Effect Of Doping Elements Research Articles

Effect of element doping on the structural stability, magnetic properties and electronic structure of SmCo5-based rare earth permanent magnets

Doping transition metals has been proven as an effective method to enhance the performance of Sm-Co based rare earth permanent magnets. However, due to the complex interactions involved, the specific effects on magnetic properties, atomic occupancy preferences and structural stability mechanisms are still to be further investigated. In this study, we systematically investigated the influence of various transition metal dopants on the structural stability, magnetic properties and electronic structure of SmCo5 rare earth permanent magnet using first-principles calculations. Our calculations show that Ti, V, Cr, Mn, Ni, Cu, Zn elements preferentially occupy the 3 g site, while Sc and Zr tend to occupy the 1a site, and Fe elements have a preference for the 2c site. Regarding structural stability, doping with Sc, Cr, Mn, Fe, Ni, Cu, Zn and Zr all contribute to enhancing structural stability, while Ti and V doping exhibit adverse effects. Magnetic calculations indicate that doping with Mn and Fe significantly increases the total magnetic moment of the SmCo5 system. Notably, at a high doping concentration of 60 at%, the Ni and Zn-doped systems exhibit an exceptionally large magnetocrystalline anisotropy energy Additionally, a change in the magnetic easy axis direction occurs when the doping concentrations of Cr, Fe, Cu and Zn reach 60 at%, 40 at%, 40 at% (and 60 at%), 40 at% (and 60 at%), respectively. Our work provides important theoretical guidance for further optimizing the performance of Sm-Co based rare earth permanent magnets.

Improving high-voltage cycling and stabilizing the electrode-electrolyte interface of nickel-rich layered cathodes by magnesium doping

Next-generation lithium-ion batteries will rely on nickel-rich layered oxides as cathode materials, but these materials are associated with structural and voltage losses. Magnesium (Mg) doping helps improve the performance of the nickel-rich layered cathode material. The Mg-modified LiNi0·90Mn0·05Co0·05O2 (NMC-90) has been successfully synthesized through a co-precipitation technique followed by calcination at 850 °C. Modified NMC-90 exhibits better-organized layers and improved interfacial properties than pristine ones based on structural, chemical, and morphological studies. In a voltage range of 2.8–4.5 V, Mg (0.01 mol%)-doped NMC-90 (NMC-M1) composite cathode shows an excellent discharge capacity of 211.11 mAh/g, whereas pristine NMC-90 (NMC-M0) attains only 210.59 mAh/g at 0.1C with an initial coulombic efficiency of 89.5 % for NMC-M1 and 87.5 % for NMC-M0 cathode. The NMC-M1 cathode demonstrated an impressive enhancement in cyclability after 60 cycles compared to the NMC-M0 at 1C rate, in which the NMC-M1 cathode attains a high capacity retention of 80 % while the NMC-M0 cathode shows only 37 %. This study illustrates the importance of studying the effects of elemental doping on cell performance. It will drive the future development of cathode materials with high Ni and low Co content.

The synergistic effect of Ta-doping and antireflective TaOx layer on the thermochromic VO2 thin films for smart windows

Current efforts to promote the use of VO2 materials as a promising candidate for thermochromic smart windows continue to be hindered by the low luminous transmittance (Tlum), the limited solar modulation ability (ΔTsol), the high phase transition temperature (Tt, ∼68 °C) and the wide thermal hysteresis (ΔT). The present work addresses these issues by fabricating an antireflective TaOx layer on the Ta-doped VO2 (i.e., VO2(Ta)) thin films. The VO2(4.35 at% Ta) thin films with low Tt of 29.87 °C and narrowed ΔT of almost zero were grown on glass substrates by magnetron sputtering at room temperature followed by rapid thermal annealing. However, the VO2(Ta) thin films show slightly enhanced Tlum of 38.31 % compared with undoped VO2 films (35.46 %) and decreased the ΔTsol by 1.83 %. The thermochromic properties are further enhanced by depositing the antireflective TaOx layer onto the VO2(Ta) thin film by reactive magnetron sputtering, which significantly increases the Tlum from 38.31 % to 48.58 %, marginally decreases the ΔTsol from 4.44 % to 4.12 %, and maintain the Tt and ΔT constant. These results verify the possibility of developing VO2 films with simultaneously increased optical transmittance, decreased Tt to suitable values, and extremely narrow ΔT by using the synergistic effect of element doping and constructing an antireflective layer.

