Titanium Atoms Research Articles

Unraveling the atomic structure evolution of titanium nitride upon oxidation

In this study, state-of-the-art aberration-corrected environmental transmission electron microscopy is utilized to investigate the atomic-scale structural evolution of titanium nitride during dynamic oxidation. Titanium nitride oxidation originates from the migration of Ti atoms along {200} that results in two distinct reaction pathways, characterized by the formation of chains of titanium vacancies and staggered titanium vacancies. We demonstrate that titanium atoms exhibit varied oxidation activity on different crystal facets, with the selection of oxidation pathways significantly influenced by the curvature of the crystal surface, which is also supported by the First Principles Calculations.

Insight into the Reversible Hydrogen Storage of Titanium-Decorated Boron-Doped C20 Fullerene: A Theoretical Prediction

Hydrogen storage has been a bottleneck factor for the application of hydrogen energy. Hydrogen storage capacity for titanium-decorated boron-doped C20 fullerenes has been investigated using the density functional theory. Different boron-doped C20 fullerene absorbents are examined to avoid titanium atom clustering. According to our research, with three carbon atoms in the pentagonal ring replaced by boron atoms, the binding interaction between the Ti atom and C20 fullerene is stronger than the cohesive energy of titanium. The calculated results revealed that one Ti atom can reversibly adsorb four H2 molecules with an average adsorption energy of −1.52 eV and an average desorption temperature of 522.5 K. The stability of the best absorbent structure with a gravimetric density of 4.68 wt% has been confirmed by ab initio molecular dynamics simulations. These findings suggest that titanium-decorated boron-doped C20 fullerenes could be considered as a potential candidate for hydrogen storage devices.

Single‐Atom Ti Decorated Carbon Black and Carbon Nanotubes: Modular Dual‐Carbon Electrode for Optimizing the Charge Transport Kinetics of Perovskite Solar Cells

AbstractIn the landscape of photovoltaic research, carbon‐based perovskite solar cells (C‐PSCs) have attracted widespread attention due to their outstanding stability. However, compared to metal‐based PSCs, their power conversion efficiency (PCE) lags markedly behind. The key lies in two primary factors: First, the inefficiency of the carbon electrode in transporting and collecting carriers; second, the energy level mismatch with adjacent functional layers. These problems increase both the charge transport resistance and the charge injection barriers, thereby diminishing the overall efficiency of the device. In this study, an effective strategy is presented to tackle this issue by developing modular C‐PSCs that utilize dual carbon electrodes and implement multiscale modulation. This approach specifically focuses on three crucial aspects: establishing a highly conductive network, ensuring sufficient interfacial contact, and achieving well‐matched energy band alignment. By synergistically incorporating 0D carbon black (CB) and 1D carbon nanotube (CNT) into dual carbon electrodes, a resilient conductive network with enhanced interfacial contact is established, creating favorable conditions for efficient carrier transfer. Additionally, the energy level structure of CB is meticulously adjusted at the molecular scale by introducing individually adsorbed titanium (Ti) atoms, effectively addressing the energy level mismatch with the hole transport layer (spiro‐OMeTAD), and notably reducing the charge injection barrier at the interface. Based on the above strategy, the PCE of the C‐PSCs has undergone a remarkable enhancement from 15.27% to 22.45%. Moreover, the device shows excellent stability, with its PCE retaining over 95% of the initial value even after 1000 h of continuous operation under one‐sun intensity.

Coadsorption of ZnTPP and 2HMCTPP on Rutile TiO2(110).

Pure zinc tetraphenylporphyrin (ZnTPP) adsorbs on rutile TiO2(110) as flat-lying molecules, mostly interacting with the surface through weak van-der-Waals interactions. Pure monocarboxyphenyl triphenylporphyrin (2HMCTPP) forms a covalent bond to the rutile TiO2(110) surface through the carboxylic acid group, yielding densely-packed layers of upright-standing molecules. If given the chance, 2HMCTPP could therefore be expected to displace the weaker-bonding ZnTPP molecules. However, if 2HMCTPP is deposited on top of a ZnTPP layer, a coadsorption structure instead forms, with the carboxylic-acid groups of the 2HCMTPP molecules bonding to titanium atoms of the surface exposed by gaps between the molecules in the flat-lying ZnTPP adsorption structure.

