Partial Density Of States Research Articles

Theoretical Study of the Magnetic Mechanism of a Pca21 C4N3 Monolayer and the Regulation of Its Magnetism by Gas Adsorption.

For metal-free low-dimensional ferromagnetic materials, a hopeful candidate for next-generation spintronic devices, investigating their magnetic mechanisms and exploring effective ways to regulate their magnetic properties are crucial for advancing their applications. Our work systematically investigated the origin of magnetism of a graphitic carbon nitride (Pca21 C4N3) monolayer based on the analysis on the partial electronic density of states. The magnetic moment of the Pca21 C4N3 originates from the spin-split of the 2pz orbit from special carbon (C) atoms and 2p orbit from N atoms around the Fermi energy, which was caused by the lone pair electrons in nitrogen (N) atoms. Notably, the magnetic moment of the Pca21 C4N3 monolayer could be effectively adjusted by adsorbing nitric oxide (NO) or oxygen (O2) gas molecules. The single magnetic electron from the adsorbed NO pairs with the unpaired electron in the N atom from the substrate, forming a Nsub-Nad bond, which reduces the system's magnetic moment from 4.00 μB to 2.99 μB. Moreover, the NO adsorption decreases the both spin-down and spin-up bandgaps, causing an increase in photoelectrical response efficiency. As for the case of O2 physisorption, it greatly enhances the magnetic moment of the Pca21 C4N3 monolayer from 4.00 μB to 6.00 μB through ferromagnetic coupling. This method of gas adsorption for tuning magnetic moments is reversible, simple, and cost-effective. Our findings reveal the magnetic mechanism of Pca21 C4N3 and its tunable magnetic performance realized by chemisorbing or physisorbing magnetic gas molecules, providing crucial theoretical foundations for the development and utilization of low-dimensional magnetic materials.

First principle study of structural and optoelectronic properties of ZnLiX3 (X = Cl or F) perovskites

The zinc-based perovskites ZnLiX3 (X = Cl or F) were investigated for their structural, electronic, and optical properties using the WIEN2k package within density functional theory (DFT). Structural properties were calculated using the generalized gradient approximation (GGA), while the modified Becke-Johnson (mBJ) potential was applied for a more accurate description of the optical and electronic properties. Both compounds are confirmed to be stable, crystallizing in the cubic Pm-3 m (No. 221) space group. ZnLiCl3 has an indirect band gap of 0.30 eV between the Γ and M symmetry points, indicating semiconducting behaviour, while ZnLiF3 exhibits an indirect band gap of 5.45 eV, typical of an insulating material. The electronic states contributing to the band structure were analyzed using the total density of states (TDOS) and partial density of states (PDOS). Optical properties, evaluated in the energy range of 0–14 eV, reveal strong optical conductivity and absorption at higher energies, while both materials show transparency to lower-energy photons. These findings suggest that ZnLiCl3 and ZnLiF3 are suitable candidates for high-frequency UV optoelectronic device applications.

Transition metal-modified armchair graphene network for high-performance hydrogen evolution reaction catalysts

This study explores the structural, electronic, and catalytic properties of armchair hexagonal graphene networks (AHGN) modified with single transition metal (TM) atoms from Period V. Substitutions of Ag, Mo, Nb, Pd, Rh, Ru, Tc, Y, and Zr were investigated, revealing significant changes in bond lengths, bond angles, and dihedral angles. The binding energies indicate that TM substitutions do not drastically destabilize AHGN, suggesting potential applications requiring modified electronic properties. Electronic investigations showed that TM substitutions influence the partial density of states (PDOS) and energy gaps (ΔE), with Tc significantly reducing ΔE, indicating a shift towards metallic behavior. Mulliken charge analysis highlighted the electron density redistribution around TM atoms and edge carbons, enhancing electronic conductivity and chemical reactivity. Based on the results, AHGN-Rh-H, AHGN-Pd-H, and AHGN-Mo-H demonstrate the most efficient catalytic performance for the hydrogen evolution reaction (HER), with ΔG values comparable to platinum, underscoring their potential for practical hydrogen production applications. Conversely, materials like AHGN-Nb-H and AHGN-Zr-H exhibit higher ΔG values, indicating lower efficiency for HER. Global reactivity parameters (GRPs) analysis revealed AHGN-Tc with the most negative chemical potential (−4.010 eV) and highest electronegativity (4.010 eV), indicating strong electron-accepting and electron-attracting abilities. These findings underscore the potential of TM-substituted AHGN for advanced electronic applications and efficient hydrogen production.

