Effect Of Ti-doping Research Articles

Effect of Ti-doping on peeling resistance of primary M7C3 carbides in hypereutectic Fe[sbnd]Cr[sbnd]C hardfacing coating and γ-Fe/M7C3 interfacial bonding strength

Alloying element Ti plays an important role in improving the mechanical properties of hypereutectic FeCrC hardfacing coating, but its peeling resistance have been neglected. Here, the hardness and wear rate of the hypereutectic FeCrC and FeCrCTi hardfacing coatings were measured. The crystal structure and orientation relationship of primary M7C3 carbide and eutectic austenite matrix were confirmed. Then, the interface properties of γ-Fe//M7C3(Ti) interface were calculated by first principles. The results show that the micro-Vickers and macroscopic Rockwell hardness of the FeCrCTi hardfacing coating are increased, and its wear rate is decreased from (4.33 ± 0.333) × 10−6 mm3/Nm to (3.64 ± 0.366) × 10−6 mm3/Nm. The Ti-doping can effectively inhibit the initiation and propagation of cracks and improve the peeling resistance of M7C3 carbide. Meanwhile, the orientation relationship of eutectic austenite/primary M7C3 carbide is γ-Fe(111)//(Cr, Fe)7C3(101¯0). Among CFe1, CrFe1 and FeFe1 interfaces, interface energy of FeFe1 model is the smallest (1.954 J/m2), and its adhesion work (Wad) is the largest (0.756 J/m2). Moreover, Wad of Ti-doped interface (4.123 J/m2) is larger than that of FeFe1 one (3.045 J/m2) after relaxed, which indicates Ti-doping is beneficial to enhance adhesive strength between γ-Fe//M7C3 interfaces, which improves the peeling resistance of M7C3 carbide.

Effect of Ti-doping and Octahedral Morphology on Electrochemical Performance of Lithium Manganate Oxide as Cathode Materials for LIBs

Effect of Ti-doping and Octahedral Morphology on Electrochemical Performance of Lithium Manganate Oxide as Cathode Materials for LIBs

Low power Ti-doped NbO2-based selector device with high selectivity and low OFF current

The crossbar array-based resistive memory is considered a potential architecture for high-density nonvolatile memory applications. However, the sneak current path problem associated with the crossbar array structure limits its use in practical applications. This limitation can be removed by employing a selector device in the crossbar array structure. Therefore, we propose NbO2 as a selector device as it operates at a rapid speed during the insulator-metal transition (IMT). Herein, we fabricated a Ti-doped NbO2 selector device and demonstrated a very low OFF current (5 × 10-11 A). The effect of Ti doping in the NbO2 device was studied by varying the Ti concentration during a radio frequency co-sputtering process. We intentionally prevented the formation of Nb2O5, and a high-quality NbO2 layer was deposited with an appropriate Ti concentration. Furthermore, we modulated the IMT characteristics of the NbO2 device by varying the Ti concentration. The fabricated Ti-doped NbO2 selector device showed an ION/IOFF ratio greater than 5 × 104. Additionally, a drift-free fast switching operation (<20 ns) was achieved for the optimized selector device. These results suggest the high suitability of IMT-based NbO2 devices in selector applications.

Enhanced optoelectronic properties of Ti-doped ZnO nanorods for photodetector applications

We report the effect of Ti-doping on structural, morphological, photoluminescence, optical and photoconductive properties of ZnO thin films. Pure and Ti(1, 3 and 5%)-doped ZnO thin films are deposited by the successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction analysis revealed the single-phase hexagonal wurtzite ZnO structure of all the films. Scanning electron microscope images suggest the formation of rod shaped particles in Ti-doped ZnO thin films. Photoluminescence spectra of all the films show emission peaks centered at 398 nm, 413 nm, 438 nm, 477 nm and 522 nm wavelengths. Optical properties support the semiconducting nature of all the films. The optical bandgap values are estimated to be 3.29 eV, 3.26 eV, 3.19 eV and 3.23 eV for ZnO, ZnO:Ti(1%), ZnO:Ti(3%) and ZnO:Ti(5%) thin films, respectively. Photoconductivity study indicates that ZnO:Ti(3%) thin film exhibits high responsivity, external quantum efficiency and detectivity of 0.30 AW-1, 97% and 5.49 × 1010 Jones, respectively, among all the films. The enhanced photoconductivity of Ti-doped ZnO thin films make them useful for optoelectronic applications.