Quantitative localisation of titanium in the framework of titanium silicalite-1 using anomalous X-ray powder diffraction

One of the biggest obstacles to developing better zeolite-based catalysts is the lack of methods for quantitatively locating light heteroatoms on the T-sites in zeolites. Titanium silicalite-1 (TS-1) is a Ti-bearing zeolite-type catalyst commonly used in partial oxidation reactions with H2O2, such as aromatic hydroxylation and olefin epoxidation. The reaction mechanism is controlled by the configuration of titanium sites replacing silicon in the zeolite framework, but these sites remain unknown, hindering a fundamental understanding of the reaction. This study quantitatively determines heteroatoms within the zeolite-type framework using anomalous X-ray powder diffraction (AXRD) and the changes in the titanium X-ray scattering factor near the Ti K-edge (4.96 keV). Two TS-1 samples, each with approximately 2 Ti atoms per unit cell, were examined. Half of the titanium atoms are primarily split between sites T3 and T9, with the remainder dispersed among various T-sites within both MFI-type frameworks. One structure showed significant non-framework titanium in the micropores of a more distorted lattice. In both samples, isolated titanium atoms were more prevalent than dinuclear species, which could only potentially arise at site T9, but with a significant energy penalty and were not detected.

Molecular dynamics simulation of the diffusion behaviour in Ti–Ag using diffusion couple method

The diffusion behaviour of the Ti–Ag system was investigated using classical molecular dynamics by simulating a diffusion couple at various temperatures. One bulk of the diffusion couple consisted of titanium atoms arranged in a hexagonal close-packed (hcp) structure, i.e., α-Ti, and the other consisted of silver atoms arranged in a face-centred cubic (fcc) structure. The modern second nearest-neighbour modified embedded-atom method (2NN-MEAM) interatomic potential was used. The mean square displacement (MSD) of Ti atoms diffusing into Ag and Ag atoms into α-Ti was recorded during the simulation. Diffusion coefficients were determined from the slopes of lines fit to linear regions of MSD dependence on time. The Arrhenius relation was used to determine the activation energy and the frequency of attempts. The activation energy of Ti was 0.61eV and frequency of attempts 1.90⋅10−8m2s−1. The determined activation energy of Ag and frequency of attempts were not considered reliable because the Ag diffusion coefficient did not grow exponentially with temperature. Ti atoms penetrated deeper and greater amounts into Ag than Ag into α-Ti and also had a greater diffusion coefficient at all temperatures. The results were compared with the available experimental data, and for these purposes, self-diffusion in α-Ti and Ag was further investigated. Finally, it was determined that Ag diffuses in α-Ti by hopping over interstitial positions and Ti in Ag via vacancies.

Efficient removal of plasticiser dibutyl phthalate on CoP cluster anchored MXene via boosting peroxymonosulfate activation: Catalytic performance and decomposition mechanism

A novel Ti3C2 synthesis method via strong alkaline etching (MXeneba) was developed to degrade dibutyl phthalate (DBP) using a CoP/MXeneba + peroxymonosulfate (PMS) system. The MXeneba's modified surface properties enabled stable Co2+ adsorption and homogeneous loading of ultrasmall CoP clusters post-phosphatisation. Complete DBP degradation was achieved within 30 min, facilitated by reactive oxygen species (ROS: SO4·-, ·OH, O2·-, and 1O2) and the highly reduced titanium atoms promoting Co3+ to Co2+ conversion. Density functional theory (DFT) calculations elucidated PMS adsorption sites and active species for DBP degradation. This study clarifies the activation mechanism, linking catalyst structure to performance, and provides insights for future advanced oxidation processes in environmental remediation. The findings emphasize the practical application and significance of the CoP/MXeneba catalyst in treating harmful plasticisers in water, contributing to efficient and sustainable water purification methods. The research also highlights this novel catalyst system's robustness and versatility in tackling diverse pollutants.

