Partial Density Of States Research Articles

A comprehensive experimental and DFT analysis on thermoelectric properties of Sb, Te co-doped Bi2Se3 polycrystals

As tellurides and selenides of Bismuth are extensively used thermoelectric materials in the low-temperature range with refrigeration application, A concerted effort is put forth to boost the ZT by co-doping the pristine Bi2Se3 with antimony (Sb) on cation end and tellurium (Te) on anion side of the compound. The double sintered solid-state reaction method is employed in the preparation of Bi2Se3 and (Bi1−xSbx)2Se2.7Te0.3 polycrystalline pellets, with x = 0.02, 0.04, and 0.06. The sample exhibits a rhombohedral structure with the space group of R 3¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\overline{3 }$$\\end{document} m. FESEM and EDAX analysis are used to confirm surface morphology and elemental composition of the produced samples. The thermoelectric measurements for the pristine and co-doped samples were conducted by the physical property measurement system as well as a considerable increase in the Seebeck coefficient of − 115 µV/K is observed for 0.02 doping of the Sb which is 4.2 times greater than as for pristine (S = − 28 µV/K). Higher concentration doping (x = 0.04, 0.06) has not reflected any Seebeck coefficient advancement. In contrast, the lowest total thermal conductivity at a low-temperature regime (< 50 K) is observed for x = 0.06 doping concentration which at near room temperature increases beyond the pristine thermal conductivity; whereas, x = 0.02, 0.04 doping concentration shows a decrement in total thermal conductivity at low, at room temperature region the values are almost equivalent to that of pristine. The co-doped samples’ electrical resistivity is substantially less than pristine sample. The highest power factor of 3 × 10–4 µW/mK2 is obtained for the x = 0.02 sample. The highest ZT value for the x = 0.02 sample is almost 28 times more than a pristine sample. We conducted a study where we combined experimental and DFT methods to investigate thermoelectric properties incorporated into pristine and doped with antimony and tellurium on Bi2Se3. We have employed this combination to investigate the partial density of states, Seebeck coefficient, power factor using the Boltzmann transport equation. Theoretical thermoelectric data were derived and compared to experimental observations. Hence, using combined experimental and theoretical investigations helps to predict with higher accuracy of thermoelectric properties of semiconducting materials.

Effects of different Ti concentrations doping on Li2MnO3 cathode material for lithium-ion batteries via density functional theory

Li2MnO3 is extensively studied for a cathode material in lithium-ion batteries because of its high voltage and specific capacity. Nevertheless, it has the disadvantages due to low conductivity and Li-ion diffusion. To modify its performance, we determine the structure stability and electronic properties of Li2MnO3 cathodes doped with different Ti-ion concentrations using the spin-polarized density functional theory including the Hubbard term (DFT + U). For the calculations, cell parameters, formation energies, band gaps, total density of states, partial density of states and stability voltages are determined. The results highlight that the expansion of the cell volumes by Ti-ion impurities has a positive effect on the diffusion of Li ions in these cathodes. Because of the minor voltage changes, Li2MnO3 cathode doped with a Ti-ion concentration of 0.250 exhibits the highest voltage stability. Overall, these results are effective for the lithium-ion battery application based on Ti-doped Li2MnO3 cathodes.

Adsorption of Water on Vacancy Defective h-BN Bilayer at B and N Sites

&lt;&gt;Two dimensional (2D) materials are used to manufacture the various gadgets. Their properties are therefore appealing. In the present work, we have studied the structural, electronic, and magnetic properties of 2D bilayer hexagonal-Boron Nitride (h-BN), single B vacancy defect on h-BN (B-hBN), single N vacancy defect on h-BN (N-hBN), water adsorption; on B-hBN (w-B-hBN) and on N-hBN (w-N-hBN), materials by spin-polarized density functional theory (DFT) methods employing Quantum ESPRESSO (QE) computational tools. The structural stability of the h-BN, B-hBN, N-hBN, w-B-hBN, &amp; w-N-hBN materials has been investigated by determining their minimum ground state energy and binding energy, and found that they are stable materials. The pristine h-BN bilayer supercell structure is also found to be more compact than other defective configurations. By analyzing the band structures and density of states (DoS) plots of these materials, we have examined their electronic properties, and found that pristine h-BN has a broad bandgap, whereas B-hBN, N-hBN, w-B-hBN, &amp; w-N-hBN exhibit semiconducting nature. The DoS and partial density of states (PDoS) computations of the considered materials are used to study their magnetic properties. It is found that pristine h-BN is a non-magnetic, and B-hBN, N-hBN, w-B-hBN &amp; w-N-BN are magnetic materials. Therefore, vacancy defects on pristine h-BN, and water adsorption on vacancy defected h-BN materials cause it to change from non-magnetic to magnetic. They could find use in the domain of device applications.