Relationship between doped structure and properties of zinc oxide film

Overview of relevant research fields: Introduce the basic concepts and background of oxidizing thin films and doped materials. Discuss the characteristics, applications, and effects of doping on the performance of oxidizing thin films. Types and effects of doping elements: Introduce commonly used doping elements in oxidizing thin films, such as Al, Ga, Sn, etc. Discuss the effects of different doping elements on the properties of thin films, such as electrical, optical, and magnetic properties. Temperature and concentration effects: Exploring the effects of doping temperature and concentration on the properties of oxidizing thin films. Analyze the mechanisms and patterns of the effects of temperature and concentration on lattice structure, defect morphology, and carrier concentration. Application Fields and Prospects: Review the research progress of oxidative thin film doping in various application fields, such as optoelectronic devices, catalysts, sensors, etc. Looking forward to the future development direction and potential application fields of doping in oxidizing thin films. When writing a review, ensure accurate citation of relevant literature and analyze and discuss from multiple perspectives. In addition, pay attention to using concise and clear language to make it easy for readers to understand and obtain information. The most important thing is to ensure that the literature review complies with academic integrity and ethical standards, and adheres to citation norms.

Carbon doped hexagonal boron nitride as an efficient metal-free catalyst for NO capture and reduction.

The electrochemical NO reduction reaction (NORR) towards NH3 is considered a promising strategy to cope with both NO removal and NH3 production. Currently, the research on NORR electrocatalysts mainly focuses on metal-based catalysts, while metal-free catalysts are quite scarce. In this work, we have systematically investigated the properties of pristine and C/O doped h-BN for efficient NO capture and reduction. Our results reveal that the basal plane of pristine h-BN is inert to the adsorption of NO, while doping C or O can significantly enhance the NO capture abilities of h-BN. Then, we highlight that C-doped h-BN exhibits excellent NORR catalytic performance with a relatively low limiting potential of -0.28 V. Further analysis shows that the suitable adsorption strength of NO on the C-doped h-BN surface is the prime reason for its excellent NO reduction activity, which is shown to be due to appropriate electronic interactions between the active site and NO. Last but not least, the catalytic selectivity of h-BN towards the NORR is confirmed by inhibiting the competing hydrogen evolution reaction. Our findings not only provide deeper insight into the essential effect of element doping on the catalytic activities of h-BN, but also propose general design principles for high-performance metal-free NORR electrocatalysts.

Microstructure and high-temperature tribological properties of Ti/Si co-doped diamond-like carbon films fabricated by twin-targets reactive HiPIMS

In order to enhance high-temperature tribological properties of the diamond-like carbon (DLC) films, Ti/Si co-doped DLC films were synthesized by twin-targets reactive high power impulse magnetron sputtering and effects of doped elements on mechanical performances were investigated. The results showed that a mid-doped DLC film with a Ti content of 13.8 at.% and a Si content of 12.6 at.% obtained the best high temperature tribological performance and its wear resistance was significantly less affected. The friction coefficient of the Ti/Si co-doped DLC film at 450 °C dropped to as low as 0.08. In addition, compared with the mono Ti-doped DLC film, its wear rate at 450 °C decreased from 5.24 × 10−4 to 1.40 × 10−5 mm3·N−1·m−1. Raman spectra revealed that Si could hinder the sp3-C to sp2-C transition at elevated temperatures, which impeded adhesive wear in the high temperature tribological process.

Effects of elemental doping on phase transitions of manganese-based layered oxides for sodium-ion batteries

Effects of elemental doping on phase transitions of manganese-based layered oxides for sodium-ion batteries