Chiral charge density waves induced by Ti-doping in 1T-TaS2

We investigate the Ti-doping effect on the charge density wave (CDW) of 1T-TaS2 by combining scanning tunneling microscopy measurements and first-principle calculations. Although the Ti-doping induced phase evolution seems regular with an increase of the doping concentration (x), an unexpected chiral CDW phase is observed in the sample with x = 0.08, in which Ti atoms almost fully occupy the central Ta atoms in the CDW clusters. The emergence of the chiral CDW is proposed to be from the doping-enhanced orbital order. Only when x = 0.08, the possible long-range orbital order can trigger the chiral CDW phase. Compared with other 3d-elements doped 1T-TaS2, the Ti-doping retains the electronic flatband and the corresponding CDW phase, which is a prerequisite for the emergence of chirality. We expect that introducing elements with a strong orbital character may induce a chiral charge order in a broad class of CDW systems. The present results open up another avenue for further exploring the chiral CDW materials.

Atomic Insights into Ti Doping on the Stability Enhancement of Truncated Octahedron LiMn2O4 Nanoparticles.

Ti-doped truncated octahedron LiTixMn2-xO4 nanocomposites were synthesized through a facile hydrothermal treatment and calcination process. By using spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM), the effects of Ti-doping on the structure evolution and stability enhancement of LiMn2O4 are revealed. It is found that truncated octahedrons are easily formed in Ti doping LiMn2O4 material. Structural characterizations reveal that most of the Ti4+ ions are composed into the spinel to form a more stable spinel LiTixMn2−xO4 phase framework in bulk. However, a portion of Ti4+ ions occupy 8a sites around the {001} plane surface to form a new TiMn2O4-like structure. The combination of LiTixMn2−xO4 frameworks in bulk and the TiMn2O4-like structure at the surface may enhance the stability of the spinel LiMn2O4. Our findings demonstrate the critical role of Ti doping in the surface chemical and structural evolution of LiMn2O4 and may guide the design principle for viable electrode materials.

Synergistic effect of ultrathin thickness and surface oxygen vacancies in high-efficiency Ti-mediated Bi2MoO6 for immense photocatalytic nitrofurantoin degradation and Cr(VI) reduction

Crystal defects have been broadly regarded to modulate the photoreactivity of semiconductors, mostly concerning the crystal and electronic structure of materials. On the other hand, oxygen defect-engineering is a fundamental approach to improve the photolysis activity of materials. Herein, an interactive hybrid intermediate strategy with oxygen defect-engineering was utilized to fabricate atomically-thin Ti-doped Bi2MoO6 nanosheets. Experimental results unveil that the well-engineered ultrathin Ti-doped Bi2MoO6 nanosheets tune the morphology, visible light absorption, local atomic and electronic band structure of Bi2MoO6. Importantly, the Ti-doping hugely affects the BET specific surface area and porosity of Ti-Bi2MoO6 (72 m2 g−1) in contrast to bulk Bi2MoO6, which is 19 m2 g−1. Furthermore, the density functional theory calculations were carried out to explore the effect of Ti-doping on electronic band structure and the surface charge distribution in Ti-Bi2MoO6. It was found, rather than acting as a recombination center for photogenerated charge carriers, the defect caused by Ti doping mediated O vacancies in the crystal structure of Bi2MoO6, which favors the photogenerated charge carriers transfer and enhances the photocatalytic reactivity due to delocalized nature. With the advantages of atomically-thin structure Ti-Bi2MoO6 nanosheets, the synergistic effect of ultrathin thickness of Ti-Bi2MoO6 and oxygen vacancies has remarkably improved the photocatalytic activity towards the degradation of nitrofurantoin, and photoreduction of Cr(VI) in a highly acidic and alkaline medium. The present work opens a door for enhancing the photolysis performance of Bi2MoO6-based photocatalysts with excellent photolysis activity in the various environmental remediation processes.

Effect of Ti-doping on dosimetric properties of MgAl2O4 single crystals

Optical and dosimetric properties of Ti-doped (0.05, 0.1, 0.2, and 0.5%) MgAl2O4 single crystals grown by the floating zone method were investigated. All Ti-doped MgAl2O4 single crystals showed photoluminescence (PL) and thermally stimulated luminescence (TSL) at 470 nm. The PL decay time constant of this luminescence was approximately 6 μs, and the emission origin was ascribed to charge transfer (CT) related to Ti4+. The 0.1% Ti-doped MgAl2O4 single crystal showed the highest intensity of TSL glow peaks unlike the result of PL quantum yields (QYs). In TSL dose response functions, 0.1 and 0.2% Ti-doped MgAl2O4 single crystals showed detection limit that comparable with some commercial products.

