Temperature-Dependent Orientation of Diamond Films on Titanium and Structural Evolution of Interfacial Layers

X-ray diffraction analytical techniques have been used to investigate the influence of the deposition temperature (650-850°C) on the composition and microstructure of the transition layers formed at the interface between titanium substrates and diamond thin films. The diamond coatings were produced by hot-filament chemical vapor deposition using a 1% methane/hydrogen mixture. X-ray diffraction analysis, performed both through q-2q scans and at grazing incidence, allowed investigation of the crystallographic properties and of the structural evolution of the various phases (TiC, TiH2, α-Ti) generated inside the intermediate reaction layers. The temperature-dependent orientation of diamond crystallites is discussed with reference to the complex structure of these interfacial layers.