Effect of varying Ti/V ratio on synthesis, thermal behavior, optical band gap, and electrical properties of (TixV1−x)2AlC MAX phase

Abstract

Bimetallic solid solution MAX phases have attracted significant interest because of their tunable properties. Easy machinability, relatively low densities, high elastic constants, catalytic activity, etc., make (Ti,V)2AlC MAX phase an appreciable candidate for different mechanical, electrical, and electrochemical based applications. Earlier reported synthesis methods of bimetallic MAX phases are not economical due to high temperature, high pressure, an inert atmosphere, etc. Herein we present an alternative route, modified molten salt shielded synthesis, to produce (TixV1−x)2AlC MAX phases with varying Ti/V ratio. X-ray diffraction shows the shift in main peak positions with varying Ti/V ratios. Post oxidation XRD of the MAX phase constituents shows that increasing Ti / V ratio increases the peak intensity of TiO2 and reduces the intensity of V2O5. UV–vis spectroscopy data illustrate that increasing the Ti/V ratio enhances the optical band gap. Calculated thermodynamic parameters like activation energy, entropy, enthalpy, and Gibb’s free energy manifest the reaction kinetics of the oxidation behavior of the MAX phases. Electrical resistivity measured at room temperature decreases with increasing Ti/V values. The outcome of this present systematic and meticulous work provides greater insight into the synthesis of the solid solution based (TixV1−x)2AlC MAX phase and its thermal, optical, and electrical behavior with varying Ti/V ratios.