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A comprehensive investigation of the unexplored mechanical, electronic, Mulliken bond population, vibrational, optical and thermophysical properties of the synthesized compounds NbInX2 (X = S, Se) have been made for the first time using the density functional theory. The chemical, mechanical and dynamical stabilities of the compounds are established in our calculations. Both compounds are soft, machinable and brittle. The anisotropic nature of the studied compounds is shown by 3D representations of elastic moduli. The density of states and electronic band structure demonstrate that the compounds are metallic. Fermi surfaces of both compounds are almost similar and contain both hole- and electron-like topologies. The characteristics of chemical bonding among different atoms of the compounds are studied via a charge density distribution map and bond population analysis. Both the compounds possess optical anisotropy. Reflectivity is high (above 44%) in the IR–visible–UV region indicating that the phases may be effective in reducing solar heat. Minimum thermal conductivity, kmin (used to select appropriate material for thermal barrier coating) and its anisotropy are calculated for the first time. The results show that both compounds have kmin much smaller than the reference value of 1.25Wm−1K−1. [ABSTRACT FROM AUTHOR]

The crystal structure, electronic properties, and optical properties of 4H-SiC were investigated using first-principles calculations based on density functional theory (DFT) under high pressure. By analyzing the variations in relative volume, Si--C bond length, and structural energy of 4H-SiC across different pressures, it is found that the structure remains stable without any phase transitions up to 70 GPa. Beyond 70 GPa, the RS structure with metallic characteristics becomes energetically more favorable. Interestingly, as pressure increases, the semiconductor bandgap of 4H-SiC shows an unexpected widening trend. Concurrently, significant changes occur in its optical properties, including absorption characteristics, dielectric function, and refractive index, highlighting the potential of pressure to finely tune the electronic and optical properties of 4H-SiC. This study not only confirms the remarkable physical properties and application potential of 4H-SiC under extreme high pressure, but also provides a theoretical foundation for its use in high-pressure optoelectronic devices. [ABSTRACT FROM AUTHOR]

Combined with the genetic algorithm and CALYPSO software, the geometrical and electronic structures of the ground states of Mon(n=2-13) and MonC (n=1-12) clusters were studied in detail by density functional theory. The average bond length, average binding energy, second-order difference energy, splitting energy and Highest Occupied Molecular Orbital - Lowest Unoccupied Molecular Orbital (HOMO-LUMO) of the ground state structure were calculated to investigate the stability of the ground state structure with respect to the total atomic number. The calculated results showed that the stability of the ground-state structures of Mo, clusters could be improved by doping with individual C atoms. The second-order differential energy and splitting energy of the clusters were combined to show that the stability of Mo, clusters is higher at n = 6 and 9, and that of Mon C clusters is higher at n =4, 7 and 10. [ABSTRACT FROM AUTHOR]

This study explores cobalt–cerium (Co90Ce10) thin films deposited on silicon (Si) (100) and glass substrates via direct current (DC) magnetron sputtering, with thicknesses from 10 nanometer (nm) to 50 nm. Post-deposition annealing treatments, conducted from 100 °C to 300 °C, resulted in significant changes in surface roughness, surface energy, and magnetic domain size, demonstrating the potential to tune magnetic properties via thermal processing. The films exhibited hydrophilic behavior, with thinner films showing a stronger substrate effect, crucial for surface engineering in device fabrication. Increased film thickness reduced transmittance due to photon signal inhibition and light scattering, important for optimizing optical devices. Furthermore, the reduction in sheet resistance and resistivity with increasing thickness and heat treatment highlights the significance of these parameters in optimizing the electrical properties for practical applications. [ABSTRACT FROM AUTHOR]

This paper employs first-principles calculations to comprehensively investigate the structural, dynamic, electronic, mechanical, and optical properties of A 2 BH 6 (A = K, Rb; B Ge, Sn) perovskite hydrides. Mechanical, thermodynamic, and dynamic stabilities are confirmed through calculations of elastic constants, formation energies, and phonon dispersion. The B/G ratio, below 1.75, indicates a brittle nature and a preference for covalent bonding. Electronic property analysis reveals that these hydrides are indirect band gap semiconductors with band gap values of 1.897 eV, 2.468 eV, 2.129 eV, and 2.657 eV, respectively. Optical property studies demonstrate high ultraviolet absorption. A key focus of this study is the gravimetric hydrogen storage capacities, which are found to be 3.84 wt% for K 2 GeH 6 , 2.97 wt% for K 2 SnH 6 , 2.48 wt% for Rb 2 GeH 6 , and 2.09 wt% for Rb 2 SnH 6. These findings not only enrich the research on the physical properties of perovskite hydrides but also provide an important theoretical basis and new options for the development of efficient hydrogen storage materials. The crystal structure, hydrogen storage capacity and band gap value of A 2 BH 6 (A = K, Rb; B Ge, Sn). [Display omitted] • A 2 BH 6 (A = K,Rb; B Ge,Sn) perovskite has been investigated using first-principles. • A 2 BH 6 (A = K, Rb; B Ge, Sn) exhibits thermodynamic, mechanical and dynamical stability. • A 2 BH 6 (A = K, Rb; B Ge, Sn) is a medium width indirect band gap semiconductor. • A 2 BH 6 (A = K, Rb; B Ge, Sn) has a hydrogen storage capacity of 2.09 W% to 3.84 W%. • The desorption temperature is found to be 221.1 K for K 2 SnH 6. [ABSTRACT FROM AUTHOR]

