Xiaoxu Zhao, Weiwei Sun, Dechao Geng, Wei Fu, Jiadong Dan, Yu Xie, Paul R C Kent, Wu Zhou, Stephen J Pennycook, Kian Ping Loh
Molybdenum carbide (Mo2 C), a class of unterminated MXene, is endowed with rich polymorph chemistry, but the growth conditions of the various polymorphs are not understood. Other than the most commonly observed T-phase Mo2 C, little is known about other phases. Here, Mo2 C crystals are successfully grown consisting of mixed polymorphs and polytypes via a diffusion-mediated mechanism, using liquid copper as the diffusion barrier between the elemental precursors of Mo and C. By controlling the thickness of the copper diffusion barrier layer, the crystal growth can be controlled between a highly uniform AA-stacked T-phase Mo2 C and a "wedding cake" like Mo2 C crystal with spatially delineated zone in which the Bernal-stacked Mo2 C predominate...
February 20, 2019: Advanced Materials