Systematic high-throughput exploration of quaternary M′2M″AlB4 phases

A desired prerequisite when performing a quantum mechanical calculation is to have an initial idea of the atomic positions within an approximate crystal structure. The atomic positions combined should result in a system located in, or close to, an energy minimum. Designing low-energy structures for large multi-component systems is, however, often a challenging task as the degrees of freedom are close to infinite. The low-energy basins of (M′xM″1-x)3AlB4 material systems are herein explored by combining cluster expansion and crystal structure prediction methodologies with density functional theory calculations. Low-energy structures are specifically found at the (M′1/3M″2/3)3AlB4 composition, and this for multiple crystal symmetries. A subsequent high-throughput phase stability search was performed considering the identified low-energy structures at the (M′1/3M″2/3)3AlB4 composition where M′ and M″ were alloyed with Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, and Co for both ordered and disordered structures. Nine quaternary phases were predicted stable with five of these favoring structures with M-sites in the form of a simulated solid solution.