Thermodynamic stability of Li-B-C compounds from first principles.

Area of Science:

• Materials Science
• Solid-State Chemistry
• Computational Materials Science

Background:

• The prediction of high-temperature superconductivity in LiBC spurred interest in related materials.
• The thermodynamic stability of lithium-boron-carbon (Li-B-C) compounds is crucial for material synthesis but remains under-explored.
• Understanding phase stability is key to designing novel superconducting materials.

Purpose of the Study:

• To computationally investigate the thermodynamic stability of known and novel Li-B-C compounds.
• To assess the stability of BC3 polymorphs and Li-B-C phases.
• To identify potentially stable Li-B-C configurations.

Main Methods:

• Density Functional Theory (DFT) calculations were employed.
• Calculations included Li chemical potential in LiBC and analysis of B-C phases.
• Evolutionary algorithms and rational design were used to explore new configurations.

Main Results:

• The thermodynamic stability of Li-B-C compounds was characterized.
• Metastable BC3 polymorphs were rationalized.
• Recently reported BC3, LiBC3, and Li2B2C phases were found to be dynamically and thermodynamically unstable.
• More favorable Li2B2C configurations were identified but remain above the stability threshold.

Conclusions:

• Many recently proposed Li-B-C materials lack thermodynamic stability.
• Further theoretical and experimental efforts are needed to achieve stable Li-B-C superconducting materials.
• The study provides insights into the stability landscape of Li-B-C systems.