Transition Metals Titanium Research Articles

Non-Linear Thermophysical Behaviour of Transition Metal Titanium

The propagation of ultrasonic waves in the hexagonal closed packed (hcp) structured lanthanide metal titanium has been investigated in the temperature range 300–1000 K. For this, initially the higher-order elastic constants (second-order elastic constants (SOECs) and third-order elastic constants (TOECs)) were computed using the Lennard-Jones interaction potential model. With the help of SOECs, other elastic moduli such as Young’s modulus (Y), bulk modulus (B), shear modulus (G), Poisson’s ratio (σ) and Pugh’s ratio (B/G) were computed using the Voigt-Reuss-Hill approximation. Three types of orientation-dependent ultrasonic velocities, including Debye average velocities, were evaluated using the calculated SOECs and density of titanium in the same temperature range. Thermophysical properties such as lattice thermal conductivity, thermal relaxation time, thermal energy density, specific heat at constant volume and acoustic coupling constant were evaluated under the same physical conditions. The ultrasonic attenuation due to phonon-phonon interaction is most significant under the chosen physical conditions. The ultrasonic properties of titanium are correlated with thermophysical properties to understand the microstructural features and nature of the material.

A twist on a classic scaffold: rational design of a new bimetallic platform.

Herein, we report the synthesis of a modular family of novel bimetallic tetraamidodiamine (tada) ligands, Li4-R-tada (R = Me3Si, tBuMe2Si, and iPr3Si). These silylamido ligands display two distinct binding pockets whose steric profiles can be easily tuned by choice of the substituents on silicon. We also show that salt metathesis is a convenient route to install these new ligands on the early transition metals titanium(IV) and vanadium(III).

Steering Single-Electron Metal-Metal Bonds and Hyperfine Coupling between a Transition Metal-Lanthanide Heteronuclear Bimetal Confined in Carbon Cages.

Metal complexes bearing single-electron metal-metal bonds (SEMBs) exhibit unusual electronic structures evoking strong magnetic coupling, and such bonds can be stabilized in the form of dimetallofullerenes (di-EMFs) in which two metals are confined in a carbon cage. Up to now, only a few di-EMFs containing SEMBs are reported, which are all based on a high-symmetry icosahedral (Ih) C80 cage embedding homonuclear rare-earth bimetals, and a chemical modification of the Ih-C80 cage is required to stabilize the SEMB. Herein, by introducing 3d-block transition metal titanium (Ti) along with 4f-block lanthanum (La) into the carbon cage, we synthesized the first crystallographically characterized SEMB-containing 3d-4f heteronuclear di-EMFs based on pristine fullerene cages. Four novel La-Ti heteronuclear di-EMFs were isolated, namely, LaTi@D3h(5)-C78, LaTi@Ih(7)-C80, LaTi@D5h(6)-C80, and LaTi@C2v(9)-C82, and their molecular structures were unambiguously determined by single-crystal X-ray diffraction. Upon increasing the cage size from C78 to C82, the La-Ti distance decreases from 4.31 to 3.97 Å, affording fine-tuning of the metal-metal bonding and hyperfine coupling, as evidenced by an electron spin resonance (ESR) spectroscopic study. Density functional theory (DFT) calculations confirm the existence of SEMB in all four LaTi@C2n di-EMFs, and the accumulation of electron density between La and Ti atoms shifts gradually from the proximity of the Ti atom inside C78 to the center of the LaTi bimetal inside C82 due to the decrease of the La-Ti distance. The electronic properties of LaTi@C2n heteronuclear dimetallofullerenes differ apparently from their homonuclear La2@C2n counterparts, revealing the peculiarity of heteronuclear dimetallofullerenes with the involvement of 3d-block transition metal Ti.

Robust PANI@MXene/GQDs Based Fibre Fabric Electrodes via Microfluidic Wet-Fusing Spinning Chemistry.

