Titania Films Research Articles

Anodization-Processed Colored Radiative Thermoregulatory Film.

Colored radiative thermal management materials (RTMM) not only provide superior thermoregulatory performance but also satisfy aesthetic requirements. However, the complexity of the preparation procedures and constrained color selection have hindered their widespread adoption. Here, we presented a facile one-step anodizing strategy for fabricating colored dual-mode RTMM based on titanium film (Ti) and P(VDF-HFP) with mid-infrared (MIR) emissivities of 0.07 and 0.96, respectively, which allow for on-demand temperature modulation (rise of 28.2 K and drop of 9 K) without energy consumption. Furthermore, demonstrations of a colored radiative warming membrane also validate the effectiveness of anodizing treatment. The colored Ti/nano PE membrane with 10.8 μm thickness enables a temperature rise of 2.3 K on real human skin, which is much higher than that of commercial fabric with 120 μm thickness (0.7 K). This strategy provides insights for the scalable fabrication and application of colored low emissivity materials, contributing to the goal of a sustainable society.

Effects of Scandium doping on the deuterium absorption and desorption behavior of titanium films

Understanding the effects of Scandium (Sc) on the hydrogen absorption and desorption capabilities and the underlying mechanisms within Ti–Sc alloys is crucial for their applications as hydrogen storage materials. In this study, we explore the influence of Sc on deuterium (D) behavior in Titanium (Ti) films through a combination of experimental characterization and theoretical simulations. The Sc-doped Ti films with different Sc ratio were prepared using magnetron sputtering. Our findings indicate that Sc doping raises the D absorption temperature from 350 °C to 500 °C, and the Sc-doped Ti deuteride films exhibit higher apparent activation energies and temperatures for D desorption. Results from both experiments and DFT calculations indicate that these phenomena are attributed to the atomic size effect, in which the larger Sc atoms reduce the Ti–H spacing, thereby strengthening the interaction between the adjacent Ti atoms and H atoms. The enhanced interaction presents a greater challenge for H atom diffusion within α-Ti and complicates the dissociation of TiH2. This study provides a vital theoretical and experimental basis for understanding the effects of Sc doping on the hydrogen absorption and desorption properties in titanium alloys.

Characterization and Performance Analysis of TiO<sub>2</sub> Coated UHMWPE for Biomedical Applications

Ultra-high Molecular Weight Polyethylene (UHMWPE) is a highly versatile polymer known for its exceptional mechanical properties, however, its limited life as an implant material for Total Joint Replacement (TJR) necessitates surface modification to extend its lifespan. This study aims to enhance the surface properties of UHMWPE through application of ceramic coatings. Magnetron sputtering method was used to deposit thin film of white Titania (TiO2) on the material’s surface. To evaluate the surface characteristics, such as surface roughness, uniformity and structure, coated and uncoated samples were analyzed through Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and X-ray Diffraction Analysis (XRD). The material performance in relation to biological context was investigated through Contact Angle measurement. A comparative analysis of coated and uncoated samples was then performed. The coated samples showed better wettability compared to uncoated sample. This fact highlights the hydrophilic nature of film. The results of the coated UHMWPE suggest that this surface modification technique could significantly extend the lifespan of UHMWPE implants in TJR, potentially addressing the current limitations associated with their longevity.

Investigating the influence of RF power on the surface morphological and optical properties of sputtered TiO2 thin films

Thin films of titanium dioxide (TiO2), with thicknesses ranging from 105 to 231 nm, were deposited on glass substrates using radio-frequency (RF) magnetron sputtering in an argon atmosphere at four distinct RF power levels: 40, 70, 100, and 130 W, with the deposition time kept constant. The crystalline structure, surface morphology and optical and semiconductor properties of the obtained films were analyzed using X-ray diffraction (XRD), Atomic Force Microscopy (AFM) and UV–visible transmittance spectroscopy. These analyses revealed that the crystallinity of the films improves with increasing RF power, corresponding to an increase in film thickness. Consequently, the samples transition from poorly crystalline or amorphous structure to a monocrystalline rutile phase with a (110) texture. However, at the highest RF power studied, this texture is partially disrupted by the formation of nanocrystals with different orientations. The surface roughness exhibited multifractal characteristics, with complexity systematically decreasing and surface stiffness reducing as RF power increased. Refractive indices and optical band gap energies were determined using the Swanepoel and Tauc plot methods, respectively. The films exhibited a notable increase in the refractive index and a decrease in the optical band gap, from 3.81 eV to 3.52 eV, as the RF power was increased. This underscores the influence of RF power on the optical and semiconductor properties of TiO2 films.

