a second chapter, specific examples of neutron studies of interstitial alloy systems. Comprehensive texts on neutron scattering have been written by Bacon [1], Windsor [2] and others. In addition, a three volume set in “Experimental Methods in Physics” [3] is dedicated to the subject, and includes numerous reviews of methods and results, covering many of the subjects discussed here. An earlier book also covers many of these topics [4].