Standard Article

X-ray and Neutron Diffuse Scattering Measurements

X-Ray Techniques

  1. Gene E. Ice,
  2. James L. Robertson,
  3. Cullie J. Sparks

Published Online: 12 OCT 2012

DOI: 10.1002/0471266965.com073.pub2

Characterization of Materials

Characterization of Materials

How to Cite

Ice, G. E., Robertson, J. L. and Sparks, C. J. 2012. X-ray and Neutron Diffuse Scattering Measurements. Characterization of Materials. 1–28.

Author Information

  1. Oak Ridge National Laboratory, Oak Ridge, TN, USA

Publication History

  1. Published Online: 12 OCT 2012

Abstract

Diffuse scattering from crystalline solid solutions is used to measure local compositional order among the atoms, dynamic displacements (phonons), and mean species-dependent static displacements. It can also provide information on defects including vacancies, interstitials, dislocations and truncated sample dimensions. In locally ordered alloys, fluctuations of composition and interatomic distances break the long-range symmetry of the crystal within local regions and contribute to the total energy of the alloy. Local ordering can be a precursor to a lower temperature equilibrium structure that may be unattainable because of slow atomic diffusion. In addition to local atomic correlations, neutron diffuse scattering methods can be used to study the local short-range correlations of the magnetic moments. Interstitial defects, as opposed to the substitutional disorder defects described above, also disrupt the long-range periodicity of a crystalline material and give rise to diffusely scattered x-rays, neutrons, and electrons.

This article will concentrate on the use of diffuse x-ray and neutron scattering from single crystals to measure local chemical correlations and chemically specific static displacements. Particular emphasis is placed on the use of resonant (anomalous) x-ray techniques to extract information on atomic size from binary solid solutions with short-range order. By separating this diffuse intensity into its component parts we are able to recover pair correlation probabilities for the three kinds of pairs in a binary alloy. The interpretation of diffuse scattering associated with dynamic displacements of atoms from their average crystal sites are discussed briefly in this article.

Keywords:

  • x-ray diffuse scattering;
  • Neutron Diffuse Scattering;
  • single crystals;
  • EXAFS;
  • resonant scattering