Structural, electronic and optical properties of α -Si3N4, β-Si3N4 and γ-Si3N4 using density functional theory

Density Functional Theory (DFT) has in recent years gained a lot of popularity and has become an efficient and reliable tool in the study of material properties. This is specifically due to its computational convenience and excellent results in the prediction of material properties, which is aided by the development of highly efficient and accurate functionals. DFT has successfully been applied in a vast study of material at both ground and excited states. In this study based on DFT structural, optical, electronic properties and phonon frequency of silicon nitrides of different phases were studied using the GGA as exchange-correlation functional. For the electronic band gap calculation the results was obtained using the GGA and the hybrid HSE06 respectively for α -Si3N4 with space group (P31c), β-Si3N4 with space group (P63/m) and γ-Si3N4 phase polymorph with space group (14‾3d). Results obtained for the phases α -Si3N4 shows a narrow indirect band gap while β and γ -Si3N4 indicate a wide indirect band gap material for wide possible application in high temperature and high-power applications. Cohesive energy calculation and phonon frequencies were obtained to check the mechanical and dynamic stability of the three different phases. Results obtain for density of states, partial density of states and the optical properties, such as absorption coefficient, refractive index, extinction coefficient, reflectivity and electron energy loss spectra which all show good agreement with previous studies and relative experimental data.

Zn-doped hollow cubic MnO2 as a high-performance cathode material for Zn ion batteries.

Manganese-based compounds have the characteristics of high theoretical capacity, low cost and stable performance, thus become a research hotspot for cathode materials of zinc-ion batteries (ZIBs). However, in the process of charging and discharging, it is accompanied by problems such as structural collapse and low conductivity, which resulted in severe capacity degration during cycles. In this paper, a kind of Zn2+ doped MnO2 hollow cube cathode material (Zn-MnO2) was prepared by self-sacrificing template method. The Zn2+ doped in MnO2 crystals can induce oxygen vacancies in the structure, thereby improving the structural stability ion diffusion coefficient and electrical conductivity of the material. After 100 cycles at 0.3 A g-1, the high specific capacity of 281.2 mA h g-1 is still maintained. Through ex-situ XPS and ex-situ XRD tests, the mechanism of charge-discharge process was discussed. The results show that the storage mechanism of Zn-MnO2 is H+ and Zn2+ insertion/removal and Mn3+/Mn2+ two-electron reaction pathway. The total state density (TDOS) and partial state density (PDOS) of Zn-MnO2 and MnO2 further demonstrated that the doping of Zn2+ enhanced the electron conductivity and is beneficial to the electron transfer during the electrochemical reaction.

Harnessing the half-metallicity and thermoelectric insights in Cs2AgMBr6 (M = V, Mn, Ni) double halide perovskites: A DFT study

Herein, we undertake a detailed exploration of the structural stability, magneto-electronic behavior, and thermoelectric properties of Cs₂AgMBr₆ (M = V, Mn, Ni) halide double perovskites using first-principles approach. The study commences with a meticulous assessment of both structural stability and thermodynamic properties employing various metrics. Energy minimization across different phases, utilizing the Birch-Murnaghan equation of state, confirms the ferromagnetic phase as energetically favoured, supported by Curie-Weiss constants of 98 K, 100 K, and 150 K for V, Mn, and Ni-based perovskites, respectively. Mechanical properties, including hardness, stiffness, ductility, and fracture strength, are derived from the simulated elastic constants, ensuring the mechanical stability of the materials. Electronic structure analysis, performed using the PBE-GGA and GGA + mBJ functionals, reveals that Cs₂AgMBr₆ compounds exhibit half-metallic ferromagnetism, with 100 % spin polarization at the Fermi level. Analysis of the partial density of states highlights the half-metallic ferromagnetic mechanism, confirming predominant ferromagnetic order through parameters such as the exchange splitting energy (Δx), p-d exchange interaction energy (Δx(p-d)), crystal-field energy (Ecrys), and exchange constants (N₀α and N₀β). The negative values of the exchange constants further validated the dominant ferromagnetic order in both s-d and p-d interactions, with unpaired electrons contributing magnetic moments of 2 μB for V, 4 μB for Mn, and 1 μB for Ni-based perovskites. Also, the Curie temperatures are calculated as 385 K, 747 K, and 204 K for V, Mn, and Ni-based perovskites. The overall findings, which reveal 100 % spin polarization and high zT values, underscore the significant potential of Cs₂AgMBr₆ halide perovskites for advancing spintronics and thermoelectric applications.