Ripples on graphene play a crucial role in manipulating its physical and chemical properties. However, producing ripples, especially at the nanoscale, remains challenging with current experimental methods. In this study, we report that tiny ripples in graphene can be generated by the adsorption of a single metal cation (Na+, K+, Mg2+, Ca2+, Cu2+, Fe3+) onto a graphene sheet, based on the density functional theory calculations. We attribute this to the cation–π interaction between the metal cation and the aromatic rings on the graphene surface, which makes the carbon atoms closer to metal ions, causing deformation of the graphene sheet, especially in the out-of-plane direction, thereby creating ripples. The equivalent pressures applied to graphene sheets in out-of-plane direction, generated by metal cation–π interactions, reach magnitudes on the order of gigapascals (GPa). More importantly, the electronic and mechanical properties of graphene sheets are modified by the adsorption of various metal cations, resulting in opened bandgaps and enhanced rigidity characterized by a higher elastic modulus. These findings show great potential for applications for producing ripples at the nanoscale in graphene through the regulation of metal cation adsorption. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai University / Shanghai Daxue Xuebao is the property of Journal of Shanghai University (Natural Sciences) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The experimentally synthesized graphene-type boron single layer (g-borophene) and its hydrogenated derivative (borophane in Cmmm symmetry) have been confirmed as normal metals, which are not appropriate for applications in the semiconductor field. Based on first-principles calculations, a new adsorption pattern (P6/mmm) with semiconducting feature has been proposed as a metastable phase for hydrogenated borophene. The results show that P6/mmm phase is both dynamically and mechanically stable. Its total energy is 4.829 eV atom−1, which is slightly higher than that of the ground state Cmmm configuration (4.858 eV atom−1). The HSE06-based band structures show that P6/mmm phase is a semiconductor with an indirect band gap of 1.86 eV and such a band gap can be effectively modulated by external strains. Our work shows that surface hydrogenation has the opportunity to induce a metal-insulator transition in two-dimensional borophene and provide a new two-dimensional semiconductor for potential applications in nano-electronic devices. [ABSTRACT FROM AUTHOR]

The effects of different Mn concentrations on the generalized stacking fault energies (GSFE) and elastic properties of MnxCoCrFeNi high-entropy alloys (HEAs) have been studied via first-principles, which are based on density functional theory. The relationship of different Mn concentrations with the chemical bond and surface activity of MnxCoCrFeNi HEAs are discussed from the perspectives of electronic structure and work function. The results show that the plastic deformation of MnxCoCrFeNi HEAs can be controlled via dislocation-mediated slip. But with the increase in Mn concentration, mechanical micro twinning can still be formed. The deformation resistance, shear resistance, and stiffness of MnxCoCrFeNi HEAs increase with the enhancement of Mn content. Accordingly, in the case of increased Mn concentration, the weakening of atomic bonds in MnxCoCrFeNi HEAs leads to the increase in alloy instability, which improves the possibility of dislocation. [ABSTRACT FROM AUTHOR]

Orthohydrogen and parahydrogen (hereinafter referred to as "orthohydrogen-parahydrogen") conversion reaction affects the liquefaction process of hydrogen at low temperature and is an important step in the storage and transportation of liquid hydrogen. Traditional iron-based catalysts face problems such as the aggregative growth of active species, the insufficient resistance ability of water and the poor tolerance ability of high temperature. To solve above problems, α-Fe2O3 was encapsulated into amorphous silica with abundant pore structures, and the encapsulated α-Fe2O3@SiO2 catalyst with high catalytic performance in orthohydrogen-parahydrogen conversion was prepared. SEMXRD and H2-TPR were used to investigate the effects of the encapsulated structure on surface morphologies, crystal structures and reduction abilities of catalysts. The catalytic performances of catalysts were evaluated by test device, and the relationship between the encapsulated structure and catalytic performance was analyzed and summarized. The results show that the encapsulated structure can optimize the pore structure of the catalyst, regulate the electronic property of active sites, improve the structural stability and high temperature tolerance ability of the catalyst, and thereby improve the catalytic performance. When the volume space velocity is 600 min-1, under the action of α-Fe2O3@SiO2 and α-Fe2O3/SiO2 (without encapsulation), parahydrogen volume fractions at the outlet of the device are 41.8% and 37.6%, and the orthohydrogen conversion rates are 22.4% and 16.8%, respectively, indicating that encapsulated iron-based catalysts have high potential for application in the field of orthohydrogenparahydrogen conversion. [ABSTRACT FROM AUTHOR]

The substitutional doping of nitrogen is an efficient way to modulate the electronic properties of graphene and carbon nanotubes (CNTs). Therefore, it could enhance their physical and chemical properties as well as offer potential applications. This paper provides an overview of the experimental and theoretical investigations regarding nitrogen-doped graphene and CNTs. The formation of various nitrogen defects in nitrogen-doped graphene and CNTs, which are identified by several observations, is reviewed. The electronic properties and transport characteristics for nitrogen-doped graphene and CNTs are also reviewed for the development of high-performance electronic device applications. [ABSTRACT FROM AUTHOR]

Recently, bulk Mg3X2 (X=As, Sb) have been intensively studied for their unique properties for thermoelectric use. However, studies on their two-dimensional counterparts are not sufficient. In this work, we systematically investigated the electronic, mechanical, vibrational, and piezoelectric properties of Mg3X2 (X = As, Sb) monolayers. The results indicate that both monolayers have negative formation energies with dynamical and mechanical stability. Mg3As2 monolayer is a narrow band gap semiconductor, while Mg3Sb2 monolayer is an indirect one. The origin of the band structure was revealed by the calculated partial density of states. The bonding property of both monolayers was analyzed by different methods. Elastic constants were obtained by density functional perturbation theory, and the related physical quantities were derived and analyzed. In-plane strengths along the zigzag and armchair directions of both materials were calculated, and the fracture mechanisms were uncovered. The vibrational modes at the Brillouin center were classified through group theory analysis, and the corresponding eigenvectors and frequencies were calculated and presented. Infrared vibrational spectra were simulated, and the reason for the vanishment of some infrared peaks was disclosed. Piezoelectric and dielectric coefficients were also computed and discussed. [ABSTRACT FROM AUTHOR]

