Titania Films Research Articles

Functional modification of TC4 by Cu-containing titanium dioxide films

To improve the biological fouling and corrosion resistance of Ti6Al4V (TC4) in marine environments, copper-containing titanium dioxide (TiO2(Cu)) films were prepared by magnetron sputtering TiO2(Cu) powder targets. The morphologies of the films showed that they became rough and coarse from 1.6 nm of the TiO2 film to approximately 9 nm of the TiO2(Cu) films, which might be owing to the increase in the deposition rates from 1.33 to 2.08 nm/min. No diffraction orientations of the TiO2 and Cu phases were found compared to those of the TiO2(Cu) powder. Ti, O, and Cu were detected using X-ray photoelectron spectroscopy to confirm the composition of the films. The ratio of Cu2+ increased as the Cu content of the films increased, whereas that of Cu/Cu + scarcely changed. The TiO2 and TiO2(Cu) films exhibited photocatalytic effects and their photocatalytic intensities decreased as the Cu content increased. Hydrophobicity was enhanced by the addition of Cu to the film. The antibiological fouling effect of the TiO2(Cu) films remained unchanged as the Cu/Ti ratio varied. Compared with those of TC4, the corrosion current densities of the TiO2(Cu) films decreased by one order of magnitude and the corrosion potentials increased by 350 mV in artificial seawater, indicating that the corrosion resistance of TiO2(Cu)/TC4 was improved. Importantly, Cu was in abundance in the films for both antibiological and corrosion resistance functions owing to the saturated ratio of Cu/Cu+ irrespective of the Cu/Ti ratio in the films.

Tailoring bisphosphonate-doped titanium films to optimally couple cellular responses and antibacterial activity for biomedical applications.

Titanium (Ti) is widely utilized as an implant material; nonetheless, its integration with bone tissue faces limitations due to a patient's comorbidities. To address this challenge, we employed a strategic approach involving the growth of thin films by spin-coating and surface functionalization with etidronate (ETI), alendronate (ALE), and risedronate (RIS). Our methodology involved coating of Ti cp IV disks with thin films of TiO2, hydroxyapatite (HA), and their combinations (1:1 and 1:2 v/v), followed by surface functionalization with ETI, ALE, and RIS. Bisphosphonate-doped films were evaluated in terms of surface morphology and physical-chemical properties by techniques such as electron microscopy, confocal microscopy, and x-ray photoelectron spectroscopy. The antibacterial potential of bisphosphonates alone or functionalized onto the Ti surface was tested against Staphylococcus aureus biofilms. Primary human bone mesenchymal stem cells were used to determine in vitro cell metabolism and mineralization. Although RIS alone did not demonstrate any antibacterial effect as verified by minimum inhibitory concentration assay, when Ti surfaces were functionalized with RIS, partial inhibition of Staphylococcus aureus growth was noted, probably because of the physical-chemical surface properties. Furthermore, samples comprising TiO2/HA (1:1 and 1:2 v/v) showcased an enhancement in the metabolism of nondifferentiated cells and can potentially enhance the differentiation of osteoblastic precursors. All samples demonstrated cell viability higher than 80%. Addition of hydroxyapatite and presence of bisphosphonates increase the metabolic activity and the mineralization of human bone mesenchymal cells. While these findings hold promise, it is necessary to conduct further studies to evaluate the system's performance in vivo and ensure its long-term safety. This research marks a significant stride toward optimizing the efficacy of titanium implants through tailored surface modifications.

Production of Titanium Films via Segregation of Ce-Ti Alloy Coexisting with LiF-based Molten Salts

Production of Titanium Films via Segregation of Ce-Ti Alloy Coexisting with LiF-based Molten Salts

Dopamine Sulfonate Ligand-Assisted TiO2 Deposition Enabling Highly Efficient and Stable Perovskite Solar Cells.

