The electronic structure in the new transition-metal carbide ${\mathrm{Ti}}_4\mathrm{Si}{\mathrm{C}}_3$ has been investigated by bulk-sensitive soft x-ray emission spectroscopy and compared to the well-studied ${\mathrm{Ti}}_3\mathrm{Si}{\mathrm{C}}_2$ 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 intercalated 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 ${\mathrm{Ti}}_4\mathrm{Si}{\mathrm{C}}_3$ and ${\mathrm{Ti}}_3\mathrm{Si}{\mathrm{C}}_2$ are discussed in relation to the number of Si layers per Ti layer in the two systems and the corresponding change of materials properties.

• Received 11 August 2006

DOI:https://doi.org/10.1103/PhysRevB.74.205102