When Two Becomes Three: Predicting Stable Ternary Boron-Based Compounds by Populating Unique Lattice Sites in Binary Prototype Structures

Boron-based materials are known for their excellent mechanical properties and structural versatility. However, the discovery of such novel materials is often hindered by challenging synthesis procedures, such as high temperature and pressure, which is why theoretical guidance can be used to identify candidates most promising for synthesis. In this study, new chemical phase spaces are explored utilizing the Materials Project database. 16 boron-based binary prototype structures are identified, each featuring two unique non-boron lattice sites. These sites are subsequently populated with elements from Groups 2 to 14 and expanded into 27 552 ternary compounds. Phase stability assessments identify 166 stable ternary compounds, 155 of which are mechanically stable. Analysis reveals a strong correlation between boron concentration and mechanical properties, with boron-rich compounds exhibiting higher Vickers hardness and improving shear and Young's moduli. Notably, multiple ternary compounds demonstrate significant mechanical property enhancements over their binary counterparts, with some showing Young's modulus improvements of up to 50%. These findings exemplify a pathway for designing novel boron-based materials with exceptional mechanical characteristics.