Synthesis, characterization and first principle modelling of the MAB phase solid solutions: (Mn1-xCrx)2AlB2 and (Mn1-xCrx)3AlB4

Abstract

The MAB phases are a family of layered ternary transition metal borides, with atomically laminated crystal structures comprised of transition metal boride (M-B) layers interleaved by single, or double, Al (A) layers. Herein, density functional theory is implemented to evaluate the thermodynamic stability of disordered (Mn1-xCrx)2AlB2, and disordered and ordered (Mn1-xCrx)3AlB4 quaternaries. The (Mn1-xCrx)2AlB2 solid solutions were synthesized over the entire range of substitution. A (Mn1-xCrx)3AlB4 solid solution was produced, on the base of Cr3AlB4, to form (Mn0.33Cr0.66)3AlB4. Powder X-ray diffraction shows lattice parameter shifts and unit cell expansions indicative of successful solid solution formations.