Ti Films Research Articles

Electroplating titanium film on 316L stainless steel in LiCl–KCl–Tix+ (2 < x<3) molten salts

To improve the anti-corrosion properties of 316L stainless steel, titanium (Ti) metal films were electroplated on it using LiCl–KCl molten salts as the electrolyte, and low-valence Tix+ (2 < x<3) as the solute. The solute was produced by the reaction of Ti4+ and Ti0 via mixing K2TiF6, and Ti metal (sponge Ti) in the melts. Anti-corrosion test has shown significant enhancement in the stability of the Ti-coated 316L due to the presence of Ti film. However, the anti-corrosion properties did not enhance with an increase in the thickness of the Ti layers owing to a possible defect in the thicker Ti layers.

Effects of heat treatments on the microstructure and the adhesion of Cr, Ti, Al, Zr HiPIMS films deposited on APS Al2O3 and ZrO2-8Y2O3 coatings

While several studies deal with thin film depositions on bulk ceramics, little is known about film applications on thermally sprayed ceramics. Hence, atmospheric plasma sprayed Al2O3 and ZrO2-8Y2O3 coatings served as substrates for the deposition of metallic films (Cr, Ti, Al, and Zr) by means of high power impulse magnetron sputtering (HiPIMS). Subsequently, these duplex coatings were heat treated in a vacuum furnace at 300 °C and 600 °C to investigate influences on the phase formation, residual stress state, mechanical properties, and film adhesion. The Cr and Al films crystallized in a cubic lattice and the Zr films exhibited a hexagonal lattice. The crystallization of the Ti film was substrate dependent, i.e. on alumina substrate the Ti film was cubic, while it was hexagonal on zirconia. Furthermore, heat treating the Ti and Zr films at 600 °C in vacuum led to an oxygen exchange generating c-TiO and m-ZrO. Heat treating the Cr film on Al2O3 substrate provoked a significant stress relaxation leading to an increased adhesion. However, depositing Al films on alumina and zirconia substrates resulted in the highest adhesion in the as-deposited state due to the low Young's modulus. In general, it was shown that phase transformations, increased lattice mismatches as well as differences in the thermal expansion behavior of the substrate and the film had a negative influence on the film adhesion.

Fabrication and characterization of transparent Cr-decorated TiO2 nanoporous electrode for enhanced photo-electrocatalytic performance

A Cr-decorated TiO2 nanoporous transparent electrode was fabricated by DC sputtering, anodization, and thermal evaporation methods, respectively. Ti films were deposited on fluorine-doped tin oxide (FTO) coated glass and anodized to obtain a transparent TiO2 nanoporous film (TN). The fabricated electrodes were characterized using a field emission scanning electron microscope (FESEM), atomic force microscope (AFM) and X-Ray diffraction (XRD). Photoelectrochemical activity of prepared films was investigated by photo-electrocatalytic degradation of RhB dye under constant voltage and UVA light irradiation. The Cr-decorated TiO2 nanoporous film (CTN) served as an electrode and exhibited better photo-electrocatalytic performance than a TN electrode. Results show that Cr decoration increased photoelectrochemical activity significantly due to more efficient charge separation and lower recombination rate.

Microstructures of titanium oxide thin films grown continuously on stainless steel wires by PVD in an inverted cylindrical magnetron: Towards an industrial process

Producing colored coatings by Physical Vapor Deposition (PVD) in an in-line way is an interesting industrializing process. Moreover, the durability of vacuum coatings is an advantage for architectural applications such as outdoor decoration. In this project, titanium dioxide coatings were produced over moving stainless steel wires via direct current (DC) reactive magnetron sputtering PVD in an inverted cylindrical magnetron. The samples were characterized by transmission electron microscopy (TEM) coupled with ASTAR (Automated crystal orientation mapping on TEM -ACOM- with precession tool -DigiSTAR-) orientation-phase mapping and EDS (Energy Dispersive X-ray Spectroscopy) chemical mapping. The microstructure of TiOx thin films is analyzed as a function of the O2 flux in the chamber. In the metallic mode, a 300 nm polycrystalline hexagonal Ti film is obtained in 2 min 30 s at 1000 W. For the same power and same time but in the poisoned mode, a 40 nm titanium dioxide film composed of both rutile and anatase columnar grains is obtained. A peculiar mode is the transition one, where in a single pass through the chamber a multilayer of ≈230 nm hexagonal Ti and ≈70 nm pure rutile titanium dioxide is grown. This multilayer is a result of a heterogeneous magnetic field, hence of the chamber poisoning. All these thin films present chemical, structure and grain size gradients because of an original process (in-line and cylindrical inverted magnetron) with plasma density heterogeneity.