The metal oxide electron transport layers (ETLs) with flat morphology and high electrical quality are essential to manufacture highly efficient perovskite solar cells (PSCs), in which the regulation of the metal oxide deposition process plays a crucial role. Herein, a judiciously designed dopamine sulfonate (DS) ligand-assisted deposition of titanium dioxide (TiO2) films approach is implemented based on electrostatic repulsion and steric hindrance of assembled ligands to improve colloidal nanoparticles dispersity in precursor and effectively inhibit their aggregation, which could enable obtaining smooth topography of TiO2 films and initiating growth of top high-quality perovskite films. Furthermore, sulfonate bridges bonded on the perovskite buried layer that is beneficial to form better buried interface contact and accelerate electron extraction. As a result, the PSCs employing DS/TiO2 ETLs exhibit the best power conversion efficiency of 24.53% with impressive storage stability and operation stability, i.e., remaining more than 88% of their initial efficiency upon storage N2 glovebox without encapsulation over 4000 h, and the efficiency does not attenuate significantly under maximum power point for 60 h.

Electrochemical Studies of The Corrosion Resistance of Bismuth Titanate Thin Films Deposited by RF Sputtering

Thin films of bismuth titanate were grown on stainless steel (316L) and titanium alloy (Ti6Al4V) substrates using the magnetron sputtering technique. The surface morphology of these films was observed with a scanning electron micrograph (SEM). The electrochemical studies used to evaluate the corrosion resistance of the substrate-coating set were the potentiodynamic polarization (Tafel) tests and electrochemical impedance spectroscopy (EIS), both done in a solution of NaCl (3%) as an electrolyte. The SEM showed that the morphology of the coatings grown on a titanium alloy Ti6Al4V substrate was generally homogeneous with a smooth surface but with unmelted material in some regions, while the morphology of the thin films grown on stainless steel 316L was mainly granular, with the presence of a few holes or craters. The potentiodynamic polarization curves showed that the corrosion resistance of the coated samples was better than that of the bare substrate because the corrosion current obtained from the coated samples was lower by two orders of magnitude than that exhibited by the uncoated substrates, and in addition, the corrosion potential of the coated samples was greater than that of the bare substrate. The EIS test showed the presence of a passive thin film of titanium oxide on the titanium alloy substrate.

A study on the fabrication procedure for a high-D/Ti-ratio-deuterated-titanium film on the disk-type neutron generator target

This study aims to present thin film deposition and deuterium adsorption procedure to fabricate disk-type targets with high D/Ti values for a neutron generator and increase their lifespan. The neutron target consists of a titanium thin film with hydrogen loading, and a copper substrate for heat removal. We optimized the incident deuterium ion beam energy and thin film thickness using Geant4 simulations. Additionally, we calculated the expected neutron yield under the optimized conditions. The hydrogen adsorption conditions were optimized by comparing the H/Ti results as per hydrogen adsorption temperature and loading time using titanium foils of different thickness values. Hydrogen (or deuterium) adsorption ratio is strongly influenced by the surface condition and the deposition conditions of the thin film. A titanium film was deposited in various conditions of plasma DC power and substrate temperature. The quality of the thin film was evaluated through surface roughness evaluation and thin film sheet resistance for each deposition conditions. Subsequently, the hydrogen adsorption results were compared according to the quality of the thin titanium films, and the thin titanium film deposition conditions with the highest hydrogen adsorption ratio were confirmed. The selected conditions were applied to conduct deuterium adsorption. In conclusion, this study underscores the critical relationship between thin film quality and hydrogen (or deuterium) adsorption ratio, reinforcing the importance of optimizing thin film deposition parameters for the design of neutron generator disk-type targets with high quality of film and extended lifespan.

Fano resonance and enhanced sensing in the excitation of the surface phonon polariton

The surface phonon polariton is a collective oscillation mode of phonons and incident electromagnetic waves in polar dielectric materials. Compared with the surface plasmon polariton, it has low loss and can be applied to the mid-infrared band. A surface phonon resonance sensor based on waveguide-coupling is proposed. The sensor structure is a typical Kretschmann configuration consisting of a germanium (Ge) prism, a silicon carbide (SiC) layer, an indium selenide (In2Se3) film, a titanium dioxide (TiO2) film, and the surrounding dielectric. The reflectivity possesses significant asymmetric Fano resonance dips. In sensing applications, the waveguide-coupling structure yields a sensitivity by intensity of 11278RIU−1 and a figure of merit of 10344RIU−1. Our investigation provides an alternative method for refractive index sensing, thus opening up opportunities for the design of various phonon devices based on Fano resonance.