Critical Role of Framework Flexibility and Disorder in Driving High Ionic Conductivity in LiNbOCl4.

Understanding Li-ion transport is key for the rational design of superionic solid electrolytes with exceptional ionic conductivities. LiNbOCl4 is reported to be one of the most highly conducting materials in the recently realized new class of soft oxyhalide solid electrolytes, exhibiting an ionic conductivity of ∼11 mS·cm-1. Here, we apply X-ray/neutron diffraction and pair distribution function analysis─coupled with density functional theory/ab initio molecular dynamics (AIMD)─to determine a structural model that provides a rationale for the high conductivity that we observe experimentally in this nanocrystalline solid. We show that it arises from unusually high framework flexibility at room temperature. This is due to isolated 1-D [NbOCl4]- anionic chains that exhibit energetically favorable orientational disorder that is─in turn─correlated to multiple, disordered, and equi-energetic Li+ sites in the lattice. As the Li ions sample the 3-D energy landscape with a fast predicted diffusion coefficient of 5.1 × 10-7 cm2/s at room temperature (σicalc = 17.4 mS·cm-1), the inorganic polymer chains can reorient or vice versa. The activation energy barrier for Li migration through the frustrated energy landscape is especially reduced by the elastic nature of the NbO2Cl4 octahedra evident from very widely dispersed Cl-Nb-Cl bond angles in AIMD simulations at 300 K. The phonon spectra are predominantly influenced by Cl vibrations in the low energy range, and there is a strong overlap between the framework (Cl, Nb) and Li partial density of states in the region between 1.2 and 4.0 THz. The framework flexibility is also reflected in a relatively low bulk modulus of 22.7 GPa. Our findings pave the way for the investigation of future "flex-ion" inorganic solids and open up a new direction for the design of high-conductivity, soft solid electrolytes for all-solid-state batteries.

Computational systematic study of pressure driven changes in electronic, optical, elastic, mechanical, thermodynamic and thermoelectric properties of CaZrO3 for optoelectronic and thermoelectric applications

Calcium Zirconate Oxide (CaZrO3) was studied in this work for its electronic, optical, structural, thermoelectric and thermodynamic properties in the consistent external pressure from 0 to 100 GPa. The correlation functionals utilized have been Generalized Gradient Approximations (GGA) and Heyd-Scuseria-Ernzerhof (HSE03). The structure maintains its cubical structure for a maximum of 100 GPa, while the lattice parameters gradually decrease when exposed to external pressure. Band structure are seen an indirect band at 0–40 GPa whereas direct band at 60–100 GPa (4.737–4.629 eV). To further comprehend the band gap, decrease with the estimated partial densities of states (PDOS) for bulk CaZrO3 for Ca, Zr and O are also estimated. Optical properties such as absorption I(ω), complex optical conductivity σ (ω), complex dielectric function ε(ω), loss function L(ω), reflectivity R(ω) and complex refractive index n(ω) varies significantly with external pressure ranges from 0 to 100 GPa. Mechanical stability is only observed at pressures up to 0–100 GPa becomes stable according to elastic constants. According to Pugh's ratio, the compound is ductile at 0–100 GPa. Whereas Poisson ratio shows metallic bonding up to 100 GPa, our predicted findings show anisotropic nature. According to the thermoelectric properties, these phases could potentially beneficial for thermoelectric devices. Thermodynamic parameters with respect to both temperature and pressure, including heat capacity, thermal expansion, and Debye temperature, from 0 to 1000 K and 0–100 GPa. CZO has phonon density of states and dispersion are calculated along high symmetry directions. This structure is dynamically stable and all frequencies are in the positive phonon spectrum.

