Doped Configurations Research Articles

Next-generation cathodes for calcium-ion batteries: Leveraging NASICON structures for enhanced stability and energy density

This study focuses on developing a high-performance, stable cathode for calcium-ion batteries (CIBs) using a sodium superionic conductor (NASICON) structure to match the energy density and safety standards of current lithium- and sodium-ion batteries. Given the relatively sparse database of CIB materials compared with their lithium and sodium counterparts, expanding the range of new candidates is essential for developing high-performance batteries. To address this, we employed density functional theory (DFT) calculations, which provide a quantum-mechanical description of the electronic properties of materials, to construct a highly reliable database. To improve the accuracy and efficiency, we integrated machine learning interatomic potential with DFT to stabilize the NASICON-type structures, CaxNaV’yV’’2-yBzP3-zO12, where x = 0.8, 0.5, 0; y = 1, 0.5; z = 0.5, 0; V’ and V’’ are transition metals that support stable doped configurations at the V- and P-sites. From the initial 176 candidates, the top 10 materials that facilitate stable structures were identified based on selection criteria focusing on formation energy < 0 eV/atom, energy above hull = 0 eV/atom, gravimetric capacity ≥ 150 mAh/g, -1% ≤ volume change ≤ 1%, and 3 ≤ average voltage ≤ 4.5 V. This approach advances CIB technology and outlines effective strategies for dopant selection to optimize battery cathodes, configuring a framework for future advancements in battery technology.

Structural, electronic and optical properties of Halogen (F and Cl) atoms doped Graphdiyne

Abstract This paper reports the results of a density functional theory investigation of structural, electronic, and optical properties of halogen (fluorine and chlorine) atoms doped graphdiyne. Graphdiyne is doped with fluorine and chlorine with three different doping configurations each where one, two and three atoms of fluorine and chlorine were doped into Graphdiyne at benzene ring and acetylene linkages. The most stable doped structure was determined using the results of formation energy. Monolayers for fluorine and chlorine doped graphdiyne uniformly display metallic characteristics except where two atoms were incorporated shows semiconductor characteristics. PDOS shows that the energy band near the Fermi level is mainly contributed by the C 2p orbitals. Doped configurations shows higher peak intensities and good absorption in the UV, visible light region and IR region. These findings offer a fundamental basis for the understanding and manipulation of electrical and optical properties for doped graphdiyne with halogen atoms atoms and it is suitable for promoting the potential application of graphdiyne based electronic and opto-electronic device applications operating mainly in infrared and ultraviolet range.

Atomistic simulation of Na2Ti3O7: Defects, dopants, and diffusion properties

Na2Ti3O7 exhibits promise as a safe battery material for Na-ion batteries, currently undergoing extensive research. The atomistic simulation method is employed to scrutinize defects, dopant energies, and Na-ion migration in Na2Ti3O7. Notably, the Na-Frankel energy is the lowest, and the Na-anti-site cluster energy is lower than the Na-anti-site isolated energy. The migration of Na ions is observed to predominantly occur along the ab plane, where the activation energy is measured at 0.23 eV. K and Ge ions are identified as the most suitable isovalent and tetravalent dopants for Na and Ti sites, respectively. Furthermore, the introduction of the aliovalent dopant Al3+ ion on the Ti site can form additional Na+ ions. The electronic structures of the most favorable doped configurations are discussed.

Mechanical and electrical properties of two-dimensional BN doped with carbon group elements: first-principles calculations

Abstract Research of low-dimensional nanomaterials provides a direction for solving the problems of energy and environmental pollution. In this work, the regulation mechanism of doping carbon group elements X (X = C, Si, Ge, Pb, Sn) on mechanical and electrical properties of 2D monolayer BN are investigated by first-principles calculations. Two doping sites were selected, replace B atoms (B15N16X) or N atoms (B16N15X). Lower relative enthalpies and the elastic constants, which conforming to the mechanical stability standard, fully prove the stability of the doping system. Compared with B15N16X, B16N15X has larger structural distortion, smaller elastic constants and modulus, and is more inclined to ductility. With the increase of atomic radius, the deformation degree increases and the elastic parameters decrease. C-doped by replacing B atoms improves the elastic mechanical properties of monolayer BN. Sn-doped and Pb-doped modulate the monolayer BN into ductility. More importantly, all doped configurations exhibit magnetism. The indirect band gap of the undoped system can also be modulated into a direct band gap, B15N16C, B16N15Si and B16N15Ge all have direct band gaps in the spin-down direction. Asymmetric impurity energy levels DOS further verify the magnetism of the reference system.