Effect of porosity on deuterium retention in titanium thin film

Abstract The absorption process of deuterium in titanium was studied in titanium film produced in two different types of copper substrate, one was a polished copper substrate and the other one was chemically etched copper substrate. Titanium film was produced by thermal evaporation method. It was activated at a temperature of 500 0C followed by deuteration at room temperature. Titanium film was characterized by XRD for crystallographic information, SEM for surface morphology, RGA for deuterium desorption studies and weight measurement for D/Ti ratio. The difference in porosity of both the samples is confirmed from XRD analysis and SEM images. Different diffusion process is observed in two different substrates from the RGA spectra. Presence of multiple trap sites in the thin film of both the substrates is observed from the RGA spectra. From the weight measurement, D/Ti ratio in polished substrate is found to be 1.03 whereas in case of chemically etched substrate it is 1.54.

Growth of MAPbI3 perovskite films on MWCNT-modified TiO2 thin films for solar cell applications

In this work, we have modified titanium dioxide (TiO2) films by incorporating multi-walled carbon nanotubes (MWCNTs) in TiO2-sol. TiO2 and MWCNT-modified TiO2 thin films have been prepared via solution processing spin coating route. Further, the structural, optical, and surface morphology of methyl ammonium lead iodide (MAPbI3) films have been studied onto pristine TiO2 and MWCNT-modified TiO2 films. We extensively analyze how different MWCNT concentrations impact the TiO2 and perovskite film structure, optoelectronic properties, and surface characteristics. The findings highlight that the MAPbI3 films maintain a tetragonal structure with enhanced crystallinity compact and smooth surface morphology in MWCNT-modified TiO2/MAPbI3 films. Besides this, enhanced optical absorbance in MAPbI3 films have also been observed on perovskite films fabricated onto MWCNT-modified TiO2 films with enlarged grains and a red shift in optical band gap has been observed for MWCNT-modified TiO2 films and MWCNT-modified TiO2/ MAPbI3 films. Further, various critical electrical parameters such as charge carrier concentration, Hall mobility, sheet resistance, and resistivity have been investigated to understand the effects of the incorporation of MWCNT on TiO2 films. The value of carrier concentration enhances from 3.76 × 1024 cm−3 to 6.39 × 1024 cm−3 on incorporation of MWCNT in TiO2 films. Furthermore, an enhancement in crystallinity, optical absorbance, and grain size has been observed in perovskite films fabricated onto TiO2/MWCNT films. Thus, TiO2 modification with MWCNT can tune the optical and charge transport properties of charge-transporting layer TiO2 films for perovskite photovoltaics and other optoelectronic devices.

Electrochemical behaviour of sputter-coated titanium films on AZ31 magnesium alloy

Lightweight magnesium-based structural alloy AZ31 is normally prone to high corrosion in an aqueous environment. A detailed study is reported in this work on AZ31 Mg alloy coated with Ti thin films of different thicknesses by DC sputtering to investigate the capability of Ti coating to prevent corrosion of AZ31 under an aqueous environment similar to seawater. Ti films have been fabricated to 50, 100 and 150 nm thicknesses. Utilising grazing incidence-XRD and SEM, the films’ structure and microstructure were studied. The films were amorphous. Due to corrosion, interesting micro-structures evolved. Corrosion inhibition characteristics of the Ti films were characterised by electrochemical techniques such as potentiodynamic polarisation and impedance spectroscopy. Ti films with 100 nm and 150 nm thickness show a good inhibition capability. The corrosion mechanism was investigated using XPS and X-ray energy dispersive spectra.

Study on Process Parameters of Magnetron Sputtering Titanium Coating in Deep Porous Structures.

