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This research employs the FP-LAPW approach within density functional theory to investigate the structural, optical, electronic, and elastic features of GaXCl3 (X = Be, Ca) chloroperovskites. The computational analysis, incorporating Birch Murnaghan curve optimization for structural stability and IRelast for elastic constants, affirms the anisotropic, ductile, and mechanically stable nature of both GaBeCl3 and GaCaCl3. Electronic characteristics are examined using the Tb-mBJ potential, revealing GaBeCl3 as semiconducting with a 3.03 eV direct band gap (M-Γ) and GaCaCl3 as insulating with a 4.90 eV direct band gap (X–X). Total and partial densities of states (TDOS and PDOS) provide insights into the contributions of elemental states to the band structure. Optical features explored up to 13 eV emphasize significant peaks in the spectra based on observed electronic structures. These findings contribute to a more thorough comprehension of the physical characteristics of chloroperovskites based on Gallium, paving the way for their utilization in optoelectronic devices and as insulating materials. [ABSTRACT FROM AUTHOR]

The characteristics of linear hydroelastic waves propagating in a channel covered with compressed ice are investigated. The channel has a rectangular cross-section and is assumed to be infinite in length. The fluid in the channel is non-viscous and incompressible; its flow is potential. The ice cover is modelled by an elastic plate of constant thickness frozen to the channel walls. Principal attention is paid to the investigation of the influence of ice compression on the parameters of hydroelastic waves. The problem is solved in a coupled hydroelastic formulation. The profiles of propagating waves in the channel are sought in the form of series on the normal modes of a dry plate. The modes are defined analytically through trigonometric and hyperbolic functions. It is shown that compression in the longitudinal and transverse directions has different effects on the dispersion relations of these hydroelastic waves, their shape and phase, as well as on the critical velocities and strains distribution. [ABSTRACT FROM AUTHOR]

Pathological processes often change the mechanical properties of cells. Increased rigidity could be a marker of cellular malfunction. Erythrocytes are a type of cell that deforms to squeeze through tiny capillaries; changes in their rigidity can dramatically affect their functionality. Furthermore, differences in the homeostatic elasticity of the cell can be used as a tool for diagnosis and even for choosing the adequate treatment for some illnesses. More accurate types of equipment needed to study biomechanical phenomena at the single-cell level are very costly and thus out of reach for many laboratories around the world. This study presents a simple and low-cost technique to study the rigidity of red blood cells (RBCs) through the application of electric fields in a hand-made microfluidic chamber that uses a capacitor principle. As RBCs are deformed with the application of voltage, cells are observed under a light microscope. From mechanical force vs. deformation data, the elastic constant of the cells is determined. The results obtained with the capacitor-based method were compared with those obtained using optical tweezers, finding good agreement. In addition, P. falciparum-infected erythrocytes were tested with the electric field applicator. Our technique provides a simple means of testing the mechanical properties of individual cells. [ABSTRACT FROM AUTHOR]

Laminated veneer lumber (LVL) is a structural composite lumber that has the advantages of uniform structure, high strength, and flexible size compared with natural solid wood. It is widely used in the timber industry. This paper aims to test the elastic constants of LVL using a dynamic method. It focuses on Populus deltoides LVL as the research subject and proposes a 1/3-span patch method of square-section cantilever beam for dynamic testing of wood Poisson's ratio. The elastic modulus, shear modulus, and Poisson's ratio of LVL were determined through dynamic testing using the cantilever plate transient excitation method. The accuracy of the Poisson's ratio of LVL tested with the 1/3-span patch method was verified through first-order bending mode stress–strain analysis. These results were further confirmed using a static four-point bending method. The conclusion reveals that the relative error of the LVL Poisson's ratio obtained using the 1/3-span patch method for cantilever beams and the first-order bending mode method for cantilever plates ( σ y =0 patch method) testing is 2%. The longitudinal and transverse Poisson's ratios of LVL tested with the 1/3-span patch method for cantilever beams match those obtained through the first-order bending mode method for cantilever plates and the four-point bending method. The relative error between LVL longitudinal and transverse dynamic beam elastic modulus test values and static four-point bending test values is no more than 5%. The relative error between LVL longitudinal shear modulus dynamic and static test values is 4.8%, and the results are consistent. In conclusion, the dynamic method is effective for testing the longitudinal and transverse Poisson's ratio, elastic modulus, and shear modulus of LVL. It is also more convenient than the static test method. [ABSTRACT FROM AUTHOR]

The ultrasonic characteristics of dysprosium monochalcogenides, DyX (X = S, Se and Te) as a function of temperature and crystallographic direction, are studied in present investigation. First, the second- and third-order elastic constants (SOECs and TOECs) have been computed using Coulomb and Born-Mayer potential from 0K to 500K. The mechanical properties have been evaluated with the achieved values of SOECs for finding the intrinsic properties, stability and futuristic performance of DyX. The mechanical stability and elastic moduli follow the order DyS > DySe > DyTe. Supplemental the acoustic velocities including Debye average velocity, thermal relaxation time, Debye temperature and nonlinear parameter have been computed along <100>, <110> and <111> directions in the temperature range 100K to 500K. The Debye average velocity is found to be highest for wave propagating along <110> and polarized along <...0>. Finally, the ultrasonic attenuation using the modified Mason's approach has been computed in the temperature regime 100-500K along different crystallographic directions and calculated results predict that Akheiser damping dominates over the thermal attenuation. The obtained results have been analyzed and discussed with the available literature. [ABSTRACT FROM AUTHOR]