Influence of milling energy of in-situ precursor powder on the properties of Ti-doped MgB2

The effect of Ti-doping on the electrical properties of MgB2 bulks was studied in dependence on the milling energy of the used in-situ precursor powder. Ti-powder was added to a mixture of Mg- and B-powder before milling in three different concentrations related to the atomic weight of Mg (Mg1-xTixB2 with x = 0.025/0.05/0.1). From each doping concentration two different powders were milled with a planetary ball mill (for 1 resp. 10 h, rotation speed 250 rpm). This corresponds to a milling energy of 5⋅108 J/kg resp. 5⋅109 J/kg. The electrical resistivity in normal state of the bulk samples is increasing by Ti-doping. The most interesting point is the influence of Ti-doping on the magnetic field dependence of the critical current density jc of samples prepared with powders milled with different energy. A remarkable increase of jc was found with increasing Ti-content at 4.2 K and external fields higher than around 4 T for the powder with lower milling energy. Not any effect could be measured at the powder milled with higher energy. If we take into account that the grain sizes of the samples prepared with higher energy milled powder is remarkably smaller than that of the other sample it can be noticed that Ti-doping has only a distinct effect on the grain size, like discussed in [1], of samples with coarser powder, not on high energy milled powders.

Effect of Ti Doping on Microstructure and Wear Resistance of CoCrCuFeMn High-entropy Alloys

Effect of Ti Doping on Microstructure and Wear Resistance of CoCrCuFeMn High-entropy Alloys

Synergistic effects of Ti-doping induced porous networks on electrochromic performance of WO3 films

In this study, amorphous Ti-doped WO3 films with interpenetrated porous networks were successfully fabricated via a facile sol–gel method by using a hydrolysis-tolerant titanium coupling agent (TCA) as a Ti-dopant.

Effect of Ti doping on the phase transitions, magnetocaloric effect, and exchange bias in Ni43Mn46Sn11−xTix Heusler alloys

In this work, we systematically studied the influence of Ti doping on the crystal structure, martensitic transition, magnetocaloric effect, and exchange bias in Ni43Mn46Sn11−xTix alloys. With the increase of Ti concentration, the martensitic transformation temperature increases gradually due to the effect of lattice contraction, and the ferromagnetic ordering windows in the martensitic and austenitic regions are closed at x = 1 and x = 2, respectively. This study demonstrates that relatively large magnetic entropy changes can be obtained around the paramagnetic-paramagnetic martensitic transformation under high magnetic field. Another effect of Ti doping is the enhancement of antiferromagnetic interaction, which resulting in the transformation of ground state from reentrant-spin-glass to canonical spin-glass for x⩾1. The zero-field-cooled exchange (ZEB) was realized in the composition range of 1⩽x⩽4, of antiferromagnetic interactions is a viable way to achieve ZEB in NiMn-based Heusler alloys.

Effects of Ti Doping on Hematite Photoanodes: More Surface States.

Ti doped hematite photoanodes have been intensively investigated due to their excellent activity for photoelectrochemical water oxidation. However, little attention has been paid to the doping effect on the photocurrent onset potential of hematite and the underlying mechanism. In this paper, Ti doped hematite nanorod arrays were successfully prepared through a facile treatment of hematite with TiCl₃ solution. The photocurrent of the Ti doped hematite photoanode increases by three times, and its onset potential shifts more positively as compared with that of the undoped one. Electrochemical analyses were employed to unravel the mechanism of anodic shift of the onset potential. Cyclic voltammograms and electrochemical impedance spectra confirmed that more surface states were formed in Ti doped hematite than the undoped one. As a result, lower activity towards oxygen evolution reaction (OER) and increased electron-hole recombination after light on/off in low potential region were observed in Ti doped hematite. It is concluded that these doping induced surface states may be a hindrance to charge transfer and the onset potential of Ti doped hematite shifts anodically.