In this work, we have studied the electronic properties of SnO2 by employing the density functional theory. The aim of the work is to study the comparative effect of Te doping in SnO2 in Sn and O sites. The CASTEP module is used for the simulation. 2 × 2 × 2 lattice of SnO2 was used for the study of the band structure and density of state. The electronic properties change significantly on doping the sample with Te. Also, when Te is doped in different quantities and at different sites in SnO2, the bandgap is overlapped in 0.75% Te doping at O site and the maximum is found to be 0.587 eV in 0.75% Te doping at Sn site. For pure SnO2, the bandgap is 1.064. Hence SnO2 when doped with Te influences the conductivity. [ABSTRACT FROM AUTHOR]

This paper systematically investigates the structure, stability, and electronic properties of niobium carbide clusters, NbmCn (m = 5, 6; n = 1–7), using density functional theory. Nb5C2 and Nb5C6 possess higher dissociation energies and second-order difference energies, indicating that they have higher thermodynamic stability. Moreover, ab initio molecular dynamics (AIMD) simulations are used to demonstrate the thermal stability of these structures. The analysis of the density of states indicates that the molecular orbitals of NbmCn (m = 5, 6; n = 1–7) are primarily contributed by niobium atoms, with carbon atoms having a smaller contribution. The composition of the frontier molecular orbitals reveals that niobium atoms contribute approximately 73.1% to 99.8% to NbmCn clusters, while carbon atoms contribute about 0.2% to 26.9%. [ABSTRACT FROM AUTHOR]

Double traditional metal (TM) Janus MXenes have more superior properties when compared with MXenes. The electronic and optical properties, Bader charge and quantum capacitance of ZrMCO 2 (M = Sc, Ti, V, Cr, Mn, Fe, Y, Zr, Nb, Mo, Hf, Ta, W) are explored by density functional theory (DFT). The stability of these systems is confirmed by cohesive energy. The substitution of Ti/Hf atoms results in the decrease of bandgap of ZrTiCO 2 /ZrHfCO 2 , which is induced by the redshift of conduction band minimum (CBM). ZrMCO 2 (M = Cr, Mn) are magnetic semiconductors and ZrMCO 2 (M = Sc, V, Y, Fe) are magnetic metals. All doping atoms except Hf improve the maximum quantum capacitance of ZrMCO 2 at positive bias. Wide voltage makes ZrMCO 2 (M = Nb, Ta, W) change into anode material and ZrFeCO 2 into cathode material. ZrMCO 2 (M = Sc, Mn, Y, Hf, Zr) and ZrMCO 2 (M = V, Cr) can serve as cathode and anode materials in whole voltage, respectively. Much charge accumulating between Fe and C atoms results in the smallest Fe–C bond among all M − C bonds, which indicates the strongest interaction between Fe and C atoms. Optical properties and work function are further explored. [ABSTRACT FROM AUTHOR]

Making products that are affordable, environmentally friendly, and energy‐efficient is the main objective of modern production. The objective of this research is to discover compounds that meet these parameters. The full‐potential, linearized augmented plane wave program (FP LAPW) offered by Wien2K was used to examine the structural, optical, electrical, and transport aspects of SrCaGe and SrCaSn Half‐Heusler (HHs) compounds. Generalized gradient approximation (GGA) was considered for the structural optimization and computation of elastic properties signifies inherent ductility and mechanical stability of the examined SrCaGe and SrCaSn compounds. Additionally, both materials were found to possess a direct bandgap and exhibit semiconducting behavior. The bandgap magnitudes obtained utilizing the modified Becke‐Johnson (mBJ) approximation are 0.78 and 0.52 eV for SrCaGe and SrCaSn, respectively. According to their optical characteristics, SrCaGe and SrCaSn show potential for application in optoelectronic components. Furthermore, the transport properties are evaluated by BoltzTrap program, revealing that both SrCaGe and SrCaSn exhibit figures of merit (ZT) values nearly equal to one at room temperature. This suggests their potential use in creating thermoelectric devices with highly efficient performance. The simulation study demonstrates the promising attributes of SrCaGe and SrCaSn HHs materials, positioning them as viable candidates for various applications, aligned with the goals of sustainable and efficient manufacturing. [ABSTRACT FROM AUTHOR]

In this paper, the formation of oxygen vacancy in the Al2O3 support was induced by urea doping. Through metal-support interaction, the dispersion of Ru-based active species on the surface of the Al2O3 support was improved. The electronic properties of Ru-based active centers was regulated, and then the catalytic performance of the Ru-based catalyst for Sabatier reaction was effectively improved. In this process, it was verified by nuclear magnetic resonance spectroscopy Al-NMR) that urea doping can effectively induce the formation of oxygen vacancy in the Al2O3 support. Transmission electron microscopy (TEM) showed that, the loaded Ru particles could be stabilized at about 3.7 nm on the surface of the Al2O3 support rich in oxygen vacancy, and the distribution of particle size was concentrated. By X-ray photoelectron spectroscopy (XPS) and H2 programmed temperature reduction (H2-TPR), it was found that the oxygen vacancy from the Al2O3 support can effectively regulate the electronic property of the Ru-based active sites. Sabatier reaction performance test showed that under the reaction condition of 300 °C, nco2 : = 1 : 4 and 6000 mL/(g • h), the conversion rate of CO2 could be reached at 61.25% and the selectivity of CH4 could be reached at 92.31 %. Moreover, the catalytic performance did not decrease within 20 hours of the reaction time. [ABSTRACT FROM AUTHOR]