Low-temperature Deposited Highly Sensitive Integrated All-Solid Electrodes for Electrochemical pH Detection

This article describes the process of fabricating an integrated all-solid electrode (IASE) by integrating thin films of titanium dioxide (TiO<i>2</i>) and silver/silver chloride (Ag/AgCl) onto an indium tin oxide (ITO) substrate. The fabrication of a pH sensing electrode (SE) involved utilizing a spin-coated thin film composed of TiO<i>2</i>. Thermally produced thin films of Ag/AgCl were used to develop solid reference electrodes (RE). The present work examined the impact of the drying process on the pH sensitivity and linearity of the low-temperature deposited IASE. The drying procedure was carried out within a temperature range from room temperature to 100°C. The investigation involved the examination of crystallinity, surface morphology, and thin film composition through the utilization of field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD), and energy-dispersive X-ray (EDX) methods. In addition, a comparison was made between the pH sensing performance of the IASE and a commercially available Ag/AgCl RE. The findings of this research demonstrate that the IASE sample, which underwent a drying process at a temperature of 100°C, exhibited remarkable sensitivity and linearity values of 66.7 mV/pH and 0.9827, separately, when compared to the commercially available RE.

Up-conversion materials for solid-state lighting

AbstractConventional phosphor-converted white LEDs (WLEDs), using (Stokes) down-conversion light emission, suffer from a red deficiency that increases the Color Temperature towards “cool white light” above 5000 K. The present work describes a phosphor-Up-converted WLED approach that wishes to overcome this issue by achieving white light generation (WLG) through Up-conversion photoluminescence (UCPL), without energy losses due to Stokes shift and excited by a 980 nm LED instead of the more expensive blue LEDs. The UC materials include thin films of lanthanide (Ln)-doped aluminosilicate glass multilayers, alternating (Ln)-doped aluminosilicate and titania films in the form of 1-D photonic crystals and Ln ion-implanted materials. Sol-gel (SG) processing has been used as a low-cost high purity processing method to prepare titania, as well as aluminosilicate films containing Er3+, Tm3+ and Yb3+, for WLG and possible application as WLED materials. The total Ln content varied from a high of 22 mol% to as low as 5.8 mol%. The materials prepared have been characterized by UV-Vis-NIR (using a variable angle specular reflection accessory), plus FTIR and UCPL spectroscopies. The UC light emission was analyzed with the help of CIE chromaticity diagrams. Graphical abstract

Tin-doped titanium dioxide film-enhanced electrocatalytic hydrogen evolution

Electrocatalyst water-splitting based on metal oxide nanocomposites has gained considerable interest in hydrogen evolution applications. Here, undoped titanium dioxide and tin-doped titanium dioxide films (TiO2 and Sn/TiO2, respectively) are presented for highly efficient H2 production applications. The crystal structure analysis is performed by analyzing the XRD patterns using the Rietveld refinement method and the Williamson-Hall method. XRF scans are used to confirm the doping mechanism between Sn and TiO2. The bandgap energies of undoped TiO2 and Sn/TiO2 films are 3.33 and 3.15 eV, respectively. On the other hand, the electrical conductivity values of undoped TiO2 and Sn/TiO2 films are 0.10 and 0.25 mS.cm−1, respectively. The electrochemical H2 production performance of undoped TiO2 and Sn/TiO2 films is investigated through two different methods: potentiostat measurements and analytical methods. It can be concluded that the Sn/TiO2 film exhibits higher HER performance and H2 production efficiency than the undoped TiO2 film.

Diode-Type Hydrogen Sensor Employing Pd-coated Pt Electrodes and Anodized Titania under Gaseous Atmosphere and Its Application to Oil-Deterioration Monitoring

The H2-sensing properties of the diode-type sensor using Pd-coated Pt electrodes and an anodized titania film (Pd/Pt/TiO2 sensor) were investigated in air and N2 at 250°C. The current (I)–voltage (V) characteristics of the Pd/Pt/TiO2 sensor were largely dependent on the composition of the gaseous atmospheres, and the sensor showed a large H2 response in wet air, which was comparable to that in wet N2. This indicates that the H2 response are hardly dependent on the oxygen concentration under a wet gaseous atmosphere. In addition, the oil-deterioration monitoring properties of the Pd/Pt/TiO2 sensor were also examined at 30°C. The sensor also exhibited nonlinear I–V characteristics in fresh and deteriorated oils, and the magnitudes of the current and resistance responses were largely dependent on the deterioration of the oils. These results clearly indicate that the Pd/Pt/TiO2 sensor can monitor the deterioration of oils.

