Effect of Nd doping on structure and improvement of the properties of TiO2 thin films

TiO2 thin films doped with neodymium in the range from 0.6 at.% to 6.1 at.% were prepared by high energy reactive magnetron sputtering. Investigations of structural properties performed by XRD and TEM methods revealed that neodymium dopant caused changes of the phase content and crystallite size in the prepared thin films. The doping also influenced optical properties, i.e., cutoff wavelength. Introducing a small amount of the neodymium into titania caused an increase of hardness of these coatings by ~ 30%, while the addition of higher dopant amounts resulted in a significant decrease of hardness as compared to TiO2 coatings. As high hardness as 24.9 GPa was obtained and so far such value has not been reported in the literature for titania thin films prepared by dc magnetron sputtering.