Structural Commonalities in Amorphous Elemental Materials

TL;DR

This paper analyzes structural patterns in amorphous materials, revealing universal and distinct features in their pair distribution functions and local geometries across different classes.

Contribution

It introduces a comparative analysis of amorphous semiconductors, metals, and semi-metals, highlighting universal trends and differences in their structural profiles.

Findings

Amorphous semiconductors have similar PDFs with a well-isolated first peak.

Amorphous metallic systems show a bimodal second peak with non-zero intermediate values.

Amorphous semi-metals like Bi have PDFs similar to As and Sb.

Abstract

In the In recent times, the research community has explored diverse structures and novel fabrication methods for amorphous solids. This work investigates structural trends among different classes of amorphous materials to identify universal commonalities and fundamental differences. It is found that amorphous semiconductors exhibit similar Pair Distribution Functions (PDFs), characteristic of their underlying network-forming nature. On the other hand, amorphous metallic systems also display internally consistent PDF profiles, but different from those of the semiconducting materials. A comparative analysis of short-range and medium-range order reveals that while semiconductor structures feature a well-isolated first peak, with a zero-intensity region between the first and second peaks, metallic systems maintain a significant non-zero value between the first and second peaks. Furthermore, the second peak in metallic systems is bimodal, featuring a distinct elephant-like profile. Amorphous semi-metals display a still different profile, and the PDFs for Bi, for example, are similar to those for As and Sb. To deepen this structural comparison, we have incorporated amorphous Plane Angle Distributions (PADs), providing a more complete perspective on the local geometry. We introduce a renormalization approach that uses the positions of the first peaks in the PDFs to quantify these structural coincidences and discuss the implications.