Discovery of carbon-based strongest and hardest amorphous material

TL;DR

This paper reports the discovery of novel amorphous carbon phases with high sp3 content, exhibiting exceptional hardness and strength, along with tunable semiconducting properties, suitable for advanced photovoltaic applications.

Contribution

It introduces new amorphous carbon materials synthesized under high pressure and temperature, with unprecedented mechanical and electronic properties.

Findings

The materials are the hardest amorphous carbons known to date.

They have tunable bandgaps between 1.5 and 2.2 eV.

They can scratch diamond and approach its strength.

Abstract

Carbon is likely the most fascinating element of the periodic table because of the diversity of its allotropes stemming from its variable (sp, sp2, and sp3) bonding motifs. Exploration of new forms of carbon has been an eternal theme of contemporary scientific research. Here we report on novel amorphous carbon phases containing high fraction of sp3 bonded atoms recovered after compressing fullerene C60 to previously unexplored high pressure and temperature. The synthesized carbons are the hardest and strongest amorphous materials known to date, capable of scratching diamond crystal and approaching its strength which is evidenced by complimentary mechanical tests. Photoluminescence and absorption spectra of the materials demonstrate they are semiconductors with tunable bandgaps in the range of 1.5-2.2 eV, comparable to that of amorphous silicon. A remarkable combination of the outstanding mechanical and electronic properties makes this class of amorphous carbons an excellent candidate for photovoltaic applications demanding ultrahigh strength and wear resistance.