Phase stability, elastic, electronic, thermal and optical properties of Ti3Al1-xSixC2 (0 LE x LE 1): First-principles study

TL;DR

This study uses first-principles calculations to explore how silicon incorporation affects the structural, mechanical, electronic, thermal, and optical properties of Ti3Al1-xSixC2, revealing enhanced strength and optical reflectivity.

Contribution

It provides a comprehensive first-principles analysis of Ti3Al1-xSixC2 alloys, highlighting the effects of Si content on various properties and potential applications as coatings.

Findings

Elastic parameters increase with Si content, indicating higher strength.

Alloy remains metallic with Ti 3d states crossing the Fermi level.

High reflectivity in the visible-ultraviolet region suggests coating applications.

Abstract

The structural parameters with stability upon Si incorporation and elastic, electronic, thermodynamic and optical properties of Ti3Al1-xSixC2 (0 \leq x \leq 1) are investigated systematically by the plane wave psedudopotential method based on the density functional theory (DFT). The increase of some elastic parameters with increasing Si-content renders the alloys to possess higher compressive and tensile strength. The Vickers hardness value obtained with the help of Mulliken population analysis increases as x is increased from 0 to 1. The solid solutions considered are all metallic with valence and conduction bands, which have a mainly Ti 3d character, crossing the Fermi level. The temperature and pressure dependences of bulk modulus, normalized volume, specific heats, thermal expansion coefficient, and Debye temperature are all obtained through the quasi-harmonic Debye model with phononic effects for T = 0-1000K and P = 0-50GPa. The obtained results are compared with other results where available. Further an analysis of optical functions for two polarization vectors reveals that the reflectivity is high in the visible-ultraviolet region up to ~ 10.5 eV region showing promise as good coating material. Keywords: Ti3Al1-xSixC2; First-principles; Quasi-harmonic Debye model; Mechanical properties; Band structure; Optical properties