CoxBy alloy with high hardness and high melting point has wide range of applications in many fields because of its stable chemical property, high strength, and good thermal stability. In this work, the thermodynamic and electrical properties of five CoxBy alloys (CoB, Co2B, Co3B, Co23B6 and Co5B16), were studied and compared based on a first-principles approach. The elastic constant and related mechanical property of the binary alloys were calculated by using the energy-strain method, and the thermodynamic properties such as the Debye temperature (ΘD) and the coefficient of thermal expansion (α) within a finite temperature were calculated based on the quasi-simple harmonic Debye model. By comparing the mechanical parameters of the binary alloys, it is found that the comprehensive mechanical property of the CoB alloy is the best among the studied alloys; the state density mapping indicates that all five CoxB y alloys have good metallicity and electrical conductivity, and have some potential applications in the field of electrode materials. In Co3B and Co23B6 alloys, there is a resonance peak between the d electron orbital of Co atom and the p electron orbital of B atom, indicating that there is a significant chemical bond between Co—B.The study complements the gap of thermomechanical property parameters of CoxBy binary alloys and provides a theoretical reference for the design and application of Co based or Co—B binary alloy materials.

Diamond, as a highly promising “extreme” semiconductor material, necessitates electronic property engineering to unleash its full potential in electronic and photonic devices. In this work, the diaphite nanoplatelet, consisting of (11¯${{\bar{1}}}$1) planes of diamond nanoplatelet covalently bonded with graphite (0001) planes, is facilely synthesized using one‐step microwave plasma enhanced chemical vapor deposition method. The high‐energy plasma created by the pillar plays a crucial role in the formation. Importantly, altered electronic and optical properties are determined in the diaphite nanoplatelet through electron energy loss spectrum, density functional theory calculations, and cathodoluminescence spectroscopy. It is revealed that the strong sp3/sp2‐hybridized interfacial covalent bonding in the diaphite nanoplatelet induces the electron transfer from diamond to graphite. This modulates the electronic structure of the near‐interface layer of diamond and triggers a new local trapping band below the conduction band minimum within the bandgap. Consequently, the covalently‐bonded diaphite exhibits a different optical emission characteristic ranging from 2.5 to 3.64 eV, featuring a significant peak blueshift of 430 meV compared to the H‐terminated diamond. This work demonstrates a novel method to engineer the electronic properties of diamond, opening avenues for functional semiconductor device applications of diamond. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the structural, electronic, elastic, lattice dynamic, thermodynamic, and optical properties of the face-centered cubic structure of Ca 2 ZrHfS 6 space group Fm-3m (225) double chalcogenide perovskites were calculated by first-principles calculations. The investigation is made by utilizing plane-wave ultra-soft pseudopotentials in a generalized gradient approximation (GGA-PBE). In addition, we employed GGA + U approximations for exchange correlation potential, since it improves the accuracy of band gaps. Ca 2 ZrHfS 6 has a direct band gap, and its value is 0.52 eV (0.95 eV) with GGA-PBE (GGA + U) approximations. The value of calculated formation energy is − 1.99 and describes the thermodynamic stability of Ca 2 ZrHfS 6 . The mechanical parameters such as the bulk modulus, shear modulus, Young's modulus, and elastic anisotropy are calculated from the obtained elastic constants. The absence of negative frequencies in the phonon dispersion curve and the phonon density of states confirm the dynamical stability of the system. Temperature-dependent thermodynamic properties such as free energy, entropy, and heat capacity are investigated. The calculated results have a similar trend to the existing works. Dielectric (real and imaginary) functions, absorption coefficient, electron energy loss function, reflectivity, and refractive index of Ca 2 ZrHfS 6 are calculated in the spectral range 0–22 eV and discussed in detail. The findings of this study show that Ca 2 ZrHfS 6 has an appropriate band gap and optical response from visible to ultraviolet, making it a promising candidate for use as a light detector. [ABSTRACT FROM AUTHOR]

Two-dimensional van der Waals heterostructures (vdW-HSs) have emerged as a promising method for designing high-performance nanoscale optoelectronic devices such as solar cells. Herein, we propose the vdW-HS BAs/MoSi2P4 within the context of density functional theory (DFT). The results demonstrate that the BAs/MoSi2P4 heterostructure showcases a direct band gap and exhibits a notable type II band alignment feature that enables the efficient charge separation of photoinduced electron–hole pairs. The optical absorption intensity of the individual monolayers (BAs and MoSi2P4) is significantly enhanced upon the formation of a vdW-HS. The carrier mobility of the vdW-HS is significantly high compared to that of the MoSi2P4 monolayer. The findings of our study demonstrate the potential of BAs/MoSi2P4 vdW-HS as a desirable candidate for next-generation optoelectronic devices. [ABSTRACT FROM AUTHOR]

Using first-principles calculations, the structural, electronic, piezoelectric, and optical properties of Janus Sc2CXY (X ≠ Y, X/Y = F, Cl, Br, and I) MXenes were comprehensively investigated. All of the studied MXenes are structurally stable. Both Young's modulus Y and Poisson's ratio ν are isotropic and can be modulated by the surface-functionalized halogen atoms. In addition, the band gaps of all the Janus Sc2CXY MXenes can be modulated from 0.638 eV to 1.437 eV by different functional groups. Interestingly, the semiconductor–metal transition for Janus Sc2CXI (X = F, Cl, and Br) can occur when the compressive strain reaches 6%. Furthermore, because of their symmetric breaking, the Janus Sc2CXY MXenes exhibit excellent in-plane and out-of-plane piezoelectric properties. High optical absorption is found in the visible and ultraviolet ranges for all the studied MXenes, and it is expected that they can be utilized in the fields of piezoelectric and optoelectronic nanodevices. [ABSTRACT FROM AUTHOR]

