Effect Of Doping Research Articles

Effect of Mn Doping on the Modulation of Magnetoelectric and Mechanical Properties of Cu–Ni–Sn Alloys

In this research, the magnetoelectric and mechanical properties of Cu77–xNi15Sn8Mnx (x = 0, 5, 10, 15, 20 at%) alloy are systematically studied. In the results, it is demonstrated that the magnetic properties of the alloy increase with an increase in the Mn content, as evidenced by the thermomagnetic curve and isothermal magnetization curve. The magnetic properties of the annealed Cu57Ni15Sn8Mn20 alloy reach about 15 emu g−1 at room temperature, and the Curie temperature (Tc) reaches about 360 K in a 1 k Oe magnetic field. The characteristic peak of the magnetic transition in the AC magnetic susceptibility test also corresponds to the Curie temperature. An electrical performance test calculated the resistivity of the alloy, the resistivity of Cu57Ni15Sn8Mn20 in its annealed state is about 26% lower than that of Cu77Ni15Sn8. Furthermore, the hardness test reveals that the Vickers hardness of the Cu57Ni15Sn8Mn20 alloy is about 246.2 HV, demonstrating its excellent mechanical properties. In the research, it is shown that the doping of Mn elements plays a crucial role in the magnetic properties of Cu–Ni–Sn alloys. By adjusting the content of the Mn element, the magnetic performance can be controlled. A valuable approach is provided for enhancing the performance of magnetic Cu alloys.

Dynamic Kohn Anomaly in Twisted Bilayer Graphene

Abstract Twisted bilayer graphene (TBG) has attracted great interest in the last decade due to the novel properties it exhibited. It was revealed that e-phonon interaction plays an important role in a variety of phenomena in this system, such as superconductivity and exotic phases. However, due to its complexity, the e-phonon interaction in TBG is not well studied yet. In this work, we study the electron interaction with the acoustic phonon mode in twisted bilayer graphene and one of its consequences, i.e., the Kohn anomaly. The Kohn anomaly in ordinary metals usually happens at phonon momentum q = 2k_F as a dramatic modification of the phonon frequency when the phonon wave vector nests the electron Fermi surface. However, novel Kohn anomaly can happen in topological semimetals, such as graphene and Weyl semimetals. In this work, we show that the novel dynamic Kohn anomaly can also take place in twisted bilayer graphene due to the nesting of two different Moire Dirac points by the phonon wave vector. Moreover, by tuning the twist angle, the dynamic Kohn anomaly in TBG shows different features. Particularly, at magic angle when the electron bandwidth is almost flat, the dynamic Kohn anomalies of acoustic phonons disappear. We also studied the effects of finite temperature and doping on the dynamic Kohn anomaly in TBG and discussed the experimental methods to observe the Kohn anomaly in such system.

Kinetic modeling and iso-conversional analysis of glass-ceramics of selenium doped with carbon nanomaterials

Abstract This study addresses a gap in understanding the impact of carbon nanomaterial doping on the crystallization kinetics of selenium glass, particularly when utilizing model-free iso-conversional methods. Previous research has explored the properties of elemental selenium; however, the role of dopants like multiwall carbon nanotubes (MWCNTs) and graphene in altering glass-to-crystal phase transitions at non-isothermal conditions has not been thoroughly analyzed. In the context of selenium glass crystallization, multiwall carbon nanotubes (MWCNTs), and graphene may alter the crystal growth kinetics significantly during glass/crystal phase transformation. Keeping in mind these facts, the present endeavor focuses on analyzing the doping effect of MWCNT and Graphene on the non-isothermal kinetic reaction mechanism of Selenium measured with differential scanning calorimetry (DSC) at different heating rates. The model-free relations such as Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), Tang, and Straink methods were applied using iso-conversional approach for determining the activation energy of amorphous to crystalline transformation as well as the Avrami index. Iso-conversional study yields adequate activation energy as a function of the conversion coefficient. We have observed the decreasing behavior of E c (α) along with the extent of crystallization of four iso-conversional methods. The kinetic triplet parameters (i.e., activation energy E α , rate constant K α , and order parameter n α ) have been calculated using the VHR method derived from the Johnson–Mehl–Avrami (JMA) rate equation. The value of ‘n’ is reduced with the rise in the value of the extent of conversion α which indicates the reduction in the growth rate of crystallization because of its saturation. This study provides novel insights into the thermal stability and kinetic mechanisms within doped selenium glass-ceramics, expanding the potential applications of chalcogenide glasses in phase-change memory and other fields.

