Formation Energy Analysis Research Articles

DFT investigation on the rare earth effects of Mg8Si3RE (RE=Sc, La, Ce, Yb) compounds

The mechanical and electronic properties of β phase (Mg2Si) doping with rare earth (RE) atoms (Sc, La, Ce, Yb) were investigated by first-principles based on density functional theory. The results showed that both Mg8Si3RE and Mg7Si4RE can exist stably by doping from the analysis of formation energy and cohesive energy. We found that RE atoms doping into the Mg2Si lattice tends to occupy Mg position preferentially. Doping Yb which has the largest Hv can strength the stiffness of compound, meanwhile, Mg7Si4Ce has the smallest stiffness. The ductility of Mg2Si increases after doping with La (Ce). Doping RE atoms cause strong orbital hybridization between Al and RE, so the bonding strength and stability of Mg2Si can be significantly changed.

Structural, mechanical, electronic properties and Debye temperature of tungsten-technetium alloy: A first-principles study

In this paper, we focus on the investigation of the crystal structure, mechanical properties, electronic properties and Debye temperature of tungsten-technetium alloy based on the first principles method. The configurations investigated are W15Tc1, W14Tc2, W12Tc4 and W8Tc8 alloys, respectively. The results show that the tungsten-technetium alloy still maintains a cubic lattice. The lattice constant of tungsten-technetium alloy is lower than that of pure W due to the atomic radius of technetium is smaller than that of tungsten. The formation energy analysis shows that the thermodynamic stability of tungsten-technetium alloy decreases with the increasing technetium concentration. By analyzing the elastic constant, elastic modulus and other mechanical parameters, the mechanical strength of tungsten-technetium alloy is weaker than that of pure tungsten. However, the B/G ratio and Poisson's ratio of tungsten-technetium alloy are greater than that of pure tungsten, which means that Doping technetium can improves the ductility of pure tungsten. In addition, the anisotropy, melting point and hardness, and Debye temperature of tungsten-technetium alloy is also discussed.

Vacancy-induced structural, electronic and optical properties of Hf2CO2 MXene

Two-dimensional materials have been widely studied in recent years due to their excellent properties. In this paper, we investigate the structural, electronic and optical properties of pristine and vacancy defect Hf2CO2 using first-principles calculations. The results indicate that O-vacancy (VO) is energetically more favorable than C-vacancy (VC) and Hf-vacancy (VHf) using analysis of vacancy formation energy and energetic stability. The introductions of VC and VHf result in the transition from semiconductor to metal, while introduction of VO makes the bandgap of the pristine Hf2CO2 (PH) monolayer decrease. The introduction of VHf and VC also results in occurrence of localized defect states. The introduction of VO effectively enhances the photocatalytic efficiency of the Hf2CO2 with VO (Hf2CO2-VO) monolayer. The PH and Hf2CO2-VO monolayers are semiconductors and have high optical conductivity, strong absorption and reflectivity at 2.5 eV. The charge transfer is also explored.

Origin of the N-coordinated single-atom Ni sites in heterogeneous electrocatalysts for CO2 reduction reaction.

Heterogeneous Ni–N–C single-atom catalysts (SACs) have attracted great research interest regarding their capability in facilitating the CO2 reduction reaction (CO2RR), with CO accounting for the major product. However, the fundamental nature of their active Ni sites remains controversial, since the typically proposed pyridinic-type Ni configurations are inactive, display low selectivity, and/or possess an unfavorable formation energy. Herein, we present a constant-potential first-principles and microkinetic model to study the CO2RR at a solid–water interface, which shows that the electrode potential is crucial for governing CO2 activation. A formation energy analysis on several NiNxC4−x (x = 1–4) moieties indicates that the predominant Ni moieties of Ni–N–C SACs are expected to have a formula of NiN4. After determining the potential-dependent thermodynamic and kinetic energy of these Ni moieties, we discover that the energetically favorable pyrrolic-type NiN4 moiety displays high activity for facilitating the selective CO2RR over the competing H2 evolution. Moreover, model polarization curves and Tafel analysis results exhibit reasonable agreement with existing experimental data. This work highlights the intrinsic tetrapyrrolic coordination of Ni for facilitating the CO2RR and offers practical guidance for the rational improvement of SACs, and this model can be expanded to explore mechanisms of other electrocatalysis in aqueous solutions.

