Medium-range structure in amorphous and crystalline

Abstract

The known structure of a crystalline phase is useful in investigating the unknown structure of the compositionally-equivalent glass. One essential clue is given by reciprocal-space features at low Q (scattering vector) in X-ray or neutron scattering data, which are clearly related to the medium-range structure of the glass. Interpretation of these features as “quasi-Bragg” scattering allows direct comparison between the structures of the glass and equivalent crystalline phases. An application of this method will be illustrated in the case of amorphous GeSe2. For this material the experimental data is particularly rich as partial structure factors have been measured. Correspondence between low-Q features in the neutron diffraction data for the glassy and crystalline phases is qualitatively good and extends to the partial functions too. Thus, essential features of the medium-range structure of this glass appear to be interpretable, rather easily.