This study employs first‐principles calculations to investigate the structural stability, electronic properties, and elastic properties of Co‐, Ni‐, Cu‐, and Mo‐doped β‐Si3N4. After optimizing the structure of each doped system, it can be determined that all systems are stable structures, as evidenced by the binding energy and forming energy. Then, the electronic properties of the doped systems are analyzed using the energy band and density of states. The findings reveal that the introduction of Co, Ni, and, Cu, reduces the energy bandgap compared to pure Si3N4. More notably, the doping of Mo eliminates the bandgap and results in strong metallicity in the doped systems. Moreover, all doped systems display magnetic moments. Finally, the investigation of elastic properties shows that all doped structures are ductile. The doping of Co, Ni, Cu, and Mo metals improves the toughness of Si3N4. In addition, the doping change of Co is the most obvious. These findings provide a theoretical foundation for future research on the preparation of ductile Si3N4 ceramics. [ABSTRACT FROM AUTHOR]

This study employs first‐principles calculations to investigate the structural stability, electronic properties, and elastic properties of Co‐, Ni‐, Cu‐, and Mo‐doped β‐Si3N4. After optimizing the structure of each doped system, it can be determined that all systems are stable structures, as evidenced by the binding energy and forming energy. Then, the electronic properties of the doped systems are analyzed using the energy band and density of states. The findings reveal that the introduction of Co, Ni, and, Cu, reduces the energy bandgap compared to pure Si3N4. More notably, the doping of Mo eliminates the bandgap and results in strong metallicity in the doped systems. Moreover, all doped systems display magnetic moments. Finally, the investigation of elastic properties shows that all doped structures are ductile. The doping of Co, Ni, Cu, and Mo metals improves the toughness of Si3N4. In addition, the doping change of Co is the most obvious. These findings provide a theoretical foundation for future research on the preparation of ductile Si3N4 ceramics. [ABSTRACT FROM AUTHOR]

First principles calculations based on density functional theory (DFT) were performed to investigate the structural, electronic, optical and mechanical properties of pristine GaAs compound and its alloy; Ga0.75Al0.25As, Ga0.75In0.25As, Ga0.75Sn0.25As, Ga0.75Ti0.25As. WIEN2K and Quantum expresso (QE) codes were adopted for calculations using generalized gradient approximation (GGA) in Perdew-Burke Erzenhoff (PBE) as exchange correlation function for both codes. Full potential linear augmented plane wave (FPLAPW) with the local orbital method was adopted as implement in WIEN2K code. In QE code, norm-conserving pseudopotentials were employed on a plane-wave expansion of the wave functions. Structural and electronic properties were elaborated since their result gives information about the optical and mechanical performance. Electronic band structure and optical parameters were performed using WIEN2K code. Underestimation of band gap observed from DFT calculations were corrected by using Modified Becke and Johnson (mBJ). Mechanical components were determined using QE with thermo_pw package. Lattice constant, volume, bulk modulus and other physical parameters were calculated for structural properties. Discrepancy in these parameters as observed in crystal structure is associated to difference in ionic radius of host and substituted atom. The results of band structure and density of states were calculated for electronic properties. All the studied compounds were semiconductors in nature except Ga0.75Sn0.25As which displayed metallic character. Optical parameters including extinction coefficient, absorption coefficient, refractive index, optical conductivity, optical reflectivity and energy loss function have been computed from the dielectric function at energy range of 0 to 25 eV using the Kramers-Kronig transformations. Calculated elastic function were used to compute the mechanical properties such as anisotropic, brittle characteristics, stiffness and many others. All the results were compared with available theoretical and experimental records.

Ripples on graphene play a crucial role in manipulating its physical and chemical properties. However, producing ripples, especially at the nanoscale, remains challenging with current experimental methods. In this study, we report that tiny ripples in graphene can be generated by the adsorption of a single metal cation (Na+, K+, Mg2+, Ca2+, Cu2+, Fe3+) onto a graphene sheet, based on the density functional theory calculations. We attribute this to the cation–π interaction between the metal cation and the aromatic rings on the graphene surface, which makes the carbon atoms closer to metal ions, causing deformation of the graphene sheet, especially in the out-of-plane direction, thereby creating ripples. The equivalent pressures applied to graphene sheets in out-of-plane direction, generated by metal cation–π interactions, reach magnitudes on the order of gigapascals (GPa). More importantly, the electronic and mechanical properties of graphene sheets are modified by the adsorption of various metal cations, resulting in opened bandgaps and enhanced rigidity characterized by a higher elastic modulus. These findings show great potential for applications for producing ripples at the nanoscale in graphene through the regulation of metal cation adsorption.

The substitutional doping of nitrogen is an efficient way to modulate the electronic properties of graphene and carbon nanotubes (CNTs). Therefore, it could enhance their physical and chemical properties as well as offer potential applications. This paper provides an overview of the experimental and theoretical investigations regarding nitrogen-doped graphene and CNTs. The formation of various nitrogen defects in nitrogen-doped graphene and CNTs, which are identified by several observations, is reviewed. The electronic properties and transport characteristics for nitrogen-doped graphene and CNTs are also reviewed for the development of high-performance electronic device applications.

