Electronic structure investigation of Ti3AlC2 , Ti3SiC2 , and Ti3GeC2 by soft x-ray emission spectroscopy

The electronic structures of epitaxially grown films of Ti3AlC2 , Ti3SiC2 , and Ti3GeC2 have been investigated by bulk-sensitive soft x-ray emission spectroscopy. The measured high-resolution Ti L , C K , Al L , Si L , and Ge M emission spectra are compared with ab initio density-functional theory including core-to-valence dipole matrix elements. A qualitative agreement between experiment and theory is obtained. A weak covalent Ti-Al bond is manifested by a pronounced shoulder in the Ti L emission of Ti3AlC2 . As Al is replaced with Si or Ge, the shoulder disappears. For the buried Al and Si layers, strongly hybridized spectral shapes are detected in Ti3AlC2 and Ti3SiC2 , respectively. As a result of relaxation of the crystal structure and the increased charge-transfer from Ti to C, the Ti-C bonding is strengthened. The differences between the electronic structures are discussed in relation to the bonding in the nanolaminates and the corresponding change of materials properties.Original Publication:Martin Magnuson, J.-P. Palmquist, M. Mattesini, S. Li, R. Ahuja, O. Eriksson, Jens Emmerlich, O. Wilhelmsson, Per Eklund, Hans Högberg, Lars Hultman and U. Jansson, Electronic structure investigation of Ti3AlC2, Ti3SiC2, and Ti3GeC2 by soft x-ray emission spectroscopy, 2005, Physical Review B. Condensed Matter and Materials Physics, (72), 245101.http://dx.doi.org/10.1103/PhysRevB.72.245101Copyright: American Physical Societyhttp://www.aps.org/