Crystal structure of Cr4AlB4: A new MAB phase compound discovered in Cr-Al-B system

Abstract

In this communication, the crystal structure of Cr4AlB4, a new MAB phase compound (where M is a transition metal, A is Al or Si, B is boron) discovered in Cr-Al-B system is reported. This new MAB phase was synthesized from a mixture of CrB and Al powders at 1000 °C and its crystal structure was determined by a combination of X-ray diffraction, first-principles calculations and energy dispersive X-ray spectroscopy (EDS). Cr4AlB4 crystallizes in an orthorhombic structure with Immm space group. The lattice constants are a = 2.9343(6) Å, b = 18.8911(0) Å, c = 2.9733(7) Å, and the atomic positions are Cr1 at 4g (0, 0.2936(5), 0), Cr2 at 4h (0.5, 0.5859(7), 0), Al at 2b (0, 0.5, 0.5), B1 at 4h (0, 0.3839(8), 0.5) and B2 at 4g (0.5, 0.6646(2), 0.5).