Growth of Nanostructured TiO₂ Thin Films onto Lignocellulosic Fibers through Reactive DC Magnetron Sputtering: A XRD and SEM Study

TiO2 thin films were deposited on ginger lily (Hedychium gardnerianum) fibers using a custom-made DC reactive magnetron sputtering system with Ar/O-2 mixture at two O-2/(O-2 + Ar) ratios (50% O-2 and 75% O-2) and sputtering powers (500 and 1000 W), and their effects on the structure and surface morphology of TiO2 films were investigated. XRD analysis showed the presence of the mainly anatase phase in the deposited films, with a small fraction of rutile phase detected for TiO2 deposited with the higher oxygen percentage and sputtering power. SEM imaging revealed that the films exhibited distinct surface features depending on the deposition conditions. Specifically, films deposited with 50 O-2 % and 1000 W exhibited porosity, while the films deposited under other conditions appeared either dense with a cauliflower-like appearance or displayed surface features resembling lines and mountain ranges of coalesced particles. The grain size of dense films increased with increasing sputtering power. The deposition conditions significantly affected the resulting surface topography, with an increase in surface roughness parameters observed for both power levels when the oxygen concentration in the deposition atmosphere was increased from 50% to 75%. The adhesion tests conducted using sonication and EDS analysis revealed that almost all of the studied films exhibited good adhesion, as evidenced by the atomic content (at. %) of Ti remaining intact after sonication, indicating good adhesion. However, the porous film exhibited a slightly lower adhesion grade, suggesting that the porous structure may have influenced the adhesion properties.