Combined experimental and density functional theory approaches to address different mechanisms of nitrogen and sulfur doping on the enhancement of capacitive performance of hierarchical porous biochars

Activated carbon derived from biomass as hierarchical porous biochars (HPB) has been developed as electrode materials for supercapacitors. Nitrogen is known as the doping element that enhances quantum capacitance, but the mechanisms of sulfur doping on the quantum capacitance enhancement remain ambiguous. In this study, conventional approaches to assess the characteristics and capacitive performance of biochars were combined with density functional theory (DFT) calculations to assess different mechanisms of nitrogen and sulfur doping. The Bbiochar samples were prepared from the pyrolyzed fish bone powder at 800 °C without additional doping possessed a specific capacitance of 240 F g−1 at 1 A/g within 1 M H2SO4. Interestingly, additional nitrogen doping through urea mixing and additional sulfur doping through thiosulfate mixing prior to the pyrolysis enhanced the specific capacitance of biochar samples to exceed 400 F g−1 under the same condition. The urea mixed sample possessed low porosity but high charge transfer resistance, while the thiosulfate mixed sample possessed high porosity but low charge transfer resistance. The different underlying mechanisms were discussed through DFT calculations on graphene models designed based on the x-ray photoelectron spectroscopy (XPS) results. Nitrogen-doped configurations with topological defects mainly stored charge at the dangling atoms and possessed a relatively high quantum capacitance. Meanwhile, doped configurations of oxidized sulfur groups required relatively low formation energy and possessed large bond dipoles, corresponding to larger pore size and surface area of the thiosulfate mixed biochars. Understanding the contrary between effects of nitrogen and sulfur doping could resolve the bottleneck on enhancing the performance of electronic double layer supercapacitors.

Experimental study on toughening UV pre-curing adhesives for electrically conductive applications

Epoxy adhesives are not conductive materials, usually requiring the use of fillers to create electrical bridging between the joint's substrates. This work aims at the implementation of UV fixation, instead of clamping jigs, on doped joints to ensure enough contact bridging pressure during curing. As such, an UV pre-curable adhesive was mechanically characterised in terms of strength – bulk tensile test and TAST (shear) –, and fracture toughness – DCB (mode I) and ENF (mode II) tests –, in the neat state (reference). Afterwards, for the doped configurations – 5%v/v conductive spheres (Sph), 15%v/v aluminium (Al) and 10%v/v graphite (C) – only mode I and II tests were considered accessing the filler's toughening effect. The electrical conductivity of the real joints was assessed through electric discharge machining (EDM). In the end, the Sph's were deemed necessary for bond thickness control. And the Al (mode I +50 % and II +61 %) and C (mode I +25 % and II +42 %) powders presented improvements in toughening the adhesive. However, UV-fixation failed to provide enough clamping pressure, during curing, to maintain the electrical bridging necessary for EDM.

First-principles study on electronic and mechanical properties of boron and nitrogen co-doped fluorinated diamane

Stimulated by the successfully synthesis of fluorinated diamane (F-diamane) [Nat. Nanotechnol., 2019, 15, 59], in this paper, first-principles calculations are performed to investigate the structural, electronic and mechanical properties of fluorinated diamane (F-diamane) co-doped with B and N atoms. The stable doped structures contain BN bonds, and the structure with N atom locating at internal substitution position with B atom at neighboring external positions is most stable. The thermal stability of the doped structures is verified by molecular dynamics simulation. B and N atoms co-doping could reduce the formation energy of bilayer graphene to diamane and effectively modulate the band gap. For mechanical performance, these doped configurations exhibit excellent elastic constants, Young's modulus, shear modulus, and Poisson's ratio with isotropy. This work would promote the synthesis and potential applications of diamane.

