Ti Doping Research Articles

Unlocking the Performance of Next-generation Non-volatile Capacitive Memory Devices with Ti-doped ZnO Nano Wires via Pulsed Laser Deposition

This paper investigates the impact of titanium (Ti) doping on zinc oxide (ZnO) nano wires (NWs) in non-volatile capacitive memory devices (NVCMDs) through fabrication and characterizations. ZnO NWs were fabricated using pulsed laser deposition (PLD), while Ti thin film (TF) was deposited via electron beam evaporation (e-beam). Field emission gun scanning electron microscopy (FEGSEM) confirmed the formation of ZnO NWs and Ti-doped ZnO NWs (Ti:ZnO NWs) on an n-type silicon (Si) substrates, with elemental compositions determined by energy dispersive X-ray spectroscopy (EDX). Structural characterization was conducted on the samples using high-resolution X-ray diffraction (HRXRD). Gold (Au) interdigitated electrodes (IDE) were employed to fabricate two distinct devices: Au IDE/ZnO NWs and Au IDE/Ti:ZnO NWs. Comparative analysis revealed that the Au IDE/Ti:ZnO NWs device exhibited a lower frequency dispersion fd value (0.025×109 F) compared to Au IDE/ZnO NWs device (0.029×109 F), indicating enhanced signal propagation due to Ti doping. The Au IDE/Ti:ZnO NWs device also demonstrated a high free charge carrier donor concentration ND value of 2.02×1012 /cm3, a significant trap concentration Nt value of 4.44×1011 /cm3 at an 8MHz frequency response. Additionally, it exhibited lower tangent loss (tan(δ)) value of 7430, maximum conductance Gmmax value of 13.40 mS, lower interface trap state density (ITSD) value of 2.05×1014 eV1 cm2, a maximum memory window (∆VMW) of 6.9V at ±15V, improved endurance, and superior data retention, making the Au IDE/Ti:ZnO NWs device a promising candidate for next-generation NVCMDs applications.

Enhancing CO2 Adsorption on MgO: Insights into Dopant Selection and Mechanistic Pathways

Inspired by our recent success in designing CO2-phobic and CO2-philic domains on nano-MgO for effective CO2 adsorption, our ongoing efforts focus on incorporating dopants into pristine MgO to further enhance its CO2 adsorption capabilities. However, a clear set of guidelines for dopant selection and a holistic understanding of the underlying mechanisms is still lacking. In our investigation, we combined first-principles calculations with experimental approaches to explore the crystal and electronic structural changes in MgO doped with high-valence elements (Al, C, Si, and Ti) and their interactions with CO2. Our findings unveiled two distinct mechanisms for CO2 capture: Ti-driven catalytic CO2 decomposition and CO2 polarization induced by Al, C, and Si. Ti doping induced outward Ti atom displacement and structural distortion, facilitating CO2 dissociation, whereas C doping substantially bolstered the electron donation capacity and CO2 adsorption energy. Pristine and C-doped MgO engaged CO2 through surface O atoms, while Al-, Si-, and Ti-doped MgO predominantly relied on dopant–O atom interactions. Our comprehensive research, integrating computational modeling and experimental work supported by scanning electron microscopy and thermal gravimetric analysis, confirmed the superior CO2 adsorption capabilities of C-doped MgO. This yielded profound insights into the mechanisms and principles that govern dopant selection and design.

Zero-Strain Metal-Insulator Transition by the Local Fluctuation of Cation Dimerization.

The coupled electronic and structural transitions in metal-insulator transition (MIT) hinder ultrafast switching and ultimate endurance. Decoupling these transitions and achieving a zero-strain electronic MIT can overcome the fundamental limitations of MIT in solid materials. Here, this study demonstrates that iso-valent Ti dopants in supercooled VO2 epitaxial films cause MIT with minimal hysteresis without changing unit-cell volume and crystal symmetry. The Ti dopants in the VO2 lattice locally alter the configuration of V-V pairs, where the long-range ordering in V-V pairs is disrupted, and the nano-domains of V-V dimers are formed. Strikingly, these local V-V dimers persist even above the electronic transition temperature (TMI), facilitating the zero-strain electronic MIT with nanoscale structural heterogeneity. The geometrically compatible interface between insulating and metallic phases drastically enhances switching speed and endurance during electrically and optically driven zero-strain MIT. This discovery offers a fresh perspective on the scientific understanding of MIT and the improved functionality in terms of device speed and reliability by decoupling electronic and structural transitions.

