Titanium Monoxide Research Articles

Manipulating mammalian cell by phase transformed titanium surface fabricated through ultra-short pulsed laser synthesis

Developing cell sensitive indicators on interacting substrates that allows specific cell manipulation by a combination of physical, chemical or mechanical cues is a challenge for current biomaterials. Hence, various fabrication approaches have been created on a variety of substrates to mimic or create cell specific cues. However, to achieve cell specific cues a multistep process or a post-chemical treatment is often necessitated. So, a simple approach without any chemical or biological treatment would go a long way in developing bio-functionalized substrates to effectively modulate cell adhesion and interaction. The present investigation is aimed to study the manipulative activity induced by phase transformed titanium surface. An ultra-short laser is used to fabricate the phase transformed titanium surface where a polymorphic titanium oxide phases with titanium monoxide (TiO), tri-titanium oxide (Ti3O) and titanium dioxide (TiO2) have been synthesized on commercially pure titanium. Control over oxide phase transformed area was demonstrated via a combination of laser scanning time (laser pulse interaction time) and laser pulse widths (laser pulse to pulse separation time). The interaction of phase transformed titanium surface with NIH3T3 fibroblasts and MC3T3-E1 osteoblast cells developed a new bio-functionalized platforms on titanium based biomaterials to modulate cell migration and adhesion. The synthesized phase transformed titanium surface on the whole appeared to induce directional cues for cell migration with unique preferential cell adhesion unseen by other fabrication approaches. The precise bio-functionalization controllability exhibited during fabrication offers perceptible edge for developing a variety of smart bio-medical devices, implants and cardiovascular stents where the need in supressing specific cell adhesion and proliferation is of great demand.

Size effect on magnetic susceptibility of titanium monoxide nanocrystals

For the first time a magnetic quantum‐size effect is found in paramagnetic titanium monoxide nanocrystals with the sizes down to 30 nm. In situ measurements in the temperature range from 300 to 1200 K showed that the magnetic susceptibility of superstoichiometric titanium monoxide nanocrystals TiOy (y > 1) depends not only on the structural state of the sample, but also on the size of nanocrystals. The data analysis both for the ordered and disordered TiOy showed that the reason for inversely proportional dependence of Van‐Vleck paramagnetism on the size of titanium monoxide nanocrystals is distortion of local symmetry of titanium and oxygen atoms near the nanocrystal surface. Van‐Vleck contribution induced by the atomic‐vacancy disordering in titanium monoxide is proportional to the deviation of the long‐order parameter from its maximal value.

Effect of stoichiometry on the size of titanium monoxide nanoparticles produced by fragmentation

Coarse disordered and ordered titanium monoxide powders differing in composition—substoichiometric (TiO0.92), near-stoichiometric (TiO0.97 and TiO0.99), and superstoichiometric (TiO1.23)—have been disintegrated by milling. According to X-ray diffraction and scanning electron microscopy data, milling produced nanoparticles down to 20 ± 10 nm in size. The basic structure of the nanoparticles prepared from the disordered powders was identical to the parent basic structure B1. The structure of the nanoparticles prepared from the ordered powders with the C2/m structure also remained unchanged. Using the Williamson–Hall method, we assessed the effect of the stoichiometry of the starting powder on the size of the nanoparticles and found that an ordered state of near-stoichiometric titanium monoxide ensures a factor of 3 lower lattice strain in the nanoparticles.

Inclusion of the correlation short-range order in Ab initio calculations of the energy of the ground state by example of titanium monoxide TiO1.0

A variant of the distribution of structural vacancies at which the crystal structure of ordered compounds simultaneously has a long-range order and correlation short-range order has been proposed and analyzed. The long-range order determines the fraction of vacancies in the atomic and vacancy sublattices of the superstructure formed because of ordering. The correlation short-range order takes into account energy favorable correlations in the arrangement of vacancies, which exist in disordered phases and are not determined by the long-range order. The possibility of the correlation short-range order has been examined by ab initio methods by example of ordering of vacancies in titanium monoxide TiO1.0 according to the type of monoclinic superstructure M5X5mon. It has been shown that partially ordered modifications with the correlation short-range order are energetically favorable as compared to the modifications without the correlation short-range order.