Tuning the electro-optical properties of germanene nanoribbons by boron atom substitution for application in information transmission

Germanene nanoribbons, a one-dimensional material, have great potential for future technological applications. This research aims to investigate the electro-optical properties of boron-doped germanene nanoribbons with a width of five atoms. The theory used in this study is density functional theory (DFT). The original system is a narrow band gap semiconductor, with a gap size of 0.06[Formula: see text]eV. The doped configurations, which retain the honeycomb hexagonal structure, are stable and metallic in nature. The introduction of B atoms flattens the configuration, leading to a partial charge shift from Ge to B. The absorption peaks in the 3B and 5B configurations occur in the frequency range less than 500[Formula: see text]nm, indicating good absorption of visible light, and suggesting possible applications in light-sensitive components. Notably, the real part of the dielectric function’s 0z component is negative, offering immense potential for optical, microwave and communication applications.

Atomic ordered doping leads to enhanced sensitivity of phosgene gas detection in graphene nanoribbon: a quantum DFT approach

We explore a novel sensor for detection of phosgene gas by graphene derivatives such as pristine and doped graphene nanoribbons via first principles calculations. The interaction of phosgene molecule with various edge and center doped configurations of boron, phosphorus and boron-phosphorus co-doped armchair graphene nanoribbon (AGNR) and zigzag graphene nanoribbon (ZGNR) is investigated through density functional theory (DFT). P-doped systems showcase chemisorption, displaying enhanced sensitivity to phosgene detection as reflected by a more negative adsorption energy values, accompanied by a prominent charge transfer due to the doping. Regardless of nanoribbon geometry, the binding energies of P-doped systems exhibit notable uniformity within the range of −8.01 eV to −8.49 eV, however the adsorption energies in ZGNR are significantly lower than those observed in AGNR. Due to much higher(lower) electron-donating (accepting) capacity of phosphorous(boron) atoms in comparison to ‘C’ atom, substitutional doping with ‘P’ or ‘B’ atoms in AGNR has signifiant impact on the structural, electronic and adsorption properties of the nanoribbons. We observe that phosphorus doped configurations (edge/center) effectively interact with phosgene molecule with higher adsorption that corresponds to the chemisorption phenomenon. The strongest adsorption energy (−8.83 eV) is obtained for P doped configurations, followed by that for B+P co-doped AGNR (−4.23 eV). These results suggest significantly stronger adsorption of phosgene gas on P doped AGNR than on any other systems reported so far. Band structure analysis estimates that by phosphorus doping, changes in the band gap is significant and it also shows prominent changes in the band structures. Isosurface electronic charge density plots identify that the transfer of charge takes place from graphene system to phosgene molecule. Thus, significant variation in adsorption and electronic properties of P doped AGNR reveal that these geometries immensely promote the detection of phosgene gas, and may be considered as promising chemical sensor for phosgene removal.

Exploring multiferroicity, half-metallic phase, and curie temperature in X = B/C/N/F-Doped KNbO3: a DFT aspect

Multiferroic materials provide an astonishing platform for next-generation spintronic devices such as magnetoresistive random access memory. Herein, ferroelectric, electronic, and magnetic properties of the pristine and X = B/C/N/F-doped KNbO3 (KNO) perovskite oxides are explored using ab initio calculations along with modified Becke-Johnson potential, where X is doped at O-site (X@O) in both KO- and NbO2-layers. Our calculations revealed that the pristine motif is a non-magnetic insulator having an energy band gap (E g ) of 2.80 eV and spontaneous polarization (P) of 41 μCcm−2, which are close to the experimentally observed values of 3.34 eV and 37 μCcm−2, respectively. The computed enthalpy of formation and elastic parameters confirm the thermodynamic and mechanical strength of the doped configurations, respectively. It is established that X-dopants significantly reduce structural distortions and have negative influence on the value of P. The most distinctive feature of the current work is that the B/N-doped KNO system for X@O in the KO-layer exhibits n-type half-metallic (HM) ferromagnetic (FM) behavior with an E g of 1.46/2.96 eV which is sufficiently large enough to prevent any magnetic transition. In contrast, C and F-doped structures are FM insulator and n-type non-magnetic metallic, respectively. Along with this, X = B/C/N-doped KNO system for X@O in the NbO2-layer displayed FM insulating nature, while the F-doped motif becomes an n-type non-magnetic metallic. The total magnetic moment for the B/N-doped structure is 1.0, which also hints the HM FM behavior. Finally, the estimated Curie temperature using the Heisenberg 2D Hamiltonian model in magnetic doped structures is found to be high enough to be used for practical purposes.