Investigation of sensing behavior of carbon nitride (C6N8) for detection of phosphine (PH3) and phosphorous trichloride (PCl3): A DFT approach

AbstractThis study shows the exploration of the gas‐sensing capabilities of C6N8 material against toxic gases like phosphine (PH3) and phosphorous trichloride (PCl3). First‐principles study based on M05‐2X/LanL2DZ (d, p) method was performed to investigate the interaction energy (Eint.), frontier molecular orbitals (FMOs), natural bonding orbital (NBO), noncovalent interactions (NCIs), partial density of states (PDOS), molecular electrostatic potential (MEP), and quantum theory of atoms in molecules (QTAIM) analyses. The interaction energy results showed that PCl3@C6N8 (−23.45 kJ/mol) is more stable than PH3@C6N8 (−14.79 kJ/mol). A considerable decrease in the HOMO‐LUMO band gap of C6N8 was observed as a result of its complexation with the analytes. QTAIM and NCI analyses indicated the presence of weak noncovalent interactions between C6N8 and gases (PH3 and PCl3). SAPT0 analysis was performed to quantify the NCIs. MEP maps of complexes revealed the localization of electronic density on C6N8. The little recovery time of complexes (determined at 300 K) showed that C6N8 can serve as a reusable sensing material against PH3 and PCl3. Our results demonstrate that the C6N8 surface is a reliable material for detecting phosphine and phosphorous trichloride gases.

The adsorption behavior of perfluorooctane sulphonate on diamane regulated by strain

The adsorption of per- and polyfluoroalkyl substances (PFAS), such as perfluorooctane sulfonate (PFOS), is currently a critical issue in the environmental domain, yet it is not fully understood. Diamane, as a stable monolayer adsorbent, has garnered significant research interest. Defects and strain are reported to play a crucial role in regulating its electronic structure. In this study, we employ density functional theory (DFT) calculations to investigate the adsorption of PFOS on both pristine and nitrogen-vacancy (N–V) defected diamane, respectively. Additionally, we systematically examine the effects of strain in diamane along both the a- and b-directions (two directions of a monolayer) on PFOS adsorption. This analysis involves studying the adsorption energy (Eads), electron transfer, and the partial density of states. Finally, we propose the synergistic effects of N–V defects and compression strain in diamane, which enhance PFOS adsorption. Diamane is considered a promising candidate for PFOS sensing or capture.

Computational design of two-dimensional transition metal supported biphenylene as efficient electrocatalysts toward nitrogen reduction reaction

Electrochemical nitrogen reduction reaction (eNRR) at standard conditions shows promise as an innovative approach for artificial nitrogen fixation, potentially offering a more energy-efficient alternative to the Haber-Bosch method. Design and evolution of low-cost and high-efficiency electrocatalysts remain the significant challenge confronting eNRR. Single-atom catalysts have recently been intensively explored due to their 100% utilization, high activity, and high selectivity. Here, a series of transition metal atom anchored on biphenylene (TM−BPN, TM = Sc−Hg) are studied as electrocatalysts (SACs) for eNRR by density functional theory computation. Among them, 19 SACs are screened out as the most promising electrocatalyst with lower limiting potential than that on the stepped Ru (0001). The Re−BPN catalyst exhibits the highest catalytic activity with a lowest limiting potential of -0.48 V. In addition, the Re−BPN also exhibits high eNRR selectivity by suppressing the competing hydrogen evolution reaction with the Faradaic efficiency being ∼100%. Partial density of states and Bader charge analysis illuminate the origin of eNRR catalytic activity of TM−BPN. Furthermore, the SAC structure remains intact under 500 K with no bond breaking. This study deepens our insight into the utilization of SACs in N2 fixation, contributing significantly to the exploration of efficient electrocatalysts for eNRR.

Ce3Bi4Ni3 – A large hybridization-gap variant of Ce3Bi4Pt3

The family of cubic noncentrosymmetric 3-4-3 compounds has become a fertile ground for the discovery of novel correlated metallic and insulating phases. Here, we report the synthesis of a new heavy fermion compound, Ce3Bi4Ni3. It is an isoelectronic analog of the prototypical Kondo insulator Ce3Bi4Pt3 and of the recently discovered Weyl-Kondo semimetal Ce3Bi4Pd3. In contrast to the volume-preserving Pt-Pd substitution, structural and chemical analyses reveal a positive chemical pressure effect in Ce3Bi4Ni3 relative to its heavier counterparts. Based on the results of electrical resistivity, Hall effect, magnetic susceptibility, and specific heat measurements, we identify an energy gap of 65–70 meV, about eight times larger than that in Ce3Bi4Pt3 and about 45 times larger than that of the Kondo-insulating background hosting the Weyl nodes in Ce3Bi4Pd3. We show that this gap as well as other physical properties do not evolve monotonically with increasing atomic number, i.e., in the sequence Ce3Bi4Ni3−Ce3Bi4Pd3−Ce3Bi4Pt3, but instead with increasing partial electronic density of states of the d orbitals at the Fermi energy. This work opens the possibility to investigate the conditions under which topological states develop in this series of strongly correlated 3-4-3 materials. Published by the American Physical Society 2024