Abstract Various doping concentrations of boron (B)-doped germanium nanocrystal (Ge NC) films were prepared using the plasma-enhanced chemical vapor deposition (PECVD) technique followed by thermal annealing treatment. The electronic properties of B-doped Ge NCs films combined with the microstructural characterization were investigated. It is worthwhile mentioning that the Hall mobilities $${\mu }_{\mathrm{Hall}}$$ μ Hall of Ge NCs films were enhanced after B doping and reached to the maximum of 200 cm2 V−1, which could be ascribed to the reduction in surface defects states in the B-doped films. It is also important to highlight that the temperature-dependent mobilities $${\mu }_{\mathrm{H}}(T)$$ μ H ( T ) exhibited different temperature dependence trends in the Ge NCs films before and after B doping. A comprehensive investigation was conducted to examine the distinct carrier transport properties in B-doped Ge NC films, and a detailed discussion was presented, focusing on the scattering mechanisms involved in the transport process.

Hydrogen peroxide is one of the most important commercially used oxidant and exists widely in the environment. It crystallizes in a tetragonal phase via hydrogen bond at around −0.89 °C. However, many of its fundamental properties are still not well studied. To investigate systems containing hydrogen bond, van der Waals correction must be considered. In this work, we tested a series of local and non-local van der Waals corrections within the frame of density functional theory. The optPBE-vdW and the vdW-DF-CX functionals are found to be the best ones based on the relaxed lattice parameters. Then the electronic, bonding, elastic, infrared, piezoelectric and dielectric properties are studied and discussed. The results reveal that tetragonal H2O2 is an indirect band gap insulator. Bond critical point analysis, reduced density gradient analysis and crystal orbital Hamilton population analysis uncover that the H-O···H bonds are moderate hydrogen bonds, which contribute most to the formation of the crystal. The interactions between the O atoms of neighbouring H2O2 molecules also have a bit contribution. Elastic stability of tetragonal H2O2 is confirmed and its elastic anisotropy is illustrated by directional bulk and shear moduli. The vibrational modes at the Brillouin zone center are assigned, and their frequencies and eigen-displacements are calculated. Additionally, its infrared spectrum is simulated. Its Born effective charges, piezoelectric and dielectric coefficients are also obtained and discussed.

The utilization of heterostructures as photocatalysts for water decomposition is a promising method to tackle contemporary environmental challenges. This research paper presents the design of a direct Z-scheme heterostructure utilizing a monolayer of GeC and a monolayer of arsenene, based on first-principle calculations. The photocatalytic efficiency of this GeC/arsenene van der Waals (vdW) heterostructure in a direct Z scheme has been investigated. The presence of a built-in electric field from the GeC monolayer to the arsenene monolayer has been established through an analysis of band alignment, work function, charge density, and Bader charge. The GeC/arsenene heterostructure exhibits excellent and robust optical absorption efficiency for the sunlight, alongside achieving the maximum solar-to-hydrogen (STH) energy conversion efficiency, amounting to 7.28%, under a biaxial strain of +4%. Furthermore, the Gibbs free energy changes in the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) of the GeC/arsenene heterostructure have been calculated. The outcomes indicate that the GeC/arsenene heterostructure is a feasible semiconductor for photocatalytic water splitting. Band edge positions and Z-scheme photocatalytic mechanism of the GeC/arsenene heterojunction. [Display omitted] • GeC/arsenene heterostructure has a built-in electric field from GeC to arsenene layer. • GeC/arsenene heterostructure exhibits a high optical absorption under biaxial tensile strain. • The highest solar-to-hydrogen efficiency of 7.28% is obtained under +4% strain. • High catalytic activity for the hydrogen evolution reaction is confirmed by free energy calculations. [ABSTRACT FROM AUTHOR]

This study employed density functional theory (DFT) embedded in Wien2K code to evaluate the physical features of the XGeCl3 (X = Rb/Cs) cubic halide perovskites. The structural optimization has been performed considering generalized gradient approximation (GGA) and electronic properties have been computed considering modified Becke‐Johnson potential (mBJ). The formation energy and phonon dispersion analysis establish the stability of the investigated compounds. Mechanical stability is further confirmed by the computed diverse elastic coefficients. It has been discovered that the examined substances are naturally ductile. The refractive index, reflectivity, and absorption coefficient, are among the optical parameters that have been estimated and analyzed. Interesting results have been obtained for the transport properties of XGeCl3 (X = Rb/Cs). The XGeCl3 (X = Rb/Cs) exhibits a high Seebeck coefficient (X = Rb/Cs) and the largest figure of merit (about 0.99), indicating significant potential for thermoelectric applications. [ABSTRACT FROM AUTHOR]

The rare earth metal doped Si-based semiconductor clusters have aroused increased attention in a lot of fields. Here, the structural evolution, magnetic and spectral properties of bimetallic Eu2 doped silicon-based clusters, Eu2Sin− (1 ≤ n ≤ 12), have been investigated using artificial bees colony and Saunders "Kick" global optimization techniques associated with density-functional theory calculations. The calculations show that the two Eu atoms prefer to occupy the surface position of parent silicon clusters and form exohedral geometric structures. It is found that the structural growth pattern is reflected at n = 4–8 where the two Eu atoms lie on the framework of distorted pentagon. Eu2Si5− is determined to the most stable cluster owing to the strong interaction between host Si atoms and dual Eu atoms. The natural atomic orbital method reveals that the charges always transfer from the Eu to Si parent atoms. Interestingly, the total magnetic moments are not quenched but superimposed together with introduction into Si-based cluster, 4f electrons almost remain in two Eu atoms and hardly participate in the molecular Si–Eu bonding. Moreover, theoretical photoelectron spectra are predicted in order to provide a theoretical guidance for the future photoelectron spectroscopy experiments of double rare earth metal doped Si-based semiconductor clusters. [ABSTRACT FROM AUTHOR]