Exploration of lead free half-metallic double perovskites Li2Mo(Cl/Br)6 for spintronic device: DFT-calculations

The intrinsic spin of electrons has revolutionized the various aspects in the field of electronics, like data storage and quantum computing. Magnetic, structural, mechanical, transport and thermoelectric aspects of the Li2Mo(Cl/Br)6 double perovskites have been examined using the Wein2k and BoltzTraP code. These compounds having cubic structure with negative enthalpy of formation confirms their thermodynamic stability. The energy versus volume optimization for both ferromagnetic (FM) and antiferromagnetic phases (AFM) indicate AFM state due to greater release of energy in this configuration. Double exchange model p-d hybridization for partial density of states (PDOS) is investigated in band structures and half-metallicity feature is reported. The spin–orbit interaction with hybridization in d states of Mo and integral magnetic moment reveals strong spin polarization. The thermoelectric features (Seebeck coefficient, power factor, and figure of merit, electrical and thermal conductivities) have also been evaluated for utilization of these compounds in spintronics appliances.

Electrode Materials for NO Electroreduction Based on Dithiolene Metal–Organic Frameworks: A Theoretical Study

To quickly and efficiently screen catalytic materials with both activity and selectivity for the nitric oxide reduction reaction (NORR), we adopted a strategy that considers the activity of the side reaction hydrogen evolution reaction (HER) first. It can be seen that Fe3(THT)2 (THT = triphenylene-2,3,6,7,10,11-hexathiol) has extremely excellent HER activity, with a Gibbs free energy change (ΔG) of 0.007 eV. Based on the relationship between ΔG and theoretical exchange current density, all TM3(THT)2 can be divided into two regions: one is the absolute values of ΔG greater than 1 eV, the other is the absolute values of ΔG greater than 0 eV and less than 1eV. Obviously, the candidates with the absolute values of ΔG greater than 1 eV have poor HER performance, but this precisely provides the possibility of obtaining NORR catalytic materials with both excellent selectivity and activity. Subsequent calculation results show that the maximum ΔG change of the rate-determining step of Ta3(THT)2 is unexpectedly only 0.05 eV. Therefore, Ta3(THT)2 may be regarded as the NORR catalytic material with both excellent performance and selectivity. Based on the electron transfer and partial density of states (PDOS) analysis, it can be seen that Ta plays a crucial role in the activation stage of NO. The approach that considers the activity of the side reaction HER first may provide a new idea for rapidly screening highly selective and active NORR catalysts.

Investigating the Optoelectronic Properties of 2‐D and 3‐D CaTi1−xCuxO3 as a Phosphor Materials: A Density Functional Theory Approach

ABSTRACTThe CaTiO3 has been extensively investigated as a highly promising optical material mostly for its optoelectronic properties and its function as a host for transition metals doped in the CaTiO3. Electronic and optical properties of CaTi1−xCuxO3 (2‐D and 3‐D) have been thoroughly analyzed using first‐principles calculations based on Density Functional Theory (DFT). The calculations of these properties in both 2‐D and 3‐D configurations have performed by the use of generalized gradient approximation plus Hubbard (GGA + U). The electronic characteristics including the electronic band structure, partial density of states, and total density of states have been meticulously computed for CaTi1−xCuxO3 in both 2‐D and 3‐D. Upon analyzing the obtained results, we investigated that conduction and valence bands overlapped for both 2‐D and 3‐D structures revealing the metallic nature. We observed transitions mainly attributed to Cu‐d, Ti‐d, Ti‐p, and O‐p orbitals in both 2‐D and 3‐D configurations. Discussion delves into the significance of electronic band structure calculations in understanding optical properties. Peaks in the energy loss function are observed at 13 eV in both cases referred to the plasmon energy. Static values of the dielectric functions, extinction coefficient, reflectivity, and refraction are also computed. Our obtained results showed that the CaTi1−xCuxO3 compound in 3‐D form is more apt for optoelectronic devices and UV‐LED applications.