A DFT study on the fundamental mechanisms of quantum capacitance enhancement within the carbon-based electrodes through different classes of doped configurations from biomass-derived elements

Density functional calculations were performed on 15 functionalized graphene models to investigate the enhancement of quantum capacitance (CQ) by common dopant elements N, P, S, and O from biomaterials. Geometry optimizations and formation energy calculations demonstrated that the van der Waals radius and additional covalent bonds influenced the mechanical stress and formation energy, particularly due to the distortion of the graphene lattice caused by larger S or P atoms replacing carbon atoms. According to both the CQ and formation energy calculations, nitrogen emerged as the most promising doping element for enhancing CQ, followed by phosphorus, while sulfur showed a relatively lower contribution. Electron density profiles indicated that the improvement of CQ was facilitated by the lone pair electrons at the defects. The effects of dopants on electronic structures were further elucidated through CQ characteristics, resulting in the classification of functionalized graphene models into three types. The ‘graphitic’ type represented configurations that preserved most of the electronic structure of pristine graphene, while ‘p-type’ and ‘n-type’ represented those experienced the loss and gain of valence electrons, respectively. This electronic structure-based classification of doping provides valuable insights for future designs, enabling control over sintering and doping conditions in biomass-derived electrode materials for supercapacitors.

Extended Finite Element Method (XFEM) Model for the Damage Mechanisms Present in Joints Bonded Using Adhesives Doped with Inorganic Fillers

The use of adhesive bonding in diverse industries such as the automotive and aerospace sectors has grown considerably. In structural construction, adhesive joints provide a unique combination of low structural weight, high strength and stiffness, combined with a relatively simple and easily automated manufacturing method, characteristics that are ideal for the development of modern and highly efficient vehicles. In these applications, ensuring that the failure mode of a bonded joint is cohesive rather than adhesive is important since this failure mode is more controlled and easier to model and to predict. This work presents a numerical technique that enables the precise prediction of the bonded joint’s behavior regarding not only its failure mode, but also the joint’s strength, when inorganic fillers are added to the adhesive. To that end, hollow glass particles were introduced into an epoxy adhesive in different amounts, and a numerical study was carried out to simulate their influence on single lap joint specimens. The numerical results were compared against experimental ones, not only in terms of joint strength, but also their failure pattern. The neat adhesive, which showed 9% and 20% variations in terms of failure load and displacement, respectively. However, looking at the doped configurations, these presented smaller variations of about 2% and 10% for each respective variable. In all cases, by adding glass beads, crack initiation tended to change from adhesive to cohesive but with lower strength and ductility, correctly modeling the general experimental behavior as intended.

Electrical and optical properties of C, Ge-doped armchair silicene nanoribbons applied in optoelectronics

With the continuous development of nanotechnology, the search for new material structures plays a crucial role. Silicene nanoribbons (SiNRs) are one-dimensional materials that hold promise for numerous potential applications in the future. The electric and optical properties of C, Ge-doped armchair SiNRs are investigated in this study using density functional theory. All the doped configurations are stable and maintain the honeycomb hexagonal structure after optimization. Doping with C yields flatter structures, while doping with Ge yields larger buckling heights. The C 1–1 doping configuration is highlighted because its band gap is extended up to 2.35 eV, making it an ideal candidate for potential optoelectronic applications. The charge distribution, charge density difference, and hybridization of multiple orbitals are also systematically studied. The optical properties reveal the differences between C and Ge doping, with a clear anisotropy observed. Strong absorption occurs at high electromagnetic wave energies, while the absorption coefficient rapidly decreases in the long-wavelength range. The study of electron–hole density shows good agreement with the energy band structure, where electron–hole pairs only exist when the excitation energy is greater than the bandgap width, and not all excitation energy values give rise to electron–hole pairs. This study contributes a small part to creating potential applications in nanotechnology.