Impact of low titanium concentration on the structural, electrical and dielectric properties of Pr0.75Bi0.05Sr0.1Ba0.1Mn1−xTixO3 (x = 0, 0.04) compounds

In this work, we report the effect of Ti-doping on the structural, electrical and dielectric properties of Pr0.75Bi0.05Sr0.1Ba0.1Mn1−xTixO3 (x = 0 and 0.04) manganites synthesized by sol–gel route. X-ray structural analysis using Rietveld refinement technique reveals that our samples are single phase and crystallize in the orthorhombic system with Pbnm space group. These structures were characterized by impedance spectroscopy in the frequency range from 40 to 1 MHz and temperatures between 80 and 400 K. DC conductivity analysis shows that our samples disclose a semiconductor behaviour with a semiconductor–metal transition temperature TMS at 380 and 360 K for x = 0 and 0.04 respectively. This result shows that the TMS temperature can be controlled by varying the titanium content. AC conductivity (σAC) results show a considerable sensitivity to both temperature and frequency. The impedance plots were well described by an equivalent circuit model taking into account the contributions of semiconductor grains and insulating grain boundaries in the conduction mechanism. Furthermore, a non-Debye type of relaxation in our compounds was confirmed. In addition, we have demonstrated that the dielectric relaxation is hidden by the DC conduction mechanism.

Effects of Ti Doping on the Structural Stability and Enhanced Electrochemical Performance of α‐LiVOPO4

Lithium vanadyl phosphate has seven different crystallographic phases. Among them, α‐LiVOPO4 is chosen because of its relatively high energy density and redox voltage of 3.9 V compared to the other phosphates. In this study, Ti4+‐doped α‐LiV1−xTixOPO4 (x = 0.00, 0.003, 0.005, 0.007, and 0.01) was prepared using a sol–gel method to increase the structure stability and electrochemical performance. The triclinic structure with the space group P‐1 was confirmed by X‐ray diffraction, Fourier‐transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. Inductively coupled plasma–optical emission spectroscopy was conducted to determine the precise state. The shape and size of the particles were observed by field‐emission scanning electron microscopy. In situ X‐ray absorption spectroscopy was performed to confirm the structural behavior during the electrochemical reaction. Electrochemical measurements such as cyclic voltammetry and galvanostatic charge–discharge were conducted. α‐LiV1−xTi xOPO4 (x = 0.003, 0.005, 0.007, and 0.01) showed structural stability during cycling as well as decreased polarization during charge and discharge with the increased diffusion coefficient of lithium ions. α‐LiV0.995Ti0.005OPO4 showed the best cycling stability and rate capability among all the samples examined because Ti doping retained its site to prevent structural collapse.

Influence of Ti-doping on the magnetic exchange interaction of La0.5Ca0.5MnO3 nanoparticles

The striking effect of Ti-doping on the magnetic properties of La0.5Ca0.5MnO3 nanoparticles have been investigated by different methods. The half doped manganites are at the boundary between the ferromagnetic metallic and antiferromagnetic insulating phases. There is a delicate balance between ferromagnetic double exchange and antiferromagnetic superexchange interactions. In half doped La0.5Ca0.5MnO3 charge ordered antiferromagnetic state is destabilized below a critical size followed by development of ferromagnetism. We have seen that slight disturbance in magnetic exchange interactions by Ti-substitution (>5%) drastically changes the fraction of ferromagnetic clusters. The ferromagnetic Mn3+—O—Mn4+ interaction is suppressed by Mn3+—O—Ti4+ type of interactions. For more than 10% Ti doping the surface ferromagnetic character of the nanoparticles is largely weighed down. This suppression of ferromagnetic component by diamagnetic Ti-doping eventually leads to phase separated states with lower magnetization value.

Effect of Ti Doping on the Photoelectrochemical Water Splitting Efficiency of WO3 Photoanode