BiOCl/group-IV Xene bilayer heterojunctions: stability and electronic and photocatalytic properties.

Vertical van der Waals heterojunctions (HJs) composed of a photocatalytic star material BiOCl monolayer and group-IV Xene monolayer (silicene, germanene etc.) were studied by using first-principles calculations. Formation energy analysis and molecular dynamics simulation show that the BiOCl/Xene bilayer HJs can exist stably up to room temperature. Owing to evident charge redistribution and accumulation occurring between the bilayers, electron-hole puddles form and charge carrier transfer and separation occur in the HJs, which are beneficial to the improvement of photocatalytic performance. The HJ energy bands maintain the Dirac cones with almost linear dispersion curves, suggesting low effective mass and high mobility of carriers, and can be effectively tuned by strain. Our results show that the BiOCl/Xene bilayer HJs with high separation efficiency and high mobility of carriers and strain-adjustable bandgaps provide varieties in the functionalities of 2D van der Waals HJs and show great potentials in photocatalytic applications.

Understanding the influence of single metal (Li, Mg, Al, Fe, Ag) doping on the electronic and optical properties of g-C3N4: a theoretical study

ABSTRACT Semi-empirical tight-binding-based quantum chemistry method (GFN2-xTB) has been done to study the influence of single metal (Li, Mg, Al, Fe, Ag) doping on the electronic and optical properties of monolayer corrugated graphitic carbon nitride (g-C3N4). Based on the calculated formation energy and population analysis, we showed that the metal atom is chemically bound to the g-C3N4 surface. The metal doping reduces the vertical ionisation potential and raises the electron affinity and Lewis acidity of g-C3N4. The metal-doped g-C3N4 systems have lower band gap than that of pristine g-C3N4 which is attributed to the electron donating from the metal atom to g-C3N4. Analysis of the lowest unoccupied molecular orbital and the highest occupied molecular orbital shows that for the Fe- and Ag-doped g-C3N4 systems the separation of photo-generated electron–hole pairs is efficient, resulting in the enhancement of photo-catalytic activity.

First-Principle Prediction of Phase Stability, Electronic and Elastic Properties Study of the Mn+1ANn (A = Al, Si, M = Ti, Zr, Hf)

Theoretical prediction is the most important method for discovering new structure. The stability of the nitride MAX phase (N-MAX) Mn+1ANn, (A = Al, Si, M = Ti, Zr, Hf) was studied using first principles. The formation energy analysis of the competitive phases shows that N-MAX tends to form the larger n-index M4AN3 structure. The formation energy of the Mn+1SiNn system is higher than that of the Mn+1AlNn system, indicating that the Mn+1AlNn system has greater phase stability and experimental synthesis possibility than the Mn+1SiNn system. In all computing systems, the formation energy of Hfn+1AlNn is the lowest, indicating the largest synthesis possibility. Among all the considered structures, Hf2AlN is the material with the best comprehensive performance, such as the bulk modulus reaches 800 GPa. Due to its high elastic anisotropy, Hf4SiN3 is the excellent candidate for the precursor of MXene 2D nanosheets. The study provides a theoretical prediction for the synthesis of potentially undiscovered phases in the N-MAX systems.

Platinum doped iron carbide for the hydrogen evolution reaction: The effects of charge transfer and magnetic moment by first-principles approach

In this work, the catalytic activity towards hydrogen evolution reaction (HER) was studied for hydrogen adsorption on Pt doped Fe2C (001) surface configuration (Pt/Fe2C) and compared with pure Pt (001). The adsorption of H on the pristine Fe2C, Pt doped Fe2C, and pure Pt in (001) slab was computed. The best and promising HER activity (ΔGH∗ = −0.02 eV) is obtained at the hollow site adsorption of Pt/Fe2C (Fe13Pt3C8) compared to the experimental value of pure Pt (ΔGH∗ = −0.09 eV) suggesting the possibility of the H2 formation on the surface of Fe13Pt3C8. The structural stabilities of Fe2C and Pt/Fe2C were investigated by the formation energy analysis. Also, it is observed that to enhance the HER mechanism, the modification of the d-electron structure of Pt atoms is essential which can be achieved by the increased Pt doping. The Bader charge analysis demonstrated the charge transfer between the substrate and the adsorbed H atoms. The density of states (DOS) of pure Fe2C and optimal Pt/Fe2C were calculated which revealed the magnetic and metallic nature of these materials. In addition, the adsorption and resulted activation of H2 were facilitated by the elongation of H–H bond length in Fe13Pt3C8. This work supports the HER over single atom catalysts (SACs) with lower Pt loading but with high catalytic activity and the maximum atom utilization of SACs.

