Structure of amorphous selenium studied by neutron diffraction

• DOI: 10.1063/1.430621
• Publication Date: 2003-02-27T21:56:52Z
• Authors: F. Yssing Hansen; T. Steen Knudsen; K. Carneiro
• Keywords: 0103 physical sciences; 01 natural sciences

Neutron diffraction measurements on amorphous selenium have been performed at 293 and 80 K. Careful analyses of the instrumental corrections were made to avoid systematic errors in the measured structure factor S (κ) in the wave vector region 0 ? κ ? 12 Å−1. As a result of the data treatment, the neutron scattering cross sections of selenium are determined to be σcoh = 8.4±0.1 b and σinc = 0.1±0.1 b. Using the fact that S (κ) for large κ’s is determined by the short distances in the sample, a new method for extrapolation of the experimental S (κ) until convergence is proposed. This allows an accurate determination of g (r) showing peaks at distances that agree well with the previous x−ray experiment by Kaplow et al. for distances up to 11 Å. However, only partial agreement is obtained when finer details of g (r), e.g., the width of the first peak, are considered. Finally, we give a brief discussion of the different models for the structure of amorphous selenium, taking both diffraction measurements and thermodynamic considerations into account.