Two-dimensional (2D) transition metal titanium carbide (Ti3 C2 Tx ) as a promising candidate material for batteries and supercapacitors has shown excellent electrochemical performance, but it is difficult to meet practical applications because of its poor morphology structure, low mechanical properties, and expensive process. Here, w e propose an applied and efficient method based on microfluidic wet-fusing spinning chemistry (MWSC) to construct hierarchical structure of MXene-based fibre fabrics (MFFs), allowing the availability of MFF electrodes with ultra-strong toughness, high conductivity and easily machinable properties. First, a dot-sheet structure constructed by graphene quantum dots (GQDs) and MXene nanosheets with multi-anchor interaction in the microchannel of a microfluidic device enhances the mechanical strength of MXene fibers; next, the interfused fiber network structure of Ti3 C2 Tx /GQDs fabrics assembled by the MWSC process enhances the deformability of the whole fabrics; finally, the core-shell structure of PANI@Ti3 C2 Tx /GQDs architected by in situ polymerization growth of polyaniline (PANI) nanofibers provides more ion-accessible pathways and sites for kinetic migration and ion accumulation. Through the morphology and microstructure design, this strategy has directive significance to the large-scale preparation of conductive fabric electrodes and provides a viable solution for simultaneously enhancing mechanical strength and electrochemical performance of conductive fabric electrodes. This article is protected by copyright. All rights reserved.

Electronic stopping power in titanium for proton and helium ions from first-principle calculations

The energy loss rate from energetic proton and helium ions to electrons of a transition metal titanium (Ti) is studied using real-time time-dependent density functional theory. Nonequilibrium simulations with and without semicore electrons explicitly included in describing the electronic structure of target atoms are performed to understand their involvement in the dissipation mechanism. It is found that the low-lying $3s$ and $3p$ semicore excitations play significant roles in determining the profile of the stopping curve around and above the stopping maximum. Additionally, we investigate the effect of impact geometry on electronic stopping. An important conclusion is that although off-channeling geometry, which makes possible the strong interaction with tightly bound electrons, indeed improves the amplitude of the stopping curve, especially for the regime around the stopping maximum, it does not shift the position of the stopping maximum. Our results about the relation between effective charge and electronic stopping are in qualitative agreement with the linear response theory.

HOMO-LUMO energy gaps of complexes of transition metals with single and multi-ring aromatics

Optical and electronic properties of aromatics and their clusters are critical to interpreting phenomena ranging from flame-formed nanoparticles to interstellar dust. These properties are also important to their applications as organic semiconductor materials. Aromatic hydrocarbons often form coordination bonds with metal atoms and cations, forming complexes with electronic properties that differ from their parent aromatics. Metal incorporation to aromatics allows access to a versatile range of optical and electronic properties via the modulation of their band gaps. Here, we investigate the binding of four fourth-row transition metals (titanium, chromium, iron, and nickel) with four aromatic molecules (benzene, naphthalene, pyrene, and coronene), and the HOMO-LUMO energy gap of the metal-aromatic complexes using density functional theory calculations. Neutral and cationic (1+ and 2+) complexes are studied at different geometrical and spin configurations, and their binding energies and HOMO-LUMO gaps are computed for the ground state. It is observed that binding with metals can reduce the HOMO-LUMO gap of the aromatics significantly, and the gap energy of the metal-aromatic complexes is closely correlated with their ionization energy. The number of possible transitions from occupied to unoccupied molecular orbitals was also calculated, showing similar spectral energy features for naphthalene, pyrene, and coronene with and without metal incorporation.

Effects of transition metals for silicon-based lithium-ion battery anodes: A comparative study in electrochemical applications