Altering the content of an alloying element in alloy materials will inevitably affect the content of other elements, while the effect is frequently disregarded, leading to subsequent negligence of the common influence on the physical properties of alloys. Therefore, the correlation between alloying elements and physical properties has not been adequately addressed in the existing studies. In response to this problem, the present study focuses on the Al10Ti15Nix1Crx2Cox3 alloys and investigates the competitive interplay among Ni, Cr, and Co elements in the formation of physical properties through a single-element (SE) analysis and a multi-element (ME) analysis based on the first principles calculations and the partial least squares (PLS) regression. The values of C11 and C44 generally increase with the incorporation of Ni or Cr content in light of SE analysis, which is contrary to the inclination of ME analysis in predicting the impact of Ni and Cr elements, and the Ni element demonstrates a pronounced negative competitive ability. The overall competitive relationship among the three alloying elements suggests that increasing the content of Ni and Cr does not contribute to enhancing the elastic constants of alloys, and the phenomenon is also observed in the analysis of elastic moduli. The reason is that the SE analysis fails to account for the aforementioned common influence of multiple alloying elements on the physical properties of alloys. Therefore, the integration of SE analysis and ME analysis is more advantageous in elucidating the hidden competitive mechanism among multiple alloying elements, and offering a more robust theoretical framework for the design of alloy materials. [ABSTRACT FROM AUTHOR]

The impact of variations in the content of single alloying element on the properties of alloy materials has been extensively discussed, but the influence of this change on the content of multiple alloying elements in the alloy materials has been disregarded, as the performances of alloy materials should be determined by the collective influence of multiple alloying elements. To address the aforementioned issue, the present study conducted a comprehensive investigation into the impact of variations in the content of alloying elements, namely Ni, Cr, and Co, on the structural and mechanical properties of L12-(Nix1Crx2Cox3)3Al precipitates using the high-throughput first-principles calculations and the partial least squares (PLS) regression, and the competitive mechanism among these three elements was elucidated. The findings demonstrate that the same alloying element may exhibit opposite effects in both single element analysis and comprehensive multi-element analysis, for example, the effect of Ni element on elastic constant C11, and the influence of Cr element on Vickers hardness and yield strength. The reason for this is that the impact of the content of other two alloying elements is ignored in the single element analysis. Meanwhile, the Co element demonstrates a significant competitive advantage in the comparative analysis of three alloying elements for different physical properties. Therefore, the methodology proposed in this study will facilitate the elucidation of competition mechanisms among different alloy elements and offer a more robust guidance for experimental preparation. [ABSTRACT FROM AUTHOR]

In the present work, the density functional theory calculation has been performed for RbMgF 3-x H x with GGA-PBE approximation implemented in CASTEP code. First time the structural, mechanical, electronic and optical properties of perovskite RbMgF 3-x H x (x = 0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.65, 1.80, 1.95, 2.25, 2.55, 2.85 and 3.0) has been investigated in details along with hydrogen storage applications. The results of formation enthalpy and elastic constants indicate that the materials are synthesizable. It has been found that the concentration of hydrogen storage decreases the elastic moduli and anisotropy whereas the bandgap becomes narrow because of the shifting of conduction band toward the fermi level. This indicates that hydrogen inclusion altered the electronic properties of the material and material can also be used in various optoelectronic devices alongwith hydrogen storage application. The crystal structure shifted from cubic to tetragonal during the hydrogen storage. The optical properties were thoroughly investigated between 0 and 10 eV. It has been found optical properties are enhanced with the doping concentration of hydrogen, which makes them good candidates for optoelectronic devices. The gravimetric ratio of hydrogen increased up to 2.61% with hydrogen incorporation. The presented material is an efficient material not only for opto-electronic applications but also for hydrogen storage as well. • Electronic and optical properties of H-doped RbMgF 3 are studied. • All studied materials are indirect band gap semiconductors. • Density of states were investigated with reduction of band gap from 6.263 to 2.124 eV. • The RbMgF 3-x H x is a good transmitter and shows good optical response in the visible region. • The gravimetric storage capacity (%) values are varied from 0.39 % to 2.61 %. [ABSTRACT FROM AUTHOR]

