Si Atoms Research Articles

Tailoring Superatomic Stability with Transition Metals in Silicon Cages: Shrinking to M@Si15 (M = Re, Os, Ir).

The design of materials with intriguing electronic properties is crucial for advancing nanoscale technologies, where precise control over atomic structure and electronic behavior is essential. Metal-encapsulating silicon cage superatoms (SAs) provide a new paradigm for molecular-scale material design, allowing fine-tuning of both structure and electronic characteristics. The formation of superatoms mimicking halogens, noble gases, and alkali metals has been well-studied, particularly with M@Si16, where early transition metals from groups 3 to 5 stabilize within a Si16 cage, achieving a 68-electron configuration. For late transition metals with excess electrons, a Si15 cage offers enhanced stability by fulfilling the 68-electron rule with one fewer Si atom. This research synthesizes Si15 cage-SAs with rhenium (Re) from group 7 and iridium (Ir) from group 9 on p-type and n-type organic substrates. The stability of Re@Si15 and Ir@Si15 is evaluated via oxidative reactivity with X-ray photoelectron spectroscopy and theoretical calculations, including osmium (Os) from group 8. Re@Si15-, Os@Si150, and Ir@Si15+ exhibit superatomic behaviors similar to halogens, noble gases, and alkali metals due to the 68-electron shell closure. Among them, Re@Si15- on p-type organic substrates shows superior electronic and geometric properties. These findings advance our understanding of M@Sin systems for transition metals, addressing longstanding questions about their properties at n = 15 and 16.

Experimental Charge Density Study of Hypersilyl Sulfur Diimide

AbstractIn here three newly synthesized silyl substituted sulfur diimides S(NSi(SiMe3)3)2 (2), S(NSi(NMe2)3)2 (3) and S(NSiHiPr2)2 (4) are presented. 2 is characterised by experimental charge density investigations and compared to the di‐tert‐butyl sulfur diimide S(NtBu)2 (1). While the silylation seems not to have much impact on the sulfur‐nitrogen bonding the increase of negative charge at the nitrogen atoms is obvious. Hence, the silylated molecules should be better donors in metal chelation, provided the change from the genuine E/Z conformation to E/E is facilitated. Indeed, their calculated free energy gaps between initial and transition states, related to the rotation of the silyl substituted derivatives 2–4, interestingly found via different rearrangements, turned out to be only a third of that of 1, despite of changing the substituents linked to the Si atoms. This is due to the longer and more polar N−Si bonds compared to the N−C bonds.

Crystal Chemistry at Interfaces Between Liquid Al and Polar SiC{0001} Substrates

Silicon carbide (SiC) has been widely added into light metals, e.g., Al, to enhance their mechanical performance and corrosion resistance. SiC particle-reinforced metal matrix composites (SiC-MMCs) exhibit low weight/volume ratios, high strength/hardness, high corrosion resistance, and thermal stability. They have potential applications in aerospace, automobiles, and other specialized equipment. The macro-mechanical properties of Al/SiC composites depend on the local structures and chemical interactions at the Al/SiC interfaces at the atomic level. Moreover, the added SiC particles may act as potential nucleation sites during solidification. We investigate local atomic ordering and chemical interactions at the interfaces between liquid Al (Al(l) in short) and polar SiC substrates using ab initio molecular dynamics (AIMD) methods. The simulations reveal a rich variety of interfacial interactions. Charge transfer occurs from Al(l) to C-terminating atoms (Δq = 0.3e/Al on average), while chemical bonding between interfacial Si and Al(l) atoms is more covalent with a minor charge transfer of Δq = 0.04e/Al. The prenucleation at both interfaces is moderate with three to four recognizable layers. The information obtained here helps increase understanding of the interfacial interactions at Al/SiC at the atomic level and the related macro-mechanical properties, which is helpful in designing novel SiC-MMC materials with desirable properties and optimizing related manufacturing and machining processes.