Thermodynamic description of the Ti–O system

Abstract Phase diagram and thermodynamic data of the complete binary Ti–O system are assessed using the Calphad method. The main focus is on the proper description of high temperature titanium monoxide TiO x phase using the common compound energy formalism. The structural data of this complex solid solution phase could be successfully modeled together with the phase equilibrium and thermodynamic data, embedded in the comprehensive Ti–O assessment. The presentation of all original phase equilibrium data in the entire system indicates the well or less well established regions in comparison with the calculated phase diagram.

Family of Ti5O5 superstructures

Orthorhombic (space group Pmmm) and tetragonal (space group P422) models are proposed for the Ti5O5 (Ti5■O5□) family of nonstoichiometric titanium monoxide Ti x O z with double imperfection. The disorder-order (Ti x O z (space group Fm $$\overline 3 $$ m)-Ti5O5 (space group Pmmm) and Ti x O z (space group (Fm $$\overline 3 $$ m)-Ti5O5 (space group P422)) transition channels include five superstructure vectors, which belong to stars {k 10}, {k 4(1)}, and {k 4(2)} or {k 10}, {k 6(1)}, and {k 6(2)}, respectively. The functions of distribution of Ti and O atoms over the sites of the model Ti5O5 superstructures are calculated. The well-known cubic and monoclinic Ti5O5 superstructures are compared with the model orthorhombic and tetragonal superstructures. It is shown that, as temperature decreases, two physically allowable transformation sequences related to the Ti5O5 superstructure formation are possible in nonstoichiometric titanium monoxide Ti x O z .

Elimination of vacancies in titanium monoxide under high pressure in combination with high temperature

The material design with controlled structure was performed on titanium monoxide with structural vacancies on both sublattices. The polycrystalline powder of disordered titanium monoxide TiO0.98 with B1 structure was subjected to high pressures up to 60 kbar and high temperatures up to 2273 K. The X-ray powder diffraction of as-prepared and treated powders revealed cubic single-phase crystals. The lattice constant of this phase increased from 417.6(3) to 418.5(3) pm due to decreasing vacancy concentration on the titanium sublattice from 13.3 to 8.5 at.% after a highest pressure-highest temperature treatment for 1 h.

Computation of diatomic molecular spectra for selected transitions of aluminum monoxide, cyanide, diatomic carbon, and titanium monoxide

Laser ablation studies with laser-induced breakdown spectroscopy (LIBS) typically emphasize atomic species yet fingerprints from molecular species can occur subsequently or concurrently. In this work, selected molecular transitions of aluminum monixide (AlO), diatomic carbon (C2), cyanide (CN), and titanium monoxide (TiO) are accurately computed. Line strength tables are used to describe the radiative transitions of diatomic molecules primarily in the visible, optical region. Details are elaborated of the computational procedure that allows one to utilize diatomic spectra as a predictive and as a diagnostic tool. In order to create a computed spectrum, the procedure requires information regarding the temperature of the diatomic transitions along with other input such as the spectral resolution. When combined with a fitting algorithm to optimize such parameters, this procedure is used to infer information from an experimentally obtained spectrum. Furthermore, the programs and data files are provided for LIBS investigations that also reveal AlO, C2, CN, and TiO diatomic spectra.

Formation of titanium monoxide (001) single-crystalline thin film induced by ion bombardment of titanium dioxide (110).

A plethora of technological applications justify why titanium dioxide is probably the most studied oxide, and an optimal exploitation of its properties quite frequently requires a controlled modification of the surface. Low-energy ion bombardment is one of the most extended techniques for this purpose and has been recently used in titanium oxides, among other applications, to favour resistive switching mechanisms or to form transparent conductive layers. Surfaces modified in this way are frequently described as reduced and defective, with a high density of oxygen vacancies. Here we show, at variance with this view, that high ion doses on rutile titanium dioxide (110) induce its transformation into a nanometric and single-crystalline titanium monoxide (001) thin film with rocksalt structure. The discovery of this ability may pave the way to new technical applications of ion bombardment not previously reported, which can be used to fabricate heterostructures and interfaces.