The utilization of hydrogen energy has garnered significant attention as a viable and environmentally friendly energy alternative. However, there exist some technological challenges pertaining to the storage of hydrogen. In this context, the present study utilizes first-principles calculations to examine the physical characteristics of Na 2 (Be/Mg)H 4 hydrides to better understand their potential for use in hydrogen storage applications. The structure stability of Na 2 BeH 4 and Na 2 MgH 4 hydrides is assessed by formation enthalpy and phonon dispersion calculations. Elastic constants have been utilized to determine the elastic and mechanical stabilities of the studied hydrides. Both hydrides satisfy the established Born stability criteria, suggesting that both Na 2 BeH 4 and Na 2 MgH 4 are mechanically stable compounds. The assessment of electronic properties reveals that Na 2 BeH 4 and Na 2 MgH 4 have semiconducting characteristics with direct and indirect band gaps of 2.22 and 3.10 eV, respectively. Furthermore, various optical characteristics have been evaluated and compared. The computed values of gravimetric and volumetric hydrogen storage capacities for Na 2 Be H 4 (Na 2 Mg H 4) hydrides are 6.78 (5.38) wt% and 85.11 (62.78) g H 2 l − 1 , respectively, fulfilling the standard set by US-DOE for 2025. This study suggests that both Na 2 Be H 4 and Na 2 Mg H 4 hydrides have the potential to be an incredibly efficient choice for solid-state hydrogen storage. • Na 2 (Be/Mg)H 4 hydrides have been investigated for solid-state hydrogen storage. • Both Na 2 BeH 4 and Na 2 MgH 4 hydrides are found to be structurally and thermodynamically stable. • Na 2 (Be/Mg)H 4 hydrides are found to be electronically semiconducting. • Highest gravimetric and volumetric hydrogen storage capacities are determined for Na 2 BeH 4. • Na 2 (Be/Mg)H 4 hydrides fulfilling the standard set by US-DOS for 2025. [ABSTRACT FROM AUTHOR]

We performed first principles calculations to study silicon carbide (SiC) crystal structure of mechanical with five interatomic potentials. We calculate elastic constants, bulk, shear, Young's moduli, hardness, and Poisson's ratio for polytypes of SiC. For each property, we report perfect and deformity crystal structures. In perfect condition, we appear the cubic structure (3C) is the most steady than hexagonal structures (4H, 6H). We compare interatomic potentials for structural parameters, formation energy, and elastic constants. Among potentials Edip, Meam, Tersoff 2005, and Vashishta are the most excellent results in lattice parameters, cohesive energy, density, and cell volume. Additionally, Tersoff 2005 is a better potential for elastic properties and formation energy calculation. We follow our calculations by investigating the brittleness/ductility of SiC by calculating Stability conditions, Cauchy's pressure, Pugh's ratio, and hardness. Among mechanical properties, we find out less stability in the point defect effect on hexagonal structures. The calculated results indicate that silicon vacancy has more rate in the mechanical properties; however, the C44, bulk shear, and Young's modulus are comparable to higher changing within the three types of SiC structures. In the random vacancy of SiC, C11, and C12 have a swing than carbon and silicon vacancies. Moreover, we demonstrate that carbon vacancy has a higher range than other vacancies. [ABSTRACT FROM AUTHOR]

Graphene allotropes with varied carbon configurations have attracted significant attention for their unique properties and chemical activities. This study introduces a novel two-dimensional carbon-based material, termed Graphsene (GrS), through theoretical study. Comprising tetra-, penta-, and dodeca-carbon rings, GrS's cohesive energy calculations demonstrate its superior structural stability over existing graphene allotropes, including graphyne and graphdiyne families. Phonon dispersion analysis confirms GrS's dynamic stability and its relatively low thermal conductivity. All calculated GrS elastic constants meet the Born criteria, ensuring mechanical stability. Ab-initio molecular dynamic simulations show GrS maintains its structure at 300 K. HSE06 calculations reveal a narrow electronic bandgap of 20 meV, with the electronic band structure featuring a highly anisotropic Dirac-like cone due to its intrinsic structural anisotropy along armchair and zigzag directions. Notably, GrS is predicted to offer exceptional catalytic performance for the oxygen reduction reaction, favoring the four-electron reduction pathway with high selectivity under both acidic and alkaline conditions. This discovery opens promising avenues for developing metal-free catalyst materials in clean energy production. [ABSTRACT FROM AUTHOR]

In this work, we present a study of the structural, optical, elastic, thermoelectric and thermodynamic properties of iridium manganese (IrMn) using the code "WIEN2k" with the full potential linearized augmented plane wave (FP-LAPW) method. The lattice constants of the IrMn compound are calculated by the generalized gradient approximation with Perdew–Burke–Ernzerhof (GGA-PBE). Indeed, we have studied the magnetism exhibited by the compound IrMn. We found that the antiferromagnetic phase of this material is the most stable phase. The magnetic moment, plasma frequency, bandgap, elastic constants, and electronic and magnetic properties of this material are deduced and discussed. We have shown that the antiferromagnetic phase is the most stable with a minimum energy value of around −1034947.477 eV. We optimized the c ∕ a ratio and found that its value is approximately c ∕ a ≈ 0.923133. On the other hand, the absorption and reflectivity coefficients, the optical conductivity and the dielectric tensor are studied. In addition, the thermo-electric and thermodynamic properties have been illustrated. The IrMn compound could be useful for different applications of spintronics. [ABSTRACT FROM AUTHOR]

