Electronic structure and chemical bonding in Ti4SiC3 investigated by soft x-ray emission spectroscopy and first principle theory

TL;DR

This study investigates the electronic structure and chemical bonds in Ti4SiC3 using soft x-ray emission spectroscopy and first-principles calculations, revealing insights into its bonding and properties compared to related compounds.

Contribution

It provides a detailed analysis of Ti4SiC3's electronic structure and chemical bonds, highlighting differences from Ti3SiC2 through combined experimental and theoretical approaches.

Findings

Modified spectral shape for buried Si layers due to hybridization

Increased Ti-C covalent bond strength from structural relaxation

Differences in electronic structure related to Si layer number

Abstract

The electronic structure in the new transition metal carbide Ti4SiC3 has been investigated by bulk-sensitive soft x-ray emission spectroscopy and compared to the well-studied Ti3SiC2 and TiC systems. The measured high-resolution Ti L, C K and Si L x-ray emission spectra are discussed with ab initio calculations based on density-functional theory including core-to-valence dipole matrix elements. The detailed investigations of the Ti-C and Ti-Si chemical bonds provide increased understanding of the physical properties of these nanolaminates. A strongly modified spectral shape is detected for the buried Si monolayers due to Si 3p hybridization with the Ti 3d orbitals. As a result of relaxation of the crystal structure and the charge-transfer from Ti (and Si) to C, the strength of the Ti-C covalent bond is increased. The differences between the electronic and crystal structures of Ti4SiC3 and Ti3SiC2 are discussed in relation to the number of Si layers per Ti layer in the two systems and the corresponding change of materials properties.