Si segregation deters prenucleation at the interfaces between liquid-aluminum and TiB2 substrates, the origin of ‘Si poisoning’

The mechanism of ‘Si poisoning’ of Al-Ti-B based grain-refiners in Al-Si alloys has been a topic of intensive study for over half a century. We here investigate prenucleation of Al at the Si segregated interfaces between liquid Al and TiB2{0001} substrates using ab initio techniques. Our study reveals that chemical affinity between Ti and Si atoms empowers Si segregation at the Al(l)/substrate interface during solidification. The Si interfacial segregation curbs atomic ordering in the liquid Al adjacent to the substrate. Consequently, prenucleation of Al atoms at the Al(l)/{0001}TiB2 interface is deteriorated and thus, the subsequent nucleation process adversely affected, which causes the so-called ‘Si poisoning’ effect during the practice of grain refinement via inoculation with addition of TiB2 particles in Al-Si alloys.

MoS[formula omitted] containing (Si, Se, P+Cl) structure doping and (Au and Ag) surface decorating as a sensor of Methanethiol biomarker: A first-principles study

MoS2 monolayer is a highly promising material for gas and biosensors due to its exceptional physical and chemical properties. Recent research suggests that modified MoS2 monolayers demonstrate improved properties compared to unmodified ones. In this study, we employed density functional theory to investigate MoS2 doped and decorated with transition metallic atoms such as Ag and Au, as well as non-metallic atoms like Se, Si, P, and Cl, for the detection of the Methanethiol biomarker. In this regard, the adsorption energy, charge transfer, adsorption distance, I-V, TDOS, PDOS, and sensitivity are calculated for each structure. The results reveal that the adsorption energy and charge transfer of the Methanethiol biomarker on MoS2 modified with Ag, Au, and Si atoms are higher than that of unmodified MoS2. The most significant changes in I-V curves and chemical adsorption occurr in these structures. The highest sensitivity is achieved when the MoS2 monolayer is decorated with Ag atoms, Au decorated, and doped with two Si atoms, respectively. Also, doping with Se, P, and Cl atoms results in the lowest adsorption energy, charge transfer, and sensitivity. This study provides valuable insights into the potential applications of both unmodified and modified MoS2 as Methanethiol biomarker sensor materials.

Ability of a MoSi2 coating to resist erosion-corrosion from the impact of atomic oxygen

Atomic oxygen (AO), in the residual atmosphere of low-Earth-orbit space, may violently collide with spacecraft at a relative speed of up to 8 km/s and an impact energy of nearly 5 eV/atom. These collisions can lead to a series of physical and chemical reactions that may result in increased sputtering-erosion and corrosion of the exposed surface with performance degradation. This work examined the behavior of MoSi2, a commonly used coating, when exposed to AO using a ground-based space environment simulator. The erosion-corrosion kinetics and evolution of the microstructure and element distributions were analyzed. After MoSi2 was subjected to a total gas fluence of 9.72×1022 atoms/cm2 in 675 h, the erosion yield reached an exceptionally low value of 10-28 cm3/atom, indicative of its superior AO resistance, and XRD, SEM, XPS and EPMA were applied to analyze the phase transition of the coating surface: first it was released of adsorbed gas molecules and contaminants on the coating surface; then outside Mo and Si atoms were also sputtered, and the remaining Mo and Si atoms were gradually oxidized; finally, a continuous protective oxide film was generated which effectively resisting AO collisions. After AO impact, an ultrathin defensive granular oxide layer of MoO3 and SiO2 generated from the original smooth MoSi2 coating. Density functional theory calculations were conducted to clarify the thermodynamic and electronic structure mechanisms underlying the AO oxidation of the MoSi2 coating.