The Effects of Ti/Ni Doping on the Friction and Wear Properties of DLC Coatings

Diamond-like carbon (DLC) coatings doped with Ti and Ni elements were deposited on 316 L stainless steel substrate using magnetron sputtering technology. The morphology, microstructures, and performances of the coatings were detected using scanning electron microscopy, a Raman spectrometer, nanoindenter, scratch tester, and a tribological machine. The effects of element doping on the microstructures, friction and wear properties of DLC coatings were analyzed. The results revealed that Ti/Ni doping ensures the uniform cover and tight fit of DLC coatings on the substrate. Additionally, Ni-doped DLC coatings have a much smoother surface and denser texture with higher bonding strength and enhanced hardness (7.5 GPa) though Ti doping also can improve the bond strength to some extent. The presence of Ni both in the 316 L substrate and in Ni-doped DLC coatings improves interface matching, decreases structural differences, and increases bonding strength. Moreover, the presence of Ni effectively inhibits oxidation and corrosion in friction interfaces, stabilizes the friction coefficient, and enhances wear resistance. Therefore, based on this study, it was concluded that reasonable matching between the dopant elements and the substrates can effectively improve the performance of DLC coatings.

Strategies for Advanced Supercapacitors Based on 2D Transition Metal Dichalcogenides: From Material Design to Device Setup.

Recently, the development of new materials and devices has become the main research focus in the field of energy. Supercapacitors (SCs) have attracted significant attention due to their high power density, fast charge/discharge rate, and excellent cycling stability. With a lamellar structure, 2D transition metal dichalcogenides (2D TMDs) emerge as electrode materials for SCs. Although many 2D TMDs with excellent energy storage capability have been reported, further optimization of electrode materials and devices is still needed for competitive electrochemical performance. Previous reviews have focused on the performance of 2D TMDs as electrode materials in SCs, especially on their modification. Herein, the effects of element doping, morphology, structure and phase, composite, hybrid configuration, and electrolyte are emphatically discussed on the overall performance of 2D TMDs-based SCs from the perspective of device optimization. Finally, the opportunities and challenges of 2D TMDs-based SCs in the field are highlighted, and personal perspectives on methods and ideas for high-performance energy storage devices are provided.

Electrochemical performance of Na4MnCr(PO4)3/C cathode affected by different transition metal dopants for sodium ion batteries

Na4MnCr(PO4)3 (NMCP) has been considered as one kind of privileged cathodes with high energy density for sodium ion batteries (SIBs) due to three-electron redox reaction during the insertion/extraction process. Nevertheless, its practical use is restricted by its low intrinsic conductivity and serious Jahn-Teller distortions. Herein, a facile doping strategy was presented to address the above issues, and the effects of different kinds and quantities of transition metal dopants on electrochemical performance of NMCP were systemically studied. The results reveal that Ni50-NMCP/C has the most effective doping composition, showing a discharge capacity of 143.0 mAh g−1 at 50 mA g−1 and long-term cyclic stability with capacity retention of 55.7 % at 1000 mA g−1 over 500 cycles, higher than those of the pristine NMCP (106.6 mAh g−1 at 50 mA g−1 and 38.8 % capacity retention at 1000 mA g−1). The substitution of Ni2+ for Mn2+ promotes electron conductivity and structural stability, rendering improved electrochemical performance. Moreover, the promising electrochemical performance of Ni50-NMCP/C//HC full cell demonstrates the anode's potential for use. This study indicates a quick way to understand the effects of elemental doping on NMCP and explore novel high energy and high stability cathodes for SIBs.

Effects of Element Doping on the Structure and Properties of Diamond-like Carbon Films: A Review

Diamond-like carbon (DLC) films with excellent anti-friction and wear resistance, can effectively reduce the energy loss of tribosystems and the wear failure of parts, but the high residual stress limits their application and service life. Researchers found that doping heterogeneous elements in the carbon matrix can alleviate the defects in the microstructure and properties of DLC films (reduce the residual stress; enhance adhesion strength; improve tribological, corrosion resistance, hydrophobic, biocompatibility, and optical properties), and doping elements with different properties will have different effects on the structure and properties of DLC films. In addition, the comprehensive properties of DLC films can be coordinated by controlling the doping elements and their contents. In this paper, the effects of single element and co-doping of carbide-forming elements (Nb, W, Mo, Cr, Ti, Si) and non-carbide-forming elements (Cu, Al, Ag, Ni) on the properties of microstructure, mechanical, tribological, optical, hydrophobic, corrosion resistance, etc. of DLC films are reviewed. The mechanisms of the effects of doping elements on the different properties of DLC films are summarized and analyzed.