Theoretical Calculation of Dissolved Gas in Transformer Oil Using the Gas Sensitive Properties of Sc- and Ti-Modified ZrS2.

To guarantee the secure functioning of the complete power system and minimize the risks associated with oil-filled transformers during their operation, it is greatly important to carry out gas sensing studies of dissolved gases in transformer research. Through the utilization of first-principles density functional theory calculations, the adsorption energy, electronic characteristics, and recuperation duration of ZrS2 modified with Sc and Ti were examined. The results show that compared to those of the initial ZrS2 material, the doping of TM atoms Sc and Ti significantly improved the adsorption properties of the material, and the adsorption of CO and C2H4 showed chemisorption. The adsorption capacity for gases decrease in the following order: C2H4 > CO > H2. The calculated recovery times indicate that Sc-ZrS2 and Ti-ZrS2 were ideal carbon monoxide sensing materials under the specific conditions. The results of this work can establish a fundamental rationale for the use of ZrS2 in sensing the conditions of oil-immersed transformers.

Multi-scale structure and reinforcement mechanisms of multi-element composite ceramic coatings

Ceramic coating is of significant importance for improving metallic materials in terms of mechanical properties or durability, which is commonly encountered in the field of machinery, civil engineering, and aerospace, etc. However, ceramic materials optimization is a great challenge due to the complex multi-scale design from atomic to macro level. This paper investigates the multiscale characteristics of multi-element composite ceramic coating, including electronic properties, 3D pore structure, and engineering performances and gives their bottom-up connections, via first-principles calculations and multiscale experiments. The doping of Ti, Zr, and Ce in the alumina-based ceramic crystal improves the overlap of electronic clouds between oxygen and metal atoms, which modifies the atomic charges and enhances the ionic bonding. In terms of microstructure, it reveals the mechanisms of phase transformation toughening effect of ZrO2 and the grain refinement and grain boundary purification effects of CeO2, which facilitates the amelioration of pore structure and macro mechanical properties. It provides multiscale information on the phase stability of multi-element alumina-based ceramics, shedding light on the fundamental atomic level mechanisms that play a crucial role in customizable functional designs.

Real-space investigation of polarons in hematite Fe2O3.

In polarizable materials, electronic charge carriers interact with the surrounding ions, leading to quasiparticle behavior. The resulting polarons play a central role in many materials properties including electrical transport, interaction with light, surface reactivity, and magnetoresistance, and polarons are typically investigated indirectly through these macroscopic characteristics. Here, noncontact atomic force microscopy (nc-AFM) is used to directly image polarons in Fe2O3 at the single quasiparticle limit. A combination of Kelvin probe force microscopy (KPFM) and kinetic Monte Carlo (KMC) simulations shows that the mobility of electron polarons can be markedly increased by Ti doping. Density functional theory (DFT) calculations indicate that a transition from polaronic to metastable free-carrier states can play a key role in migration of electron polarons. In contrast, hole polarons are significantly less mobile, and their hopping is hampered further by trapping centers.

Investigation of the Effects of Different Phases of TiO2 Nanoparticles on PVA Membranes