Densely packed glass structure caused by seven-coordinated Zr in high elastic modulus Al2O3–SiO2–ZrO2 glasses

Al2O3–SiO2–ZrO2 ternary glasses were fabricated using a levitation technique. The addition of ZrO2 to the Al2O3–SiO2 glasses strongly affected their thermal, mechanical, and structural properties. Several compositions were partially vitrified at the laser-melted area without levitation although their melting required temperatures higher than 2000°C. With increasing ZrO2 content, the elastic moduli linearly increased, and the 50Al2O3–20SiO2–30ZrO2 glass exhibited a Young′s modulus of 166 GPa and Vickers hardness HV of 11 GPa. Conversely, crack resistance significantly decreased with the addition of ZrO2. Density measurements, Zr L2,3-edge and K-edge X-ray absorption fine structure analyses, and 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy were performed to investigate the local structure around Zr, Al, and Si in the glasses. Zr formed distorted ZrO7 as in monoclinic ZrO2, which has been rarely found in conventional oxide glasses. The highly oxygen-coordinated Al atoms such as AlO5 and AlO6, were the main components in the glasses rather than AlO4. The majority of Si atoms form SiO4 with four bridging oxygen (Q4). Among the four bridging oxygens, the number of oxygens connected to Al or Zr clearly increased with decreasing SiO2 content. The high packing density of the ternary glasses that resulted in high elastic moduli originated from the highly oxygen-coordinated Zr and Al and their close bonding with SiO4 without generating nonbridging oxygens.

Precipitation strengthening behavior of Custom 455 stainless steel during tempering at 420 °C

After solid solution at 850 °C, the Custom 455 was aged at 420 °C for different times. The hardness changes were measured using a Vickers hardness tester, and the microstructure and composition of the second phase were studied using atom probe tomography (APT) and high-resolution transmission electron microscopy (HRTEM). The APT results indicate that in the early stage of aging, Cu atoms first segregate and attract Ti to form CuTi clusters; As the aging time increases, Ti atoms in CuTi clusters attract Ni and form CuTiNi clusters, resulting in a rapid increase in sample hardness; Subsequently, CuNiTi clusters grew and gradually separated into Cu-rich and NiTi-rich particles; As the aging time further increases, some NiTi-rich particles grow into rod-shaped Ni3Ti precipitates, while others have Si atoms and grow into spherical G phase particles. The orientation relationship between Cu-rich phase, Ni3Ti phase, and G phase is: [100]M//[0–11]Cu//[-12–10]Ni3Ti//[100]G, (011)M//(111)Cu//(0004)Ni3Ti//(022)G. The formation of the Cu-rich, Ni3Ti, and G phase resulted in a hardness peak of 538 HV after 16 h of aging. Subsequently, the decrease in hardness caused by the coarsening of the Cu-rich and Ni3Ti particles was offset by the newly formed G phase, resulting in a slow decrease in hardness.

Fabrication of Ripple Structured Silicon Carbide (SiC) Films for Nano‐Grating and Solar Cell Applications

AbstractIn the present study, we aim to investigate the self‐organization of unexplored silicon carbide (SiC) film surfaces under 30 keV oblique Ar+ ions irradiation and hence unprecedented tailoring of optical and electrical characteristics with view of their uses in solar cells, gratings and nano‐ to micro‐scale devices. The surface morphology mainly consisted of triangular shaped nanoparticles which evolves into nanoscale ripple structures with an alignment parallel to the projection of ion beam direction. For the first time, we have demonstrated the fabrication of highly‐ordered ripple patterns with wavelength in visible region over SiC films and applicable as nano‐gratings. The underlying mechanism relies on the structural rearrangement due to transition of film microstructure from amorphous to mixed phase (crystalline, nano‐crystalline and amorphous) and lowering of C=C and C−C vibration modes by the heavier Si atoms. These nanostructured silicon carbide film shows unparalleled optical (energy gap decreases from 4.60±0.4 eV to 3.16±0.2 eV) & electrical characteristics (conductivity increases from 6.6×10−11 to 1.12×10−3 S/m with linear I−V behavior). Thus, we propose that ripple structured SiC films with wide band gap, high refractive index and high electrical conductivity with ohmic behaviour are promising candidates for application as window layer in solar cells and opto‐electronics.