Magneto-Structural Transition and Refrigeration Property in All-D-Metal Heusler Alloys: A Critical Review

Abstract: All-d-metal Heusler alloys has attracted much attention due to its unique magnetic properties, martensite transformation behavior and related solid-state refrigeration performance. These unique type alloys are recently discovered in 2015 and have been widely studied; however, systematic reviews on their magneto-structural transition and refrigeration property are rare. In this review, we first summarize the preparation techniques and microstructure of the bulk alloys and ribbons. Then the magnetic transition and martensite transformation behavior are reviewed, focusing on the correlation between magneto-structural transition and refrigeration properties. The effects of element doping, external magnetic and mechanical fields on the martensite transformation and corresponding magnetic entropy change are summarized. We end this review by proposing the further development prospective in the field of all-d-metal Heusler alloys.

Improving electrical and thermal properties synchronously via introducing CsPbBr3 QDs into higher manganese silicides

Higher manganese silicide (HMS) is a P-type medium temperature thermoelectric (TE) material, which has attracted widespread attention over the past few decades due to its remarkable mechanical properties, excellent chemical and thermal stability, as well as the non-toxicity, abundance and competitive price. The peak power factor (PF) of HMS is as high as ∼1.50 × 10−3 W m−1 K−2 because of its intrinsic high electrical conductivity and Seebeck coefficient. However, the thermal conductivity of HMS is also high, resulting in relatively low zT values. Introducing nano-dispersion in the matrix is one of the most effective methods to enhance the TE properties via reducing the lattice thermal conductivity significantly without drastic changes on the other parameters. In this study, CsPbBr3 QDs with uniform size were synthesized and introduced into HMS bulks. The PF (at 823 K) was enhanced to 1.71 × 10−3 W m−1 K−2, which is improved 14.0% approximately compared with that of pure HMS owing to the combined effect of element doping and energy filtering. The lattice thermal conductivity (at 823 K) decreased from 2.56 W m−1 K−1 to 1.99 W m−1 K−1 synchronously (∼22.0%) due to the intensive phonon scattering caused by Cs doping, and the embedding of Pb riched CsPbBr3 QDs and Pb QDs. A maximum zT value of 0.57 (823 K) is achieved in CsPbBr3 QDs/HMS composites, which is 36.0% higher than that of pure HMS. Predictably, for other TE materials, it is also feasible to improve the TE properties via introducing metastable quantum dots.

Effects of elemental doping, acid treatment, and passivation on the fluorescence intensity and emission behavior of yellow fluorescence carbon dots

Hydrothermal methods are commonly used to synthesize carbon dots (CDs), but the synthesized CDs have the disadvantage of low quantum yields. In this paper, we used acid treatment, elemental doping, and passivation to treat the CDs, which could increase the quantum yield from 36% to 42%, 61% and 68%, respectively, and the doping and passivation treatments resulted in red-shifted and blue-shifted emission behavior of the CDs. The optical properties, morphology and chemical structure of CDs are analyzed to investigate the reasons for the quantum yield increase and the mechanism of excitation dependent emission (EDE) and excitation independent emission (EIE). The increase of quantum yield is mainly due to the increase of pyridine N content. The different optical behaviors depend mainly on the surface states of CDs. C–OH and C–O–C can create new energy levels leading to the appearance of EDE properties. C=O is an electron-absorbing group that weakens the conjugation effect leading to blue shift.

Predictions on the Phase Constitution of SmCo7-XMx Alloys by Data Mining.

Based on a home-built Sm-Co-based alloys database, this work proposes a support vector machine model to study the concurrent effects of element doping and microstructure scale on the phase constitution of SmCo7-based alloys. The results indicated that the doping element’s melting point and electronegativity difference with Co are the key features that affect the stability of the 1:7 H phase. High-throughput predictions on the phase constitution of SmCo7-based alloys with various characteristics were achieved. It was found that doping elements with electronegativity differences with Co that are smaller than 0.05 can significantly enhance 1:7 H phase stability in a broad range of grain sizes. When the electronegativity difference increases to 0.4, the phase stability becomes more dependent on the melting point of the doping element, the doping concentration, and the mean grain size of the alloy. The present data-driven method and the proposed rule for 1:7 H phase stabilization were confirmed by experiments. This work provides a quantitative strategy for composition design and tailoring grain size to achieve high stability of the 1:7 H phase in Sm-Co-based permanent magnets. The present method is applicable for evaluating the phase stability of a wide range of metastable alloys.

