Effect of ‘Ti’ particle size in the synthesis of highly pure Ti[formula omitted]SiC[formula omitted] MAX phase

Abstract

We report here the effect of the particle size for a significant precursor material, i.e. ‘Ti’ for the synthesis of the high pure MAX (Ti3SiC2) phase by heating at high temperature in an argon atmosphere. It is observed that ‘Ti’ metal powder with a comparatively lower particle size (∼20μm) produces several intermetallics and carbides, leading to the formation of an impure MAX phase, while ‘Ti’ metal powder with a higher particle size (∼200μm) gives rise to a highly pure Ti3SiC2 MAX phase. The underlying reason behind this is thoroughly investigated through physico-chemical evidences, like XRD, FESEM, TEM, etc. With the help of first-principle density functional calculations (DFT), the electronic structures of the pure and impure MAX phases were ascertained. The DFT calculations revealed that the highly mobile p-electron of carbon is abundant in the highly pure MAX phase as compared to the impure MAX phase. This was supported by electrical property measurements, which showed at least a three times enhancement in electrical conductivity for the highly pure Ti3SiC2 MAX phase as compared to the impure one.