Characterization method of conductive film state of micro-cathode arc thrusters

Micro-Cathode Arc Thruster (μCAT) is an advanced electric propulsion system developed in the past decades to meet the maneuvering requirements of space microsatellites. However, the constraint on the its application is the short lifespan of the thruster. This is attributed to the conductive film, a key component of thruster discharge. In this study, we propose a measurement method for μCAT conductive film, and enables the evaluation of the evolution process of film thickness. The method is based on the four-probe resistivity testing theory and size effect fitting model, and establishes a method for characterizing the thickness and resistivity of μCAT conductive films. A comparison was made between the corrected resistivity test results of 1, 2, 5, and 10 μm film and the fitting results of the titanium film, revealing an error ofapproximately 10%. Additionally, a total of 2500 ignition experiments were conducted to verify the film thickness and resistance measurement of this method. This research serves as a valuable basis for the lifetime investigation of μCAT. Consequently, the thickness of the film progressively decreases with each discharge cycle, and the resistivity exhibits a corresponding increase due to the size effect. This method could be used as an effective method for exploring the μCAT lifespan and performance.

Solar driven photocatalytic colored co–TixOyNz amorphous film prepared through air plasma treatment of sputtered titanium film

Colored co–titanium oxides and oxynitride amorphous thin film were fabricated through air plasma treatment of sputtered titanium films. Air plasma treatment led to the removal of the passive film that developed on the titanium film surface, and changes in the structural and optical properties of the films. The amorphous nature, grain size, and thickness of the films remained invariant after the treatment process. The surface roughness of the films increased upon plasma treatment. UV-vis spectroscopy study showed the reduction of the bandgap energy of the films after the air plasma treatment and the maximum reduction was found for the thinner film. The 60min air plasma treatment of the thinner film (AD5: film with 5 min deposition time) leads to the changes in bandgap from 4.11 eV to 3.26 eV, and significant Urbach energy values pointed to the formation of defect states. XPS analysis highlighted that the plasma treatment process led to the formation of titanium oxides (TiO2, Ti2O3) and oxynitrides (TiON), accompanied with Ti2+ defect states in the bandgap. The degradation of methylene blue dye solution with plasma-treated film (PT5) as the photocatalyst resulted in 88% degradation efficiency under 240min irradiation of solar simulator. The degradation has also been checked with natural solar illumination and is found to have a 90% degradation efficiency in 480min.

Improvement of titanium film uniformity by magnetron sputtering with electromagnetic coil design

A novel magnetron assembly based on a combination of permanent magnet and adjustable electromagnetic coil is proposed for improved uniformity of the magnetron sputtering deposition process. The design of the magnetron sputtering system containing a rotating substrate and an off-axis arranged magnetron. A numerical framework has been developed to describe the evolution of the plasma density and distribution of sputtered particles. Specifically, the finite element method (FEM) was used to calculate the magnetic field and to model the magnetron sputtering discharge, and binary-collision Monte Carlo method was used to determine the transport of sputtered atoms to the substrate. Through parametric analyses, it was found that increasing the substrate-to-target distance, gas pressure, and coil current intensity benefits the uniform distribution of particles. The condition where the off-axis displacement of the magnetron effectively enhances uniformity. A strategy for optimizing deposition uniformity by combining adjustable current with an off-axis magnetron arrangement was proposed, which reduce the non-uniformity of film thickness by 77.6 % compared to the traditional fixed magnetic field model.

Features of the structure and resistive switching of titanium oxide films on Y-cut piezoelectric substrate of a LiNbO3 crystal

The difference in the structure of titanium oxide thin films deposited on fused silica substrates and the Y-cut of a lithium niobate crystal is demonstrated. In both cases, the film is amorphous; however, an insignificant amount of rutile crystallites is observed in the film formed on the Y-cut of the lithium niobate crystal. It is shown that the electrical characteristics of the films depend not only on the material of the substrate, but, in the case of the lithium niobate substrate, also on the direction of an electric field. This is caused by the deformation of the substrate due to the inverse piezoelectric effect.