Hydrogen storage is an urgent issue for mobile applications, to overcome this issue solid materials have a potential role for hydrogen storage applications. Moreover, the perovskite hydride materials have been extensively investigated for improvement in the field of hydrogen storage. However, this work is focused on the computational study of XAlH 3 (X: Na, Mg) perovskite-type hydrides for different physical properties and hydrogen storage applications. Both materials were found thermodynamically, and mechanically stable from the negative formation energy and elastic properties. They exhibited cubic phases with computed lattice constants are 3.827 Å and 3.752 Å, respectively. The electronic properties indicated that both compounds have a metallic nature, and found the high contribution of Al-p state, and H-1s state near the Fermi level. However, the Hirshfeld net charge analysis detected, that charge transfer from Al and X (Na, Mg) atoms to H atoms. Furthermore, the metallic hydrides have promised candidates for hydrogen storage applications. Both compounds have observed non-magnetic behavior with zero magnetic moments. Elastic constants were calculated to determine the mechanical stability of the compounds, it was found that MgAlH 3 is harder than NaAlH 3 , and it exhibited that higher Bulk, Shear, and Young's modulus. The Poisson's, and Pugh's (G/B) ratios suggested that ionic boning of the atoms, additionally, Pugh's ratio (B/G) and Cauchy pressure (C p) confirmed that NaAlH 3 ductile and MgAlH 3 is brittle behavior. Besides this, Optical properties were determined for both compounds including the dielectric function, conductivity, refractive index, absorption, and loss function. It is found that the MgAlH 3 compound optical more suitable than NaAlH 3 due to calculated optical factors promised and both compounds are undertaken for solar cells, optoelectronics, and energy storage applications. Finally, the computed hydrogen storage capacity for NaAlH 3 and MgAlH 3 compounds are 6.01 wt%, and 5.56 wt% respectively. These results revealed that both have the potential materials for hydrogen storage, but NaAlH 3 unique material to fulfill the US-DOE criteria of 2020. [Display omitted] • Aluminum-based hydride XAlH 3 (X: Na, Mg) has been first time investigated using the DFT method. • XAlH 3 (X: Na, Mg) non-magnetic and metallic nature materials, which are potential candidates for hydrogen storage application. • Both materials are hard, ionic bonding between the atoms, while NaAlH 3 is ductile and MgAlH 3 brittle nature materials. • The calculated gravimetric hydrogen storage densities are 6.01 wt%, and 5.56 wt% for NaAlH 3 and MgAlH 3 materials. [ABSTRACT FROM AUTHOR]

According to ASTM E1426, X-ray elastic constants (XEC) are measured using four-point bending fixtures on specimens with a length-to-width ratio of at least four (with a width sufficient enough for a strain gage to be mountable) and width-to-thickness ratio of greater than one. Typically, recommended sample dimensions for four-point fixtures are approximately 102 mm in length, 19 mm in width and 1.5 mm in thickness. However, the requirement of such larger dimensions limits sample extraction in engineering components with limited cross-section. Analytically, XECs can be estimated using either Voigt, Reuss, Kroner and modified Kroner models with single-crystal elastic constants (SCEC) of any material/alloy of interest as inputs. Even though several procedures for estimating SCECs are demonstrated in the literature, the lack of portability in them demands alternate approaches for measurement. Therefore, in this study, an alternate approach of estimating XEC constants from a cubic sample of Nickel-based super-alloy polycrystalline material was demonstrated. SCECs, C11, C12 and C44 were extracted by minimizing the difference between experimentally measured and analytically predicted ultrasonic parameters such as longitudinal velocity, shear velocity and attenuation coefficients. Further, using the predicted SCECs, the XECs were estimated using a modified Kroner approach. It was observed that the proposed approach predicted XECs within 3% error compared to those measured using ASTM E1426. [ABSTRACT FROM AUTHOR]

Based on density functional theory (DFT), the structural and physical properties of NaCaZ (Z = N, P, As) half-Heusler (HH) semiconductor materials have been studied under pressure up to 20 GPa. The ground state results show that the NaCaZ are chemically stable in α -phase structure and exhibit semiconducting behavior with an indirect bandgap. The optical parameters like the real and imaginary components of complex dielectric function, the absorption coefficient and refractive index are investigated and discussed. The obtained results show that NaCaZ have low value of reflectivity and high absorption coefficient in low ultraviolet and visible regions and exhibit small changes under pressure. Pressure-based elastic constants and their derivative parameters show that NaCaZ are mechanically stable and have brittle nature. Above 10 GPa, NaCaP and NaCaAs have ductile nature. The phonon dispersions calculations with pressure show that NaCaN and NaCaP are dynamically stable, in contrast, NaCaAs is dynamically unstable at ambient pressure. Above 10 GPa, the studied compounds are dynamically stable. The mechanically, dynamically stable with low reflectivity and high absorption coefficient in the low ultraviolet and visible regions make these materials more promising as absorbers of solar cells, optoelectronic and 2D applications. [ABSTRACT FROM AUTHOR]