TiO thin films on GaN(0001)

Physical features of titanium monoxide layers deposited on p‐GaN(0001) substrate are reported in this paper. TiO was deposited under ultrahigh vacuum at room temperature. As revealed by scanning tunneling microscopy (STM) the deposit had grainy structure. The X‐ray and ultraviolet photoelectron spectroscopy (XPS/UPS) studies have shown that, depending on the altered by annealing morphology of the TiO‐based film, work function of the system underwent changes and electronic structure of the deposit displayed metallic character. The formation of specific TiN and ON bonds is confirmed by spectroscopic techniques. Electrical conductance of the TiO‐based/p‐GaN interface has been studied by current‐sensing atomic force microscopy (CS‐AFM) with Au‐covered tip. Formation of ohmic nano‐contacts on p‐GaN surfaces was observed over whole probed surface. The contacts were homogeneous in contrast to the grainy structure of TiO‐based film. The results suggest that TiO may be considered as an intermediate semiconducting layer (ISL) useful for p‐GaN electrical contact engineering.

In situ study of atomic-vacancy ordering in stoichiometric titanium monoxide by the magnetic susceptibility

An in situ temperature study of a variation in the degree of long-range order in stoichiometric titanium monoxide has been performed by the magnetic susceptibility method. The measurements have been performed on annealed and quenched titanium monoxide in the temperature range from 300 to 1200 K. It has been found that the degree of long-range order depends on the regime and temperature of annealing of the initial samples. The degree of long-range order in the process of measurement of the magnetic susceptibility varies from 0.21 to 1.00; the larger the degree of long-range order, the smaller the magnetic susceptibility. Furthermore, the long-range order parameter decreases with an increase in the temperature above 1200 K and vanishes sharply at the order-disorder transition temperature. According to the results of this work, the critical long-range order parameter is 0.21 and the temperature of the nonequilibrium disorder-order transition is about 1073 K.

Decomposition pathways of formamide in the presence of vanadium and titanium monoxides.

Thermally feasible decomposition pathways of formamide (FM) in the presence of vanadium VO(X(4)Σ(-)) and titanium TiO(X(3)Δ) monoxides are determined using density functional theory (BP86 functional) and coupled-cluster theory (CCSD(T)) computations with large basis sets. These diatomic metal oxides have been shown to be present in the prebiotic conditions. The dehydration, decarbonylation and dehydrogenation reactions of the molecular and dissociative complexes of FM and MO (M = V, Ti) turn out to be more favourable than those of the ground state isolated FM. The effect of addition of one or two water molecules on energy barriers is also probed for these reaction pathways. In some cases, a combined catalytic effect when adding water is observed. This enhanced catalytic effect was not observed in previously reported cases of FM transformation, for example, when adding water molecules into the mineral-catalyzed isomerizations of FM. The dehydration process of MO-FM complexes without the presence of water is found to be more feasible than the decarbonylation and dehydrogenation. The overall energy barrier for the non-water VO-FM dehydration is ∼3 kcal mol(-1) lower than the reference energy of the separated systems, whereas those of the two latter reactions are higher than the reference. Although the TiO-FM dehydration has a larger overall barrier of 14 kcal mol(-1) as compared to the VO-FM counterpart, the two other decomposition pathways still have much higher energy barriers. Direct formation of urea and H2CO from a FM dimer and indirect formation of urea from FM via the intermediate HNCO are also established. Urea formation in an indirect pathway is preferred. These low-energy-barrier pathways leading to the formation of important prebiotic molecules suggest that metal monoxides MO could play an important catalytic role in the prebiotic reactions of FM.