MAX phase borides, the potential alternative of well-known MAX phase carbides: A case study of V2AB [A = Ge, P, Tl, Zn] via DFT method

This study predicted four new MAX phase borides via the DFT method, with a comprehensive and thorough approach. The stability of the predicted phases has been thoroughly studied using formation energy, phonon dispersion curve (PDC), and elastic constants (Cij). The metallic nature of the studied phases is confirmed through the computation of the electronic band structure and density of states (DOS). Their bonding nature is disclosed using the partial density of states, Mulliken population analysis, and charge density mapping. The mechanical behavior is investigated in depth by calculating elastic constants, elastic moduli, Poisson's & Pugh ratio, machinability index, and Vickers hardness. Different anisotropic indices are also computed to demonstrate the elastic anisotropy. The Debye temperature (ΘD), Grüneisen parameter (γ), phonon thermal conductivity (kph), minimum thermal conductivity (kmin), thermal expansion coefficient (TEC), and melting temperature (Tm) are all calculated, and the suitability of the studied phases as thermal barrier coating (TBC) materials has been discussed. Finally, the optical constants are calculated and analyzed, further certifying the metallic nature of the herein-studied phases. The reflectivity spectra of all the herein selected compounds reveal their potential as coating materials to lessen solar heating. Among the studied phases, V2PB exhibits the best thermo-mechanical properties for potential applications in diverse fields, such as structural components and TBC materials. The potential applications of our findings are vast, and the obtained results reveal that the predicted phases are indeed potential alternatives to their counterpart carbides.

The impact of stress and interface composition on the study of CsF/CsPbX3 inorganic perovskite heterojunctions

In this paper, using first-principles calculations, we have shown that the electronic properties of the CsF/CsPbX3 (X = Cl, Br, I) heterojunctions can be effectively modulated by applying in-plane strain. The CsF/CsPbX3 heterojunction structures exhibit low-lattice mismatch ratios (Cl-Br-I, 3.6 %-1.8 %-4.3 %). Pb²⁺ and F⁻ attract each other to form PbF2, Cs+ and X−attract each other to form CsX. The binding energies are -0.578, -0.406, and -0.723 eV (Cl, Br and I), respectively, indicating that CsF/CsPbI3 exhibits the superior stability. Three heterojunctions are direct band gap semiconductors and the band gaps increase compared to inorganic perovskites (ΔEg:CsPbCl3CsPbBr3CsPbI3, 0.640–0.652–0.601 eV). The partial density of states indicates that the band gap contribution is related the [PbX3]− octahedron and F−. It is evident from the absorption spectra that the interaction of the CsF/CsPbX3 heterojunctions produces a blue shift. By combining multiple layers of CsF and CsPbX3, an overall broad spectral response can be achieved. The optical parameters of CsF/CsPbX3 are consistent with the changes in the band gap. This study demonstrates that CsF can enhance the stability adjust of the spectral response range of inorganic perovskite sensors, and improve the optical absorption performance. The study provides valuable theoretical guidance for the research of high-performance CsF/CsPbX3 heterojunction sensors.

Structural, Optical, and Magnetic Properties of Brownmillerite KBiFe2O5 and KBiFe1.95Ti0.05O5+ via Reactive Templated Method.