Physiological silicon incorporation into bone mineral requires orthosilicic acid metabolism to SiO44.

Under physiological conditions, the predominant form of bioavailable silicon (Si) is orthosilicic acid (OSA). In this study, given Si's recognized positive effect on bone growth and integrity, we examined the chemical form and position of this natural Si source in the inorganic bone mineral hydroxyapatite (HA). X-ray diffraction (XRD) of rat tibia bone mineral showed that the mineral phase was similar to that of phase-pure HA. However, theoretical XRD patterns revealed that at the levels found in bone, the 'Si effect' would be virtually undetectable. Thus we used first principles density functional theory calculations to explore the energetic and geometric consequences of substituting OSA into a large HA model. Formation energy analysis revealed that OSA is not favourable as a neutral interstitial substitution but can be incorporated as a silicate ion substituting for a phosphate ion, suggesting that incorporation will only occur under specific conditions at the bone-remodelling interface and that dietary forms of Si will be metabolized to simpler chemical forms, specifically [Formula: see text]. Furthermore, we show that this substitution, at the low silicate concentrations found in the biological environment, is likely to be a driver of calcium phosphate crystallization from an amorphous to a fully mineralized state.

Electronic properties of [111] hydrogen passivated Ge nanowires with surface substitutional lithium

In this work, a density functional theory study of the lithium (Li) effects on the properties of hydrogenated germanium nanowires (H-GeNWs) is developed. In particular, the electronic band structures, densities of states, formation energies, and Li binding energies of H-GeNWs grown along the [111] crystallographic direction with a diamond structure for different concentrations of surface substitutional Li atoms were studied. Ge nanowires with hexagonal cross sections and three different diameters were considered. The results indicate that all studied H-GeNWs maintain a semiconducting behaviour and the size of the energy band gap is a function of the diameter and the concentration of substitutional surface Li atoms. The formation energy analysis reveals than the energy stability of the nanowires increases when the nanowire diameter and the concentration of Li atoms augment. The results of this work give insight of how the electronic properties of H-GeNWs change during the charging process and open the possibility to incorporate them as electrodes in Li-ion batteries.

Interface engineering of InGaAs/InP layer for photocathode

InGaAs photocathode commonly relies on the buffer layer to mitigate the lattice mismatch between the InGaAs emission layer and the substrate layer and thus enhance the photoemission performance. In this article, the influence of the interface layer between the InGaAs emission layer and the InP substrate layer of the InGaAs photocathode without the buffer layer on the photoemission performance is studied. The GaAs-As-InP model and the GaAs-P-InP model are built based on the First Principle. Then, after the calculation and analysis of the energy band structure and the density of states, As atom layer is used as the interface, based on which the InGaAs-As-InP model is established. It is found by the analysis of energy band structure and formation energy that the energy level is added at the InGaAs-As-InP interface, the band gap is not greatly reduced, and the formation energy is -10.56 eV/nm2, so a relatively stable interface can be formed. The optical properties of the interface show that both the reflectivity and the absorption rate are the lowest in the 1000–2000 nm band of the main response region of the InGaAs photocathode. This is conducive to the absorption of light energy in the emission layer and the generation of photoelectrons. The charge transfer at the interface leads to the formation of a built-in electric field which is gradually weakened from the interface to both sides and directed from the InGaAs emission layer to the InP substrate layer, facilitating the transport of photoelectrons generated at the interface to the surface of the emission layer. For the InGaAs photocathode without the buffer layer, its InGaAs-As-InP interface is beneficial to the generation of photoemission and the transport of photoelectrons. Growing the InGaAs emission layer directly on the InP substrate layer when preparing InGaAs photocathode can improve the photoemission efficiency of the InGaAs photocathode.