Adsorption differences of xanthate, dithiophosphate and dithiocarbamate on stibnite (010) surface with Cu2+ activated: Combined DFT calculations and experiments

Antimony is an important strategic metal resource. Stibnite as one of the main sources of antimony resources, efficiently recycling stibnite has always been a topic of interest. Currently, there is a scarcity of research examining the adsorption differences of butyl xanthate (BX), sodium diethyldithiocarbamate (DDTC) and ammonium dibutyl dithiophosphate (ADD) on the stibnite (010) surface with Cu2+ activated based on atomic scale. This study investigates the adsorption differences of BX, DDTC and ADD on the stibnite (010) surface with Cu2+ activated, combining density functional theory with experiments. DFT calculations showed that there are five adsorption sites of Cu2+ on the stibnite surface, analysis of partial density of states (PDOS) indicated that the difference in hybridization strength between Cu 3d and S 3p orbitals caused discrepancy in adsorption sites performance. Analysis of PDOS, Mulliken population and electron density difference, it can be concluded that the collector interaction strongly with the stibnite surface with Cu2+ activated and the difference of charge transferred by S atoms during the interaction process is the main reason for the differences in adsorption performance and the varying stability of CuS bonds in adsorption models. Under comprehensive comparison the flotation experiments and adsorption tests showed that with Cu2+ activation, the recovery rate of stibnite was significantly improved with DDTC and the adsorption effect was optimal. Finally, the adsorption performance sequence on Cu2+ activated stibnite surface for the three collectors is as follows: DDTC > ADD > BX. This study combining experimental and DFT calculations, provides guidance for the development of efficient collectors for stibnite flotation in the future.

Evaluating the Effect of Metal, Nonmetal, and Co-Doping on Brookite TiO2

The study utilizes the OLCAO-LBFGS-GGA-PBESol method to investigate the structural properties of both doped and undoped brookite TiO2. Electronic characteristics are explored employing the OLCAO-LBFGS-MGGA-TB09+c approach. Detailed analyses of Density of States (DOS) and Partial Density of States (PDOS) are conducted to understand band structures. Both doped and undoped scenarios exhibit a direct bandgap. Moreover, doping induces a reduction in the bandgap value, enhancing its potential for photovoltaic and photocatalytic applications. The study also establishes a strong agreement between the derived lattice parameters and bandgap for pure brookite TiO2 and experimental lattice parameters and bandgap value.

First‐principles calculations on LaX3 (X: Sb, Sn) as electrode material for lithium‐ion batteries

AbstractUsing first‐principle calculations, we investigate the rare‐earth intermetallic compound LaX3 (X = Sb and Sn) as a cathode material for rechargeable lithium‐ion batteries (LIBs). The calculations have been performed to look into the stability of the structure and the electronic properties of host LaX3 as well as its lithiated phases, LixLa1−xX3 (0 &lt; x ≤ 1). In this study, we have observed a structural phase transformation of these intermetallic compounds from a cubic to a tetragonal structure upon lithiation to host structure. The ground state energy is calculated using the WIEN2k package to determine the structure stability and volume change due to lithium addition, which is further used to calculate the formation energy, open circuit voltage (OCV), and lithium‐ion storage capacity. The equilibrium structural parameters for all the phases are determined by achieving a total energy convergence of 10−4 Ry. The estimated band structure along high‐symmetry lines in the first Brillouin zone and the total as well as partial density of states demonstrate unequivocally that the addition of lithium does not change the metallic nature of these electrode materials. We have also calculated the theoretical lithium‐ion storage capacity and OCV for all the compounds. Despite a higher value for OCV larger than 5 V, many of the investigated materials could not be found suitable from a synthesis point of view due to positive formation energies. The formation energy calculation shows that LaSb3, with a 50% concentration of Li, is the most stable compound out of those investigated here. The calculated OCV for Li0.5La0.5Sb3 is 4.27 V. This is substantially higher than the value obtained up to this point for LIBs, which ranges from 3.20 to 3.65 V/cell. These improved results related to the most stable alloy (Li0.5La0.5Sb3) investigated in this work indicate that it is necessary to check the experimental feasibility of its synthesis and actual device performance.