Brownmillerite KBiFe2O5 (KBFO) and KbiFe1.95Ti0.05O5+ (KBFTO) ceramics were synthesized using the prereacted nanopowders of KFeO2 (KFO) and BiFeO3 (BFO), and KFO and BiFe0.95Ti0.05O3+ (BFTO), respectively, via the reactive templated method. The powder X-ray diffraction patterns confirmed the monoclinic phase of the KBFO and KBFTO samples. The incorporation of Ti4+ at Fe3+ site prevented the formation of a secondary phase (Bi2Fe4O9) in the KBFTO sample. Our experimentally determined lattice parameters for the orthorhombic P2/c KBFO and KBFTO are consistent with our density functional theory (DFT) computed lattice parameters (within a 5% error). Scanning electron microscopy images revealed an average grain size of ∼1.38 and 0.85 μm for KBFO and KBFTO, respectively. The calculated optical band gaps of the KBFO and KBFTO using the Kubelka-Munk function from their UV data were found to be 1.69 and 1.71 eV, respectively. The measured surface area of KBFTO (1.339 m2 g-1) obtained from BET analysis was double that of KBFO (0.698 m2 g-1). KBFTO's room-temperature magnetization was 0.986 emu g-1, which was twice that of the KBFO, while its room-temperature conductivity measured using impedance spectroscopy was 5.69 × 10-3 S m-1 which was 10 times that of KBFO. Notably, our DFT calculations showed that the small Ti dopant concentration enhanced the partial density of states (PDOS) above the Fermi level. It shifted the Fermi level toward higher energy, and the oxygen PDOS for KBFTO was significantly enhanced relative to KBFO, which ultimately helped improve the conductivity.

A THEORETICAL STUDY OF THE PHYSICAL PROPERTIES OF HEXAGONAL GALLIUM NITRATE USING DENSITY FUNCTIONAL THEORY

First-principles calculations based on density functional theory (DFT) have been used to investigate structural, electronic, optical and thermodynamic aspects of the α-GaN crystal. Based on local density approximations (LDA), Generalized gradient approximation (GGA) and meta-generalized gradient approximation (m-GGA) functional methods, the band gap energies of α-GaN crystals have been estimated as 1.962 eV, 2.069 eV and 2.354 eV. The band gap energies that are presented in these studies are in accordance with the ones from the other experimental and theoretical studies. Besides, our findings give us knowledge about the electronic and optical properties of α-GaN crystal. The band gap energies in the α-GaN crystal are the key factors that define its electrical and optical characteristics. They are the energy range in which the electrons can be exited from the valence band to the conduction band, which in turn affects the material's conductivity and the ability of the material to absorb and emit light. The approximate of our results with the previous researches indicates the reliability of our findings and thus increases our knowledge of α-GaN's electronic and optical phenomena. The orbital characteristics of the Ga and N atoms were found by simulating the density of state and the partial density of state for α-GaN. Besides the analysis of the band structure, density of states and optical properties of the compound we also included. The results show that α-GaN has a direct bandgap, which is at the G point in the Brillouin zone. This is the reason for its great potential for the development of optoelectronic devices. Also, we use the three approximations that are given earlier to find the optical characteristics (the absorption coefficient) of the compound. In addition to that, the thermodynamic properties that can be calculated like Debye temperature, enthalpy, free energy, entropy and heat capacity enable us to understand the thermal behavior of the compound better. The heat capacity of α-GaN is detected to be 17.3 Jmole-1K-1, with a Debye temperature of 824.6K. This research will offer a detailed interpretation of α- G-N, covering all its basic properties and the possible applications in optoelectronic and electronic devices. The results of this study are very important and the new technologies that will be developed based on the α-GaN research will be very beneficial.

Anisotropic electronic structure study of MgB2C2 using soft X-ray emission 0spectroscopy microscopes.

The anisotropic electronic structure of MgB2C2 was studied using soft X-ray emission spectroscopy electron microscopes. MgB2C2 fragments were selected by examining C K-emission profiles. C and B K-emission and Mg L-emission spectra were obtained, revealing common and distinct structures that reflect the mixing of valence orbitals. Since the material is reported to have two-dimensional B-C honeycomb layers, the orientational dependence of these emission spectra was also examined. Experimental data were compared with theoretically calculated partial density of states of the valence bands of the material. The C K-emission profile showed an apparent orientational dependence, while the B K-emission exhibited minimal dependence. This difference originated from the different energy distributions of C-2pz and B-2pz components in the valence bands. The Mg L-emission intensity was very small, likely due to charge transfer from Mg atoms to B-N layers. The Mg L-emission profile showed a peak related to structures in C-K and B-K. An unexpected intensity was observed just above the valence bands, which also showed orientational dependence, possibly due to a small deviation from the ideal composition of Mg:B:C = 1:2:2.