First-principles study on the lithiation process of amorphous SiO anode for Li-ion batteries with Bayesian optimization.

Amorphous silicon monoxide (a-SiO), which contains Si atoms with various valence states, has attracted much attention as a high-performance anode material for lithium (Li) ion batteries (LIBs). Although current experiments have provided some information during charge/discharge cycles, further investigation of structural changes at the atomic scale is needed. To investigate the lithiation process of a-SiO using first-principles simulations and machine learning techniques, we developed a computational code employing Bayesian optimization to efficiently identify stable sites for Li insertion in the large search-space of amorphous models to reproduce the actual lithiation process and compared this approach to the conventional random scheme by applying it to an a-SiO model previously generated with neural network potentials. The lithiation process based on Bayesian optimization resulted in lower formation energies compared to the conventional random scheme, indicating a more stable structure. During lithiation, Li atoms tended to enter the silicon (Si) phase after the SiO2 phase, in agreement with experimental results. We analyzed the structural changes and observed significant differences in the structural evolution between the conventional and new schemes. Our study highlights the significant influence of the lithiation process on the structural transformation of a-SiO materials, which in turn affects the reversible capacity of the material. These findings will provide a framework for improving the performance and lifetime of a-SiO materials.

A comparative AIMD study of electronic excitation-induced amorphization in 3C-SiC, TiC, and ZrC

In the present study, an ab initio molecular dynamics (AIMD) method was employed to investigate the effect of electronic excitation on the micro-structural evolution of 3C-SiC, TiC, and ZrC. The AIMD results demonstrated that electron excitation induces a crystalline-to-amorphous phase transition in all carbide compounds. The determined threshold electronic excitation concentration for 3C-SiC, TiC, and ZrC at 300 K is 4.06%, 5.28%, and 4.26%, respectively. The mean square displacement of C atoms is larger than those of Si, Zr, and Ti atoms, which results from the smaller atomic mass of the C atom. These results indicate that the structural amorphization of 3C-SiC, TiC, and ZrC is primarily attributed to the displacement of C atoms. It is noted that amorphization induced by electronic excitation represents a solid–solid transition rather than a solid–liquid transition. It is further verified that the ⟨Si−C⟩ bond is a covalent characteristic, whereas the ⟨Ti−C⟩ or ⟨Zr−C⟩ bond is a mixture of ionic, metallic, and covalent characteristics, which may lead to different radiation tolerances of carbide compounds. The present results suggest that electronic excitation may contribute to the structural amorphization of carbides under low- or medium-energy electron and ion irradiation, and advance the fundamental comprehension of the radiation resistances of carbide compounds.

Comparative Study of Si−O−Al and Si−O−Si Bond Stability in HZSM‐5 Zeolite Under Steam and Hot Liquid Water Environments

AbstractUnderstanding the changes in the zeolite framework and catalytic active sites during zeolite‐based vapor‐phase and aqueous catalytic processes is crucial. Herein, the evolution of framework T atoms (Si and Al) in ammonium hexafluorosilicate (AHFS)‐treated HZSM‐5 zeolite under steam and hot liquid water (HLW) environments was inverstigated using various characterization techniques. In HLW, Si−O−Si bonds exhibit poorer hydrothermal stability than Si−O−Al bonds, in contrast to steam. Significant Si atom leaching occurs regardless of whether the framework tetrahedral Al atoms (Al(IV)‐1) are removed. Similar to steam, Al(IV)‐1 species in HLW sequentially evolve into partially coordinated framework Al species and then into extra‐framework Al (EFAL) species through partial and complete hydrolysis. The generated EFAL species act as Lewis acid sites, but their local structures or chemical environments may differ. These findings reveal the difference in the T−O−T bonds attacked by water molecules: the Si−O−Al bonds are primarily attacked in steam, whereas the Si−O−Si bond are primarily attacked in HLW.