Interaction of Titanium Atoms with the Surface of Perfect and Defective Carbon Nanotubes

The dispersion of metal atoms over the surface of 1D and 2D carbon systems is the most affordable way to control their properties, which are attractive for many applications in electronics, power engineering, and catalysis. In this work, the features of the interaction of titanium atoms with the surface of carbon nanotubes, caused by various structural defects on these surfaces, were studied by first-principles computer simulation based on the density functional theory. Nanotubes (7, 7) and (11, 0) with similar diameters (≈1 nm) but different types of conductivity, metallic and semiconductor, respectively, were chosen for the study. Three types of defects were studied: a single vacancy, a double vacancy, and a topological defect. Two possible orientations of each type of defect relative to the tube axis were considered. We mainly used the basis of atomic-like orbitals (the SIESTA package) and in some test calculations also the basis of plane waves (the VASP package). Computational experiments have shown that the binding energy of Ti atoms with a defect-free nanotube is always lower than with defective ones, regardless of the used approximation for the exchange-correlation functional (LDA or GGA). The binding energies predicted in the LDA approximation are noticeably higher than in the GGA approximation (up to ~15% for the (7, 7) tube and up to ~50% for the (11, 0) tube). The strongest coupling occurs when the titanium atom is adsorbed on a nanotube with a single vacancy. The resulting configuration can be considered as a defect in the substitution of one carbon by a titanium atom.

Compositional-Dependent Structural Parameters and Energetics of Hibonite: Quantum-Chemical Investigation.

One of the first minerals to condense from the early solar nebula was hibonite (CaAl12O19), demonstrating a hexagonal crystal structure. There are five unique aluminum cation sites (M1-M5) in hibonite. Although hibonite contains aluminum, it can also have 3d transitional metals that substitute at aluminum cation sites, such as titanium, and other metals such as magnesium. Titanium can occur in multiple oxidation states, linking to redox conditions. A single substitution occurs when a single aluminum atom is replaced by a single titanium atom, causing the Ti to take on a 3+ oxidation state. On the other hand, Ti achieves an oxidation state of 4+ during a double substitution when a pair of aluminum atoms is replaced by a titanium and a magnesium atom. A density functional theory-based calculation is used to explore the relationship between the number of substitutions and the lattice parameters of the hibonite crystal. The calculated results reveal that the lengths of both unit cells (a and c) increase with an increasing number of single or double substitutions. The rate of increment per substitution depends on the cation sites, M1-M5, and substitution types. Along with the expansion of the unit cell of the hibonite due to the substitution, the substituted unit cell gains energy (and in turn stability) compared to the substituted unit cell without expansion, dependent on the lattice site and substitutions.

Production of High-Power Nitrogen Sputtering Plasma for TiN Film Preparation

High-density nitrogen plasma was produced using a high-power pulsed power modulator to sputter titanium targets for the preparation of titanium nitride film. The high-power pulsed sputtering discharge unit consisted of two targets facing each other with the same electrical potential. The titanium target plates were used as target materials with dimensions of 60 mm length, 20 mm height, and 5 mm thickness. The gap length was set to be 10 mm. The magnetic field was created with a permanent magnet array behind the targets. The magnetic field strength at the gap between the target plates was 70 mT. The electrons were trapped by the magnetic and electric fields to enhance the ionization in the gap. The nitrogen and argon gases were injected into the chamber with 4 Pa gas pressure. The applied voltage to the target plates had an amplitude from −600 V to −1000 V with 600 μs in pulse width. The target current was approximately 10 A with the consumed power of 13 kW. The discharge sustaining voltage was almost constant and independent of the applied voltage, in the same manner as the conventional normal glow discharge. The ion density and electron temperature at the surface of the ionization region were obtained as 1.7 × 1019 m−3 and 3.4 eV, respectively, by the double probe measurements. The vertical distribution of ion density and electron temperature ranged from 1.1 × 1017 m−3 (at 6 cm from the target edge) to 1.7 × 1019 m−3 and from 2.4 eV (at 6 cm from the target edge) to 3.4 eV, respectively. From the emission spectra, the intensities of titanium atoms (Ti I), titanium ions (Ti II), and nitrogen ions (N2+) increased with increasing input power. However, the intensities ratio of Ti II to Ti I was not affected by the intensities from N2+.