In order to improve the energy conversion efficiency and power density of the tritium-powered betavoltaic battery, titanium was deposited on the inner surface of the deep porous three-dimensional structure semiconductor as a tritium absorption material. Therefore, magnetron sputtering technology was used to explore the parameters of titanium coating on the inner surface of a deep porous semiconductor. First, the effects of argon pressure and sputtering power on the properties of titanium films were studied. The properties of the titanium films were characterized by a scanning electron microscope and an atomic force microscope. The optimized sputtering parameters were obtained as follows: argon pressure of 0.5 Pa and sputtering power of 80 W. Based on this parameter, the background vacuum and coating angle were changed, and the titanium film was coated in the deep porous structure. Energy dispersive spectrometry line scan and surface scan were used to analyze the coating results, which showed that these two parameters directly affected the content of titanium in the channel, and the area of titanium in the channel structure accounted for more than 50% under each test condition.

Role of Surface Chemistry in Pyrrole Autoxidation.

Chemical compounds in liquid hydrocarbon fuels that contain five-membered pyrrole (Py) rings readily react with oxygen from air and polymerize through a process known as autoxidation. Autoxidation degrades the quality of fuel and leads to the formation of unwanted gum deposits in fuel storage vessels and engine components. Recent work has found that the rate of formation of these gum deposits is affected by material surfaces exposed to the fuel, but the origins of these effects are not yet understood. In this work, atomic layer deposition (ALD) is employed to grow aluminum oxide, zinc oxide, titanium dioxide, and manganese oxide films on silicon substrates to control material surface chemistry and study Py adsorption and gum nucleation on these surfaces. Quartz crystal microbalance (QCM) studies of gas-phase Py adsorption indicate 1.5-2.8 kcal/mol exergonic adsorption of Lewis basic Py onto Lewis acidic surface sites. More favorable Py adsorption onto Lewis acidic surfaces correlates with faster polypyrrole (PPy) film nucleation in vapor phase oxidative molecular deposition (oMLD) polymerization studies. Liquid-phase studies of Py autoxidation reveal primarily particulate formation, indicating a homogeneous PPy propagation step rather than a completely surface-based polymerization mechanism. The amount of PPy particulate formation is positively correlated with more acidic surfaces (lower pH-PZC values), indicating that the rate-limiting step for Py autoxidation involves Lewis acidic surface sites. These studies help to establish new mechanistic insights into the role of surface chemistry in the autoxidation of pyrrolic species. We apply this knowledge to demonstrate a polymer coating formed by vapor phase polymer deposition that slows autoxidation by 2 orders of magnitude.

Microstructural, optical, and photocatalytic properties of TiO2–Bi2O3–GO thin films obtained by sol-gel for applications with sunlight

The following study presents the structural, optical, and photocatalytic properties of thin films of titanium dioxide (TiO2) and bismuth trioxide (Bi2O3) in their pure state, as well as mixtures of both oxides in different atomic proportions (with respect to Ti and Bi) and as films modified with a dispersed phase of graphene oxide (GO). The films were sintered at 400 °C, 450 °C, 500 °C and 550 °C. The synthesis of the oxides was carried out by the sol-gel method and the material deposits were synthesized by the dip-coating technique. For mixtures with atomic proportions of 50% and 70% Bi2O3, bismuth titanates were obtained with Bi2(Ti2O7) (cubic) stoichiometry at 550 °C and Bi4Ti3O7 (orthorhombic) stoichiometry at 500 °C, respectively. It was determined that the Bi2(Ti2O7) compound presents the best photocatalytic properties in the degradation of tartrazine in aqueous solution using solar radiation, achieving up to 30% in the photodegradation of the dye. The GO was incorporated in 2% p/p to the precursor solutions of TiO2 and Bi2O3; the resulting materials presented a better photocatalytic activity.

Insulator Metal Transition-Based Selector in Crossbar Memory Arrays

This article investigates resistive random access memory (ReRAM) crossbar memory arrays, which is a notable development in non-volatile memory technology. We highlight ReRAM’s competitive edge over NAND, NOR Flash, and phase-change memory (PCM), particularly in terms of endurance, speed, and energy efficiency. This paper focuses on the architecture of crossbar arrays, where memristive devices are positioned at intersecting metal wires. We emphasize the unique resistive switching mechanisms of memristors and the challenges of sneak path currents and delve into the roles and configurations of selectors, particularly focusing on the one-selector one-resistor (1S1R) architecture with an insulator–metal transition (IMT) based selector. We use SPICE simulations based on defined models to examine a 3 × 3 1S1R ReRAM array with vanadium dioxide selectors and titanium dioxide film memristors, assessing the impact of ambient temperature and critical IMT temperatures on array performance. We highlight the operational regions of low resistive state (LRS) and high resistive state (HRS), providing insights into the electrical behavior of these components under various conditions. Lastly, we demonstrate the impact of selector presence on sneak path currents. This research contributes to the overall understanding of ReRAM crossbar arrays integrated with IMT material-based selectors.