Effect of element doping and substitution on the electronic structure and macroscopic magnetic properties of SmFe12 -based compounds

The mechanisms underlying the enhancement of magnetic anisotropies (MAs) of Sm ions, owing to valence electrons at the Sm site and the screened nuclear charges of ligands, are clarified using a detailed analysis of crystal fields (CF). In order to investigate the finite-temperature magnetic properties, we developed an effective spin model for SmFe$_{12}X$ ($X$=H, B, C, and N) and SmFe$_{11}M$ ($M$=Ti, V, and Co), where the magnetic moments, CF parameters, and exchange fields were determined by first-principle calculations. Using this model, the MA constants and magnetization curves at finite temperatures were investigated using a recently introduced analytical method [T. Yoshioka, H. Tsuchiura, and P. Nov\'ak, Phys. Rev. B {\bf 102}, 184410 (2020)]. In SmFe$_{12}X$, the doped light elements $X$ are assumed to be at the $2b$ site, and in SmFe$_{11}M$, the substitution site of Fe is systematically investigated for all inequivalent $8f$, $8i$, and $8j$ sites. We found that the first-order MA constant $K_1$ is increased by a factor of about two when hydrogen is doped to the $2b$ site and when Fe is replaced by Ti or V at the $8j$ site, owing to the attraction of the prolate $4f$ electron cloud to the screened positive charges of the surrounding ligand ions. We found that when Fe is replaced by Co, the MA increases at all temperatures regardless of the substitution site. The substituted Co attracts electrons, which reduces the electron density in the region from the Sm site to the empty $2b$ site. This causes the $4f$ electron cloud at the Sm site to be fixed along the $c$-axis direction, which improves the MA. The calculated temperature dependence of $K_1(T)$ and $K_2(T)$ in SmFe$_{11}$Co qualitatively reproduces the experimental results in the case of Sm(Co$_x$Fe$_{1-x}$)$_{12}$ for $x$=0.1 and 0.07.

A review on the effects of various elemental doping and nanostructuring of [formula omitted]-[formula omitted]/[formula omitted] composites on the thermoelectric performance enhancement

Thermoelectric device is a transformative technology for renewable energy generation. It is designed in a small compact feature with a quiet mechanism and has no gas emission, enabling it to conserve energy and preserve the global environment. Iron disilicide (β-FeSi2/Si) composite materials prepared by eutectoid reaction is found promising for thermoelectric applications. The strategies to enhance the thermoelectric properties of these composites are mainly by conducting band structure engineering such as elemental doping and nanostructure engineering. This article reviews the effects of elemental doping and nanostructuring of β-FeSi2/Si composite materials. Mn and Co were found to be the most common dopants due to their contribution to carrier mobility and carrier concentration. Other dopant elements such as Al, introduced point defects on the composite structure that is effective in lowering thermal conductivity. P was also found to be effective on both electronic and lattice contribution of thermal conductivity. Furthermore, in thin films structure, flatter surface is highly recommended rather than the crystallinity of films to enhance carrier mobility and suppress thermal conductivity. Thus, the way to optimize β-FeSi2/Si composite materials were discovered by the significant number of studies on refinement of composite structure into nanoscale. From these studies, electrical conductivity value was significantly enhanced while reducing its thermal conductivity and Seebeck coefficient value. The deterioration of Seebeck coefficient is yet to be improved hence was estimated possible by introducing doping mechanisms. Therefore, this review concludes some potential strategies for improving Seebeck coefficient while simultaneously increasing electrical conductivity and decreasing thermal conductivity towards enhancing its thermoelectric performance.

Metal Emulsion-Based Synthesis, Characterization, and Properties of Sn-Based Microsphere Phase Change Materials.