Effective hydrogen storage is a crucial requirement for harnessing hydrogen as an energy source. Among various storage methods, solid-state hydrogen storage holds promise but necessitates extensive investigation. This study employs density functional theory within the WIEN2k code to improve the desorption temperature and kinetic properties of MgH 2 by introducing Be in combination with transition elements (Ni, Cu, and Zn). The gravimetric hydrogen storage capacity for all studied compounds exceeds 6%. Introduction of different transition elements with Be leads to improvements in formation and cohesive energies, as well as in desorption temperature. Mechanical stability, determined through elastic constants, is confirmed for all hydrides meeting the Born stability criteria. Detailed analyses encompass bonding characteristics, shear modulus, bulk modulus, Cauchy pressures, elastic anisotropy, and Vickers Hardness tests. Electronic properties reveal that Mg 2 BeZnH 8 exhibits the semiconductor nature, and properties are further improved by using TB-mBJ approach. Electronic charge density calculations unveil interatomic bonding nature. Numerous previously unexplored thermodynamic aspects of these hydrides have been investigated and are now presented. • Orthorhombic Mg 2 BeTMH 8 (TM = Ni, Cu and Zn) have been investigated by using density functional theory. • The gravimetric hydrogen storage capacity for all compounds studied exceeds 6%. • Mg 2 BeZnH 8 has low desorption temperature than other two studied hydrides. • All the studied materials are mechanically stable and hard. • Electronic properties reveal that these hydrides exhibit semiconductor nature, except Mg 2 BeNiH 8. [ABSTRACT FROM AUTHOR]

The electronic structure, phase transition pressure and mechanical properties of light rare-earth bismuthides (PrBi, NdBi, PmBi and SmBi) have been investigated by full geometry optimization using Vienna Ab-Initio Simulation Package (VASP) which has been used in combination with the projector augmented wave (PAW) method and the generalized gradient approximation (GGA) over the local density approximation (LDA) for exchange-correlation functional. We focus our attention on the lattice constants and elastic constants of these compounds. These compounds undergo a phase transition from the NaCl (B1) structure to the body-centered tetragonal (BCT) structure. We also report the density of states (DOS) of these rare earth bismuthides. In the case of PrBi and NdBi, the 4f states are treated as valence states. The effects of on-site Coulomb repulsion and the spin-orbit coupling (SOC) on the electronic structure are also studied. [ABSTRACT FROM AUTHOR]

In this work, we study the pressure dependence of elastic constants of wurtzite indium nitride semiconductor based on Landau free energy expansion. Elastic constants are obtained as functions pressure up to second order. We have also evaluated the bulk modulus (B) and anisotropies of compressibility and shear for wurtzite indium nitride as functions of pressure. Agreement with previously obtained results based on first-principles calculations is found to be satisfactory. [ABSTRACT FROM AUTHOR]

We have studied the electro-optical properties of the 4-pentyl-4-biphenylcarbonitrile nematic liquid crystal also known as 5CB doped by 0.5%wt of pure and cobalt-incorporated TiO2 nanoparticles. The obtained results show that the effect of the NPs on the electrooptical properties is mainly due to the modification of the dielectric and the viscoelastic properties of the nematic in the presence of the NPs. Furthermore, the nematic isotropic transition temperature of all doped samples remained almost unchanged. This indicates that the order parameter was almost unchanged too. A significant decrease in the dielectric anisotropy and the splay elastic constant was observed. The rotational viscosity has been deduced from response time data; it was found that rotational viscosity shows a significant increase for cobalt-incorporated TiO2. However, the rotational viscosity was decreased for pure TiO2 nanoparticles compared to pure 5CB. [ABSTRACT FROM AUTHOR]

A numerical investigation of the influence of porosity, pore size, and planar defects (microcracks) on the elastic constants, compressive and tensile strength of a fine-grained matrix in a SiO2 refractory ceramics is presented. The modeling results show a qualitatively different effect of the 3D (pores) and 2D (microcracks) defects on its effective elastic properties. An increase in porosity leads to a decrease in Young's modulus and the strength of the refractory matrix, while the trend in the Poisson's ratio behavior depends on the degree of pore structure connectivity. Microcracks also reduce the effective strength and Young's modulus of the matrix but, unlike the pores, they cause an asymmetry in the effective elastic properties. The Young's modulus of the matrix decreases more slowly under compression than under tension, and the Poisson's ratio trend is the opposite (an increase under compression and a decrease under tension). The quantitative estimates of the effective mechanical characteristics of the fine grain matrix can be used in multiscale computer models of traditional and advanced SiO2-based refractories. [ABSTRACT FROM AUTHOR]

