Theoretical Prediction and Synthesis of (Cr 2/3 Zr 1/3 ) 2 AlC i -MAX Phase

Guided by predictive theory, a new compound with chemical composition (Cr 2/3 Zr 1/3 ) 2 AlC was synthesized by hot pressing of Cr, ZrH 2, Al, and C mixtures at 1300 °C. The crystal structure is monoclinic of space group C 2/ c and displays in-plane chemical order in the metal layers, a so-called i -MAX phase. Quantitative chemical composition analyses confirmed that the primary phase had a (Cr 2/3 Zr 1/3 ) 2 AlC stoichiometry, with secondary Cr 2 AlC, AlZrC 2, and ZrC phases and a small amount of Al–Cr intermetallics. A theoretical evaluation of the (Cr 2/3 Zr 1/3 ) 2 AlC magnetic structure was performed, indicating an antiferromagnetic ground state. Also (Cr 2/3 Hf 1/3 ) 2 AlC, of the same structure, was predicted to be stable.