Deeply insight into the inhibition mechanism of SO2 on mercury oxidation over Mn/CNT: A DFT study

Mn/CNT is a kind of low temperature catalyst, which can effectively remove elemental mercury from flue gas at low temperature, but its mercury removal ability was significantly inhibited by SO2. In this work, the inhibition mechanism of SO2 was investigated by first-principle calculation based on density functional theory. Three different surfaces of Mn/CNT were constructed: MnO/CNT, MnO2/CNT and Mn2O3/CNT, and the adsorption of Hg0 and SO2 on these three surfaces were studied. It suggests that adsorption energy of Hg0 on MnO/CNT is the highest, which is −2.42 eV. Combined with the electron partial density of states (PDOS) after adsorption, SO2 can compete with Hg0 for the same Mn active site on the catalyst surface during the adsorption process, and the adsorption capacity of Hg0 is weaker than that of SO2. Oxidation path of Hg0 to HgO on the surface of Mn/CNT indicates that the generation of HgO needs to cross at least two energy barriers, with energies of 0.552 eV and 1.25 eV, respectively. However, when Hg0 was oxidized to HgO and adsorbed on the surface of Mn/CNT, SO2 could reduce it to Hg0 again, generating SO3 to block elemental mercury oxidation.

Exploration of the structure, electronic and optical properties of AB 2(PO3)5 polyphosphates: a first-principle approach

The density functional theory method was applied using the gradient PBE, incorporating the hybrid PBE0 functional along with dispersion corrections D3(BJ). These objectives were accomplished through the utilization of the CRYSTAL package, employing a localized atomic orbital basis. Calculations encompassing crystal properties, including electronic, structural, and linear/nonlinear opto-electronic characteristics, were conducted for monoclinic AB 2(PO3)5. Specifically, the polyphosphates investigated in this study are RbPb2(PO3)5, CsPb2(PO3)5, KBa2(PO3)5, and RbBa2(PO3)5. It was demonstrated that in monoclinic phosphates, phosphorus and oxygen atoms form infinite chains [PO4]∞ based on the· ⋯ O1-P-O1 ⋯ ·structure. Alkali metal and lead (barium) atoms are surrounded by oxygen atoms O2, forming polyhedra. Infrared absorption spectra calculations confirmed the presence of chain backbone structural units. Additionally, band structure and partial density of electronic states were determined. The nature of valence and unoccupied states was also investigated. In lead-doped compounds, lead atoms contribute to the formation of upper-valence and lower-unoccupied states. Conversely, in barium-doped compounds, the upper valence states are primarily formed by O2 p-states, while the lower unoccupied states are formed by phosphorus. Also, the coefficients of second harmonic generation and birefringence were calculated, assessing the potential use of phosphates as nonlinear optical materials.

Pd-anchored VSe2 for glucose sensing: Prediction from first principle simulations

Accurate detection of glucose molecule is clinically important for treatment of diabetes. The sensor should efficiently detect the glucose molecule with suitable response time. The conductivity of the sensor material thus plays a vital role in fast and precise sensing. Layered vanadium di-selenide (VSe2) is a transition metal dichalcogenide (TMDC) with metallic characteristics. The current study is to portray a theoretical exhaustive investigation about enhancement in effectual detection of glucose using VSe2 decorated with transition metals (TM) such as Ag and Pd. We have performed extensive DFT simulations to relate adsorption energy of glucose with pristine and decorated VSe2. Introduction of TM to pristine VSe2 was found to increase the adsorption energy of glucose which increases the sensitivity of metal- anchored VSe2. Comprehensive partial density of states (PDOS) and total density of states (TDOS) analysis has been carried out to analyse orbital interaction and qualitative charge transfer which has also been measured using Bader charge analysis. In addition to that, permanency of the best decorated system has been verified through molecular dynamics calculation and modality of recurrent serviceability has been determined by means of recovery time estimation. This is crucial since as on today, most of the available glucose detectors are meant for single usage. Our theoretically derived findings clearly point to the prediction that TM-decorated layered VSe2 can be an efficient glucose sensor, if practically developed in forthcoming times. The obtained results will thus potentially be beneficial for experimentalists for scheming and evolving VSe2-based glucose sensors.

