The strongest and toughest predicted materials: Linear atomic chains without a Peierls instability

Abstract

<h2>Summary</h2> The strength and toughness of materials are important for applications. A linear atomic chain, carbyne, has been previously predicted to have the highest strength and toughness. To discover materials with higher gravimetric strength and toughness, we herein investigated B, C, N, BC, BN, and CN chains by first-principles calculations. We found that B, C, BC, and BN chains are stable when under tension at room temperature. B chains have the highest recorded gravimetric toughness (16.9 kJ g⁻¹), whereas BC chains have the highest recorded gravimetric strength (91.8 GPa g⁻¹ cm³) and high toughness (15.3 kJ g⁻¹), surpassing the predicted performance of carbyne (76.4 GPa g⁻¹ cm³ and 9.4 kJ g⁻¹). Electronic structure analyses show that the higher strength and toughness of the BC and B chains, compared with carbyne, originate from their strong chemical bonding and the absence of a Peierls instability up to strain to failure. The potential fabrication and applications of BC and B chains are discussed.