The strength, conductivity, elasticity, inactivity against lithium, and tunability properties of transition metals (TMs) are the major reasons these metals are used to synthesize silicon-based lithium-ion battery (LIBs) composite anodes. This is because TMs significantly influence and improve the overall electrochemical performance of LIB electrodes by mitigating the undesired expansion of silicon. The effects of different elemental transition metals copper (Cu), titanium (Ti), nickel (Ni), and iron (Fe) on the electrochemical performance of silicon-based composites were compared, and the phases formed during milling were correlated to the behavior of the composites in which they are present. The excellent performance of these electrodes was attributed to the reaction mechanism of transition metals after the first conversion reaction during lithiation and remained inactive during the ensuing cycles. It was found that the strength and ductile nature of nickel accounts for relieving mechanical stress induced on Silicon during the insertion and extraction of lithium ions. All copper-containing composites showed high stability in cycling but low capacity, which is attributed to the high amounts of copper, contained in these composites and the reaction of copper with silicon during milling. The presence of titanium improved the electrical conductivity and mechanical strength of the electrodes. Iron-containing composites were observed to highly withstand deformation due to the strength of the matrix. Moreover, the addition of 10 wt. percentage carbon improved the cycle performance and rate capability of Cu-Fe-Si-C, Cu-Ni-Si-C, Ni-Fe-Si-C, and Ni-Ti-Si-C. These composites showed stable cycling performance of 654.42 mAh g–1, 686.16 mAh g–1, 657.56 mAh g–1, and 643.29 mAh g–1 respectively after 100 cycles capacity at 1 C.

On the Mechanism of Heterogeneous Water Oxidation Catalysis: A Theoretical Perspective

Earth abundant transition metal oxides are low-cost promising catalysts for the oxygen evolution reaction (OER). Many transition metal oxides have shown higher OER activity than the noble metal oxides (RuO2 and IrO2). Many experimental and theoretical studies have been performed to understand the mechanism of OER. In this review article we have considered four earth abundant transition metal oxides, namely, titanium oxide (TiO2), manganese oxide/hydroxide (MnOx/MnOOH), cobalt oxide/hydroxide (CoOx/CoOOH), and nickel oxide/hydroxide (NiOx/NiOOH). The OER mechanism on three polymorphs of TiO2: TiO2 rutile (110), anatase (101), and brookite (210) are summarized. It is discussed that the surface peroxo O* intermediates formation required a smaller activation barrier compared to the dangling O* intermediates. Manganese-based oxide material CaMn4O5 is the active site of photosystem II where OER takes place in nature. The commonly known polymorphs of MnO2; α-(tetragonal), β-(tetragonal), and δ-(triclinic) are discussed for their OER activity. The electrochemical activity of electrochemically synthesized induced layer δ-MnO2 (EI-δ-MnO2) materials is discussed in comparison to precious metal oxides (Ir/RuOx). Hydrothermally synthesized α-MnO2 shows higher activity than δ-MnO2. The OER activity of different bulk oxide phases: (a) Mn3O4(001), (b) Mn2O3(110), and (c) MnO2(110) are comparatively discussed. Different crystalline phases of CoOOH and NiOOH are discussed considering different surfaces for the catalytic activity. In some cases, the effects of doping with other metals (e.g., doping of Fe to NiOOH) are discussed.

Synthesis of transition metal titanium oxide (MTiOx, M = Mn, Fe, Cu) and its application in furazolidone electrochemical sensor

Importance in the precise determination of Furazolidone (FZD) on biological, food, and water samples were established for regulating health and nutrition, diagnosis/treatment, pharmacological research, and food/drug quality monitoring. Thus, the sensitive and accurate determination of FZD is necessary. Here, we construct facile and low-cost Metal Titanate (MTiOx, M = Mn, Fe, Cu) as an electrode modifier via a different one-step synthesis method. By the virtue of unique properties, MnTiO3 has been successfully employed in the electrochemical evaluation of FZD such as high active surface area (0.1252 cm2) and high electron transfer kinetics with low charge transfer resistance (Rct = 374.65 Ω) with good electro-catalytic kinetic parameters. In this regard, MnTiO3 is employed in the electrochemical evaluation of FZD through cyclic voltammetry (CV) and Differential Pulse Voltammetry (DPV) techniques. The proposed MnTiO3/GCE sensor shows exquisite electrochemical characteristics including a wide linear range (0.05 to 1101.6 µM), nanomolar detection limit (4.05 nM), and encouraging sensitivity (68.77 µA µM−1 cm−2). Moreover, it also exemplifies exquisite selectivity, repeatability, reproducibility, and storage stability therefore; MnTiO3 is employed in the practical feasibility analysis in various real samples, which shows excellent recovery results.