Quantum Chemical Model Calculations of Adhesion and Dissociation between Epoxy Resin and Si-Containing Molecules.

There is no doubt that when solid surfaces are modified, the functional groups and atoms directly bonded to solid atoms play a major role in adsorption interactions with molecules or resins. In this study, the adhesion and dissociation between epoxy resin and molecules containing Si atoms were analyzed. The analysis, conducted in contact with the solid surface of silicon, utilized quantum chemical calculations based on a molecular model. We compared some Si-containing molecular models to test quantum chemical calculations that contribute to the study of adhesion and dissociation between epoxy resins and solid surfaces somehow other than simple potential energy curve calculations. The AFIR (artificial force induced reaction) method, implemented in the GRRM (global reaction route mapping) program, was employed to separate an epoxy resin model molecule and three types of silicon compounds (Si(CH3)2(OH)2, Si(CH3)4, and (CH3)2SiF2) in three directions, determining their minimum dissociation energy when changing the applied energy by 2.5 kJ/mol. In systems with weak hydrogen bonds, such as Si(CH3)4 or (CH3)2SiF2, the energy required for dissociation was not large; however, in systems with strong hydrogen bonds, such as Si(CH3)2(OH)2, dissociation was more difficult in the vertical direction. Although anisotropy due to hydroxyl groups was calculated in the horizontal direction, dissociation remained relatively easy.

Ultra‐Thin Strain‐Relieving Si1−xGex Layers Enabling III‐V Epitaxy on Si

AbstractThe explosion of artificial intelligence, the possible end of Moore's law, dawn of quantum computing, and the continued exponential growth of data communications traffic have brought new urgency to the need for laser integration on the diversified Si platform. While diode lasers on group III‐V platforms have long‐powered internet data communications and other optoelectronic technologies, direct integration with Si remains problematic. A paradigm‐shifting solution requires exploring new and unconventional materials and integration approaches. In this work, it is shown that a sub‐10‐nm ultra‐thin Si1−xGex buffer layer fabricated by an oxidative solid‐phase epitaxy process can facilitate extraordinarily efficient strain relaxation. The Si1−xGex layer is formed by ion implanting Ge into Si(111) and selectively oxidizing Si atoms in the resulting ion‐damaged layer, precipitating a fully strain‐relaxed Ge‐rich layer between the Si substrate and surface oxide. The efficient strain relaxation results from the high oxidation temperature, producing a periodic network of dislocations at the substrate interface, coinciding with modulations of the Ge content in the Si1−xGex layer and indicating the presence of defect‐mediated diffusion of Si through the layer. The epitaxial growth of high‐quality GaAs is demonstrated on this ultra‐thin Si1−xGex layer, demonstrating a promising new pathway for integrating III‐V lasers directly on the Si platform.

Annulated 1,4-Disilabenzene-1,4-diide and Dihydrogen Splitting.