Electrically driven spin resonance of 4f electrons in a single atom on a surface

A pivotal challenge in quantum technologies lies in reconciling long coherence times with efficient manipulation of the quantum states of a system. Lanthanide atoms, with their well-localized 4f electrons, emerge as a promising solution to this dilemma if provided with a rational design for manipulation and detection. Here we construct tailored spin structures to perform electron spin resonance on a single lanthanide atom using a scanning tunneling microscope. A magnetically coupled structure made of an erbium and a titanium atom enables us to both drive the erbium’s 4f electron spins and indirectly probe them through the titanium’s 3d electrons. The erbium spin states exhibit an extended spin relaxation time and a higher driving efficiency compared to 3d atoms with spin ½ in similarly coupled structures. Our work provides a new approach to accessing highly protected spin states, enabling their coherent control in an all-electric fashion.

Multi-layers hexagonal hole MXene trap constructed by carbon vacancy defect regulation strategy enables high energy density potassium-ions storage

Due to the slow reaction kinetics of potassium-ions with large size radius in layered materials, the energy density of aqueous potassium-ion hybrid supercapacitors (PIHCs) is severely limited. At the same time, the treatment of defects is a “double-edged sword” in energy storage materials, which requires targeted and precise regulation. In order to solve this problem, multi-layers hexagonal hole MXene trap was constructed by using the carbon vacancy defect regulation strategy, and high specific capacitance and energy density potassium-ion storage was realised in PIHCs. The structure-activity relationship at the atomic level was elucidated in combination with the pseudo-capacitance effect caused by the change of valency of newly exposed titanium atoms in the inner wall of the hexagonal hole MXene trap. By density functional theory, the adsorption energy and kinetic analysis of multi-layers hexagonal hole MXene for potassium-ions were calculated, and the optimal position and quantity of potassium-ions were determined. By quantitative analysis of electron band structure and differential charge density, the internal mechanism of high conductivity and energy density of multi-layers hexagonal hole MXene PIHCs was revealed.

A comparative DFT study of CO and NO capture by copper- and titanium-functionalized SiC and GeC monolayers

In this work, the interactions of NO and CO molecules with silicon carbide (SiC) and germanium carbide (GeC) graphene-like nanosheets, functionalized with titanium and copper atoms, are comparatively studied through density-functional calculations. The results indicate that NO and CO molecules are only slightly adsorbed on the pristine carbide nanosheets. Also, the copper and titanium adatoms are chemisorbed on the monolayers, leading to stable functionalized carbide nanosheets. These adatoms greatly enhance the binding energies of CO and NO. In particular, the titanium-functionalized GeC monolayers display the highest adsorption energies for CO and NO and also the largest changes in their work functions upon molecule adsorption, indicating that they could be useful for trapping or detecting these molecules.

Rapid conversion of carbon dioxide into titanium carbide by atmospheric microwave plasma

The accelerating climate warming requires fast methods to reduce atmospheric carbon dioxide levels. Here, we converted carbon dioxide into titanium carbide using four magnetrons which were sequentially operated to emit microwave on titanium swarf. Carbon dioxide molecules dissociated in the plasma to react with ionized titanium atoms to form a stable titanium carbide product, using a microwave frequency is 2.3 gigahertz and 800 watts electrical power for each magnetron. Results show a reduction of carbon dioxide concentration from 2000 to 385 ppm within 30 s. Titanium carbide could be further functionalized as a three-dimensional printed gas sensor.

Thermal self-crosslink after etching for regulated preparation of Ti3C2 type MXene membrane and its preliminary gas separation