Exploring the multifaceted properties of novel oxide-based perovskites ABO3 (A=Nd and B[dbnd]Lr, Y): A DFT study

The full-potential linear augmented plane wave with local orbital (FP-LAPW) technique is now used in this approach to better understand the structural, electronic, optical and mechanical properties of simple cubic oxide perovskite. NdLrO3 and NdYO3 compounds are studied by employing the density functional theory (DFT) with CASTEP code for the first time. The lattice parameters are found 4.2462 and 4.2301 Å for NdLrO3 and NdYO3 respectively. Both the compounds have 1.9 eV and 1.4 eV band gap showing the direct band gap nature of both materials. The exchange-correlation (XC) energy has been selected during this investigation with the Local Density Approximation (LDA) approach. We optimize as well as clarify the elastic constants Cij, the bulk modulus B, elasticity modulus G, Young's modulus of stretch Y, and the Poisson ratio v. Every substance shows anisotropic behavior. NdLrO3 and NdYO3 compounds exhibit a direct band-gap nature, as revealed by the electronic band structure computations. These compounds were all classified as semiconductors. To quantify the number of localized electrons in various bands, partial density of states (PDOS) and total density of states (TDOS) were deployed. Both compounds are computed by fitting the dispersion relation of the imagined component. Optical properties showed that these compounds were excellent absorbers of incident radiation. Therefore, it may be assumed that these compounds could be employed in magnetic sensors because of anisotropic magnetic behavior and to capture the ultraviolet range of solar radiations.

First-principles screening of XSbF3 (X = Ba and Ra) fluoroperovskites: an insight into structural, optoelectronic and thermal properties

This work presents a computational study of the physical properties such as structural, electronic, optical and thermal properties of XSbF3 (X = Ba and Ra) fluoroperovskites. The calculations were performed using the density functional theory (DFT) calculations in conjunction with Quantum Espresso code. The stability of the crystal structure XSbF3 compounds is determined by binding energy (Eb) computations. The Eb values for BaSbF3 and RaSbF3 compounds are −19.25 and −20.04eV respectively, indicating that both studied compounds are stable. The optimized lattice constants for BaSbF3 and RaSbF3 compounds are 5.03 and 5.06 Å, respectively. The evaluation of electronic properties is conducted by electronic band structure, total density of states (DOS), and partial density of states (PDOS). It is observed from the PDOS plots that the p-states of Sb and F whereas the d-states of X atoms have the major contribution in the formation of the band structure. Various optical properties have been computed and compared. The static value of ε10 highlights the metallic nature of the studied compounds while RaSbF3 stands out for having the highest recorded value of ε20. The maximum nω values for BaSbF3 and RaSbF3 are 8.46 and 6.86 respectively indicating their potential for photoelectric applications. Furthermore when examining the properties it is evident that the BaSbF3 compound stands out as a material for energy storage because of its higher electron energy at 2.36 KJ/N.mol and lower electron free energy of −2.55 KJ/N.mol compared to the RaSbF3 compound. On the other hand, the RaSbF3 compound is an efficient material for catalysis due to its high ability to absorb heat energy from the external source, as compared to the BaSbF3 compound. This study is the first computational investigation of XSbF3 (X is Ba and Ra) compounds, which provides valuable insights into the physical properties of sb-based fluroperovskites and their potential applications.

Acceleration mechanisms of Fe and Mn doping on CO2 separation of CaCO3 in calcium looping thermochemical heat storage