E-beam Fluorinated CVD Graphene: in-situ XPS study on stability and NH3 adsorption doping effect.

Graphene exhibits promise in gas detection applications despite its limited selectivity. Functionalization with fluorine atoms offers a potential solution to enhance selectivity, particularly towards ammonia (NH+) molecules. This article presents a study on electron-beam fluorinated graphene (FG) and its integration into gas sensor platforms. We begin by characterizing the thermal stability of fluorographene, demonstrating its resilience up to 450°C. Subsequently, we investigate the nature of NH3 interaction with FG, exploring distinct adsorption energies to address preferential adsorption concerns. Notably, we introduce an innovative approach utilizing XPS cartography for simultaneous analysis of fluorinated and pristine graphene, offering enhanced insights into their properties and interactions. This study contributes to advancing the understanding and application of fluorinated graphene in gas sensing technologies.

The effect of acceptor and donor doping on the electronic properties of the half-Heusler TiNiSn.

Optimizing the electronic transport properties of thermoelectric compounds is commonly achieved by either donor or acceptor atom doping to increase the conduction of the appropriate carrier type, electrons or holes, respectively. Enhancing carrier mobility and carrier concentration will both lead to optimized electronic properties. In this work the effect of various dopants on the electronic properties of TiNiSn was explored, by modeling the doping of an ideal compound on the Ti-sublattice with acceptor or donor elements. Using ab initio DFT calculations and a set of analytical expressions of transport properties, the temperature dependencies of the electronic properties were calculated, to examine possible n-type or p-type dopants to be used in further experimental studies.

Insights into Novel Doping Effect of Fe-Doped ZnS Nanostructures Derived from Oxystelma Esculentum: Kinetics-Based Photocatalysis, Nitrogen Fixation, and Antifungal Efficacy

Implementing greener approaches is a sustainable and eco-friendly methodology for nanocomposite synthesis. This work reports the sustainable fabrication of Fe-doped ZnS (Fe0.3Zn0.7S) nanocomposite and its broad-spectrum applications. The systematic characterization was carried out using several advanced analytical techniques. DLS, Zeta potential, SEM, XPS, and TEM performed morphological and size assessments of the engineered nanocomposite. Eventually, XRD provided valuable insights into the crystalline behavior of nanocomposite. The nanocomposites were then treated against the organic dye Safranin O, which displayed 93% degradation within an hour with the rate constant value of 0.0326 min−1. Parameters influencing the percentage degradation, such as temperature, pH, etc., were also discussed. Moreover, an LCMS test was also conducted to evaluate the presence of reactive intermediates. Safranin O’s degradation was confirmed by identifying intermediate products, such as compounds with m/z values of 335.84, 321.81, 306.79, 292.77, and 257.32, which were indicative of progressive dye breakdown. Finally, the photocatalytic enactment examination verified that the prepared nanocomposite’s nitrogen fixation rate (38.96 µmolg−1) was way greater (~4 times) than the pristine compound. In addition, prepared nanoparticles demonstrated a befitting ability to eliminate a wide range of threatening pathogenic fungi. The doping of Fe into ZnS further enhanced the inhibition against Fusarium oxysporum.

Ceria nano architectonics with doping effect of Co2+ on pinkish red luminescence and high energy storage applications

Ceria nano architectonics with doping effect of Co2+ on pinkish red luminescence and high energy storage applications

Effect of Fe doping on the electronic properties of CoSn Kagome semimetal.