Introduction: PVA/TiO2 nanocomposite membranes are prepared by solution casting technique where different phases of TiO2 nanoparticles like brookite, brookiterutile and rutile are dispersed in PVA matrix. Sol-gel method was employed to prepare TiO2 nanoparticles, while different phases of TiO2 have been obtained by controlling the calcination temperature. Methods: PVA/TiO2 nanocomposite membranes were characterized by XRD, FTIR, AFM, TEM, UV-visible and PL techniques. XRD results confirmed the presence of different phases of TiO2, exhibiting 3.3 nm, 8.4 nm, and 35.7 nm mean crystalline size. The XRD studies also confirmed that TiO2 nanoparticles became properly dispersed to the PVA matrix, leading to increased PVA crystallinity after doping of different phases of TiO2 nanoparticles. UV-visible analysis revealed an increase in absorption intensity and peak position shifts slightly towards longer wavelengths, which indicates that nanofillers tuned the band gap of PVA. The doping of the TiO2 (brookite) phase in the PVA matrix results in a decreased in PL intensity. Results: This suggests that the PVA/TiO2 (brookite) membrane exhibits a greater degree of photocatalytic activity in comparison to the other two composites. According to the FTIR investigation, the hydroxyl (OH) groups present in PVA interact with the dopants Ti+ ions via intra- and intermolecular hydrogen bonds to produce charge transfer complexes (CTC). The AFM study shows surface roughness details for PVA and PVA/TiO2 composite membranes. The average grain size of TiO2 nanoparticles calculated from TEM images is in good agreement with the grain size calculated by XRD. Conclusion: By adjusting the phase of TiO2 nanoparticles into PVA matrix, composites can be developed that are optimized for a variety of applications such as water purification, UV protection, self-cleaning surfaces, lithium-ion batteries, and optoelectronic devices.

A superior Mn5CeTi5Ox catalysts for synergistic catalytic removal of chlorobenzene and NOx: Performance enhancement and mechanism studies

The transition metal titanium-doped Mn-Ce-Ox catalysts catalyst were employed to achieve synergetic removal of NO and CB at 180–220 °C. The Mn5CeTi5Ox catalyst with a molar ratio of Mn/Ce/Ti = 5:1:5 exhibits excellent activity, and the NOx and CB removal efficiencies reach 96 % and 89 % at 160–220 °C, respectively. The selectivity for N2 and CO2 are 93 % and 78 %, respectively. The N2-physisorption, NH3-TPD, H2-TPR and XPS results show that Ti doping makes the catalyst possess a mesoporous structure, suitable particle sizes, and excellent redox and Lewis site properties. All of these features contribute to the observed high NO and CB removal efficiency. The synergetic removal of CB and NO over Mn5CeTi5Ox results from the synergistic catalysis between the redox and the solid acid. On the one hand, in the synergistic removal process, CB and NH3 are competitively adsorbed on the catalyst surface, resulting in a decrease in the NH3-SCR activity. On the other hand, the removal of NO and CB has a synergetic effect. The byproduct NO2 produced by the NH3-SCR reaction promotes the oxidation of CB, which is beneficial for CB removal. Moreover, the consumption of NO2 indirectly promotes the NH3-SCR reaction, which partially compensates for the decrease in the NO removal efficiency caused by competitive adsorption between NH3 and CB. Ti doping promotes the participation of the SCR byproduct NO2 in the CBCO reaction and promotes the formation of maleic acid, an intermediate product of CB oxidation. In summary, the Mn5CeTi5Ox catalyst exhibits good activity for the synergistic removal of NOx and CB and is a promising candidate for the effective and economical removal of NO and CB during waste incineration.

Relations of magnetic and electrochemical anti-corrosion properties of (Zr, Ti)-doped NdCeFeB magnets with Ti content

Zr and Ti were co-doped into NdCeFeB sintered magnets to improve the magnetic and electrochemical anti-corrosion properties. Both performance are found closely associated with Ti content. At 0.15 wt%Ti, the sample shows higher coercivity without energy product loss compared to the Ti-free sample and other Ti additions, due to the matrix-phases refinement and optimized distribution of RE-rich phases. For this sample, its corrosion current density and charge transfer resistance are 1.94 μA/cm2 and 1734 Ω•cm2 in NaCl solution respectively, which exhibits obviously improved corrosion resistance in comparison with the Ti-free magnet. The charge transfer resistance has been increased by 45.6 %. The apparently improved corrosion resistance is mainly attributed to the decreased amount of active reaction channels and the enhanced protective effect of TiO2, arising from the increment of Ti-rich precipitates. When the content of Ti dopant exceeds 0.5 wt%, the beneficial effects of Ti are overshadowed by the harmful effect of the density reduction on anti-corrosion performance, and the charge transfer resistance decreased with further increasing the dopant content. The new findings provide a theoretical basis for improving physicochemical properties of NdCeFeB magnet.