Probing Gold-Doped Germanene Nanoribbons for Nanoscale Interconnects Under DFT-NEGF Framework

Gold-doped germanene nanoribbons (Au-GeNRs) are investigated for their potential as interconnects, using density functional theory combined with nonequilibrium Green’s function formalism. Various stable doping sites for both zigzag and armchair GeNRs (ZGeNR and AGeNR) are investigated. Based on formation energy ($$E_{{{\mathrm{FE}}}}$$) analysis, all considered Au-GeNRs are revealed to be thermodynamically stable. The analysis also shows that near-edge-doped ZGeNR (with $$E_{{{\mathrm{FE}}}} = -3.46$$ eV) is the most stable configuration. It is shown through $$E-k$$ structures and density-of-states profiles that Au-doping results in metallic GeNR irrespective of the edge states and ribbon width. To further explore the prospects for the use of Au-doped GeNR for interconnect applications, important small-signal dynamic parameters (including $$R_Q, L_K,$$ and $$C_Q$$) for various doped configurations are explored. The present investigations also take into account the effect of bias voltage on $$R_Q, L_K, C_Q$$. It is revealed that, with the exception of the edge-doped ZGeNR configuration, bias voltage has a prominent effect on these parameters for every configuration. Thus, edge-doped ZGeNR (with $$L_K = 4.41$$ nH/$$\upmu $$m, $$C_Q = 4.21$$ pF/cm) represents a potential candidate for nanoscale interconnect applications among the considered configurations.

Band-Gap Engineering of Mo- and W-Containing Perovskite Oxides Derived from Barium Titanate

Ferroelectric oxide perovskites are promising materials for use in photovoltaic devices, due to their ability to exploit the bulk photovoltaic effect to achieve high power-conversion efficiency. In this work, we use first-principles methods to investigate the ferroelectric perovskite $[{\mathrm{Ba}\mathrm{Ti}\mathrm{O}}_{3}{]}_{x}\text{\ensuremath{-}}[{\mathrm{Na}\mathrm{Ti}}_{1/2}{\mathrm{Mo}}_{1/2}{\mathrm{O}}_{3}{]}_{1\ensuremath{-}x}$ and $[{\mathrm{Ba}\mathrm{Ti}\mathrm{O}}_{3}{]}_{x}\text{\ensuremath{-}}[{\mathrm{Na}\mathrm{Ti}}_{1/2}{\mathrm{W}}_{1/2}{\mathrm{O}}_{3}{]}_{1\ensuremath{-}x}$ solid solutions for potential use in ferroelectric-based photovoltaics. We find that compositional variations change the band gap, shifting it to the edge of the visible range for the 25% ${\mathrm{Na}\mathrm{Ti}}_{1/2}{\mathrm{Mo}}_{1/2}{\mathrm{O}}_{3}$ composition and to the visible range for some Mo-cation and W-cation arrangements for the 50% ${\mathrm{Na}\mathrm{Ti}}_{1/2}{\mathrm{Mo}}_{1/2}{\mathrm{O}}_{3}$ and 50% ${\mathrm{Na}\mathrm{Ti}}_{1/2}{\mathrm{W}}_{1/2}{\mathrm{O}}_{3}$ compositions. Mo and W substitutions both maintain the ferroelectric properties of the parent ${\mathrm{Ba}\mathrm{Ti}\mathrm{O}}_{3}$. While the A-site cation arrangement has a minor effect on the band gap, the variations in the B-site cation arrangement and the cation displacements affect the band gap by up to 0.8 eV. Analysis of the structures and the calculated band-gap values shows that the band gap is controlled by the identity of the substituent cation, the O-B-O angles, the relative orientations of the Mo and W substituent atoms, and the B-cation displacement. We demonstrate the thermodynamic feasibility of these solid solutions by formation energy analysis. The decrease of the band gap relative to the parent ${\mathrm{Ba}\mathrm{Ti}\mathrm{O}}_{3}$ to the standard and transparent photovoltaic range combined with the ferroelectricity maintained make this earth-abundant-containing solid solution a promising candidate for use in high-performance ferroelectric-based photovoltaic devices.