The doping strategy with dark metallic oxide has proven effective in improving optical absorptions and heat storage performances of calcium-based materials for the direct solar-driven thermochemical energy storage system, but the microscopic mechanisms of accelerated decomposition of CaCO3 during heat storage process are still unclear. Carbide slag as an industrial waste with low cost and high CaO content is considered as a potential calcium-based precursor for large-scale thermochemical energy storage. Herein, the novel Fe-doped and Mn-doped calcium-based materials were synthesized from carbide slag and their optical absorption properties and heat storage performances were determined in the experiment. The optimum decomposition temperatures of CaCO3 during heat storage process decreased 10.5 °C and 18.6 °C due to Fe doping and Mn doping, respectively. The acceleration mechanisms by Fe doping and Mn doping for enhancing the CO2 separation of CaCO3 in the calcination stage of the heat storage process were investigated by density functional theory (DFT) calculations. The structural parameters, partial density of states, electron differential densities and energy barriers during CO32– dissociation in heat storage process on the doped CaCO3 and undoped CaCO3 surfaces were compared to clarify the effects of Fe doping and Mn doping on the CaCO3 decomposition. The energy barriers of Fe-doped material and Mn-doped material are 1.68 eV and 1.42 eV, respectively, which are 29.4% and 40.3% lower than that of undoped material. This work helps to understand the microscopic mechanisms of accelerated CaCO3 decomposition by Fe and Mn during heat storage process.

First-principles calculation to investigate structural, electronic, optical, and thermodynamics properties of perovskite KXO3 (K[dbnd]Ta and Zn) alloys for photovoltaic and smart window applications

Compounds KXO3 (X = Zn and Ta) properties are explored using CASTEP (Cambridge serial total energy package) software along with Generalized Gradient Approximation (GGE) and PBE exchange-correlation functionals that have pm3m (221) symmetry with cubic. Electronic characteristics associated with the electronic band structure (phase), total density of states TDOS, partial DOS, and elemental PDOS have been calculated. KTaO3 and KZnO3 show an indirect energy bandgap of 1.61 eV and 4.53 eV, respectively; thus, KTaO3 is a semiconductor while KZnO3 is an insulator. Optical properties disclose that maximum absorption occurs in both visible and ultra-violet ranges of the electromagnetic (EM) spectrum of KTaO3 and KZnO3. The elastic properties of the compounds show that KTaO3 is ductile and KZnO3 is brittle, and the brittleness of the compound will increase the reflection of the radiation, and KTaO3 will conduct radiation more frequently in the visible region.

Strain effects on electronic and dynamical properties of half-Heusler semiconductors: insights from Meta-GGA

In this study, we investigated the effects of mechanical strain, including both tensile and compressive strains, on the electronic properties and dynamical stability of two ternary half-Heusler compounds: TiIrSb and ZrIrSb. We employed the plan wave pseudo-potential method (PW-PP) within the density functional theory (DFT) framework. Our calculations were performed using both the GGA-PBE and Meta-GGA-SCAN approximations. Furthermore, to compute the phonon dispersion, we employed the R2SCAN functional instead of SCAN for both compounds, addressing numerical challenges encountered with the latter. In the absence of strain, our calculations revealed that both compounds exhibit semiconducting behavior, featuring an indirect band gap at identical locations in the Brillouin Zone. Notably, the SCAN functional consistently predicted a larger band gap compared to the corresponding values obtained with PBE for both compounds. Specifically, the band gap expanded significantly, creating a noticeable separation between the valence and conduction bands. For TiIrSb, it increased from 0.84 eV with PBE to 1.05 eV with SCAN, while for ZrIrSb, it increased from 1.41 eV with PBE to 1.71 eV with SCAN. Under the application of strains, both compounds demonstrated an increased band gap under compressive strain, while the application of tensile strain led to a decrease in the band gap, resulting in an indirect-to-direct band gap transition for ZrIrSb. Remarkably, under all strain values, whether tensile or compressive, the SCAN functional consistently exhibited a larger band gap compared to PBE, indicating its accurate description of the material’s electronic structure. The calculated Density of States (DOS) and Partial Density of States (PDOS) reveal that the valence band extremum (VBM) primarily consisted of Ti/Zr-d orbitals, while the conduction band maxima (CBM) predominantly involved strong hybridization between Ti/Zr-d, Ir-d, and Sb-p states. Notably, the SCAN functional predicted higher orbital contributions to Total Density of States (TDOS) compared to the PBE approximation. Importantly, both half-Heusler materials exhibited mechanical and dynamical stability under various strain conditions.

