X-ray Photoelectron Spectroscopy of Ti3AlC2, Ti3C2Tz, and TiC Provides Evidence for the Electrostatic Interaction between Laminated Layers in MAX-Phase Materials

By L. Näslund, P. Persson, J. Rosen. Journal of Physical Chemistry C, 2020

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: The inherently nanolaminated Ti 3 AlC 2 is one of the most studied MAX-phase materials. MAX-phases consists of two-dimensional M n +1 X n -layers (e.g., T 3 C 2 -layers) with strong internal covalent bonds separated by weakly interacting A-layers (e.g., Al-layers), where the repetitive stacking of the M n +1 X n -layers and the A-layers suggests being the foundation for the unusual but attractive material properties of the MAX-phases. Although being an important parameter, the nature of the bonding between the M n +1 X n -layers and the A-layers has not yet been established in detail. The X-ray photoelectron spectroscopy data presented in this paper suggest that the weak interaction between the Ti 3 C 2 -layers and the Al-layers in Ti 3 AlC 2 is through electrostatic attraction facilitated by a charge redistribution of the delocalized electrons from the Ti 3 C 2 -layers to the Al-layers. This charge redistribution is of the same size and direction as between Ti atoms and Al atoms in TiAl alloy. This fi nding opens up a pathway to predict and improve MAX-phase materials properties through A-layer alloying, as well as to predict new and practically feasible MXene compounds.

Subfields: Materials Chemistry, Mechanical Engineering

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