Analog and digital resistive switching in W/TiO2/ITO devices: the impact of crystallinity and Indium diffusion

The resistance-switching memristor with capabilities of information storage and brain-inspired computing has prime importance in recent research. In this study, the impact of crystallinity and Indium diffusion on the existence of analog and digital resistive switching in a W/TiO2/ITO device has been reported. The memristor devices are fabricated by depositing titania films by sol–gel and spin-coating techniques. The films annealed at 250 °C and 400 °C were characterized using x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy (XPS). The characteristic anatase phase started appearing after annealing at 400 °C, whereas the 250 °C annealed sample was in the amorphous state. The electrical characterization revealed significant differences in the switching characteristics of amorphous and crystalline samples, especially in the switching interface, compliance properties, and current conduction mechanism. The grain boundary assisted oxygen vacancy migration, and the diffusion of indium ions from the ITO bottom electrode helped the crystalline sample to show highly stable and reproducible resistive switching compared to amorphous film. The XPS studies confirmed the indium ion diffusion in the crystalline sample. The oxygen vacancy-induced barrier modulation and conductive filament formation caused characteristic switching in amorphous and crystalline samples, respectively. Schottky emission in the amorphous film and SCLC mechanism in the crystalline film confirmed the experimental results. This study provides a distinctive viewpoint and an innovative strategy for developing multifunctional resistive switching devices.

Phase selectivity upon flash-lamp annealing of sputter deposited amorphous titanium oxide films

We report the impact of flash-lamp-annealing (FLA) on the structural evolution of amorphous titania (TiO2) films produced by DC reactive magnetron sputtering. TiO2 films were grown at room-temperature at different oxygen partial pressure (PO2) and subsequently annealed as a function of the FLA energy density. X-ray diffraction confirms that FLA induces phase formation from the initial amorphous state with a general transition from anatase to rutile by increasing the FLA energy density (temperature). Interestingly, the transformation onset of anatase to rutile is achieved at lower energy densities for higher PO2. On the contrary, films with a highly resilient anatase phase can be produced at relatively low PO2. A detailed analysis of the pristine amorphous structure carried out by X-ray absorption near-edge structure indicates the role of oxygen sites in the observed phase transformation. In particular, oxygen vacancies seem to stabilize the anatase phase at high temperatures. The results show the relevance of subtle changes in the initial amorphous structure for phase selectivity in TiO2 films upon FLA.

Analysis of micro-hole formation in titanium nanofilms using a low power CW laser

This study investigates the mechanisms and dynamics governing microhole formation in titanium nanofilms under the influence of a continuous-wave low-power laser emitting at 1070 nm. Two distinct configurations were explored: one in which the laser interacted with the titanium film in an air environment (referred to as configuration AM), and the other in which the laser beam passed through glass before reaching the titanium film (referred to as configuration SM). Our experiments demonstrated that microhole formation is possible in both configurations. However, the threshold powers, hole characteristics, and time scales involved differ significantly between AM and SM configurations. Temperature distribution simulations, based on a linear absorption model, revealed notable differences in peak temperatures between these two configurations, primarily attributed to variations in focal spot size and Fresnel losses. These temperature variations resulted in significantly different mechanisms of material removal in both configurations. In the AM configuration, the boiling temperature was not achieved, even at the highest power; however, a melting pool was formed at powers exceeding 50 mW. Thus, the primary driver of microhole formation was the Marangoni effect, which caused molten material to flow tangentially towards the edges of the molten pool. Furthermore, titanium oxidation was identified as a competing process contributing to changes in optical transparency and potentially inhibiting the complete formation of holes. Conversely, within the SM configuration, boiling temperatures are easily achieved, leading to localized boiling and the formation of gas bubbles near the glass–titanium interface. As a result, the rupture of the bubble through the capping molten layer led to a vigorous expulsion of both gas and material, allowing for the creation of microholes even at remarkably low laser power levels (10 mW). Notably, in this configuration, the influence of titanium oxidation is negligible due to the relatively short time scale involved (hundreds of microseconds).