Flexible Antibacterial Respiratory Monitoring Sensor Based on Controllable Au-Modified Surface of Highly {001} Preferred Anatase Titanium Dioxide Thin Film.

Respiratory signals are critical clinical diagnostic criteria for respiratory diseases and health conditions, and respiratory sensors play a crucial role in achieving the desired respiratory monitoring effect. High sensitivity to a single factor can improve the reliability of respiratory monitoring, and maintaining the hygiene of the sensors is also important for daily health monitoring. Herein, we propose a flexible Au-modified anatase titanium dioxide resistive respiratory sensor, which can be mechanically compliantly attached to curved surfaces for respiratory monitoring in different modalities (i.e., respiratory intensity, frequency, and rate). The uniform and preferentially oriented anatase titanium dioxide films gained by the polymer-assisted deposition technique can be fabricated on flexible substrates through a liquid-assisted transferring process. The Au modification can enhance surface plasmon resonance to facilitate the photocatalytic activity of titanium dioxide, and the optimized distribution of Au on the surface of titanium dioxide film made the sensor have an excellent antibacterial effect. The uniquely designed encapsulation can effectively control the contact between the surface of titanium dioxide films and electrodes, allowing the flexible sensor to exhibit fast response time (0.71 s) and recovery time (1.06 s) to respiratory as well as insensitivity or low sensitivity to other factors (i.e., gas composition, humidity, temperature, stress, and strain). This work provided an effective strategy for flexible wearable respiratory sensors and has great potential in daily respiratory monitoring for health management and pandemic control.

TiO2/PDA Multilayer Nanocomposites with Exceptionally Sharp Large-Scale Interfaces and Nitrogen Doping Gradient.

The evolving field of photocatalysis requires the development of new functional materials, particularly those suitable for large-scale commercial systems. One particularly promising approach is the creation of hybrid organic/inorganic materials. Despite being extensively studied, materials such as polydopamine (PDA) and titanium oxide continue to show significant promise for use in such applications. Nitrogen-doped titanium oxide and free-standing PDA films obtained at the air/water interface are particularly interesting. This study introduces a straightforward and reproducible approach for synthesizing a novel class of large-scale multilayer nanocomposites. The method involves the alternate layering of high-quality materials at the air/water interface combined with precise atomic layer deposition techniques, resulting in a gradient nitrogen doping of titanium oxide layers with exceptionally sharp oxide/polymer interfaces. The analysis confirmed the presence of nitrogen in the interstitial and substitutional sites of the TiO2 lattice while maintaining the 2D-like structure of the PDA films. These chemical and structural characteristics translate into a reduction of the band gap by over 0.63 eV and an increase in the photogenerated current by over 60% compared with pure amorphous TiO2. Furthermore, the nanocomposites demonstrate excellent stability during the 1 h continuous photocurrent generation test.