Magnetron sputtered Zn-Ta2O5 thin films for electronic, thermoelectric, and optical applications

In the current study, the optical and electronic properties of Zn-Ta2O5 have been investigated as a potential optoelectronic material. Theoretically, the density functional theory was employed to pure and Zn doped Ta2O5 compositions using the Wien2k code. For experimental investigations uniform thin films were fabricated by magnetron co-sputtering technique on the silicon substrate. The optical, thermoelectric, electronic, and morphological properties were studied by relating the outcomes of simulations and experimental results providing the correlation among the findings. Graphs of the total density of states and partial density of states revealed the hybridization between the dopant and host orbitals. The p-d hybridization of O and Ta atoms was shown by the density of states. Structural studies reveal the growth of primary phase identified as orthorhombic Ta2O5. The grain growth of the Zn-Ta2O5 thin films gradually increase as the Zn content was increased and led to more compact film formation. Zn incorporation improves the thermal transport properties by increasing the Seebeck coefficient and reducing thermal conductivity. Band gap values were reduced by increasing the Zn concentration and recorded value was observed as 3.07 eV for Ta2O5 and 1.77 eV for maximum zinc concentration. Optical characteristics are measured in relation to photon energy which shows enhancement by the Zn doping. The outcomes of the current study manifest that these materials provide great potential for thermoelectric and optoelectronic applications.

Guiding nitrogen doped vanadium pentoxide nanoclusters on cobalt sulfide nano-flakiness as stable seamless interface anode toward highly energy density and durable asymmetric supercapacitors

Interaction of the interface-heterostructures is crucial to rapid ionic conductivity and highly energy density of electrode materials toward supercapacitors. Herein, a novel anode heterostructure is synthesized using cobalt sulfide (CoS) nanoflowers as a substrate for composite nitrogen doped vanadium pentoxide (denoted as N-V2O5@CoS) by combination of hydrothermal and calcination method. As expected, the N-V2O5@CoS electrode possesses superhigh specific surface area that significantly enhances the specific capacitance, and its unique porous interconnected structure not only reduces the volume effect during the cycles, but also greatly enhances the conductivity of electron transfer. The as-prepared N-V2O5@CoS electrode has a specific capacitance of up to 2413.6F/g at a current density of 1 A/g, and can still maintain 87.51 % of the initial capacitance after 5,000 cycles at a high current density of 10 A/g. More importantly, the partial density of states (PDOS) ares obtained through theoretical calculations reveal that the interaction of heterogeneous interfaces is contributed by the p-orbitals of C, O and S and d-orbitals of V and Co. In addition, asymmetric supercapacitor (ASC) with N-V2O5@CoS as the positive electrode and activated carbon (AC) as the negative electrode has a high voltage of 1.7 V, which achieves an outstanding energy density of 71.6 W h kg−1 at a power density of 849.8 W kg−1, showing excellent cycle stability (retain 90.6 % of the initial capacitance after 10,000 charge/discharge cycles). This paper offers novel paradigm for the doping of metal oxides and the development of heterostructures, which provides support for their use as advanced energy storage materials.

Strain effect on the electronic and optical characteristics of FAGeX3 (X=Cl, Br, and I) perovskite materials: DFT analysis

This study investigates the electronic and optical properties of a perovskite material known as Formamidinium Germanium Halide (FAGeX3), where X represents the elements Chlorine (Cl), Bromine (Br), and Iodine (I). We explore the bandgap, density of state (DOS), and partial density of state (PDOS) to understand their electronic properties. We use two methods, PBE and HSE-06, to determine the bandgap. Further, we investigate the optical properties by investigating the real and imaginary functions of the dielectric constant, refractive index, electron energy loss function, and absorption coefficient. Our research extends to the impact of biaxial strain, both tensile and compressive, in the −6% to +6 % range. Without strain, the materials exhibit direct bandgaps at the R point, with FAGeCl3 showing the highest bandgap (2.1359 eV), followed by FAGeBr3 (1.7325 eV), and FAGeI3 with the lowest (1.2581 eV). Our results reveal that applying tensile strain increases the bandgap and induces a blueshift, shifting the optical responses to shorter wavelengths, while compressive strain reduces the bandgap and causes a redshift, enhancing longer wavelength responses. Our findings demonstrate that FAGeX3 perovskites exhibit highly tunable electronic and optical properties under strain, making them exceptional candidates for advanced optoelectronic applications.