Study of the Ti/InGaAs solid-state reactions: Phase formation sequence and diffusion schemes

The development of Complementary Metal Oxide Semiconductor (CMOS)-compatible contact technology on III–V materials based on Ti for electronics or photonics applications was studied. In this framework, solid-state reactions between Ti thin films (20 nm) and In0.53Ga0.47As layers grown on InP substrates were studied from the as-deposited state up to 550°C using a combination of advanced X-ray diffraction (in-plane reciprocal space mapping), Auger electron spectroscopy and transmission electron microscopy analyses. The phase formation sequence was solved. At low temperature, an amorphous Ti–Ga–As intermixing layer coexists with the Ti film. As of 250°C, the first crystalline phase to form is Ti2Ga3. At 300°C, a new crystalline phase appears, namely TiAs2. On the other hand, TiAs and metallic In form at 350°C and Ti is completely consumed between 450 and 500°C. The diffusion of the various species lead to the formation of a non-nominal Ga-rich InxGa1−xAs layer and at 550°C to the formation of polycrystalline GaAs. Ti was found to be the main diffusing species at low temperature whereas III and V elements are the dominant diffusing species at higher temperatures. The nature of the phases formed above and below the original Ti/InGaAs interface might explain the In accumulation at the interface, the TiAs phase acting as a diffusion barrier.

Micro-structural and bonding structure analysis of TiAlN thin films deposited with varying N2 flow rate via ion beam sputtering technique

Abstract Titanium aluminum nitride (TiAlN) thin films were deposited on Si(1 0 0 ) substrate using titanium and aluminum targets in 1:1 ratio at various N2 flow rates using ion beam sputtering (IBS) technique. The morphology, particle and crystallite size of TiAlN thin films were estimated by field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), and grazing incidence X-ray diffraction (GIXRD) technique, respectively. The SEM images of the TiAlN thin films revealed smooth and uniform coating, whereas AFM images confirmed the particle size varying from 2.5 nm to 8.8 nm, respectively. The crystallite size and lattice strain were observed to vary from 4.79 nm to 5.5 nm and 0.0916 and 0.0844, respectively, with an increase in N2 flow rate in the TiAlN thin films. The X-ray absorption near edge structure (XANES) results showed Ti L, N K and O K-edges of TiAlN coating within a range of 450 eV to 470 eV, 395 eV to 410 eV and 480 eV to 580 eV photon energy, respectively. The electronic structure and chemical bonding of state of c-TiAlN thin film of Ti L, N K and O K-edges were analyzed through semi-empirical curve fitting technique.

Multiscale plasma and feature profile simulations of plasma-enhanced chemical vapor deposition and atomic layer deposition processes for titanium thin film fabrication

Mechanisms of titanium (Ti) thin films deposited in plasma-enhanced (PE) chemical vapor deposition (CVD) and atomic layer deposition (ALD) processes have been elucidated via multiscale plasma and feature profile simulations. Firstly, by iterating a 2D reactor-scale plasma simulation and a feature-scale deposition profile simulation, a shared surface reaction model has been determined for PECVD processes. Ti film thicknesses and profiles consistently computed both along a wafer surface and inside a test structure agreed very well with the experimental data. Then, another multiscale simulation, with the same plasma model and the surface reaction model to which the Eley–Rideal surface kinetics is added, has been applied to a PEALD process. The simulation succeeded again in reproducing and explaining the non-conformal Ti film deposition observed in experiments, while conformal Ti films are obtained in PECVD processes. Through the simulation work, comprehensive mechanisms of Ti film deposition, which cover both PECVD and PEALD processes, have been discussed and proposed in this study.

Ti, Zr and Ta coated UHMWPE aiming surface improvement for biomedical purposes

Ultra-high molecular weight polyethylene (UHMWPE) is widely used in bearing components. However, in this type of application, wear issues leading to formation of debris in regions near the implant may arise, causing inflammation of the tissue. Due to this, this paper seeks to improve surface properties by the deposition of Ti, Zr and Ta thin films on the surface of UHMWPE by magnetron sputtering. It was possible to define which of the deposited films presented better results. Metallic coatings with thicknesses ranging from 288 to 440 nm showed a significant improvement in wettability, hardness, toughness and roughness. In addition, they showed excellent adhesion strength front to pull-off and nanoscratch tests, and no contaminants in the compositional analyzes performed by Rutherford backscatter spectrometry (RBS). From an electrochemical viewpoint, the order of choice for metal coating over UHMWPE would be Ta, Ti, and Zr, respectively. Overall, these coatings offer an improved surface for biomedical applications, especially when mechanical stresses are required.