Computational and experimental study on undoped and Er-doped lithium tantalate nanofluorescent probes

We present a combined density functional theory (DFT) and experimental work on lithium tantalate LiTaO3 (LT) and its Er-doped counterparts. We calculate the electronic and optical properties for both LT and LT:Er+3, with Er occupying either Li or Ta sites, at 4.167 mol%. The generalized gradient approximation (GGA) calculations show that the Er-4 f bands appear closer to the conduction band bottom and to the valance band top, for the first and second doped configurations, respectively. This agrees with changes in the imaginary part of the frequency dependent dielectric function between the doped configurations. There are striking differences between the GGA and the hybrid functional HSE06 calculations for the band structures of the doped configurations. HSE06 accurately predicts the location in energy for all Er-4 f orbitals: These are now spread in energy and appear above and below the Fermi energy. We synthesized LT:Er+3 nanoparticles, validated through X-ray diffraction and Scanning Electron Microscopy. Differential scanning calorimetry and thermogravimetric analysis confirmed increases in the activation energy and lowering of the reaction temperature due to Er+3 doping. The LT:Er+3photoluminescence showed strong f–f emission in the visible and near-infrared regions, in an excellent agreement with the HSE06 electronic information.

Boron-doped armchair germanene nanoribbons with a width of six atoms in an external field: a DFT study

Density functional theory (DFT)has been used to study the structure and electronic properties of boron-doped armchair germanene nanoribbons materials. The doped configurations are all stable in the electric field by the σ bond and the π bond. The doped structures can be semi-conductive or semi-metallic depending on the doping substitution positions. The doping configuration B:Ge = 1:1 proved to be superior and stable in the electric field, and the doping changed this structure to become planar. With three different directions of electric field, the horizontal electric field has the most influence on the geometric structure, multi-orbit hybridization as well as the spatial charge distribution of the doped systems. The magnetization of the systems changes with the changing direction of an electric field, anti-ferromagnetic structures are found in meta-configuration and ortho-configuration with longitudinal electric fields, and 1-1 configuration with perpendicular electric fields and horizontal electric fields. The ortho-configuration with an electric field of 0.5V/m with an extended band gap of 0.69eV is perfectly applicable in room-temperature field-effect transistors; other configurations have potential in nanoscale applications.

Enhanced mechanical, electronic, magnetic, and optical properties of penta-BCN by Ni-doping

We performed first-principles density functional theory (DFT) calculations on Ni-doped penta-BCN (p-BCN) with different feasible doping configurations, and compared the results with the pristine counterpart. All the variants of the doped structures are structurally and mechanically stable, with the B-site being the most favorable doping site. The lattice constants, bond lengths, and thickness of the doped monolayers are increased relatively from that of p-BCN, tailoring the Young’s modulus, Poisson’s ratio, and mechanical anisotropy. While the band gap is reduced for each of the doped configurations, an induced magnetism is only observed in the B- and N- sites, with a total magnetic moment of 1 μB. The optically suitable lower band gap enhances the static dielectric constant, and refractive index, and allows for high optical absorption in the infrared, visible, and ultraviolet regions, with small energy loss and reflectance possessing strong optical anisotropy. These premium upgrades in p-BCN by Ni-doping establish the structures as excellent candidates for nanomechanical, spintronics, and optoelectronic devices.