Chlorophyll derivative sensitized monolayer Ti3C2Tx MXene nanosheets for photocatalytic hydrogen evolution

Hydrogen production by photocatalytically splitting water is considered as a promising strategy for solar to chemical energy conversion to solve global energy problems. Ti3C2Tx is a two-dimensional transition metal titanium carbide material with excellent electrochemical properties. Nevertheless, the application of Ti3C2Tx as a co-catalyst in photocatalysis presents many challenges, which is mainly due to its lower photocatalytic activity. In this work, monolayer Ti3C2Tx nanosheets were prepared as efficient co-catalysts for the photocatalytic water splitting for H2 evolution through the delamination and exfoliation process of pristine two-dimensional titanium carbide Ti3C2Tx MXene. In addition, a chlorophyll-a derivative (Chl) was used as an effective visible light harvester by a simple one-step deposition process on monolayer Ti3C2Tx nanosheets, and a novel noble metal-free Chl@monolayer Ti3C2Tx photocatalyst was successfully synthesized for the photocatalytic water splitting to hydrogen evolution reaction (HER). It was found that the optimal Chl@monolayer Ti3C2Tx composite had the best HER performance as high as 106 μmol/h/gcat, which was much higher than that of the pristine Chl@Ti3C2Tx composite.

Observation of high-pressure bcc phase of titanium at 243 GPa

In this study, the pressure-induced phase transition of the 3d transition metal titanium (Ti) has been investigated at pressures up to 290 GPa at room temperature using an x-ray diffraction technique with a micro-beam. From the analysis of powder x-ray diffraction patterns, the high-pressure δ phase (orthorhombic, Cmcm) was found to transform to the β phase (body-centered cubic: bcc, Im3m) at 243 GPa. Although the volume reduction at this phase transition was less than 1%, the coexistence of the δ phase suggests that the transition is of the first order. The isothermal bulk modulus at zero pressure, B0, and the pressure derivative of B0, B0′, were estimated to be 125(2) GPa and 3.46(6) GPa, respectively, by least squares fitting to the Vinet equation of state based on the P–V data of the δ and β phases. This transition to the bcc phase verified predictions from theoretical studies and demonstrated the systematics of the pressure-induced structural phase transition in transition metals.

Study of microwaves energy conversion into electric current on semiconductor material NaxCuyTiz

Converting microwaves energy into electric current has been studied through co-precipitation and sintering process on the semiconductor material. Most of the application of these methods still had a challenge of lowering the resistivity value of semiconductor material. Some researches indicated by adding molten salt into semiconductor material can reduce the resistivity value. In this study, the synthesis process by combining the co-precipitation and sintering method of transition metal (titanium and copper) and alkali metal (Sodium) shown an improvement in lowering resistivity problems. Composition ratio, temperature, and distance of radiation were the variable of measurement in this research. Three semiconductor materials NaxCuyTiz were synthesized by using 60 ml of hydrochloric acid (HCl) and 80 ml of ammonium hydroxide (NH4OH) as a reagent in co-precipitation method and sintering at temperature 500°C. An Olympus microscope was used to analyze the microstructures of all three materials. Fractions x, y, and z in the materials were determined by analysis of X-ray spectrograph model 2501. The resistivity values of three materials, namely as Na0.52Cu0.37Ti0.11, Na0.26Cu0.39Ti0.35, and Na0.26Cu0.67Ti0.07 were obtained by varying the temperature of measurement. The microwave radiation was measured by observing the output voltage and current along with the radiation at a variable distance (60, 90, 10, 150, 180, and 210 cm) through the semiconductor material. The experiment showed that material Na0.52Cu0.37Ti0.11 had low resistivity and small bandgap energy as 0.875 eV and able to convert microwave energy from 1.624 × 10−24 Watt to 9.137 Watt at 60 cm of microwaves radiation distance.

