Computational analysis of stable hard structures in the Ti-B system

Area of Science:

• Materials Science
• Computational Chemistry
• Solid State Physics

Background:

• Titanium borides (Ti-B) are critical intermetallic compounds with diverse applications.
• Understanding their lowest energy crystalline structures is essential for predicting material properties.

Purpose of the Study:

• To computationally predict the most stable crystalline structures of various titanium boride compounds.
• To identify novel, stable titanium boride phases and investigate their electronic and mechanical properties.

Main Methods:

• Density Functional Theory (DFT) combined with Particle Swarm Optimization (PSO).
• Calculation of convex-hull diagrams and phonon dispersion relations for stability analysis.
• Analysis of electronic band structure, density of states, and elastic moduli.

Main Results:

• Predicted six new metastable phases for established Ti-B stoichiometries (TiB, TiB2, Ti3B4).
• Identified four new stable titanium boride compounds (Ti2B-PSA, Ti2B3-PSB, TiB3-PSC, TiB4-PSD).
• Discovered α- and β-TiB2 phases exhibiting semi-metal properties and high Vickers hardness (≈39.5 GPa), approaching superhard material limits.

Conclusions:

• The study successfully predicted novel, thermodynamically and dynamically stable titanium boride structures.
• The predicted materials possess promising electronic and mechanical properties, including high hardness and elastic moduli.
• These findings provide a foundation for future experimental synthesis and applications in high-temperature structural materials.