Numerical study of titanium film ablation under different ultrafast laser parameters: a molecular dynamics simulation combined with a two-temperature model

Numerical study of titanium film ablation under different ultrafast laser parameters: a molecular dynamics simulation combined with a two-temperature model

Investigating the growth behavior of titanium dioxide film prepared with direct current pulsed–magnetron sputtering technology

The direct current pulsed magnetron sputtering technology is employed to deposit TiO2 film onto the glass and Si(100) substrates. After annealing treatment, TiO2 film displays anatase (001) preferential orientation. The growth behavior of deposited and annealed TiO2 films is investigated. The results show that in the original stage, TiO2 film growth behavior is in Volmer–Weber mode, which is dominated by the diffusion effect. Considering the rivalry between TiO2 crystal nuclei, both crystallographic orientation and diffusion effects jointly dominate the film growth behavior in the rest stage. More importantly, the annealing treatment resulted in the coalescence of TiO2 crystal nuclei, as well as the growth of TiO2 crystal nuclei. Most importantly, after coalescence and growth of TiO2 nuclei, the anatase [001] crystal orientation of TiO2 grains remains the same as the normal direction of TiO2 film. Finally, after annealing treatment, TiO2 films comprise anatase (001) preferential orientation.

Spectroscopic analysis of color origins in titanium-based thin films deposited by cathodic arc deposition

The distinctive colors observed in titanium-based (Ti-based) decorative coatings fabricated by cathodic arc deposition originate from the unique electronic, morphological, and chemical properties of these films. Most Ti-based film colors arise from their surface band gaps, as measured by electron energy loss spectroscopy, with the exception of the lowest brightness (TLB) and green hues. The green color in titanium dioxide films typically results from interference between light reflected from the film and substrate interfaces. In contrast, the black color in Ti-based coatings stems from the chemical structure, specifically the presence of Ti-C and C=C(sp2) bonds within the film. Moreover, the large band gap of the TLB film surface is attributed to surface oxidation, as detected by soft X-ray spectroscopy. Significantly, the film thickness and surface roughness are characterized by field emission secondary electron microscopy and atomic force microscopy, respectively.

Measurement of Gaussian laser beam radius using nanosecond-pulse laser etching of titanium film

A method for measuring the Gaussian laser beam radius based on nanosecond-pulse laser etching (NPLE) was proposed. The NPLE method has the advantages of simple operation, low cost and high accuracy. It can be used to directly measure the laser beam size in the range of 0.25 ∼ 6 W without attenuating the laser energy. In the experiments, 1064 nm pulsed laser beam was used to etch titanium film, the size and position of the laser beam waist were measured. The experimental results are consistent with the calibration values of the CCD method, it indicates that the NPLE method is feasible.

Synthesis and Characterization of Cobalt-doped Titanium Dioxide Thin Films as Solar Cell Components using UV-SEM Analysis

Research has been carried out in the form of the synthesis and characterization of thin films of titanium dioxide with the addition of cobalt doping. The purpose of this research was to synthesize and characterize thin films related to optical properties, morphological shapes, and components of thin film compounds that are good for use as basic materials for the development of nanoparticle technology in the form of solar cells. The research was carried out in two stages, namely synthesis such as preparation of glass substrates, preparation of sol-gel solutions, deposition of solutions onto glass substrates, and heating of TiO2:Co thin film samples. The next stage is the thin film characterization test, where the optical properties of the thin film, such as absorbance, transmittance, gap energy, and activation energy, are measured using a UV-vis spectrophotometer, while morphological data and components of the thin layer compounds are measured using a Scanning Electron Microscope-Energy Dispersive X-rays (SEM-EDX). Based on data analysis and discussion, it was found that the optical properties, such as the transmittance value of the thin film, experienced the lowest point at a wavelength of 250–280 nm with a maximum percentage value of 62.14 to 78.85%. The greater the doping concentration, the lower the transmittance value. This condition is inversely proportional to the absorbance value of the maximum TiO2:Co thin film, which is in the region with a wavelength of 280–300 nm and a value of 5.70–6.31. The greater the doping concentration, the greater the absorbance value. The energy bandgap values of TiO2:Co thin films for doping concentrations (0, 5, 10, 15, 20)% were 3.44; 3.39; 3.38; 3.32; 3.22 eV for the direct energy bandgap and 3.86; 3.85; 3.84; 3.85; 3.82 eV for the indirect energy gap. The activation energy of the TiO2:Co thin film decreased from 2.86 to 2.26 eV. As for the morphological data of the TiO2:Co thin film, it was found that the greater the concentration of doping, the layer was deposited evenly, finely, and homogeneously. Regarding the data on the components of the thin layer compounds, it was found that the percentage of TiO2 content was in the range of 64.48–95.94%, while for Co, it was in the range of 0.00–19.21%.