Doping sites observation of deep-level impurities in hyperdoped silicon via high-resolution transmission electron microscopy

The direct observation of the doping sites of deep-level impurities in hyperdoped silicon is essential to determine the impurity diffusion, distribution, and precipitation via different hyperdoping processes or thermal annealing conditions. This is crucial to clarify the functioning of a mechanism, which can improve the impurity electroactivity. However, this observation, which is usually performed by using high-resolution transmission electron microscopy (HRTEM), is limited by some restrictions in the microscopic imaging conditions, such as the microscope resolution, the defocus of the objective lens, the specimen thickness, and the projected orientation of the specimen (i.e. the zone axis). Therefore, to eliminate these restrictions, conventional field-emission-gun HRTEM images in combination with image processing (deconvolution) were investigated in order to obtain structure images with atomic resolution. Both the substitutional and the interstitial doping sites of oxygen, chalcogen (sulfur and selenium), and transition metal (titanium and cobalt) impurities in silicon were determined by image contrast analysis. Finally, the favorable conditions for the direct observation of doping sites were defined.

Coordinative bonding perturbation of some first series transition metal ions by the glycine ligand

The coordinative bonding interaction involving glycine ligand with three randomly, selected transition metals ions chromium, nickel and titanium is analysed using standard perturbation principles. The experimental data is collected by accurately measuring the spectral shifts or relative strengths of perturbations from corresponding electronic spectra of the solution complexes and through supportive DFT calculations using some innovative approaches. The observed spectral shifts are interpreted as glycine ligand perturbations on the appropriate excited electronic state of the transition metal ion following coordinative bonding interaction. The neighbouring excited but unperturbed states including the ground state facilitate the redistribution of the perturbation energy within the manifold of the transition metal ion electronic energy states. The information allows for a detailed new insight into the intrinsic mechanism of coordinative bonding interaction.

A comparative study of the interaction of nickel, titanium, palladium, and gold metals with single-walled carbon nanotubes: A DFT approach

Abstract Interactions between transition metal atoms, nickel, titanium, palladium and gold and (3,3), (4,2), (6,0) and (5,1) carbon nanotubes were studied using first principles calculations. The Fermi energy levels of the carbon nanotubes studied were found to increase during interactions with the transition metal atoms. Amongst the four metals, gold atom was found to have an enhanced interaction with the nanotubes transforming from semiconducting to a conducting tube. Titanium was also found to show similar characteristics to gold only when the atom was placed in the middle of the carbon nanotubes. Nickel and palladium atoms interactions did not affect much the electronic properties of the carbon nanotubes, with some slight changes in the electronic properties at some specific sites of the nanotubes. It is proposed from this study that, the carbon nanotube-metal interactions could be used as a guide to shed light on the electronic properties of such materials which could become promising engineering materials and revolutionize the electronic industry.

Structure, thermal stability and chromaticity investigation of TiB2 based high temperature solar selective absorbing coatings

Transition metal titanium diboride (TiB2) is a promising material for the solar selective absorbing coatings due to its favorable spectral selectivity and thermal stability. In this research, spectrally selective TiB2/Al2O3 tandem absorber is deposited on stainless steel (SS), which exhibits a high solar absorptance (αs = 0.93) and a low thermal emissivity (ε = 0.11). In this tandem absorber, the TiB2 acts as the main absorber layer and the Al2O3 acts as an antireflection layer. The tandem absorber coating is systematically characterized by ultra-high resolution scanning electron microscope (SEM), UV–vis-NIR spectrophotometer, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Micro-Raman techniques. The thermal stability in vacuum of the SS/TiB2/Al2O3 tandem absorber coatings is investigated in the temperature range of 400–800 °C for 2 h and 100 h, respectively. SEM and Raman spectra indicate that the change of surface morphology and chemical composition for the coating result in the degradation of optical performance. With the different annealed temperature, the SS/TiB2/Al2O3 tandem absorber coatings exhibit different color, which is further investigated using chromaticity diagram.