Perovskites are considered emerging materials for use in solar cells and thermoelectric generators and renewable energy due to their high stability, lack of lead content, environmentally friendly nature, and exceptional performance. Hence, a comprehensive study of the structural, optical, electronic and elastic properties of KXF3 (X = Nb, Ti, Zr) was conducted using a first-principles approach. The structural stability of the material was confirmed by examining its formation energy, Gold-Schmidt tolerance and Birch-Murnaghan equation of state (EOS) curve. The negative formation energy for these compounds represents the structural stability.The electronic study reveals that in spin down configuration there is band gap between valence and conduction bands while in spin up configuration the valence and conduction bands are overlapped at fermi level indicating that understudy compounds are half metallic. The elastic constants relationship, namely C11 – C12 > 0, C11 > 0, C11 + 2C12 > 0, and B > 0, establishes the mechanical stability of compounds. However, these materials are also identified as being mechanically brittle, anisotropic, and ductile. For checking the suitability of the studied compounds in the optical applications, we determined the real and imaginary parts of their respective dielectric functions, absorption coefficients, optical conductivities, refractive index and lastly reflectivity as a function of wide range of incident photon energies upto 40 eV. The study of these compounds reveals that they can be potential candidates for optoelectronic devices. [ABSTRACT FROM AUTHOR]

The CsCl‐type (B2) phase of FeSi (B2‐FeSi) has been proposed as a candidate phase in the ultralow‐velocity zones (ULVZs) at the base of the lower mantle and in the Earth's inner core. However, the elastic properties of B2‐FeSi under relevant conditions remain unclear. Here we determine the density, elastic constants, and velocities of B2‐FeSi at high pressures (90–390 GPa) and temperatures (3,000–6,000 K) relevant to the Earth's lower most mantle and the inner core, using first‐principles molecular dynamics simulations. At the base of the lower mantle, B2‐FeSi shows significantly lower velocities and a higher density than those of the ambient mantle. Mechanical mixing models suggest the presence of ∼27–39 vol% B2‐FeSi in the silicate mantle is consistent with the reduced velocities and the elevated density of ULVZs observed seismically. On the other hand, the hcp‐Fe and B2‐FeSi mixture exhibits higher bulk sound velocity compared to the PREM under inner core conditions. Adding superionic H in the interstitial sites of B2‐FeSi lowers its density but has little effect on the bulk sound velocity of B2‐FeSi, precluding H‐bearing B2‐FeSi as a major component in the Earth's inner core. Plain Language Summary: Under Earth's deep lower mantle and inner core pressures and temperatures, iron silicide (FeSi) takes a CsCl‐type crystalline structure (B2‐FeSi). It has been proposed that B2‐FeSi is a potential component in the ultralow‐velocity zones (ULVZs) at the base of the lower mantle and in the inner core. Here, we apply first‐principles molecular dynamics simulations to determine the density and elastic wave velocities of B2‐FeSi under deep Earth conditions and compare its properties to seismic observations. At core‐mantle boundary conditions, a mixture of B2‐FeSi with the ambient mantle exhibits elastic behaviors consistent with the observations of ULVZs, suggesting its possible presence. However, at inner core conditions, B2‐FeSi and H‐bearing B2‐FeSi have substantially higher bulk sound velocity than that of the seismic model, invalidating its presence in the inner core as a major component. Key Points: B2‐FeSi shows markedly lower velocities than those of the PREM at the base of lower mantle but higher velocities at inner core conditionsThe presence of H in B2‐FeSi reduces both the P‐ and S‐wave velocities of B2‐FeSi, but has little effect on the bulk sound velocityThermoelastic properties of B2‐FeSi are more consistent with its presence in the ultra‐low velocity zones than in the Earth's inner core [ABSTRACT FROM AUTHOR]

In this work, we have employed the first-principles calculations to investigate the phase stability and mechanical and optoelectronic characteristics of Hf2AX (A=Al, Si and X=C, N) MAX phases. Phase stabilities of Hf2AX compounds have been evaluated by the formation enthalpy computations and phonon dispersion curves, which indicate that all studied compounds are structurally and dynamically stable. The mechanical stability has been determined by elastic stiffness constants, which confirms that the studiedMAX phases aremechanically stable. The computed results for Pugh's and Poisson ratios indicate the brittle nature of Hf2AX MAX phases. It is interesting to note that Si-based MAX phases possess high values of B/G, indicating that they are harder than Al-based compounds. The obtained band structures and partial density of states indicate the metallic character of all Hf2AX compounds. The strong hybridization of d-orbitals of Hf with p-orbitals of N and the comparatively weaker hybridization of p-orbitals (Hf) with Al/Si p-orbitals is observed. The presence of pseudogaps near the Fermi energy level emerges due to the orbital hybridization involving Hf, Al/Si, and C/N atoms. The analysis of charge density difference maps reveals the presence of a strong covalent bond between the Hf and C/N atoms, whereas a relatively weaker covalent bond is seen between the Hf and Al/Si atoms. Furthermore, numerous optical characteristics have been investigated to account for the behavior of the Hf2AX compounds to those of impinging electromagnetic rays. The highest absorptivity is noticed within the energy range of 7.5-12.5 eV. The optical spectra in the range of 1.7 eV (IR) to 9 eV ultraviolet (UV) have been observed for the investigated MAX phases, predicting their suitability as proficient energy absorbers within the UV region. The Intriguing properties of Hf2AX compounds are anticipated to be appropriate materials for a variety of applications. [ABSTRACT FROM AUTHOR]