Optical Properties of Titanium in the Regime of the Limited Light Penetration

In this study, the titanium layers from 12 to 1470 nm thick were fabricated by using the method involving dynamically changed working gas pressure (gas injection magnetron sputtering). The influence of the deposition time on the optical and electrical properties of Ti films, as well as on their microstructure, are considered. The samples are investigated by means of spectroscopic ellipsometry, atomic force microscopy, X-ray diffraction, and confocal optical microscopy. Additionally, for the Ti layers, the sheet resistance was determined. The produced coatings exhibit privileged direction of growth (002). The obtained results show a gradual increase in the mean relaxation time of free-carriers with the increase in the thickness of titanium film. However, the plasma energy exhibits maximum for the coating with the thickness of 93 nm. For such thickness, the lowest value of optical resistivity (about 200 cm) was observed. It was found that the dc- and optical resistivity exhibit similar values for titanium films with thickness up to 93 nm. For thicker Ti layers, significant differences in resistivities (dc- and optical) were noticed. The behavior of the Drude parameter (the plasma energy), calculated optical resistivity, and discrepancies between values of optical and dc-resistivities for thicker Ti coatings can be explained as a result of the limited light penetration.

The self-repairing of ion irradiation damaged Mo–S–Ti (MoST) lubricant films by thermal annealing

Mo–S–Ti composite films deposited by magnetron sputtering were irradiated by 2 MeV Au2+ with a high fluence of 3.3 × 1015 ion cm−2. Upon intense bombardment by 2 MeV Au2+, the Mo–S–Ti thin film exhibits sensitivity to radiation-induced amorphization at room temperature. Afterwards, thermal annealing experiments on the irradiated thin films were conducted over the temperature range of 200 °C–900 °C. Subsequent annealing experiments found that the effect of heavy ion irradiation on Mo–S–Ti films was a reversible reaction, with the irradiation-damaged MoS2 lattice being completely self-repaired by thermal annealing. In the annealing temperature range of 200 °C–600 °C, no evidence of an amorphous to recrystallized transition was observed. When the temperature was increased to as high as 700 °C, the damaged MoS2 molecules were well recrystallized. HRTEM images of irradiated samples annealed at 700 °C strikingly found that the self-repaired MoS2 crystallites preserving long range ordering were still rearranged in an intrinsic (0 0 2) crystal orientation. MoS2 nanocrystals that survived the ion bombardment step may provide some nucleus for subsequent MoS2 grains growing dominantly in the (0 0 2) direction in thermal annealing. Compared with the difficult recrystallization in thermal annealing, the irradiation-amorphized MoS2 phases were easily self-repaired under friction. The low transition potential barrier from irradiation-induced amorphization to crystallization, achieved by mechanical working, may be an important reason for the quick recrystallization.

Proliferation of Saos-2 and Ca9-22 cells on grooved and pillared titanium surfaces.

Surface nanostructures in titanium (Ti) oral implants are critical for rapid osseointegration. The purpose of this study was to evaluate the growth of osteoblast-like (Saos-2) and epithelial-like (Ca9-22) cells on nanopatterned Ti films. Ti films with 500nm grooves and pillars were fabricated by nanoimprinting, and seeded with Saos-2 and Ca9-22 cells. Cell viability and morphology were assessed by cell proliferation assay and scanning electron microscopy, respectively. As assessed after 1 hour, proliferation of Saos-2 cells was most robust on grooved films than on pillared and smooth films, in this order. These cells approximately doubled on grooved and pillared substrates in 24 hours and after 5 days, but not on smooth surfaces. In contrast, Ca9-22 cells favored smooth surfaces, followed by grooved and pillared films. Indeed, cells sparsely adhered to pillared films over 5 days of incubation (p <0.05). The data show that Saos-2 and Ca9-22 cells respond differently to different nanostructures, and highlight the potential use of nanopatterns to promote bone regeneration or to prevent epithelial downgrowth at the implant-bone interface.