Quantum phenomena in two-dimensional Kagome materials lead to exotic topological states and complex magnetism. Here, we have investigated the detailed electronic properties of Co$_{1-x}$Fe$_x$Sn with Fe doping to explore the competing electronic interactions for the origin of complex magnetism and topological properties. We find that the screening effect in the valence electrons increases while the correlation effect decreases with an increase in the doping concentration ($x$). Valence fluctuations observed at Co and Fe L$_{2,3}$ edges showed systematic changes in the magnitude of divalent and trivalent states with the increase in $x$. Fe $3d$ states are more screened by the conduction electrons than the Co $3d$ states. A comparison of the theoretical and experimental density of states showed different natures of localized states with dominating screening effects on the surface and dominating correlation effects in the bulk for $x$~$>$~0. We have observed localized flat bands on the CoSn (001) surface while quasi-localized flat bands on the Co$_{0.94}$Fe$_{0.06}$Sn (001) surface. The distinct character of the bulk and surface band structure is confirmed in the Fe-doped composition. Hence, the bulk-surface interaction present in Co$_{1-x}$Fe$_x$Sn gives rise to the origin of valence fluctuation, complex magnetism, and topological properties.

Flexible Fe-Doped NiO/Ni-Foam Substrate Nano-System Based Electrode with Tunable Opto-Electrochemical Attributes for Supercapacitor Applications

Abstract This work underlines the modification and effect of iron doping on different characteristics of NiO nanoparticles. The facile hydrothermal method was followed to form pristine and iron doped( 4% and 8% ) NiO sample. The X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), transmission electron microscopy (TEM), UV–Vis spectroscopy and Raman spectroscopy techniques were employed for the identification of phase, morphology, microstructural details and optical property of the as synthesized Fe doped NiO samples. XRD measurements of the as synthesized Fe doped NiO samples revealed the polycrystalline nature with the crystallite size varying from 11nm – 20nm showing hexagonal structure. Surface morphology investigation carried out by using SEM showed the varied morphology of as synthesized samples . UV-Vis investigation revealed a red shift with increasing iron doping content, which corresponds to a decrease in optical bandgap values from 3.4eV for pure NiO to 2.2eV for 8% Fe doped NiO sample thus giving a wide tunable absorption bandgap . The study of cyclovoltammetry and PEIS demonstrates the novelty of this work showing exceptionally high electrochemical performance in a three-electrode system with highest specific capacitance of 977F/g at scan rate of 20mV/sec for 8% doped sample .

Effects of terbium concentrations on the characteristics of Ga2O3 films

Abstract This study investigates the incorporation of Tb into Ga2O3 films and its influence on their structural, optical, and luminescent properties. Tb composition in Ga2O3 films was controlled by adjusting the Tb composition in the targets. X-ray diffraction analysis unveiled lattice expansion as Tb composition increased. Atomic force microscopy images depicted consistently smooth film surfaces across varying Tb compositions. Optical transmission spectra demonstrated high transmittance and direct bandgap transitions, with no notable alteration observed in the bandgap concerning Tb composition. Photoluminescence spectra exhibited characteristic Tb ion emission peaks, with intensities initially increasing before reaching a plateau, attributed to a balance between increased luminescent centers and deteriorated crystal quality. This study significantly enhances our understanding of Tb doping effects in Ga2O3 films and offers valuable insights for their application in optoelectronics.

Breaking Scaling Relations for Enhanced Electrochemical CO2 Reduction to CO by Introducing Soft Metal Dopants to Thiolates-Protected Coinage Metal Nanoclusters.

Density functional theory calculations are employed to investigate the effects of various metal dopants on thiolates-protected transition metal nanoclusters (NCs) for CO2 reduction, focusing on deviations from the linear scaling relation between COOH* and CO* for high CO selectivity. We first explore the most favorable positions for different dopants in several M25 (M=parent metal) NCs and assess the potential for ligand removal under reducing conditions. Furthermore, we construct an activity volcano for CO production in D1M24(D=dopant) NCs, revealing that NCs composed of coinage parent metals with group 12 metal dopants exhibit the most significant deviation from the scaling relation. This behavior is attributed to the tendency of these NCs to bind COOH* in a bidentate form, which stabilizes the O atom of COOH* through interactions with the oxyphilic dopants. As a result, several group 12 metal doped coinage metal NCs are identified as new promising candidates for syngas production due to their high activity towards both CO and H2 production.