The paper is concerned with the derivation of asymptotically consistent equations governing the long-wave flexural response of a two-layered rectangular plate with high-contrast elastic properties. In the general case, the plate is under dynamic and variable surface, volume, and edge forces. Performing the asymptotic integration of the three-dimensional (3D) elasticity equations in the transverse direction and satisfying boundary conditions on the faces and interface, we derived the sequence of two-dimensional (2D) differential equations with respect to required functions in the first two approximations. The eight independent restraints for the generalized displacements and stress resultants are considered to formulate the 16 independent variants of boundary conditions. One of the main results of the paper is the Timoshenko–Reissner type equation capturing the effect of the softer layer and taking into account the in-plane deformation induced by the edge forces. Comparative calculations of natural frequencies were carried out based on our and alternative models. [ABSTRACT FROM AUTHOR]

Seismic anisotropy is key to constrain mantle flow, but it is challenging to image and interpret it. Existing large-scale tomography models of seismic anisotropy typically show large discrepancies, which can lead to completely distinct geodynamical interpretations. To better quantify the robustness of anisotropy tomography, we create a 2-D ridge-to-slab geodynamic model and compute the associated fabrics. Using the resulting 21 elastic constants, we compute seismic full waveforms, which are inverted for isotropic and radially anisotropic structure. We test the effects of different data coverage and levels of regularization on the resulting images and on their geodynamical interpretation. Within the context of our specific imposed conditions and source–receiver configuration, the retrieved isotropic images exhibit substantial artificial slab thickening and loss of the slab's high-velocity signature below ∼100 km depth. Our results also show that the first-order features of radial anisotropy are well retrieved despite strong azimuthal anisotropy (up to 2.7 per cent) in the input model. On the other hand, regularization and data coverage strongly control the detailed characteristics of the retrieved anisotropy, notably the depth–age dependency of anisotropy, leading to an artificial flat depth–age trend shown in existing anisotropy tomography models. Greater data coverage and additional complementary data types are needed to improve the resolution of (an)isotropic tomography models. [ABSTRACT FROM AUTHOR]

In this emerging technological era, lead-free (Li-based) inorganic halides have drawn a lot of researchers' consideration due to their optoelectronic applications. Based on this, we explored theoretically mechanical, optical, and thermoelectric features of halides Li2TlBiY6 (Y = Cl, Br, I) by employing first-principle simulations (Wien2k code). Our finding of optoelectronic parameters using appropriate mBJ approach is in favorable alignment to previously reported data, and PBEsol is employed to scrutinize structural as well as mechanical features of these materials. The Born stability and formation energy are examined concerning the structural stability associated with all halides. The distinction between brittle and ductile nature is investigated concerning the calculation of elastic constants of the cubic symmetry. Being based on the mBJ potential, the bandgasps for Li2TlBiCl6, Li2TlBiBr6, and Li2TlBiI6 are 2.8 eV, 2.3 eV, and 1.9 eV, correspondingly. To confirm their optimal absorbability in the electromagnetic domain (visible), all halides were further analyzed concerning dielectric parameters. Additionally, thermoelectric properties are explained in detail within the temperature range of 300-800K using classical Boltzmann theory, making them promising materials for thermoelectric applications. [ABSTRACT FROM AUTHOR]

Currently, in some domestic and foreign mines, the backfill drilling pipeline experiences a rupture phenomenon even when the wear degree is low. This results in a delay in production due to the filling becoming 'sick'. This paper presents, for the first time, the damage mechanism from a mechanical perspective and re-derives the anti-extrusion strength model of the backfill drilling pipeline. We investigate the influence of the law on the anti-extrusion strength of pipelines from the perspective of strata and cement rings. We then verify the theoretical and simulation results through engineering examples. The results demonstrate that the Mises stress criterion is a suitable modification principle for the anti-extrusion strength model of the backfill drilling pipeline. The anti-extrusion strength of the pipeline is related to the elastic modulus and Poisson's ratio of the stratum, and the thickness of the cement ring. It is negatively affected by the depth of the stratum. For hard strata, a cement ring with a smaller elastic modulus is suitable, while for soft stratum, a cement ring with a larger elastic modulus is recommended. When the missing angle of the cement ring is less than 60°, the stress concentration factor increases up to 2.2. The stress unloading capacity of the cement ring ranges from 32.7% to 37.8%, and optimal performance of the cement ring is achieved when it has high strength and low rigidity. The backfill filling pipeline of a copper mine abroad was destroyed due to external extrusion force exceeding its anti-extrusion strength value. The modified pipeline anti-extrusion strength model is 18.2% higher than the pipeline API strength value. This finding can inform the design of the backfill filling pipeline for China's kilometer-deep wells in the future. [ABSTRACT FROM AUTHOR]

