Electronic structure and chemical bonding of nc-TiC/a-C nanocomposites

TL;DR

This study investigates how the electronic structure and charge transfer in nc-TiC/a-C nanocomposites depend on grain size, revealing increased ionicity and interface bonding crucial for understanding their properties.

Contribution

It provides new insights into the electronic structure and interface bonding mechanisms in nc-TiC/a-C nanocomposites, highlighting the effect of grain size on charge transfer.

Findings

Charge transfer increases as grain size decreases.

Ionocity of TiC nanocrystallites increases with smaller grains.

Interface bonding plays a key role in nanocomposite properties.

Abstract

The electronic structure of nanocrystalline (nc-) TiC/amorphous C nanocomposites has been investigated by soft x-ray absorption and emission spectroscopy. The measured spectra at the Ti 2p and C 1s thresholds of the nanocomposites are compared to those of Ti metal and amorphous C. The corresponding intensities of the electronic states for the valence and conduction bands in the nanocomposites are shown to strongly depend on the TiC carbide grain size. An increased charge-transfer between the Ti 3d-eg states and the C 2p states has been identified as the grain size decreases, causing an increased ionicity of the TiC nanocrystallites. It is suggested that the charge-transfer occurs at the interface between the nanocrystalline TiC and the amorphous C matrix and represents an interface bonding which may be essential for the understanding of the properties of nc-TiC/amorphous C and similar nanocomposites.