Chemical, Morphological, Structural, Optical, and Magnetic Properties of Transition Metal Titanium (Ti)-Doped LaFeO3 Nanoparticles

In the present work, pure and transition metal titanium (Ti)-doped LaFe1−xTixO3(x = 0.0, 0.2, 0.4, and 0.6) nanoparticles have been successfully synthesized by hydrothermal synthesis technique for various molar ratios of 0.2, 0.4, and 0.6. The prepared samples were grinned and annealed in furnace at 600 ∘C/4 h. The X-ray diffraction (XRD) analysis confirms the phase orthorhombic formation of LaFeO3 and Ti-doped LaFeO3. The stoichiometric analysis was performed through energy-dispersive X-ray studies (EDX). The micro-structural features of surface morphology were examined by field emission scanning electron microscopy (FESEM). Further, surface nanocrystalline of the titanium (Ti)-doped LaFe1−xTixO3 was also investigated through high-resolution transmission electron microscopic (TEM) analysis. The enhancement of room temperature magnetization value has been observed from the M–H curve which is measured using vibrating sample magnetometer (VSM).The weak ferromagnetic behavior was observed from hysteresis loop. From hysteresis loop, saturation takes place when the applied magnetic field intensity is 15 kOe.

Trimetallic oxide nanocomposites of transition metals titanium and vanadium by sol-gel technique: synthesis, characterization and electronic properties

Novel titanium and vanadium based trimetallic oxide nanocomposites (TMONCs) have been synthesized using metal salts of titanium-vanadium along with three others metals viz. tin, aluminium and zinc as precursors by the sol-gel method. Aqueous ammonia and hydrazine hydrate were used as the reducing agents. The preparations of nanocomposites were monitored by observing the visual changes during each step of synthesis. The synthesized TMONCs were characterized using UV–vis, SEM, EDX, TEM and DLS. Band gap of the synthesized TMONCs ranges from 3–4.5 eV determined using tauc plot. FTIR study revealed the molecular stretching and bending peaks of corresponding M–O/M–O–M bonds thus confirming their formation. Molecular composition and particle size were determined using EDX and DLS respectively. Molecular shape, size and surface morphology have been examined by SEM and TEM.

Nonlinear optical and electronic properties of Cr-, Ni-, and Ti- substituted C20 fullerenes: A quantum-chemical study

Density functional theory calculations have been performed for structures, electronic and non-linear optical properties of C20 fullerene and transition metals (chromium, nickel, and titanium) doped fullerene. The NBO charge distribution analysis reveals that doping with transition metal alters the charge distribution of C20 fullerene. The changes are more pronounced on doping with Ti followed by Cr and Ni, respectively. The dipole moment for TiC19 is higher than Cr C19 and NiC19 and it decreases monotonically across the period. The first hyperpolarizability of C20 fullerene is remarkably increased by transition metal doping. The first hyperpolarizability of Ti C19 is 2.5×103, three orders of magnitude higher than that of pure fullerene. The density of states (DOS), and frontier molecular orbital analyses confirm significant orbital hybridization upon metal doping in C20 fullerene, which suggest potential application of new clusters which may be important for the future development of fullerene-based nanodevices.

Dynamical study of Debye temperature and combined density of states of TiO2

In present paper, it is focused on theoretical study of TiO2 with particular emphasis on vibrational phonon properties by means of van der Waals three-body force shell model (VTBFSM). Present model includes van der Waals interactions (VWI) and three-body interactions (TBI) in the framework of both ion polarizable rigid shell model (RSM) with short-range interactions effective up to the second neighbor. The Coulombic ion–ion interaction contribution to the dynamical matrix is calculated by the Kellerman.1 Therefore, it may be inferred that the present model is the most realistic model for complete harmonic dynamical behavior of the crystals. The lattice dynamical study of phonon properties of transition metal titanium dioxide (TiO2) has been presented by means of VTBFS model. Titanium is an extremely light semiconducting material, exhibiting stable bcc structure in a certain temperature range 0–300 K normal pressures Debye temperature variation and combined density of states (CDS) of TiO2 has been studied in this work. At high temperature, strength and oxidation resistance of Ti alloys has improved. The model predictions are found to be in reasonable agreement with experimental data.2