Morphology and structural development of reduced anatase-TiO2 by pure Ti powder upon annealing and nitridation: Synthesis of TiOx and TiOxNy powders

It is well known that nitriding of titanium is suitable for surface coating of biomaterials and in other applications such as anti-reflective coating, while oxygen-rich titanium oxynitride has been applied in thin film resistors and photocatalysis. Thus in this work anatase was reduced with pure titanium powder during annealing in argon. This was done to avoid any metallic contamination and unwanted residual metal doping. As a result, interesting and different types of particle morphology were synthesized when the pre-milled elemental anatase and titanium powders were mixed. The formation of metastable face centred cubic and monoclinic titanium monoxide was detected by the X-ray diffraction technique. The phases were confirmed by energy dispersive X-ray spectroscopy analysis. Raman analysis revealed weak intensity peaks for samples annealed in argon as compared to those annealed under nitrogen.

Fragmentation of disordered titanium monoxide of stoichiometric composition TiO

Fragmentation was carried out for coarse crystalline disordered titanium monoxide of stoichiometric composition TiO containing up to 16 at.% of structural vacancies in each titanium and oxygen sublattices. According to X-ray diffraction analysis, the fragmentation attained the nanometric size of titanium monoxide particles. In spite of the small size of the nanoparticles (about 30 nm) and high degree of induced microstrains of the crystal lattice (~0.57%), their atomic structure retained the main features of the disordered cubic structure of coarse crystalline titanium monoxide with the space group Fm-3m.

Formation, characterization, structure and bonding analysis of the metal–carbon bond OM-(η6-C6H6) (M = Sc, Ti) complexes in solid matrix: Infrared spectroscopic and theoretical study

The reactions of ScO and TiO molecules with benzene have been studied in solid argon with infrared absorption spectroscopy combining with theoretical calculations. Laser-evaporation of bulk higher oxide targets prepared the scandium and titanium monoxide molecules. The scandium and titanium monoxide molecules reacted with benzene to form the typical transition metal–carbon bond (MCB) complexes, OM-(η6-C6H6) (M = Sc, Ti), which have been identified on the basis of isotopic infrared studies and density functional calculations. The theoretical calculation results illustrate the deformation of the planar carbon skeleton of benzene takes place and the bond lengths of M–O are largely elongated upon OM-(η6-C6H6) (M = Sc, Ti) complexes. The population results illustrate the OM-(η6-C6H6) are determined to have 2A1 and 1A1 electronic ground state both with C2v symmetry arising from 2Δ and 1∑− of excited-state ScO and TiO reaction with benzene, respectively. The OSc-(η6-C6H6) and OTi-(η6-C6H6) are both stable d–pπ coordination compounds and can also not be photoisomerized by UV irradiation under low temperature in solid argon matrix. Natural bond orbital analyses conclude that the OTi-(η6-C6H6) system includes two equivalent Ti–C single bonds with strong binding bond energies.

Diatomic Molecular Emission Spectroscopy of Laser-induced Titanium Plasma

Previous research regarding laser-induced breakdown spectroscopy (LIBS) of titanium normally focuses on the atomic and ionic Ti spectral transition lines. However, after a characteristic time subsequent to laser ablation, these lines are no longer discernable. During this temporal regime, the diatomic molecular transition lines of titanium monoxide (TiO) are prominent in the laser-induced plasma (LIP) emissions. TiO has long been studied in the contexts of stellar emissions, allowing for some of the molecular transition bands to be accurately computed from theory. In this research, optical emission spectroscopy (OES) of laser-induced plasma (LIP) generated by laser ablation of titanium is performed in order to infer temperature as a function of time subsequent to plasma formation. The emission spectra of the resulting ablation plume is imaged as a function of height above the sample surface. Temperatures are inferred over time delays following plasma formation ranging from 20 μs-200 μs. Computed TiO A3Φ – X3Δ, Δv = 0 transition lines are fit to spectral measurements in order to infer temperature. At tdelay = 20 μs-80 μs, the observed plume contains two luminescent regions each with a distinctly different temperature. As the plume evolves in time, the two regions combine and an overall temperature increase is observed.