Methylbenzene sensors using Ti-doped NiO multiroom spheres: Versatile tunability on selectivity, response, sensitivity, and detection limit

Pure and Ti-doped NiO multiroom spheres were prepared via ultrasonic spray pyrolysis, and their gas sensing characteristics were investigated. The sensor using 10 at% Ti-doped NiO multiroom spheres exhibited an unprecedented high response (resistance ratio = 337.8) to 1 ppm p-xylene at 350 ℃, whereas the sensor using pure NiO multiroom spheres exhibited a negligibly low response (1.3). Moreover, the control of the Ti doping and film thickness provided intriguing strategies for tuning the xylene and methylbenzene sensing characteristics, such as the selectivity, response, sensitivity (slope between response and gas concentration), and detection limit. The versatile tunability on gas sensing characteristics was explained by the Ti-doping-induced variation of the oxygen adsorption, mesoporosity, specific surface area, and charge-carrier concentration, as well as the control over the reforming and oxidation of the analyte gases using the multiroom-structured micro-reactors with high catalytic activity.

Structures and adhesion of hcp thin film coating interfaces on a single-crystal bcc substrate by PVD: Ti/Mo and Zr/Mo

Polycrystalline hcp Ti and Zr thin films were developed on single-crystal bcc-Mo (110) substrate using PVD method. XRD analysis suggests the preferred facet relation of (0001)hcp//(110)bcc. Sandwich supercell models were then constructed to evaluate the interface energy, adhesion strength and bonding nature from the first principles. The Burgers and Pitsch-Schrader orientation relation (OR) were predicted as the most energy-favored for the PVD Ti and Zr thin film interfaces on the Mo (110), respectively. Interface adhesion was predicted to be fairly strong for both interfaces. The d-d orbital interaction between Ti/Zr and Mo is found closely associated with the spatial redistribution of Bader valence charges. The resulting new bonds across the interfaces are rather delocalized, showing a mixed covalent and weak ionic bond character. These results strongly suggest that single-crystal Mo (110) is a promising substrate for developing high quality hcp Ti or Zr thin films through PVD.

Improving the Mechanical Properties of SiC-ceramics by means of Vacuum Electron-ion-plasma Alloying with Titanium

The investigation results of elemental and phase composition, state of defective substructure and microhardness of the surface layer of «film (Ti)/substrate (SiC-ceramics)» system (Ti film 0.5 μm thick was deposited on the surface of SiC-ceramics) subjected to treatment with an intense pulsed low-energy electron beam (15 J/cm2, 200 μs, 0.3 s−1, 20 pulses) are presented. It is shown that irradiation of the «film (Ti)/substrate (SiC-ceramics)» system with an electron beam is accompanied by the formation of multielement multiphase (SiC; TiC; Ti5Si3) surface layer having submicro- and nanocrystalline structure. Microhardness of the irradiated surface layer reaches a value of 74 GPa, that is twice the value of microhardness of SiC-ceramics (36 GPa).

Влияние перколяционного перехода на электропроводящие и оптические свойства сверхтонких металлических пленок

In paper the investigation results of features of electrophysical, optical and plasmonic properties changes in ultrathin metallic films during percolation transition from island structure to continuous are representative. It was shown that during Ti and Pt thin films condensation a change of their electrical conductivity above the percolation threshold is well described in the framework of the classical percolation theory. The resonance behavior of localized plasmons and surface (propagating) plasmon-polaritons in Au metal films during a percolation transition was studied. It was shown that when the film becomes to a granular state a decrease in the Q-factor of surface plasmon-polariton resonance is observed in the vicinity of the percolation transition, which is associated with excitation of localized plasmons in metallic nanoparticles. For all studied coatings the percolation threshold was determined.

Synthesis of TiN, Ti, and TiSi2 Thin Films for the Contact System of Solar Cells

The influence of deposition parameters, such as: the magnetron power in the range 690–1400 W, the silicon substrate temperature 23–170°C, the N2 gas flow rate 0.9–3.6 L/h, the Ar gas flow rate 0.06‒3.6 L/h, the ratio of N2/Ar gas flows 1–60 on the thickness, the density, and the composition of the deposited films is analyzed. The maximum density 5.247 g/cm3 corresponding to the TiN0.786 = Ti56N44 composition has been achieved at the following deposition parameters: 1200 W, N/Ar = 1.8/0.06 L/h = 30, 0.8 Pa, 320 s, and 100°C. At temperatures 700–800°C, the mutual diffusion of titanium and silicon atoms through the interface leads to the active nucleation, the formation of nanocrystals and low-resistance metallization layers. X-ray diffraction shows that, during annealing at 700°C (30 min, Ar), the formation of phase TiSi2 due to the diffusion of Ti atoms into silicon is twice more intense than the formation of Ti5Si3 due to the diffusion of silicon atoms into titanium as a result of high hardness of titanium. The average sizes of TiSi2 decreases from 7.1 to 5.6 nm at 750°C due to the crystallization of the nuclei and increase to 9.2 nm at 800°C.