First-principles investigations of the stability and electronic properties of fluorinated Janus MoSSe monolayer

The stability and electronic structures of fluorinated Janus MoSSe (MoSSe-Fx, x = 0–16) were investigated by the first-principles method. Energetically, the Setop site of Janus MoSSe is the most favorable site for F-adsorption. Based on the adsorption, binding and formation energy analysis, it seems the fluorinated Janus MoSSe is stable. The analysis of the electronic density distribution and orbital hybrid shows that the fluorinated Janus MoSSe forms stable structure as well. Then, the electronic structure and work function change with the concentration of F atoms analyzed. With the increase of adsorbed F atoms, the bandgap of Janus MoSSe-Fx decreases from 1.456 (pristine case, [Formula: see text]) to 1.073[Formula: see text]eV (semi-fluorinated case, [Formula: see text]), and changes from direct to indirect bandgap semiconductor. It is noteworthy that there are some additional doping levels near the valence band after F adsorbed, which originated from the F 2[Formula: see text] doping states. The charge population analysis shows that electrons transfer was from Se to F atoms. It is worth noting that the charge on F atom (MoSSe-F16) is two times more than Se atoms in pristine Janus MoSSe (MoSSe-F0). As a result, the built-in electric field pointed from Mo to F atoms is enhanced, resulting in the tremendous increase of the work function for fluorinated Janus MoSSe. The work function changes from 5.22[Formula: see text]eV ([Formula: see text]) in pristine case to 8.30[Formula: see text]eV after semi-fluorinated ([Formula: see text]). Therefore, due to the adjustable work function and built-in electric field, the fluorinated Janus MoSSe monolayer shows better properties for applications in the piezoelectric device, optoelectronic device or photocatalyst.

X3N (X=C and Si) monolayers and their van der Waals Heterostructures with graphene and h-BN: Emerging tunable electronic structures by strain engineering

Using density functional theory, we explore the electronic structures of the two-dimensional (2D) C3N and Si3N, as well as C3N-based van der Waals heterostructures with graphene and h-BN. The two-dimensional (2D) C3N is demonstrated to be an indirect semiconductor with atomically flat nanostructure, while the 2D buckled Si3N exhibits metallic property. The semiconductor-metal transition can be obtained under compressive strain of −8% and tensile strain of 14% for the 2D C3N, and the metal-semiconductor transition can be achieved when 10% stretch strain is applied for the Si3N. Moreover, the C3NBN heterojunctions with three different stackings are energetically favorable based on the formation energy analysis. The Dirac-like point of C3N is broken as the interlayer distance is decreased, and the band alignments of the C3NBN heterojunctions are significantly affected by the external strains. In contrast, both AA- and AB-stacked C3N-graphene heterojunctions possess excellent Ohmic contact. The p-type Ohmic contact of the AA stacking can be switched to the n-type provided that the vertical distance is substantially decreased. The tunable electronic properties of the 2D C3N and the comprehensive understanding of C3N-based van der Waals heterostructures influenced by strain engineering may facilitate their practical applications for nanoelectronics and optoelectronics.

Band gap engineering of a MoS2 monolayer through oxygen alloying: an ab initio study

Oxygen (O) alloying in a MoS2 monolayer appearing in different shapes: line-ordered, cluster and random have been theoretically designed, for band gap engineering in order to extend its nanotechnological applications. The thermodynamic stability, structural and electronic properties of these alloy configurations at each concentration have been comparatively studied using the density functional theory methods. Based on the formation energy analysis, the O line-ordered alloys are most stable compared to the well known random and cluster alloys at high concentration, while at low concentration they compete. The lattice constants of all the alloyed systems decrease linearly with the increase in O concentration, consistent with Vegard’s law. The Mo–O bond lengths are shorter than Mo–S leading to a reduction in the band gap, based on density of state analysis. The partial charge density reconciling with the partial density of states analysis reveals that the band gap reduction is mainly contributed by the Mo 4d and O 2p orbitals as shown at the band edges of the density of states plots. Creation of stacking of MoS2 with MoO2 gives metallic character, with Mo 4d orbital crossing the Fermi level. The O alloys in a MoS2 monolayer should be considered to be an effective way to engineer the band gap for designing new nanoelectronic devices with novel performance.