The isolation of silicon analogues of phenyl anions such as (C6H5)- and (C6H4)2- is challenging owing to their extremely high reactivity associated with their silylene character and weak C-Si π-interaction. Herein, we report the first annulated 1,4-disilabenzene-1,4-diide compound [(ADC)Si]2 (5) based on anionic dicarbene (ADC) scaffolds (ADC = PhC{N(Dipp)C}2; Dipp = 2,6-iPr2C6H3) as a green-yellow crystalline solid. Compound 5 is prepared by KC8 reduction of the Si(IV) chloride [(ADC)SiCl3]2 (3) or the cyclic bis-chlorosilylene [(ADC)SiCl]2 (4), which are also prepared for the first time. 5 is a neutral molecule, and each of the two-coordinated Si(I) atoms has a lone pair and an unpaired electron. Experimental and theoretical data indicate delocalization of the silicon unpaired electrons, resulting in a 6π-electron C4Si2 ring in 5. The diradical character (y) for 5 amounts to 15%. At room temperature, 5 readily reacts with dihydrogen (H2) to form the elusive bis-hydridosilylenes [(ADC)SiH]2 (Z)-6 and (E)-6. The [4 + 2]-cycloaddition of 5 and PhC≡CPh in yielding the barrelene-type bis-silylene [(ADC)SiCPh]2 (7) emphasizes the diradical reactivity of 5. With elemental sulfur, 5 results in the S2- and S3-bridged silathione derivatives [(ADC)Si(S)]2(μ-S2) (8a) and [(ADC)Si(S)]2(μ-S3) (8b). Moreover, the treatment of 5 with Fe2(CO)9 affords the Fe(0) complex [(ADC)Si(Fe(CO)4)]2(μ-CO) (9), in which each silicon atom serves as a two-electron σ-donor ligand and shares one electron with the bridging CO unit to form two Si-C bonds. The molecular structures of all compounds have been established by X-ray diffraction, and representative compounds have been analyzed by quantum chemical calculations.

Recent perspective on polymeric Semimetal (Si, Ge and As) and nonmetal (N and P) doped C70-Fullerene system: Comparative electronic, dynamic behavior and chemotherapy docking with ADMET analysis

Fullerene system, based on carbon atoms, was studied and its structural modification was built with consideration of several elements such as Si, N, P, Ge, and As, where doped modified systems were constructed. Synthetic routes survey was considered to acquire the structures' availability in further applications related to structure properties investigation. The computational investigation of these designed systems was described using the most popular approach of density functional theory (DFT). Electronic behavior for all systems was studied especially through density of states (DOS) spectra, molecular electrostatic potential (MEP), and frontier molecular orbitals (FMOs) for best comparison towards stability with less energetic properties, where C-fullerene was predicted as a more stable candidate as its ∆E with value of 1.714 eV. Molecular dynamic simulation (MD) was considered to predict the stability of the atoms in the system during the physical movement at 100 ps. A polymeric model of triple Fullerene rings was linked for each Semimetal atom (Si, Ge, and As) to predict the radial distribution function (RDF) and dynamic behavior for stability conditions. The calculated energy parameters such as potential, kinetic, and non-bond energies mainly described the system movement stability during the simulation time. Molecular docking analysis of the modified doped systems was performed for chemotherapy prediction of the studied systems against breast cancer target protein (5NWH) to evaluate the inhibition strength through active sites binding affinity. The estimated binding affinity of Si-fullerene was found the most favorable result (-12.73 kcal/mol). ADMET properties were estimated for further drug-like prediction through comparative pharmacokinetic factors.

Study of the physical nature of Mn4Si7 crystals formed by the diffusion method using an X-ray diffraction

Mn4Si7 silicide crystals obtained by the diffusion method were studied using an X-ray diffractometer (XRD-6100) SHIMADZU. As a result of research, 14 peaks were identified in the Mn4Si7 crystal, corresponding to the database (COD-1530134).The size of Mn4Si7 silicide crystals (DDiff) ranged from 6.2 × 10−10 m to 9.1 × 10−8 m, the lattice tension between crystal atoms (εDiff) from 0.31 to 3.71, the dislocation density on the surface (δDiff) varied in the range from 1 × 1011 to 3.2 × 1014. It was found that the degree of crystallization of Mn4Si7 was 9.3 %, and the degree of amorphism reached 90.7 %. It has been established that the degree of crystallization of Mn4Si7 silicides is relatively low due to the fact that the Mn and Si atoms are non-stoichiometrically bonded to each other, and the degree of amorphism is high.