Inflow process of Fe, Ni, and Cr impurities in Ti sponge during kroll process

To produce Ti sponge for aerospace applications, the inflow process of Fe, Ni, and Cr impurities has been investigated by obtaining the distribution of the concentrations of these impurities, analyzing the microstructure and elemental composition of specimens, and calculating the formation enthalpies of the Mg–Ti–Fe, Mg–Ti–Ni and Mg–Ti–Cr ternary systems via the Miedema and Troop models. Fe, Ni, and Cr impurities are heterogeneous enriched, and the sides of the sponge mass have relatively higher impurity contents. This is caused by contamination from the stainless-steel reaction retort. The inflow process of impurities consists of two steps: the dissolution of impurities in liquid Mg and the formation of alloys with the Ti sponge. The retort material, the temperature of the reaction zone, and the uniformity and thickness of the Ti film are the key factors that directly influence the impurity contents.

Direct growth of NbSe2 and TiSe2 thin flakes via deposited film selenization

We report the direct growth of thin flakes of NbSe2 and TiSe2 on c-plane sapphire substrate via the selenization of deposited Nb and Ti films, respectively. The effect of the cooling rate on the shapes of the NbSe2 thin flakes, for example, hexagons and triangles, was studied. In particular, rapid cooling after selenization of the deposited Nb film was found to be effective for growing triangular NbSe2 flakes. Raman spectroscopy of one sample prepared by rapid cooling revealed an unidentified vibration peak in addition to the prominent characteristic peaks of 2H-NbSe2. The Ti film could only be selenized by using sodium chloride as a transport agent, which resulted in the growth of TiSe2 thin flakes having a half-hexagonal shape without the incorporation of residual materials. Temperature-dependent resistances measurement, including the measurements of the temperature of maximum resistance and Rmax/R293K ratio, indicated a conventional charge-density wave transition in the TiSe2 thin flakes.

Electrochemical Polishing of Additively Manufactured Ti–6Al–4V Alloy

In this present paper, the electropolishing behavior of Ti–6Al–4V alloy fabricated by additive manufacturing in chloride-containing ethylene glycol electrolyte was surveyed. The impacts of chloride ion on surface quality and oxide film of Ti–6Al–4V were analyzed in dependence on the surface topography, roughness, weight loss ratio and compositions. The visual and microscopic results revealed that the optimally electropolished surface was attained in a 0.4 mol L−1 chloride electrolyte with a decreased surface roughness of 75.04% and a weight loss rate of 4.93%. For lower (CCl−1 ≤ 0.3 mol L−1) or higher concentrations (CCl−1 ≥ 0.5 mol L−1), a smooth and flat surface was not observed due to insufficient reactions or excessive anodic dissolution. During the electropolishing, the titanium oxides nucleated and corresponding surface tension increased, resulting in the formation of a stable TiO2 film on the surface of the Ti–6Al–4V alloy, increasing the corrosion resistance of the specimen.

Atomic diffusion bonding using oxide underlayers for optical applications

Atomic diffusion bonding of quartz glass wafers using thin Ti films, with SiO2 underlayers on wafer surfaces, provides 100% light transmittance at the bonded interface along with strong bonding energy, after post-bonded low-temperature annealing. Cross-section images obtained using transmission electron microscopy show that the bonded interface after annealing at 350 °C consists of amorphous structure including nanocrystalline grains. Structural analysis using electron energy loss spectroscopy shows that post-bonded annealing enhances oxidation of Ti with oxygen dissociated from SiO2 underlayers, and that Ti oxides form close to TiO2 or Ti4O7. This oxidation provides 100% light transmittance with high bonding strength attributable to the annealing. Moreover, we applied this technique for bonding glass and sapphire wafers using SiO2–Nb2O5 underlayers, demonstrating that 100% light transmittance and control of refractive index matching are achieved simultaneously at the bonded interface.