We present an innovative methodology for the synthesis of MXene membranes through a dual-stage process involving etching and subsequent thermal self-crosslinking. A molar ratio of 1 (Al3+):9 (F−) using HCl/LiF was employed to convert raw Ti3AlC2 (MAX phase) into MXene within 48 h at 40 °C. This procedure predominantly yielded monolayers distinguished by diameters exceeding 500 nm, elevated crystallinity and a high overall yield. Advanced characterization techniques, including FESEM, TEM, HRTEM, AFM, XPS, and FTIR, were utilized. Instrumental analysis confirmed the formation of MXene exhibiting a single-flake morphology with diameters exceeding 500 nm. These monolayers were intact and continuous, with smooth peripheries and a uniform thickness of 2.1 nm. The surfaces were predominantly composed of carbon (C), oxygen (O), and titanium (Ti) atoms, interconnected by chemical bonds such as C–Ti–O, C–Ti–OH, C–C, C–O, and Ti–O. In the subsequent phase, vacuum filtration facilitated the assembly of a self-supporting MXene membrane. Thermal treatment at 170 °C for 30 h resulted in the reinforcement of C–Ti–O bonds within the nanosheets, increasing their prevalence to 43.14 % and 19.47 %, respectively. This thermal regulation reduced the interlayer d-spacing from 4.33 to 3.54 Å, which significantly improved the gas separation efficiency beyond the Knudsen diffusion limit, as demonstrated by the αH2/CF4 value exceeding 23.0.

WITHDRAWN: Multi-layers hexagonal hole MXene trap constructed by carbon vacancy defect regulation strategy enables high energy density potassium-ions storage

Due to the slow reaction kinetics of potassium-ions with large size radius in layered materials, the energy density of aqueous potassium-ion hybrid supercapacitors (PIHCs) is severely limited. At the same time, the treatment of defects is a "double-edged sword" in energy storage materials, which requires targeted and precise regulation. In order to solve this problem, multi-layers hexagonal hole MXene trap was constructed by using the carbon vacancy defect regulation strategy, and high specific capacitance and energy density potassium-ion storage was realized in PIHCs. The structure-activity relationship at the atomic level was elucidated in combination with the pseudo-capacitance effect caused by the change of valency of newly exposed titanium atoms in the inner wall of the hexagonal hole MXene trap. By density functional theory, the adsorption energy and kinetic analysis of multi-layers hexagonal hole MXene for potassium-ions were calculated, and the optimal position and quantity of potassium-ions were determined. By quantitative analysis of electron band structure and differential charge density, the internal mechanism of high conductivity and energy density of multi-layers hexagonal hole MXene PIHCs was revealed.

Crystallographic phase stability of nanocrystalline polymorphs TiO2 by tailoring hydrolysis pH

Nanocrystal TiO2 of high crystallinity (88.72 %) polymorphs have been synthesized by a unique simple route. At a low temperature under a measurable condition with differentiated hydrolysis pH of the reaction. Here titanium isopropoxide (TTIP) is used as a precursor, isopropyl alcohol (IP) is a peptizing agent and hydrolysis medium with variable pH (2.0, 2.5, 3.5, 4.5, 5.5, 7.0, 8.5, 9.5) acts as a promoter or catalyst of the reaction. We observed in the whole powder pattern fitting (WPPF) method, TiO2 consisting of 65.0 % anatase, 68.0 % brookite and 45.0 % rutile phase in weight fraction by tailoring different hydrolysis conditions with predominant crystal plane (101), (111), (110) for the individual polymorph anatase, brookite and rutile. The crystal lattice parameters, crystal structure, volume of the crystal lattice, crystal strain, asymmetry, d-spacing and average crystallite size were also studied for the polymorph. The percent of crystallinity dominating around 54.0 to 89.0 % of the titanium and oxygen atoms are arranged regularly and periodically observed for change in the molar ratio (r) tailoring the polymorph phase stability. TiO2 polymorph followed the blue shift at 319.00 to 336.00 nm and had good stability for the decreasing particle size (11.03 nm). This phenomenon has been revealed by transmission electron microscopy (TEM) into the polymorphs. Selected area electron diffraction (SAED) and nanobeam diffraction (NBD) showed the nanocrystal anatase with the prominent miller indices (101) and interplanar distance of 0.35 nm that was revealed by HR-TEM at the lowest pH. Nano anatase is ultrafine which was confirmed by EDS.

Improving the Adhesion of Multi-Walled Carbon Nanotubes to Titanium by Irradiating the Interface with He+ Ions: Atomic Force Microscopy and X-ray Photoelectron Spectroscopy Study.