Bi-intercalated epitaxial graphene on SiC(0001)

Abstract The intercalation of graphene with suitable atomic species is one of the most frequently applied methods to decouple the graphene layer from the substrate in order to establish the classical electronic properties of graphene. In this context, we studied the bismuth (Bi) intercalation of the (6√3×6√3)R30° reconstructed so-called "zeroth layer graphene'' on SiC(0001). 
As reported earlier by Sohn et al. [J. Korean Phys. Soc. 78, 157 (2021)], two phases are formed depending on the amount of intercalated Bi, which in turn is controlled by the annealing temperature: The α phase, showing a 1×1 periodicity with respect to the substrate, and, at higher temperatures, the √3×√3 reconstructed β phase. We characterise both phases and the transformation from the α to the β phase by photoelectron spectroscopy, normal incidence x-ray standing waves, electron diffraction and electron microscopy. We clearly see an almost complete intercalation of the graphene layers in both phases, with strong (covalent) interaction between the topmost Si atoms of the substrate and the Bi intercalant, but only weak (van der Waals) interaction between Bi and the graphene layer. The n-doping of the graphene found for the α phase decreases continuously during the phase transformation, in agreement with a reduced density of the Bi intercalating layer. Missing core level shifts of the surface species as well as the normal incidence x-ray standing waves results indicate that all surface Si atoms remain saturated during the transition and no dangling bonds are formed. Low energy electron microscopy and diffraction reveal the coexistance of both phases after annealing to intermediate temperatures and allow a quantitative analysis of island sizes and numbers.

New 5-6-6-5 (fourfold) and 5-9-6 defect Configurations in g-SiC (graphene-like hexagonal monolayer silicon carbide)

Abstract Computational studies using the density functional theory (DFT) were employed to analyze defect configurations in g-SiC. The SiC supercells containing 72 atoms were used for simulation. We simulate C-vacancy (VC) and Si-vacancy (VSi). We relaxed all atoms so that the atomic force tolerance is 1.0 × 10−4 Ha/Bohr. The unrelaxed defective configurations have the same symmetry as the perfect configuration, which is a D3h symmetry. During relaxation, atoms neighboring the vacancy were displaced to reach a ground state condition. In the case of VC, a Si atom at the center of the defect has four bonds, resulting in a new 5-6-6-5 fourfold configuration with a C2v symmetry. In the case of VSi, a C atom forms bonds with two other C atoms, resulting in a new configuration, namely a 5-9-6 configuration. We identified that this configuration also has a C2v symmetry. Thus, symmetry breaking (lowering) occurs from D3h to C2v. We calculated the formation energy, which is 3.28 eV for the 5-6-6-5 fourfold and 3.92 eV for the 5-9-6 configuration. We also calculated the Density of States (DOS), and the results show that both configurations have semiconductor material properties suitable for promising optoelectronic devices with an infrared spectrum for future applications.

Characterization of L12-Al3Ce phase and its purification mechanism in the Al-Ce-TiCN alloy

Rare earth element Ce has a positive purifying effect on Fe and Si impurities in pure aluminum. In this study, we unveiled the mechanism of Ce purification of Fe and Si impurities in commercial pure aluminum at the atomic scale via utilizing the properties of TiCN nanoparticles, which exhibit distribution along grain boundaries and impede solute atom diffusion at specific cooling rates. The transition phase L12-Al3Ce was characterized in aluminum, which is considered to be an important transition phase to purified products. Furthermore, High Angle Dark Field Scanning Transmission Electron Microscopy (HADDF-STEM) and 3D Atom Probe Tomography (3D-APT) results showed that Ce could respectively enrich the Fe and Si impurities, resulting in the formation of Al-Ce-Fe and Al-Ce-Si clusters. Density functional theory (DFT) results indicated that Fe and Si atoms can incorporate into L12-Al3Ce crystal, forming more stable structures and therefore giving rise to the formation of Al-Ce-Si and Al-Ce-Fe nanoclusters. This study provides atomic-scale insights into the mechanism of Ce purifying Fe and Si impurities in aluminum.