Hydrogenated amorphous SiC (a-SiC:H) films with various Si/C ratios were prepared using the plasma-enhanced chemical vapor deposition (PECVD) technique. These films were then subjected to thermal annealing at different temperatures to induce crystallization. The electronic properties of the annealed SiC films were investigated through temperature-dependent Hall mobility measurements. It was found that the room-temperature Hall mobilities in the SiC films increased with both the annealing temperature and the Si/C ratio. This increase was attributed to the improved crystallization in the SiC films. Importantly, SiC films with different Si/C ratios annealed at different temperatures exhibited varying temperature dependence behaviors in their Hall mobilities. To understand this behavior, a detailed investigation of the transport processes in SiC films was carried out, with a particular emphasis on the grain boundary scattering mechanisms. [ABSTRACT FROM AUTHOR]

The growth law, electronic properties and spectra of Fenλ (n = 2–18; λ = 0, ±1) clusters have been examined by density functional theory (DFT) and an unbiased structure prediction method. Extensive geometry optimizations have been executed and show that the global minimum structures of Fenλ clusters have a distinct growth law when n is 8–18. For n = 8–13 and 14–18, the iron atoms grow around a decahedral and icosahedral iron cluster core, respectively. Based on the present ground states, the calculated electronic parameters are in line with the experimental values. The thermal stability of charged iron cluster is higher than that of neutral iron cluster. The octahedral and icosahedral clusters are more stable than their neighbors. The former has low chemical activity and may be a superatom. The magnetic moment of Fe atom weakens in the cluster. The UV spectra, photoelectron spectra (PES) and infrared and Raman spectra of the Fenλ clusters have been predicted and the global minimum structures of the Fen− clusters are determined by comparing the theoretical PES with the experimental results. [ABSTRACT FROM AUTHOR]

This paper systematically investigates the structure, stability, and electronic properties of niobium carbide clusters, NbmCn (m = 5, 6; n = 1–7), using density functional theory. Nb5C2 and Nb5C6 possess higher dissociation energies and second-order difference energies, indicating that they have higher thermodynamic stability. Moreover, ab initio molecular dynamics (AIMD) simulations are used to demonstrate the thermal stability of these structures. The analysis of the density of states indicates that the molecular orbitals of NbmCn (m = 5, 6; n = 1–7) are primarily contributed by niobium atoms, with carbon atoms having a smaller contribution. The composition of the frontier molecular orbitals reveals that niobium atoms contribute approximately 73.1% to 99.8% to NbmCn clusters, while carbon atoms contribute about 0.2% to 26.9%.

As the high-entropy design concept applied to the diboride ceramic system, high-entropy diboride ceramics with a wide range of composition control, is expected to become a new high-performance material for extreme high-temperature environments. Herein, the effects of four transition metal elements (Nb, Ti, Cr, W) on the phase stability and properties of (Hf, Zr, Ta)B 2 -based high-entropy diboride ceramics are systematically investigated via the first-principles calculations. All components were identified as thermodynamically, mechanically and dynamically stable from enthalpy of formation, elastic and phonon spectrum calculations. Among these, compared with the (Hf, Zr, Ta)B 2 ceramics, the addition of Nb and Ti on the metal sublattice is beneficial to improve the mechanical properties of ceramics, including Young's modulus, hardness and fracture toughness, while the introduction of Cr and W weakens the strength of covalently and ionic bonds inside the material, reducing its mechanical properties. The predicted thermophysical properties show that the high-entropy diboride ceramics containing Nb and Ti have better high-temperature comprehensive performance, including higher Debye temperature, thermal conductivity and lower thermal expansion characteristics, which is conducive to the application in extreme high-temperature environments. This research will provide important guidance for the design and development of new high-performance high-entropy diboride ceramics. [ABSTRACT FROM AUTHOR]

This research presents within the full potential linearized augmented plane wave (FP-LAPW) technique with the first-principles calculations to investigate the structural, electronic, elastic and optical properties of ternary cubic perovskites of the form TlXF3 (X= Ag and Pd) compounds. All these calculation is done by WIEN2k code within the density functional theory (DFT). The modified Becke-Johnson potential (TBmBJ) is used for the optical and electronic properties. TDOS and PDOS analysis shows that both TlAgF3 and TlPdF3 are structurally stable and the main contribution of the states in TlAgF3 compound is due to the Tl (d-orbitals) atoms and that in TlPdF3 compound, F (p-states) contributes the more. The electronic-band structure analysis shows the metallic properties having no band gaps. Optical properties are also discussed using dielectric function. Elastic calculation revealed that both compounds are anisotropic, brittle and ionic. [ABSTRACT FROM AUTHOR]

The stability, mechanical property, electronic structure, and Debye temperature of Al‐Cu‐X ternary compounds formed by X (Co, In, Ni, Pd, Ge, Ca) doped AlCu are systematically studied by first‐principles calculations based on density functional theory (DFT). The cohesive energy and formation enthalpy results of Al‐Cu‐X show that the structure is thermodynamically stable, which are consistent with the data previously reported. Elastic modulus results that are estimated by Voigt‐Reuss‐Hill approximation. It shows that Co, Ni, and Pd increase the bulk modulus of AlCu, while In, Ge, and Ca decrease the bulk modulus of AlCu. Co, In, Ni, Pd, Ge, and Ca decrease the shear modulus and Young's modulus of AlCu. In addition, the anisotropy of Al‐Cu‐X is studied by different anisotropy indexes and Young's modulus spatial distribution figure. The electronic structures of Al‐Cu‐X ternary compounds are calculated and analyzed. It shows that the Co, In, Ni, and Pd elements are mainly hybridized with the Cu‐d orbital, while Ge and Ca are hybridized with the Al‐p orbital. Moreover, the sound velocity and Debye temperature of Al‐Cu‐X are discussed. [ABSTRACT FROM AUTHOR]