Effect of doping with M (M=Al, Pd, Ti, Ge) on the electronic structure and hydrogen diffusion behavior of amorphous silicon

Amorphous silicon (a-Si) models doped with Pd, Ge, Al, and Ti (a-Si/M) at three different doping ratios are generated using Ab initio Molecular Dynamics (AIMD) high-temperature annealing, followed by analysis utilizing first-principles method. The electronic structure calculations reveal strong interactions between Al, Ge and Si, while interaction between Pd, Ti and Si are relatively weak. Moderate doping of Pd and Ti can reconstruct the a-Si surface, reduce the adsorption energy of H on the surface, and increase the Si-Si atomic gap. This will greatly reduce the energy barrier for H to diffuse on the surface and to the subsurface.

Effect of Zn, Ti and Sn dopants on the structural, morphological and optical properties of MgO nanoparticles synthesized via green combustion using Persicaria odorata leaves extract

Effect of Zn, Ti and Sn dopants on the structural, morphological and optical properties of MgO nanoparticles synthesized via green combustion using Persicaria odorata leaves extract

Frictional properties and environmental adaptability of Ti-MoS2/WC multilayer films

Magnetron-sputtered molybdenum disulfide films are extensively utilized as solid lubricating coatings in space applications as a result of their low friction coefficient and minimal contamination. However, MoS2-based films are sensitive to hygrothermal and oxidation environment, and are easily oxidized to form MoO3, which results in high friction and wear of the films, significantly reducing their operational lifespan. Especially when the spacecraft adopts the launching mode of coastal launch or ocean platform, the performance deterioration caused by oxidation of MoS2 films during transportation, storage and launch is more serious. Therefore, to enhance the frictional performance and oxidation resistance of the films in humid and salt spray environments, the Ti-MoS2/WC multilayer films with preferred (002) crystal plane orientation were prepared, achieving a friction coefficient of 0.009 in a vacuum environment and a wear rate of 1.1×10-7 mm3/N∗m. In particular, the film can maintain this extremely low coefficient of friction even after exposure to moisture or salt spray. These findings demonstrate that the dual doping of Ti and WC and the design of multilayer structures enable MoS2 films to achieve outstanding frictional performance and oxidation resistance. This is crucial for designing MoS2 films with excellent environmental adaptability.

Laser clad CoCrFeNiTixNby hypoeutectic high-entropy alloy coating: Effects of Ti and Nb content on mechanical, wear and corrosion properties

High-entropy alloys (HEAs) exhibit significant potential for advanced wear and corrosion-resistant applications. This study investigates the influence of Ti and Nb doping on the microstructure, phase composition, and properties of CoCrFeNiTixNby HEAs synthesized using high-speed laser cladding (HLC). The results demonstrate that increasing Ti and Nb content transforms the coating structure from a face-centered cubic (FCC) phase to a hybrid structure comprising FCC, body-centered cubic (BCC), and Laves phases, leading to a linear enhancement in surface hardness. The incorporation of Ti and Nb not only promotes the preferred orientation of the FCC phase (111) crystal plane but also significantly enhances tensile strength, though this comes at the expense of reduced plasticity. Specifically, the CoCrFeNiTi0.6Nb0.15 coating attains an ideal balance between strength and ductility, with a tensile strength of 1641.8 MPa and a tensile strain of 15.9 %, achieved through the formation of a eutectic structure. This coating also exhibits superior wear resistance and outstanding corrosion resistance, which are attributed to the stability of the passivation film, reinforced by the (111) crystal plane and high-density dislocations. These findings provide both theoretical and empirical foundations for the design of high-performance HEAs, underscoring their potential in industrial applications requiring robust wear and corrosion resistance.