First-Principles Prediction of Structural Distortions in the Cuprates and Their Impact on the Electronic Structure

Materials-realistic microscopic theoretical descriptions of copper-based superconductors are challenging due to their complex crystal structures combined with strong electron interactions. Here, we demonstrate how density functional theory can accurately describe key structural, electronic, and magnetic properties of the normal state of the prototypical cuprate Bi2Sr2CaCu2O8+x (Bi-2212). We emphasize the importance of accounting for energy-lowering structural distortions, which then allows us to (a) accurately describe the insulating antiferromagnetic (AFM) ground state of the undoped parent compound (in contrast to the metallic state predicted by previous studies); (b) identify numerous low-energy competing spin and charge stripe orders in the hole-overdoped material nearly degenerate in energy with the AFM ordered state, indicating strong spin fluctuations; (c) predict the lowest-energy hole-doped crystal structure including its long-range structural distortions and oxygen dopant positions that match high-resolution scanning transmission electron microscopy measurements; and (d) describe electronic bands near the Fermi energy with flat antinodal dispersions and Fermi surfaces that are in agreement with angle-resolved photoemission spectroscopy (ARPES) measurements and provide a clear explanation for the structural origins of the so-called “shadow bands.” We also show how one must go beyond band theory and include fully dynamic spin fluctuations via a many-body approach when aiming to make quantitative predictions to measure the ARPES spectra in the overdoped material. Finally, regarding spatial inhomogeneity, we show that the local structure at the CuO2 layer, rather than dopant electrostatic effects, modulates the local charge-transfer gaps, local correlation strengths, and by extension the local superconducting gaps. Published by the American Physical Society 2024

High-efficiency photocatalyst C@TiO2 with the synergy effect of carbon doping and phase transformation

High-efficiency photocatalyst C@TiO2 with the synergy effect of carbon doping and phase transformation

Effect of Nd doping on the Physical and electrocisemical properties of MnTiO, nanoparticles for supercapacitor applications

Effect of Nd doping on the Physical and electrocisemical properties of MnTiO, nanoparticles for supercapacitor applications

First-principles calculation of the effects of In doping on η-Cu6Sn5 structure, elastic anisotropy, electronic properties and fracture toughness

During the welding and service stages, the anisotropy of Cu6Sn5 between tin solder / Cu solder joints will lead to abnormal grain growth and fracture of Cu6Sn5, which will eventually lead to solder joint failure, so it is very important to study the alloying element indium (In) to reduce the anisotropy of Cu6Sn5. The effects of indium doping on the crystal structure, electronic structure and mechanical properties of η-Cu6Sn5 have been studied systematically by means of first-principles density functional theory. Through calculation, it is found that with the change of indium doping position, the crystal structure is slightly deformed, but remains stable. Indium doping changes the electronic structure of η-Cu6Sn5, and a new bonding peak is formed by the hybridization of Cu-d and In-s around -5.9eV. In addition, indium doping can significantly increase the mechanical properties of η-Cu6Sn5, including elastic modulus and hardness. Indium significantly reduces the anisotropy of η-Cu6Sn5, and the anisotropy decreases by nearly 80% at most. At the same time, the addition of indium can increase the fracture toughness of η-Cu6Sn5.

