Elaboration of a wide range of TiO₂micro/nanostructures by high power impulse inverted cylindrical magnetron sputtering

Combining a molecular modelling approach with direct current and high power impulse magnetron sputtering to develop new TiO2 thin films for antifouling applications

“…The HR-TEM observations on a cross section of these specimens confirmed that the whole layer is not crystalline: large amorphous and crystallized areas co-exist for the samples obtained with a duty cycle of 2.5 % and nanocrystallites (10 nm -20 nm) are embedded in an amorphous matrix for the synthesis with a duty cycle of 1.25 % ( figure 5). This evolution of the microstructure has already been discussed elsewhere [20] and is mainly attributed to distinct plasma regimes characterized by variable ionization rates and energies involved in the discharge depending on the duty cycle. Thus, four TiO 2 samples with various crystalline structures (amorphous, polycrystalline anatase, as well as a combination of amorphous + textured anatase (101) and amorphous + rutile with (101) preferential growth) were deposited on stainless steel to determine their efficiency in mitigating fouling.…”

“…To work in HiPIMS mode, the discharge was pulsed at a constant frequency of 250 Hz with time-ON duration of 100 s and 50 s, corresponding thus to duty cycles (i.e. T ON /(T ON +T OFF )) of 2.5 % and 1.25 % respectively [20].…”

“…Their thicknesses were found to range from 200 nm to 800 nm. Whereas the layers synthesized with the former magnetron sputtering method are usually amorphous or partially crystalline depending on the deposition setting (temperature, sample bias etc…), reducing the duty cycle of the discharge in the latter technique, so the length of the T ON periods of the discharge, allows to change the crystalline proportion in the layer but also the preferential orientation of the crystallites in the case of TiO 2 coatings [20]. XRD patterns of the as synthesized TiO 2 films are presented in figure 4.…”

“…Furthermore, the SEM observations endorse that neither cracks nor delamination nor morphological modifications occur during the annealing of the M a n u s c r i p t Page 7 of 7 sample. The mean roughness of the surfaces (R z ) was determined by AFM by using the ten points average roughness method on several areas: the value is around 60 and 80 nm for the two dcMS-synthesized coatings whereas it is only in the range of 16 to 18 nm for the HiPIMS-synthesized ones [20]. The mean roughness will certainly have less influence on the fouling induction time than the microstructure for specimens synthesized with both methods (dcMS on one side and HiPIMS on the other side).…”

Study of magnetic iron nitride thin films deposited by high power impulse magnetron sputtering

“…It is known that HiPIMS plasma is highly ionized as compared to dc-MS even though the energies of adatoms are only slightly higher in HiPIMS (∼20 eV). Such conditions lead to denser films with the relatively smaller amount of defects and vacancies in HiPIMS as compared to dc-MS. [2,4,41] Relatively smaller density of defects could result in smaller stress in the deposited films. This effect lead to improve soft-magnetic properties of films deposited using HiPIMS.…”