Preparation of inkjet-printed titanium monoxide as p-type absorber layer for photovoltaic purposes

The intrinsic p-type cubic structure titanium monoxide (TiO) with suitable band gap energy, reasonable raw material costs, and particularly simple stoichiometry has been chosen as a potential candidate in microelectronic applications, and may have the opportunity to use as a p-type absorber layer for photovoltaic purposes. Among various printing and coating techniques that have been recently explored to fabricate solar cell layers, inkjet printing is promising because of low-cost processing and precise patterning capabilities. This paper aims to fabricate TiO films on a polyimide substrate using inkjet printing. Efforts were made to reduce the starting TiO powder size down to submicron levels by using wet ball-milling to meet the ink requirements of particle sizes for office printers. The experimental results show that the dispersion stability of the prepared water-based ink was obtained by adding an ammonia solution. Optimal printability was achieved as a result of adding ethylene glycol, polyethylene glycol 1500, Triton X-100, and Foamstop 600N. Post-annealing treatment was carried out to obtain the final dense layer. Crystallinity and electrical properties of the inkjet-printed TiO layers were enhanced by post-annealing treatment, while the optical band gap from the annealed TiO showed the value of 2.57eV. These results have demonstrated the potential of using inkjet-printed TiO as a complementary absorber layer for photovoltaic applications.

Coherent potential approximation simulation of the evolution of the electronic structure of titanium monoxide with the degree of vacancy ordering

An idea is formulated and implemented to take into account the change in the electrostatic interaction between lattice sites when vacancies substitute for atoms using the coherent potential approximation in the calculation method proposed by us earlier [3]. The change in the electronic structure of titanium monoxide Ti5O5 ordered according to a monoclinic superstructure is studied as a function of the degree of vacancy ordering in the titanium and oxygen sublattices.

Carbon-Doped Titanium Oxide Films by DC Reactive Magnetron Sputtering Using CO2 and O2 as Reactive Gas

CO2 and O2 were employed as reactive gases to fabricate carbon-doped titanium oxide films using DC reactive magnetron sputtering. Microstructure, composition and optical band gap of the films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and UV–visible spectrophotometer, respectively. The results showed that carbon-doped titanium monoxide films (C-TiO) with a carbon concentration of 5.8 at.% were obtained in an Ar/CO2 mixed atmosphere. However, carbon-doped rutile and anatase (C-TiO2) with a carbon concentration of about 1.4 at.% were obtained in an Ar/CO2/O2 mixed atmosphere. The optical band gaps of C-TiO and C-TiO2 were about 2.6 and 2.9 eV, respectively. Both of them were narrower than that of pure TiO2 films. Films with narrowed optical band gap energy are promising in promoting their photo-catalytic activity.

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C<sub>2</sub>, CN, and TiO Spectra Following Laser-induced Optical Breakdown

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement is used. Here we operate a Nd:YAG laser at a frequency of 10 Hz at the fundamental wavelength of 1,064 nm. The 14 nsec pulses with anenergy of 190 mJ/pulse are focused to a 50 µm spot size to generate a plasma from optical breakdown or laser ablation in air. The microplasma is imaged onto the entrance slit of a 0.6 m spectrometer, and spectra are recorded using an 1,800 grooves/mm grating an intensified linear diode array and optical multichannel analyzer (OMA) or an ICCD. Of interest are Stark-broadened atomic lines of the hydrogen Balmer series to infer electron density. We also elaborate on temperature measurements from diatomic emission spectra of aluminum monoxide (AlO), carbon (C2), cyanogen (CN), and titanium monoxide (TiO). The experimental procedures include wavelength and sensitivity calibrations. Analysis of the recorded molecular spectra is accomplished by the fitting of data with tabulated line strengths. Furthermore, Monte-Carlo type simulations are performed to estimate the error margins. Time-resolved measurements are essential for the transient plasma commonly encountered in LIBS.