A complex study of the adhesion of multi-walled carbon nanotubes to a titanium surface, depending on the modes of irradiation with He+ ions of the "MWCNT/Ti" system, was conducted using atomic force microscopy and X-ray photoelectron spectroscopy. A quantitative assessment of the adhesion force at the interface, performed using atomic force microscopy, demonstrated its significant increase as a result of treatment of the "MWCNT/Ti" system with a beam of helium ions. The nature of the chemical bonding between multi-walled carbon nanotubes and the surface of the titanium substrate, which causes this increase in the adhesion of nanotubes to titanium as a result of ion irradiation, was investigated by X-ray photoelectron spectroscopy. It was established that this bonding is the result of the formation of chemical C-O-Ti bonds between titanium and carbon atoms with the participation of oxygen atoms of oxygen-containing functional groups, which are localized on defects in the nanotube walls formed during ion irradiation. It is significant that there are no signs of direct bonding between titanium and carbon atoms.

Synthetic Studies and Structural Aspects of Dinuclear Sulfur Titanium Compounds

AbstractA series of dinuclear sulfur‐bridged titanium derivatives [Ti(η5‐C5Me5)R(μ‐S)]2 (R=NMe2 (1), Ph (2), CH2Ph (3), CH2SiMe3 (4)) has been synthesized from the reaction of [Ti(η5‐C5Me5)Cl(μ‐S)]2 with the corresponding lithium salt or Grignard reagent. Formulation of 1–4 as symmetric dimers has been confirmed by crystallographic studies. The analogous reaction with Mg(C3H5)Cl afforded the paramagnetic mixed‐valence Ti(III)/Ti(IV) compound [{Ti(η5‐C5Me5)(μ‐S)}2(μ‐C3H5)] (5). Contrasting with complexes 1–4, compound 5 exhibits a bridging μ‐CH2CHCH2 fragment between the titanium atoms, which prevents the formation of a planar Ti2S2 core in the solid‐state structure. Complex 1 reacts with SiH3Ph to give [{Ti(η5‐C5Me5)(μ‐S)}2(μ‐NMe2)] (6), a paramagnetic mixed‐valence Ti(III)/Ti(IV) compound, structurally and electronically similar to 5. Under mild conditions, treatment of compounds 3 and 4 with H2 (1 atm) generates quantitatively the Ti(III) tetrametallic sulfide cluster [Ti(η5‐C5Me5)(μ3‐S)]4, along with the corresponding alkane.

Effects of Co on the microstructure evolution and mechanical properties of Ti-4Al-6Cr-5Mo-8 Nb alloy by ultrasonic vacuum melting

An investigation was conducted into the impact of low cobalt content on the microstructure and mechanical properties of titanium alloys. Ti-4Al-6Cr-5Mo-8 Nb-xCo (x = 0, 2, 3, 4, and 5) alloys were prepared by ultrasonic-assisted melting and casting. The changes in microstructure, mechanical properties, and the strengthening and toughening mechanisms were researched. Results show that, when the cobalt content increases from 0 to 5 wt%, the as-cast structure is all β phase. The lattice parameter of the β phase decreases from 0.3663 to 0.3114 nm, a 15% decrease. The size of primary β grains decreases from 676.8 to 310.7 μm, a 54% decrease. When the cobalt content exceeds 3 wt%, the segregation energy of cobalt increases and grain boundary segregation occurs. Grain refinement is due to constitutional supercooling caused by the β-stable element cobalt, as well as the solute drag caused by the differences in intragranular and grain boundary compositions. In addition, the size mismatch between cobalt and titanium atoms leads to lattice distortion. As the cobalt content increases from 0 to 3 wt%, the tensile strength increases from 918.1 to 1147.8 MPa, a 25% increase, while the fracture toughness increases from 51.7 to 59.7 MPa·m1/2, a 15% increase. At 5 wt% cobalt, the tensile strength and fracture toughness diminished to 247.5 MPa and 14.8 MPa·m1/2, respectively. The decrease in lattice parameters mainly lead to an increase in strength. The secondary crack leads to an increase in toughness. The decline in strength and toughness results from cobalt segregating at grain boundaries, leading to embrittlement.