Theoretical and experimental study on gas sensing properties of SnO2-graphene sensor for SF6 decomposition products

Based on theoretical calculation and experimental detection, SnO2-modified graphene (SnO2-graphene) was proposed as a gas-sensing material for the SF6 characteristic decomposition products (SO2, H2S, SOF2, SO2F2) in SF6-insulated equipment. Based on density functional theory calculations, the most stable modifying structure of single and double SnO2 on the surface of graphene is optimized. The adsorption structure, adsorption energy, and charge transfer of four gas molecules on the surface of SnO2-graphene are calculated and analyzed. Then the total density of states (DOS) and partial density of states (PDOS) of the system before and after gas adsorption were compared and analyzed to explore the interaction mechanism between different gases and SnO2-graphene. In experimental study, graphene was prepared by the modified Hummers oxidation–reduction method in the laboratory. four concentration gradients of SnO2 modified on the surface of graphene, and then specific gas sensing experiments were carried out with 10, 25, 50, 100 ppm of the SF6 characteristic decomposition products. The gap between simulation and experiment is compared and analyzed, which lays a theoretical and experimental foundation for the development of new specific sensors.

Determination of GaN nanosensor for scavenging of toxic heavy metal ions (Mn2+, Zn2+, Ag+, Au3+, Al3+, Sn2+) from water: Application of green sustainable materials by molecular modeling approach

Gallium nitride nanocage (GaN_NC) can select toxic heavy metals from water. Therefore, it has been found a selective competition for metal cations in the GaN_NC. The electromagnetic and thermodynamic attributes of heavy metals cations-trapped gallium nitride nanocage (GaN_NC) was depicted by material modeling. The data display that heavy metals cations-trapped in the GaN_NC system are resistant materials, with the firm adsorption zone in the center of the cage. Furthermore, charge transfer from GaN_NC to the heavy metals cations demonstrates clear n-type adsorbing manner. The encapsulation of heavy metals cations occurs via chemisorption. In this article, the behavior of trapping of heavy metal ions of Mn2+, Zn2+, Ag+, Au3+, Al3+ and Sn2+ by gallium nitride nanocone for sensing the water metal cations was observed. The nature of covalent features for these complexes has represented the analogous energy amount and vision of the PDOS for the p states of N and d states of heavy metal cations of Mn2+, Zn2+, Ag+, Au3+, Al3+ and Sn2+ through water treatment. The partial density of states (PDOS) can also evaluate an appointed charge group between Mn2+, Zn2+, Ag+, Au3+, Al3+, Sn2+ and GaN_NC which indicate the most stable complex of metallic visage and a certain degree of covalent specifications between heavy metals cations and gallium nitride nanocage. Furthermore, the NMR analysis indicated the notable peaks surrounding metal elements of Mn2+, Zn2+, Ag+, Au3+, Al3+ and Sn2+ through the trapping in the GaN_NC during ion detection and removal from water; however, it can be seen some fluctuations in the chemical shielding treatment of isotropic and anisotropy tensors. Based on the results in this research, the selectivity of metal ion adsorption by gallium nitride nanocage (ion sensor) has been approved as: Ag+ ˃ Au3+ ˃ Mn2+ ≫ Zn2+ ˃ Sn2+ ˃ Al3+. Using quantum theory of atoms in molecules (QTAIMs) method, intermolecular interactions and corresponding parameters at critical bonding points were also investigated.

A comprehensive theoretical analysis on structural, electronic, optical, and mechanical properties of Sr2VRuO6 compound

In this paper, using the FP-LAPW technique as implemented in the Wien2k code, we have studied the structural, electronic, optical, and mechanical properties of strontium-based compound Sr2VRuO6. In this study, we explore the properties of Sr2VRuO6 using various approximations. We present the total energy versus energy, employing the Wu-Cohen-Generalized Gradients Approximation (WC-GGA) for both nonmagnetic and ferromagnetic states. To determine the stability of this material in cubic structure, the tolerance factor (t) and octahedral factor (μ) have been calculated. The lattice parameters of Sr2VRuO6 were determined, and subsequent calculations yielded the compressive modulus, Young's modulus, shear modulus, and Poisson's ratio in both two and three dimensions. Analyzing the band structure of Sr2VRuO6 within the mBJ-GGA approximation the half metallic character is observed with an indirect bandgap of 2.34 eV. In addition, the total and partial density of states, as well as charge density maps for Sr2VRuO6 have been calculated. Furthermore, we investigated the real and imaginary parts of the dielectric function as functions of energy for Sr2VRuO6. Additionally, the study delved into the variation of the refractive index, absorption coefficient, reflectivity, and energy loss with respect to energy for Sr2VRuO6.