Extended X-ray absorption fine structure (EXAFS) investigations of Ti bonding environment in sputter-deposited nanocomposite TiBC/a-C thin films

In this study, we have successfully used the extended X-ray absorption fine structure (EXAFS) technique at the Ti-K edge to extract the local structure in a set of nanocomposite TiBC/a-C coatings deposited by a combined d.c.-pulsed and r.f.-magnetron sputtering deposition process. The sequence of Fourier transform spectra in the deposited films shows that there is an increase in the number of Ti-C bonds in the films of higher carbon content in parallel with the increment of the total carbon content. In addition, Ti-K EXAFS spectra indicate that in all the deposited TiBC/a-C films, first-shell neighbours are in a nearer structural arrangement than the one expected for a bulk hexagonal TiB2, which could be due to the formation of mixed Ti-B-C compound in a structural unit similar to the one found in h-TiB₂.