The synergistic effect of co-doping with Ti, Nb, and Ni on the hydrogen storage capacity of ZrCo

The effectiveness of element doping in enhancing the hydrogen storage performance of ZrCo alloys has been well established. However, the impact of single element doping is limited, and research on the synergistic effect of multi-element alloying remains relatively scarce. In this paper, the hydrogen storage properties of Zr0·75Ti0·125Nb0·125Co0·75Ni0.25 (ZTNCN) alloy were investigated using the first-principles method to explore the synergistic effect of Ti, Nb and Ni doping on ZrCo. The results indicate that the (−110) surface of ZTNCN undergoes significant reconstruction, leading to enhanced adsorption and dissociation of hydrogen on the surface. Moreover, there is no apparent dissociation barrier for H2, facilitating easier migration of H on the surface. The difference in atomic size leads to a variation in lattice interstices, resulting in a lower diffusion energy barrier for H compared to that of the ZrCoHx system. Through atomic substitution, the space within the 8e site becomes compressed, which makes the alloy exhibit improved resistance against disproportionation. Therefore, the synergistic effect of Ti, Nb, and Ni can greatly enhance hydrogen absorption and desorption kinetics in alloys and improve anti-disproportionation.

Enhanced phase transformation properties of VO2(M) powder by Ti doping

Enhanced phase transformation properties of VO2(M) powder by Ti doping

First-principle and experimental investigation into the interfacial characters of Ti-doped ZTA and high chromium cast iron

Ti doping can improve the interfacial wettability and bonding condition between ZTA ceramic and high chromium cast iron (HCCI), but the underlying mechanism is still unclear. Therefore, the effects of Ti doping on the interfacial characters between ZTA and HCCI were investigated by experiment and first-principles calculations. Results of XRD, SEM, and high-temperature drop test indicate the presence of Ti at the interface and its effect on the formation of interfacial diffusion layer to improve the interface wettability and bonding obviously. The heat of segregation and work of adhesion obtained by first-principle calculations shows that the improvement in interface wettability and bonding is due to the promotion of dopped Ti atoms on the diffusion of Fe, Al, and Zr elements, but not the diffusion of Ti itself. Further investigation from the electronic level reveals that the doped Ti changes the charge distribution and orbital hybridization, and thus makes the formation or enhancement of strong ionic bonds and covalent bonds at the interface, improving the bonding strength and wettability of interfaces in ZTA/HCCI. The findings of this research can offer new insights into the modification of ceramics and enlarge the application of advanced ceramic materials.

Relieving strain accumulation in ultra-high Ni cathode to achieve long cycle stability

Ni-rich cathodes with nickel content exceeding 90 % are regarded as highly promising for lithium-ion batteries (LIBs). However, the chemical-mechanical degradation caused by strain, side reactions and irreversible phase transitions will accelerate capacity fading. Especially, the mechanical degradation (cracks) caused by anisotropic strain can also accelerate chemical degradation. Herein, we effectively alleviate the anisotropic strain and the resulting cracks by Ti doping, which successfully improved the electrochemical performance of ultra-high Ni cathode. The results demonstrated that Ti doping can effectively refine the primary particles and form a tightly packed structure. Moreover, the stronger Ti-O bond incorporation into bulk efficiently stabilize lattice structure. The unique microstructure and stable lattice structure can effectively alleviate strain accumulation and chemical-mechanical degradation. Therefore, the Ti-modified cathode has the excellent electrochemical performance.