A comparative study of the metal emulsion-based synthesis of Sn-based materials in two different types of molten salts (namely LiCl–KCl–CsCl and LiNO3-NaNO3-KNO3 eutectics) is presented, and the properties of Sn, Sn-Cu and Sn-Cu-Zn microsphere phase change materials prepared in chloride salts are evaluated by differential scanning calorimetry (DSC) to understand the effect of element doping. Despite a high ultrasonic power (e.g., 600 W or above) being required for dispersing liquid Sn in the chloride system, well-shaped Sn microspheres with a relatively narrow size range, e.g., about 1 to 15 µm or several micrometers to around 30 µm, can be prepared by adjusting the ultrasonic power (840–1080 W), sonication time (5–10 min) and the volume ratio of salts to metal (25:1–200:1). Such a method can be extended to the synthesis of Sn-based alloy microspheres, e.g., Sn-Cu and Sn-Cu-Zn microspheres. In the nitrate system, however, a very low ultrasonic power (e.g., 12 W) can be used to disperse liquid Sn, and the particles obtained are much smaller. At low ultrasonic power (e.g., 12 W), the particle size is generally less than 10 or 4 µm when the sonication time reaches 2 or 5 min, and at high ultrasonic power, it is typically in the range of hundreds of nanometers to 2 µm, regardless of the change in ultrasonic power (480–1080 W), irradiation time (5–10 min), or volume ratio of salts to metal (25:1–1000:1). In addition, the appearance of a SnO phase in the products prepared under different conditions hints at the occurrence of a reaction between Sn droplets and O2 in situ generated by the ultrasound-induced decomposition of nitrates, and such an interfacial reaction is believed to be responsible for these differences observed in two different molten salt systems. A DSC study of Sn, Sn-Cu, and Sn-Cu-Zn microspheres encapsulated in SiO2 reveals that Cu (0.3–0.9 wt.%) or Cu-Zn (0.9 wt.% Cu and 0.6% Zn) doping can raise the onset freezing temperature and thus suppress the undercooling of Sn, but a broad freezing peak observed in these doped microspheres, along with a still much higher undercooling compared to those of reported Sn-Cu or Sn-Cu-Zn solders, suggests the existence of a size effect, and that a low temperature is still needed for totally releasing latent heat. Since the chloride salts can be recycled by means of the evaporation of water and are stable at high temperature, our results indicate that the LiCl–KCl–CsCl salt-based metal emulsion method might also serve as an environmentally friendly method for the synthesis of other metals and their alloy microspheres.

Borophene: Two-dimensional Boron Monolayer: Synthesis, Properties, and Potential Applications.

Borophene, a monolayer of boron, has risen as a new exciting two-dimensional (2D) material having extraordinary properties, including anisotropic metallic behavior and flexible (orientation-dependent) mechanical and optical properties. This review summarizes the current progress in the synthesis of borophene on various metal substrates, including Ag(110), Ag(100), Au(111), Ir(111), Al(111), and Cu(111), as well as heterostructuring of borophene. In addition, it discusses the mechanical, thermal, magnetic, electronic, optical, and superconducting properties of borophene and the effects of elemental doping, defects, and applied mechanical strains on these properties. Furthermore, the promising potential applications of borophene for gas sensing, energy storage and conversion, gas capture and storage applications, and possible tuning of the material performance in these applications through doping, formation of defects, and heterostructures are illustrated based on available theoretical studies. Finally, research and application challenges and the outlook of the whole borophene's field are given.

Effects of element doping and H2O presence on CO2 adsorption using hexagonal boron nitride

The characteristics of CO2 adsorbing on hexagonal boron nitride (h-BN) under various conditions are key to its application in industries. In this study, h-BN is selected as the adsorbent for CO2 adsorption and carbon/nitrogen (C/N) is the doping element. By means of density functional theory (DFT) calculations, adsorption structures, adsorption energies, distribution of electron clouds, transition state (TS) processes (free state → adsorption state) and effects of H2O are used to explain adsorption mechanisms of CO2 on pure/doped h-BN. According to calculation results, with doping of C/N, the delocalized π bond of h-BN is transformed and then CO2 adsorption on the specific site is enhanced. In the meantime, this study also reveals that h-BN should be treated as the tertiary amine in a way because H2O presence could obviously facilitate CO2 adsorption on pure/doped h-BN, consistent with existing studies. What is more, the study uncovers that the TS energy barrier of CO2 adsorption is another factor that affects adsorption strength. It is found that doping of C/N and H2O presence could reduce adsorption energy barriers and facilitate CO2 adsorption. The research results could provide valuable information about exploiting h-BN for massive CO2 adsorption in industrial situations.