Publication

Absence of charge-charge correlations at intermediate-range distances in disordered network-forming materials

Alfredo Pasquarello
2003
Journal Articles

Abstract

Applying a first-principles scheme to liquid GeSe4, we show that the charge-charge structure factor does not present any feature at the location of the first sharp diffraction peak (FSDP), despite a clear FSDP in the concentration-concentration structure factor S-CC(k). The origin of this effect is assigned in part to the finite extent of the electron density and in part to electron rearrangements. Our result provides evidence in favor of the postulate that, in binary network-forming systems, charge-charge correlations are absent on intermediate-range length scales. A FSDP in the S-CC(k) then signals the occurrence of structural defects.

Official source

https://infoscience.epfl.ch/entities/publication/e6d7380b-40b0-4abb-b4e3-bfd50d5b5394

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Alfredo Pasquarello
2003
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/e6d7380b-40b0-4abb-b4e3-bfd50d5b5394

About this result

Related concepts (27)

Structure factor

In condensed matter physics and crystallography, the static structure factor (or structure factor for short) is a mathematical description of how a material scatters incident radiation. The structure factor is a critical tool in the interpretation of scattering patterns (interference patterns) obtained in X-ray, electron and neutron diffraction experiments. Confusingly, there are two different mathematical expressions in use, both called 'structure factor'.

Powder diffraction

Powder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials. An instrument dedicated to performing such powder measurements is called a powder diffractometer. Powder diffraction stands in contrast to single crystal diffraction techniques, which work best with a single, well-ordered crystal. Diffraction grating The most common type of powder diffraction is with x-rays, the focus of this article although some aspects of neutron powder diffraction are mentioned.

Neutron diffraction

Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material. A sample to be examined is placed in a beam of thermal or cold neutrons to obtain a diffraction pattern that provides information of the structure of the material. The technique is similar to X-ray diffraction but due to their different scattering properties, neutrons and X-rays provide complementary information: X-Rays are suited for superficial analysis, strong x-rays from synchrotron radiation are suited for shallow depths or thin specimens, while neutrons having high penetration depth are suited for bulk samples.

Related publications (2)

Absence of charge-charge correlations at intermediate-range distances in disordered network-forming materials

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X-RAY-DIFFRACTION ANALYSIS OF LOW MISMATCH EPITAXIAL LAYERS GROWN ON MISORIENTED SUBSTRATES