The vertical stacking of various two-dimensional (2D) layered materials to create van der Waals heterostructures (vdWHs) has received great attention as a promising material for developing nanoelectronic and optoelectronic devices. This is because such structures can inherit the unique and favorable properties of a single 2D material. In this study, a SnSe2/MoSe2 vdWH model was built for the first time using the first-principles approach, and its electronic and optical properties were systematically investigated. The results reveal that the SnSe2/MoSe2 vdWH exhibits a type-II heterostructure with a 0.167 eV indirect band gap, which facilitates the separation of photogenerated electron–hole pairs. Notably, the electrical characteristics of the SnSe2/MoSe2 vdWH can be easily controlled by applying an external electric field or biaxial strain. Specifically, a positive electric field or tensile strain narrows the band gap, whereas a negative electric field or compressive strain widens the band gap. The energy band alignment shifts from a type-II to a type-I configuration when a negative electric field of E = −0.6 V Å–1 or a compressive strain of 10% is applied. Furthermore, SnSe2/MoSe2 vdWHs exhibit improved optical absorption across the visible to ultraviolet regions compared to the individual monolayers of SnSe2 and MoSe2. Additionally, the absorption can be influenced by external tension and electric fields. Specifically, under significant compressive strains (10%), the ultraviolet absorption peak reaches 33.5%. Interestingly, a red shift occurs with tensile strain or a negative electric field, whereas a blue shift occurs with compressive strain or a positive electric field. The proposed SnSe2/MoSe2 vdWH in this study offers valuable insights into electronic and optoelectronic device development, particularly in the context of photovoltaic devices, where enhanced ultraviolet absorption can lead to improved light-to-electricity conversion efficiency. [ABSTRACT FROM AUTHOR]

Various doping concentrations of boron (B)-doped germanium nanocrystal (Ge NC) films were prepared using the plasma-enhanced chemical vapor deposition (PECVD) technique followed by thermal annealing treatment. The electronic properties of B-doped Ge NCs films combined with the microstructural characterization were investigated. It is worthwhile mentioning that the Hall mobilities μ Hall of Ge NCs films were enhanced after B doping and reached to the maximum of 200 cm2 V−1, which could be ascribed to the reduction in surface defects states in the B-doped films. It is also important to highlight that the temperature-dependent mobilities μ H (T) exhibited different temperature dependence trends in the Ge NCs films before and after B doping. A comprehensive investigation was conducted to examine the distinct carrier transport properties in B-doped Ge NC films, and a detailed discussion was presented, focusing on the scattering mechanisms involved in the transport process. [ABSTRACT FROM AUTHOR]

The electronic and optical properties of Au, Cu, Sb doped CdTe systems were studied based on density functional theory. Au, Cu and Sb doped CdTe systems all exist stably. The hybridization of transition metal atoms with Cd atomic orbitals reduces the band gap of CdTe and improves the utilization of visible light by CdTe. The lower energy required to jump from the valence band to the conduction band promotes the migration of more photogenerated electrons, which greatly improves the optical properties of doped CdTe. Among the three systems, Sb/CdTe system shows the most significant increase of absorption coefficient in the visible light range, with photogenerated electron and hole mobilities increasing by a factor of 5. 97 times and 15.54 times compared with CdTe system, respectively. The mechanism of the enhancement of the optical properties of Au, Cu, and Sb doped CdTe is theoretically revealed by calculating the band, density of states, electron population, optical absorption function, and carrier mobility. [ABSTRACT FROM AUTHOR]

Layered oxyfluoride single-crystalline thin films of Sr2RuO3F2, Ca2RuO2.5F2, and Sr2IrO2.5F3 were fabricated via topochemical fluorination. All the fluorinated films exhibited an insulating behavior and a largely expanded c-axis than the precursors. Sr2RuO3F2 film was a Mott insulator with Ru4+ states and had two inequivalent F- sites in the SrO layers. In contrast, Ca2RuO2.5F2 film had the Ru3+ state and only one F- site in the CaO rock-salt blocks. This discrepancy is probably due to the larger lattice distortion in the Ca2RuO4 precursor. The conduction mechanism of Ca2RuO2.5F2 film was described by two-dimensional variable range hopping. The effective total angular momentum Jeff＝3/2 of Sr2IrO2.5F3 film was stabilized upon fluorination owing to the large electronegativity of fluorine. The conduction mechanism of Sr2IrO2.5F3 film was described by Efros-Shklovskii variable-range hopping. These results will be useful for modifying electronic states by anion doping to explore unprecedented electronic properties in layered oxides. [ABSTRACT FROM AUTHOR]

The primary objective of contemporary manufacturing is to produce items that are low-cost, environmentally friendly, and energy efficient. This study aimed to investigate compounds that fulfil these criteria, with a focus on CdCrO3. The full potential linearized augmented plane wave program (FP LAPW), as in Wien2K, was employed to examine the structural, electronic, thermodynamic, and transport characteristics of the material. Structural optimization was carried out using generalized gradient approximation (GGA), with lattice constants that were deemed satisfactory based on previous theoretical and experimental results. Calculations of the magnetic characteristics of CdCrO3 show that the Cr atoms are principally responsible for magnetism. The quasi-harmonic Debye model allows for the identification of thermodynamic properties including trends, the relative Debye temperature, thermal expansion parameter, relative volume, and heat capacity at various pressures and temperatures. At constant volume, a heat capacity of 52 J/mol K was determined. The thermoelectric properties were examined using the Boltzmann transport offered by the BoltzTrap program. At room temperature, CdCrO3 had a figure of merit (ZT) value that was almost equal to one, indicating that it may be used to make thermoelectric devices with the highest possible efficiency. [ABSTRACT FROM AUTHOR]