Promotion effect of nitrogen doping on the low-temperature NH3-SCR of NO over activated carbon: Characterization and mechanism analysis

Heteroatom nitrogen doping in carbon catalysts is recognized an effective strategy for tailoring the properties of carbon catalysts for various flue gas de-NOx applications. However, accurately discerning the active structures after nitrogen doping and elucidating the promotion effect on low-temperature selective catalytic reduction activity remains a formidable challenge under different nitrogen doping preparation conditions. In this study, a series of nitrogen-doped activated carbon catalysts was synthesized through the L16(45) orthogonal array design method, and the degree of influence of various preparation conditions on de-NOx catalytic activities was also assessed. The optimal preparation conditions determined by range analysis were employed to synthesize NOAC-17, achieving the NO conversion of 95% and N2 selectivity of 99% at 300 °C, respectively. Subsequently, various characterization results proved that nitrogen doping induced the formation of abundant basic groups. The imine, amide, amine, and N-6 groups altered the acid-base of the activated carbon surface and increased the adsorption of acidic NOx. The N-5 and N-Q groups enhanced electronic interaction in the carbon matrix and accelerated electron mobility in the catalytic reaction process. Moreover, the N-6 group played multiple roles beyond the aforementioned effect due to its special structure. It also enhanced the accumulation of oxygen vacancies, which were closely associated with further oxidation of adsorbed NO. The lone electron pair in the N-6 group within the activated carbon framework can alter the polarity of the catalyst, thereby exerting a positive influence on the adsorption and activation of NH3. The nitrogen-doped catalyst identified through range analysis of the orthogonal experiment primarily facilitated the NH3-SCR reaction via the E-R mechanism with supplementary contribution from L-H mechanism at low temperatures. The nitrogen doping conditions obtained for the activated carbon catalyst provide valuable insights for the strategic enhancement of its catalytic performance in low-temperature NH3-SCR reactions.

Ni-modified BaTiO3 film prepared by sol-gel with high energy storage performance

The development of lead-free dielectric capacitors with high recoverable energy storage density and high energy storage efficiency is important for improving the overall performance of electronic and power systems. BaTiO3 (BTO) is one of the most common ferroelectric materials and has attracted much attention for energy storage applications in the past decades due to its excellent dielectric and ferroelectric properties. However, high remnant polarization and low electrical breakdown strength of BTO limit its development in energy storage applications. Many efforts (e.g., elements doping, interface/heterostructure, etc.) have been made to improve the energy storage density of BTO thin films. In this paper, Ba1-xNixTiO3 thin films (x = 0, 0.02, 0.04, 0.06, 0.08; abbreviated as BNxT) were synthesized via sol-gel and spin-coated method. The effect of Ni doping on the structural, dielectric, ferroelectric and energy storage properties of BTO thin films has been studied. The results confirmed that with the increase of Ni doping, a second phase arises and the dielectric constant decreases. While appropriate Ni doping led to the improvement of the breakdown strength, further increase of Ni deteriorated the energy storage because of the high oxygen vacancy. Finally, optimized energy storage performance was obtained for BN0.04T thin film: dielectric constant of 401, dielectric loss of 0.002, recoverable energy density of 20.2 J/cm3 and energy storage efficiency of 83.6% at 965 kV/cm. Meanwhile, the remnant and maximum polarization of the films were 0.06 μC/cm2 and 50 μC/cm2, respectively. BN0.04T thin film has an excellent application prospect and is expected to appear as a component in the future composite energy storage film system.

Effect of Sr doping on the potential cathode of Ba0.875Fe0.875Zr0.125O3 for proton-conducting fuel cells

The development of innovative cathode materials exhibiting high catalytic activity and good stability holds substantial significance for proton-conducting fuel cells (PCFCs). A Co-free Ba0.5Sr0.375Fe0.875Zr0.125O3-σ (BSFZ0.375) cathode material is designed and developed in this paper. Density functional theory (DFT) calculations indicate that the oxygen vacancy formation energy and hydration energy of BSFZ0.375 are both lower than those of the potential cathode Ba0.875Fe0.875Zr0.125O3-δ (BFZ). The Sr doping can reduce the oxygen dissociation barrier at the material surface according to the Partial density of states (PDOS) result. BSFZ exhibits good chemical compatibility with BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) electrolyte and maintains good structural stability when exposed to air for 100 h at 550 °C. At 650 °C, the polarization impedance and maximum power density of single cell with BSFZ as cathode are 0.08 Ω cm2 and 572 mW cm⁻2, which improved a lot compared to parent BFZ cathode (0.13 Ω cm2 and 228 mW cm⁻2), respectively. At 650 °C and 1.3V, the single cell with BSFZ0.375 electrode electrolyzes pure water, achieving a current density of 0.6 A cm⁻2.