Impact of doping on MgB2 superconductors: A comprehensive review

This review introduces fresh insights into the ongoing discussion on doping in the MgB2 superconductor compound, enriching the comparative analysis with previous reviews. Its primary objective is to succinctly summarize and enhance comprehension regarding the influence of doping on the superconducting properties of MgB2. It delves into various aspects, including the impact on the superconducting transition temperature (Tc) and the critical current density (Jc) of the doped samples, while also shedding light on the diverse synthesis methodologies employed by different research laboratories. Throughout the review, the doping agents under scrutiny encompass a wide array, ranging from Li and Be to Bi and Pb. The properties are compared with those undoped samples crafted by the authors of each publication. This review catalogs a range of cited doping agents, including H, Li, Be, C, C15H12O2, diamond, graphene oxide, NaCl, Na2CO3, Mg, Al, Si, K2CO3, CaH2, CaCO3, Sc, Ti, Ni, Cu, Zn, MgGa, GeO2, Se, Rb2CO3, Rh, Pd, Ag, In, Sn, Sb2O3, Te, Cs2CO3, LaB6, La2O3, CeO2, Pr6O11, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, Os, Ir, Pt, Hg, Pb, and Bi. Notably, doping with Be, Na2CO3, C, Al, Rb2CO3, Cs2CO3, Hg and Pb impacts mesh parameters through either Mg or B substitution. Conversely doping with Li, CaH2, Cu, Ag, La2O3, CeO2, Pr6O11, Nd2O3, Gd2O3, Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Lu2O3, GeO2, Rh, In, Sb2O3, and Pt exhibits minimal impact on Tc. Moreover, Jc can be substantially enhanced by adding C, Zn, Ag, or Sb2O3. Remarkably, the incorporation of Pd or Pt has shown a substantial increase in Jc with a remarkable improvement of +328 % and +614 % respectively observed at 2 T and 20 K. Doping with rare earth elements such as La2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, and Ho2O3 resulted in extraordinary improvement in the value of the critical current density at 20 K under specific conditions, within a range of 0–4 T.

Modification of the hydrogen compression properties of Zr–Fe–Cr–V-based alloys through Ti doping

Hydrogen refueling stations typically rely on compressors to increase the pressure of hydrogen received from long-tube trailers, enabling efficient refill of hydrogen storage tanks. However, mechanical hydrogen compressors are unable to effectively harness residual hydrogen below 6 MPa in long-tube trailers. Herein, we developed a ZrFe2-based hydrogen compression alloy to enhance the hydrogen pressure that meets the input pressure requirement of mechanical hydrogen compressors. Specifically, the co-substitution of Cr and V for Fe was conducted to reduce the plateau slope and hysteresis, and Ti was introduced to partially substitute Zr to regulate the plateau pressure. The effects of Ti on the structure and hydrogen storage properties of Zr–Fe–Cr-based alloys have been investigated by first-principles calculations, wherein Zr1-xTixFe1.7Cr0.2V0.1 (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were designed and synthesized. The optimized Zr0.8Ti0.2Fe1.7Cr0.2V0.1 alloy provided a hydrogen absorption capacity of 1.22 wt% under 3.88 MPa H2 pressure at 300 K and achieved an effective hydrogen compression capacity of 1.07 wt% at 355 K at an H2 desorption pressure of 6.36 MPa. This advancement holds great promise for the efficient utilization of residual hydrogen at approximately 6 MPa in long-tube trailers, thus leading to a significant improvement in hydrogen transportation efficiency.

Ultrahigh Power Factor of Sputtered Nanocrystalline N-Type Bi2Te3 Thin Film via Vacancy Defect Modulation and Ti Additives.

Magnetron-sputtered thermoelectric thin films have the potential for reproducibility and scalability. However, lattice mismatch during sputtering can lead to increased defects in the epitaxial layer, which poses a significant challenge to improving their thermoelectric performance. In this work, nanocrystalline n-type Bi2Te3 thin films with an average grain size of ≈110nm are prepared using high-temperature sputtering and post-annealing. Herein, it is demonstrated that high-temperature treatment exacerbates Te evaporation, creating Te vacancies and electron-like effects. Annealing improves crystallinity, increases grain size, and reduces defects, which significantly increases carrier mobility. Furthermore, the pre-deposited Ti additives are ionized at high temperatures and partially diffused into Bi2Te3, resulting in a Ti doping effect that increases the carrier concentration. Overall, the 1µm thick n-type Bi2Te3 thin film exhibits a room temperature resistivity as low as 3.56 × 10-6 Ω∙m. Notably, a 5µm thick Bi2Te3 thin film achieves a record power factor of 6.66mWmK-2 at room temperature, which is the highest value reported to date for n-type Bi2Te3 thin films using magnetron sputtering. This work demonstrates the potential for large-scale of high-quality Bi2Te3-based thin films and devices for room-temperature TE applications.