Atomic Radial Distribution in Amorphous Selenium by X-Ray and Neutron Diffraction

Abstract

The atomic radial distribution in amorphous selenium at room temperature was determined independently from x-ray and neutron-diffraction patterns. Correction techniques were applied to reduce spurious oscillations in the distribution. The two si(s) intensity functions are in good agreement, and both methods show peaks in the radial distribution at 2.33, 3.7, 4.6, 5.8, and 7.(3) Å. The intensity patterns show no appreciable damping out of intensity peaks even at the experimental limit of s=13. This behavior results from the presence of short and well-defined interatomic distances in amorphous selenium. The intensity function can largely be accounted for by considering only two interatomic distances between the first and second nearest neighbors along the c-axis chain structure of hexagonal crystalline selenium. Thus, the spiral chain structure persists in the amorphous state with nearly unchanged geometry out to second neighbors, but in random orientations.

Magnetic superconductors

“…The calculated DOS (b) is in good agreement with the experimental spectrum for monoclinic Se [6]. From dissolution of amorphous Se in CS 2 [25], Raman scattering [26], x-ray photoemission [6] and x-ray and neutron diffraction [27,28] measurements, it is well known that the Se 8 rings are very few in number and thus negligible in amorphous Se, and that amorphous Se consists of a chain-like structure with nearly unchanged geometry from trigonal Se, but with random orientations. Therefore, we can reasonably assume that the reversal of the two peak heights in the 4p-like bonding bands of amorphous Se is mainly due to the chain structure with random sign of dihedral angle, within a framework of the model by Bullett et al [24].…”

Direct Molecular Dynamic Simulation of Light-Induced Structural Change in Amorphous Selenium

“…The calculated pair correlation function shows pleasing agreement with experiment [8] and peak positions agree closely with Refs. [15,16].…”

Collective Excitations and Thermodynamic Properties of Liquid Selenium: A Transition from Short Chain Polymer to Real Polymer System

“…1. Interaction potential of liquid selenium ninger et al [20] have shown that amorphous selenium has ªliquid-like atomic assemblageº consisting of short chains in random orientation. The results of molecular dynamics [6] have shown that the pair distribution of amorphous and liquid selenium has similar radial order but there is a thermal broadening of peaks in liquid selenium.…”