Numerical study of the effects of surface nitrogen-containing on soot formation process in ammonia/ethylene counterflow diffusion flames

In this paper, a modified soot kinetic model was developed to explore the potential inhibitory effects of nitrogen-containing functional groups on the soot surface growth process. In the modified soot kinetic model, the formation process of cyano functional groups on the soot surface was simulated through the reaction of hydrogen cyanide (HCN) and the surface open sites, and the surface cyano functional groups were assumed to no longer participate in the subsequent hydrogen-abstraction-acetylene-addition (HACA) reaction. The prediction performance of soot volume fraction (SVF) and average particle size (D63) in ammonia doping ethylene counterflow diffusion flames was compared between the traditional soot kinetic model and the modified kinetic soot model. The results show that both models reflected the suppression effects of ammonia doping on soot formation observed in the experiments. However, compared to the traditional soot kinetic model, the modified soot kinetic model exhibited better performances in predicting SVF and D63 with prediction deviations reduced by 52.7 % and 2.3 nm, respectively. The simulation results showed the formation of surface cyano functional groups led to a nitrogen content of up to 0.84 % in the soot, which is consistent with previous experimental measurements. In-depth analysis shows that the formation of cyano functional groups on the soot surface decreased the proportion of hydrogen sites and further diminished the number of open sites, resulting in reductions in the rates of HACA surface growth and the soot mass growth by up to 22 % and 29 %, respectively. It is proposed that the nitrogen-containing functional groups on the surface of soot in ammonia-doped hydrocarbon flames inhibit the formation of soot, providing an alternative pathway to the well-known gas-phase suppression mechanism.

Synthesis and Characterization of Ni2+- Zr4+ Doped Ba-Ca M-Type Hexaferrites using Sol-Gel Auto-Combustion Method

This work aims to study the effect of Zr-Ni dopant on the structure and traits of M-type barium calcium hexaferrites (BaCaM). For the first time, Ba0.8Ca0.2ZrxNixFe12-2xO19 (0.0≤ x ≤1.0) samples are synthesized employing the SGACM (sol-gel auto-combustion method). The pure phase formation of BaCaM was established by XRD data Rietveld refinement. An augmentation in both the lattice parameters (‘a’ as well as ‘c’) owing to the higher ionic radii of dopant ions as compared to Fe3+ shows that Ni2+ and Zr4+ions were successfully swapped with Fe3⁺. The "c/a" ratio lies between 3.93-3.96 disclosing that the synthesized materials possess an M-type hexagonal ferrite structure. The reduction in crystallite with an increase in doping level might be due to lattice strain generated by the larger size of Ni2+ and Zr4+ dopant ions. The presence of two bands in the wavenumber range of 400 to 880 cm-1 in FTIR spectra corresponds to the Fe–O stretching in octahedral and tetrahedral locations. The Raman peaks widen without any shifting of the peak with an increment in Ni2+-Zr4+ ions contents revealing that Ni2+-Zr4+ are incorporated into BaCaM without changing its crystal structure. According to the M-H plots Ms value enhance from 24.94 (x= 0.00) to 36.84 emu/g (x= 0.60) and beyond x=0.60, Ms values drop with an increment in Ni2+-Zr4+substitution level. A broad coercivity range lies between 4858 Oe (x = 0.0) to 653 Oe (x = 1.0), decreasing monotonically with substitution in Ni2+-Zr4+. All the synthesized material exhibits a reduction in dielectric constant value as frequency increases. Ni-Zr-doped BaCaM materials could be a suitable candidate for magnetic recording media and microwave absorber applications.