Photocatalytic/photo-electrochemical (PEC) water splitting is a process whereby H2O is split into H2 and O2 using sunlight. This solar to chemical conversion (specifically, solar-energy-driven H2 production) is an ambitious yet crucial objective for futuristic production of eco-friendly energy that is storable and transportable and can be efficiently converted into electricity using fuel cells whenever necessary. Most importantly, this process is believed to lay the foundation for a sustainable hydrogen-based energy economy, which represents a carbon-neutral approach for producing hydrogen gas using the most abundant renewable resources: water and sunlight. WO3, an n-type semiconductor, has been extensively studied as a photoanode for PEC water splitting because of its advantages such as non-toxicity, low cost, and chemical stability in acidic aqueous media. Furthermore, WO3 has a moderate hole diffusion length (~150 nm) compared to other oxides such as Fe2O3 (2–4 nm) and TiO2 (~100 nm), with inherently good electron transport properties. After absorbing a portion of the visible light during illumination, WO3 generates electron–hole pairs and its valence band edge can provide enough potential for the oxidation of water since it is located at approximately 3.0 eV versus NHE. Several strategies have been implemented to enhance the photocatalytic properties of WO3, such as morphological control, transition metal doping, noble metal loading, surface sensitization, and formation of composite materials. In particular, doping and co-doping are possible ways of tailoring the electronic band structure as well as the PEC properties of WO3. Therefore, photo-electrochemical properties of tungsten oxide (WO3) can be tailored by doping foreign atoms from which conduction band (CB)/valence band (VB) edge positions can be altered. Band edge engineering for WO3 is essential since VB maximum of WO3 is more positive more the photo-oxidation potential of H2O but CB minimum of WO3 is lower than the reduction potential of H2O to limit spontaneous solar water reduction. In view of this, here we propose a simple, single step and efficient strategy for band edge tailoring of WO3 by Ti doping for efficient solar water splitting. The physical properties of synthesized Ti doped WO3 thin films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDS), UV-Vis absorption spectra and X-ray photoelectron spectroscopy (XPS). The incorporation of Ti into WO3 reduces the crystallinity and increases the band gap of WO3. From XPS valence band analysis, we confirm that, substitution Ti into WO3 leads to slight shift up the CB maximum upwards more closed to the H+/H2 redox potential without any change in VB maximum. Compared to un-doped WO3, Ti doped WO3 exhibited an unprecedented photocurrent of 1.6 mA cm-2 (at 0.8 V vs Ag/AgCl) under simulated 1.5 AM sunlight without an added water oxidation catalyst due to the improved electrical conductivity and reaction kinetics after Ti doping. The method presented here, demonstrates a simple but systematic and efficient approach for the design and fabrication of band edge tailored WO3 photoanodes via Ti doping efficient for photo-electrochemical water splitting. Figure 1

Effect of Ti-doping on the electrochemical performance of sodium vanadium(iii) phosphate.

Na3V2−xTix(PO4)3 (x = 0.00, 0.05, 0.10, and 0.15) was successfully synthesized by a conventional solid-state route. The XRD results show that Ti is incorporated in the lattice of Na3V2(PO4)3 and the tetragonal structure has not been changed after doping. Among all the composites, the Na3V1.9Ti0.1(PO4)3 composite delivers the highest discharge capacity of 114.87 mA h g−1 at 0.1C and possesses a capacity retention of 96.23% after 20 cycles at 0.1C, demonstrating the better rate performance and cycle stability in the potential range of 2.0–3.8 V. Electrochemical impedance spectroscopy (EIS) results reveal that the Na3V1.9Ti0.1(PO4)3 composite has a lower charge transfer resistance and a higher Na-ion diffusion coefficient compared to other composites. The results indicate that Ti-doping in Na3V2(PO4)3 can effectively enhance the electrochemical performance of this tetragonal compound, especially at a high charge/discharge rate.

Effect of Ti-doping on optical and structural properties of ZnO films grown by spin coating method

ABSTRACT ZnO films with and without Ti doping were deposited on the glass substrate by the spin coating method. Zn1-xTixO films have been investigated by the XRD, field emission scanning electron microscopy (FESEM), energy dispersive x- ray spectroscopy, UV-VIS spectroscopy and atomic force microscopy (AFM) analyses. FESEM images have shown that films surface morphology clearly altered with different Ti content. AFM measurements have shown that the root mean square roughness have increased from 6.18 nm to 12.3 nm by increasing Ti doping content. By increasing Ti concentration, the transparency of the ZnO films decreased while the optical band gap increased.

Effect of Ti Doping to Maintain Structural Disorder in InOx-Based Thin-Film Transistors Fabricated by RF Magnetron Sputtering

The effect of Ti doping in an indium oxide (InOx)-based semiconductor is investigated for the thin-film transistor (TFT) property and crystal structure of the film. InOx and Ti-doped InOx (InTiOx) films deposited by RF magnetron sputtering under the same O2 partial pressure conditions were systematically compared. The TFT behavior of the InOx showed higher conductivity than that of the InTiOx and was drastically changed to metallic conduction after annealing at 150 °C. Under the annealing conditions when the electrical transition to the metallic behavior occurred, the InOx film was crystallized. The X-ray diffraction analysis revealed that the shrinkage of the In2O3 unit cell is pronounced in the case of InOx films. Thus, Ti dopants may play the role as a suppressor for shrinkage of the unit cell, i.e. maintaining neighboring In–In distances, in addition to suppression of oxygen vacancies. The In–In distance, which is related to the overlapping of In 5s orbitals, is considered to be one of the key factor for which InOx-based materials are utilized as conducting films or semiconducting channels.