Al doping in germanene nanoribbons in the presence of an external electric field

Germanene by description, is a two-dimensional material with many different properties from graphene. Germanene also has a honeycomb hexagonal form but it is not a planar structure. Germanene nanoribbons (GNRs) are created from germanene with edges that have been changed by other atoms; in this study, two of the GNRs’ edges have been modified by hydrogen. The density of states (DOS), energy formation, and band structure of the system are computed, displayed, and studied using density functional theory (DFT). Due to the presence of hydrogen at the two edges, GNRs have a narrow band gap. This research will look into Al doping in GNRs with the system being immersed in a 0.5V/Angstrom external electric field. Two configurations are examined in this section: the top configuration and the valley configuration. The doped configurations do not break up in the electric field, and both configurations become semi-metals with bands crossing the Fermi level. This research lays the groundwork for future applications in nanochip technology

Ag-doped silicene nanoribbons in the electric field

Silicene nanoribbons (SNRs) will be doped with Ag atoms, silver atoms will be substituted at several positions in the structure of SNRs to create doped configurations. An external electric field of 0.1 V/Å will be applied to the doped systems. The theory used in this study is density functional theory (DFT). The doping profiles are optimized and they are all stable in the external electric field. The formation energies of the doped configurations will be calculated, the structure of energy bands and state densities of the systems will be plotted, investigated, and discussed. The study shows that the top configuration is a semi-metal, while the meta configuration is a semiconductor. Depending on the application, the system can use a semi-metal or a semiconductor, which creates a wide range of applications in electronic technology.

New insights into NO adsorption on alkali metal and transition metal doped graphene nanoribbon surface: A DFT approach

The aim of this article is to investigate the sensing performance of NO gas molecule on the graphene nanoribbon domain for the determination of structural and electronic properties. Effect of an alkali metal (lithium) and a transition metal (iron) on the armchair oriented graphene nanoribbon (ArGNR) surface for the sensing purpose of NO gas has been performed through the quantum mechanics based Density Functional Theory (DFT) calculations. Various configurations of ArGNR doped with Li and Fe atoms such as one-edge doped, center doped, both-edge doped Li-ArGNR and Fe-ArGNR have been simulated, and a detailed comparative study of lithium and iron doping on different configurations of ArGNRs for the adsorption energy, stability analysis, band gap analysis and density of states analysis has been quantitatively evaluated. By comparing the adsorption energy of NO, it is found that Li doping enhances the strength of NO adsorption on the different variants of ArGNR. Computational results predict that the undoped ArGNR is insensitive to the NO gas adsorption with adsorption energy of about −0.41 eV. Our results determine that substitutional doping of Li doping at one edge doped and both-edge doped position increases the adsorption abilities of ArGNRs in these configurations with adsorption energies of approximately −6.92 eV and −9.64 eV that is 16 and 23 times greater than the pristine ArGNR (Pr-ArGNR). Band nature for both type of doping estimates the changing behavior of ArGNRs from semiconductor to metallic transition after the adsorption of NO molecule. It is concluded that the Li doping at one edge and both edge position of ArGNR makes it an excellent potential sensing material for the sensing purpose of NO gas as compared to the Fe doped configurations.

Enhancement of thermoelectric performance of ZrO2 via Titanium doping

In this paper, we investigated the thermoelectric (TE) properties of doped Ti-doped Zirconium Oxide (ZrO2) via first principal calulations together with the Boltzmann transport theory. We computed various TE properties of Zr1−xTixO2 for x = 0.03 and 0.06 within the temperature range of 10 K to 1200 K. This material shows the p- type behaviour in prestine and doped configurations. We achieved Figure of Merit (ZT) arround 0.82 for 3% doping of Ti at 290 K, and this is higher than that of various ZrO2 composites and several oxides like SnO2 and TiO2. Even though Zirconia has low thermal conductivity as compared to other oxides, it is not considered a good TE candidate. Despite this fact we achieved surprisingly good ZT maxima of 0.819 for 3% Ti-doping at 290 K which is 34.22% more than that of the pure material at the same temperature which makes it a good choice for room temperature applications. Hence, we believe that Ti-doped ZrO2, along with its low thermal conductivity, has a great potential to be an efficient TE material.