Controlled adsorption of gas molecules by tuning porosity of titanium film

Within microelectromechanical system sensors, the establishment of a vacuum environment is a prerequisite for the control of specific residual gas molecules. At the wafer-level package stage, the interior of the sensor can be easily converted into a vacuum environment. However, after packaging, degassing occurs due to the accumulation of fumes with additional processing, resulting in a significant reduction in sensor reliability. To counteract this, non-evaporable getter (NEG) film is commonly packaged together with the sensor to absorb the outgassing gas molecules and maintain a vacuum environment within the sensor. Most NEG films require an activation process to migrate the adsorbed gas molecules from the surface to the bulk by thermal annealing. Recently, NEG films have been considered to reduce the activation temperature and time to avoid heat damage. Depositing an anti-oxidant layer on NEG film or alloying the NEG film with metallic materials through co-sputtering to create a distinct valence state during activation was found to prevent further oxidation of NEG film. However, these methods require expensive materials and fabrication equipment. In this study, we demonstrate that a much lower activation temperature (T = 350 °C) and time (t = 10 min) for Ti NEG film can be achieved by controlling the surface morphology depending on the deposition method and condition, without requiring further treatment such as the deposition of a capping layer or co-sputtering. Increasing the grain size of the Ti NEG film results in a larger surface area, which enables more efficient adsorption of gas molecules. Additionally, higher porosity in the film increases the diffusion of gas molecules, thus enhancing the overall gas adsorption capacity. Our experiments show that the Ti NEG film, which was deposited at 7.8 Å s−1 using a sputtering method, exhibited a grain size of 411 nm and a surface roughness of 59.185 nm. Furthermore, after an activation process at 350 °C for 10 min, the atomic ratio of the adsorbed gas molecules was 23.14%.

Microstructure and Mechanical Properties of Ti6Al4V to Al2O3 Brazed Joints Using Ti-Ag/Cu-Ti Thin Films

The processing and characterizing of bonding Ti6Al4V to Al2O3 brazed joints using interlayer thin films was investigated. The brazing was conducted in a tubular furnace with an argon flux at 980 °C for 30 min. The brazing fillers consisted of different combinations of thin Ag/Cu and Ti films with variable thicknesses. The joint interface analysis involved using digital microscopy (DM) and optical microscopy (OM). Microstructural characterization and chemical composition were performed via scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Mechanical properties were assessed through microhardness and shear strength tests. Brazing successfully produced interfaces with a combination of titanium films and Ag/Cu as brazing filler. The results revealed that the interface mainly comprises Ti2Cu, TiCu2Al, α-Ti, and Ti2(Cu,Ag). Some segregation of (Ag) was observed at the interfaces, but a decrease in its amount was observed when compared to joints produced using Ag/Cu fillers. The thickness of the titanium film in the brazing filler strongly influenced the integrity of the joints. The amount of (Ag) at the interface diminished as the Ti film’s thickness decreased, leading to an improvement in the mechanical properties of the joints. Using a combination of Ag/Cu and Ti thin films revealed a potential approach to reduce the segregation of soft phases at interfaces, promoting a significant improvement in joining metal to ceramic materials.

Investigations of TiC and SiC films synthesized by DC magnetron sputtering and thermal annealing

In this research article, two-dimensional thin films of titanium, hierarchical titanium-carbon, titanium carbide, hierarchical silicon-carbon, and silicon carbide films were synthesized on the plates of AISI 304 stainless steel and glass slides, individually, using DC magnetron sputtering techniques. During the sputtering process, the creation of stable plasma was affected by the vacuum level, DC potential, plasma current, and Argon gas. The results showed that the coatings of titanium, titanium-carbon, and titanium carbide modified the optical properties of stainless steel. Additionally, titanium carbide coatings displayed a shiny gold appearance with a hardness of 1500 HV. Besides this, X-ray diffraction studies revealed a hexagonal Ti in the metallic films and C60, and diamond-like structures dispersed on its surface after the carbon coating. The spherical particulates of Ti and C60/diamond-like carbon particulates anchored on its surface were observed using scanning electron microscope analysis. The structural analysis indicated C vacant sites, which are available for ionic/electronic charge diffusion, thereby rendering these structures suitable for making Li storage batteries as electrode material.

Facile Synthesis and Characterization of TiO2/SnS Nanocomposites by Eco-Friendly Methods

The acid etching mechanism of FTO film using zinc powders has been explored, and sulfuric and hydrochloric acid solutions of different concentrations were tested as etching agents. Compact and mesoporous films of titanium dioxide were prepared by spin-coating and doctor blade techniques on FTO glass. Tin sulfide films were formed through a successive ionic layer adsorption and reaction (SILAR) process using different numbers of deposition cycles, and TiO2/SnS nanocomposites were synthesized. The thin films and the prepared composites were characterized using X-ray diffraction, UV-Vis spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses. In this study, the principal characteristics of deposited tin sulfide films on two different types of TiO2 films are shown.