Theoretical study of the mechanical and electronic properties of [111]-Si nanowires with interstitial lithium

In this work, we present a density functional study of the Young’s modulus and electronic properties of hydrogen passivated silicon nanowires (H-SiNWs) grown along [111] crystallographic direction as function of concentration of interstitial lithium (Li) atoms. The study is performed using the supercell scheme, within the local density approximation implemented in the SIESTA code. The results show that the presence of Li closes the known semiconductor band gap of the H-SiNWs showing a like metallic behavior even when just one Li atom is placed in the nanowire structure. The participation of the Li atoms in the electronic density of states is almost constant in the valence and conduction bands. The formation energy analysis show how the system loses energetic stability when the concentration of Li grows, while the binding energy per Li atom suggests the formation of Si–Li bonds. On the other hand, the Young’s modulus of the silicon nanowires (SiNWs) is higher than that of the H-SiNW and lower than the bulk value. Moreover, the Young’s modulus is almost constant independently of the Li concentration. This result indicates that the H-SiNWs support the internal stress due to the addition of Li atoms and could offer a better useful life as electrodes in Li-ion batteries. The results of this work help to understand how the electronic and mechanical properties of H-SiNWs change during the charge/discharge process and the possibility to incorporate them as electrodes in Li batteries.

Zn doping in the In0.53Ga0.47As(100)β2(2 × 4) surface for negative electron affinity photocathode: A first-principles research

InGaAs is an important ternary III-V semiconductor material with good spectral response in the near infrared region of 1–3 μm. The negative electron affinity is generated from the proper sensitization of In0.53Ga0.47As(100)β2(2 × 4) surface. Doping and sensitization are indispensable in the preparation of InGaAs photocathode. However, the surface doping mechanism of InGaAs is not clear. This article focuses on the suitable doping sites of substitutional Zn atoms for sensitization on In0.53Ga0.47As(100)β2(2 × 4) surface. Considering the symmetry, there are eight doping sites and the eight doping surface models are formed. The surface atomic structures and surface formation energies of these models are discussed. The lower the formation energy is, the more stable the surface is. Zn4 and Zn5 are the more stable doping models based on the analysis of formation energy. Therefore the band structure, surface charge distribution, work function and optical properties are further discussed for these two doping models. The Zn4 doping surface has a lower work function and reflectivity and better absorption in the range of 1–3 μm than Zn5. In a word, the InGaAs surface with Zn4 doped is more conducive to the photoelectrons transport and photoemission. Then Zn4 is the most favorable doping site for the InGaAs photocathode.

Ab initio studies of isolated boron substitutional defects in graphane

We have systematically studied energetics, structural and electronic properties of different configurations of the B atoms substituting C-H pairs located on a single hexagonal ring in a graphane system using the first-principles density functional theory (DFT). A total number of 12 distinct B dopants configurations were identified and characterized. Based on the formation energy analysis, we found that relative stability of B dopants depends greatly on the defect configurations. Our results suggest that the B substitutions prefer to be distributed randomly but avoiding the formation of homo-elemental B-B bonds in a graphane system, at any concentration. Generally, the values of band gap decrease as the number of B dopants increases, but the low energy configurations have large band gaps compared to those that have homo-elemental bonds. As a result, the band gap of graphane can be fine tuned through the change in the structural arrangement of B atoms. The adequate control of the electronic structure of graphane through doping should be essential for technological device applications.

Effect of Mo on the phase stability and elastic mechanical properties of Ti–Mo random alloys from ab initio calculations

Ti–Mo alloys are promising materials for shape memory alloys and biomedical materials. Whereas, the appearance of metastable ω phase can cause embrittlement and destroy the shape memory effect. In order to avoid the ω phase, the effect of Mo on the temperature dependent lattice parameters, phase stability and elastic mechanical properties of β, α, and ω Ti1−xMox (x = 0–2.0) random alloys was systematically investigated by using the exact muffin-tin orbitals method in combination with the coherent potential approximation. The theoretical predictions for the lattice parameters are in good agreement with the available experiments. Results show that β Ti0.96Mo0.04 can almost transform to ω phase without lattice deformation and volume change, which suggests that the athermal ω phase is easier to precipitate and grow near 4 at.% Mo content in the β Ti1−xMox alloys. The critical content of Mo for the competed stabilization of β phase at T = 300 K is ~11.2 at.%. Its valence electron concentration of 4.224 is viewed as a necessary criterion for the competed phase stability. The calculations of formation energy are used to explain successfully why the partitioning of Mo can be found in Ti0.91Mo0.09 alloy after annealing. Through the analysis of formation energy, both Mo addition and increasing temperature can stabilize the β phase. The calculated Cauchy pressure, Pugh’s ratio, Poisson ratio, and Young’s modulus suggests that ω phase is intrinsically brittle and has large Young’s modulus compared with β and α phases.