Acoustic attenuation coefficient per unit frequency square has been calculated for pure semiconductors like silicon and germanium, as well as for mixed semiconductors like gallium arsenide (III–V group) and tin telluride (IV–VI group), for longitudinal waves travelling along the crystallographic axis, within the temperature range 80–300 K. Second-order elastic constants of the materials are used to calculate the average Gruneisen parameter , using which the nonlinearity parameter DL has been calculated for different temperatures. The knowledge of DL is used for calculation of acoustic attenuation coefficient per unit frequency square due to phonon–phonon interaction and thermoelastic losses . Acoustic attenuations are found to be temperature dependent and increases with it. The magnitude of acoustic attenuation per unit frequency square due to phonon–phonon interactions is greater than that due to thermoelastic losses. The magnitude of acoustic attenuation for the investigated semiconductors is in the order Si < Ge < GaAs < SnTe. It is observed that anharmonicity of the solids which give rise to phonon–phonon interaction is the dominant cause of acoustic attenuation of propagating waves. The acoustic attenuation of propagating waves is found to be proportional to the molecular weights of semiconductors. [ABSTRACT FROM AUTHOR]

Carbon fibers have been widely used for their lightweight and high mechanical properties. In order to extensively use carbon fibers, it is important to accurately understand and account for their highly anisotropic characteristics. The anisotropy of carbon fibers can be expressed as elastic constants, however evaluation of these constants is very difficult. This study reviews literatures that have analyzed the elastic constants of carbon fibers to clarify the elastic constants of various carbon fibers. This knowledge will lead to more accurate deformation and stress state calculations for structural materials, aiding future development of even higher performance composite materials. The accurate determination of the elastic constants of carbon fibers is also expected to lead to advances in the manufacturing process of carbon fibers and further improve their mechanical properties. [ABSTRACT FROM AUTHOR]

In this article, steel slag was added into the marine silt to improve its dynamic properties. The characteristics of marine silt that can be studied by XRD, BET surface area, SEM, and FTIR were first described. Then, the influence of the sample density, water content, waste steel slag content, and the confining pressure on the dynamic shear modulus G and damping ratio λ was discussed by conducting resonant column tests. The results illustrated that the dynamic characteristics of the marine silt-steel slag admixtures were considerably improved. Additionally, G increased with the increasing steel slag content and λ increased with the decreasing steel slag content. Moreover, a dynamic model of the admixtures was developed based on the Hardin–Drnevich model. Furthermore, by comparing the dynamic characteristics of the admixtures with Nanjing sand, Fujian sand, Kiyohoro silty clay, and Wenzhou marine clay, it was found that the improved admixtures may be a more suitable geofiller in geotechnical engineering. [ABSTRACT FROM AUTHOR]

We study the flow stability and spatiotemporal spectral dynamics of cellulose nanocrystal (CNC) suspensions in a custom Taylor–Couette flow cell using the intrinsic shear induced birefringence and liquid crystalline properties of CNC suspensions for flow visualizations, for the first time. The analysis is performed at constant ramped speed inputs of the independently rotating cylinders for several cases ranging from only inner or outer rotating cylinders to three counter-rotation cases. All CNC suspensions have measurable elasticity and shear thinning, both increasing with CNC concentration. We show that the flow patterns recorded are essentially Newtonian-like, with non-Newtonian effects ranging from a decrease in wavenumbers to altering the critical parameters for the onset of instability modes. Outer cylinder rotation flow cases are stable for all concentrations whereas inner cylinder rotation flow cases transition to axisymmetric and azimuthally periodic secondary flows. However, counter-rotation cases become unstable to asymmetric spiral modes. With increasing CNC concentration, a counter-rotation case was found where azimuthally periodic wavy patterns transition to asymmetric spiral modes. Based on rheo-SAXS measurements, the shear-thinning region of CNC suspensions is expected to lead to the breakdown of the chiral nematic phase, whose elastic constants constitute the dominant structural elasticity mechanism. Thus, we interpret the Taylor–Couette stability of the CNC suspensions as dominated by their shear-thinning character due to the expected loss of elasticity in nonlinear flow conditions. [ABSTRACT FROM AUTHOR]

In this paper, we have presented the structural, elastic, mechanical, and electronic properties of the transition metal chalcogenide perovskite SnZrS3 under different pressures by using first-principles method. Our calculated lattice parameters at ambient pressure are in good agreement with the experimental and previous theoretical results. The elastic constants were evaluated numerically for orthorhombic SnZrS3 using the strain-stress approach. Orthorhombic SnZrS3 shows a strong anisotropic behavior of the elastic and structural properties. According to the calculations of the electronic properties, we find the states near the valence band top are derived from S 3p, Zr 4d, Sn 5p, and Sn 5s orbitals, and the lowest conduction band is composed of Zr 4d, S 3p, and Sn 5p orbitals. As the pressure increases, the conduction and valence band shift to lower and higher energies, respectively. These results indicated that lattice constants and band gap decrease with the increase of pressure. [ABSTRACT FROM AUTHOR]

In this work, the Density Functional Theory (DFT) analysis of the Tl2SnX3 series (X = S, Se, Te) is performed, and the ground states are confirmed by the calculation of the elastic constant Cij. Based on the DFT calculation, the Tl2SnX3 structures are direct‐gap semiconductors with bandgaps of 1.434, 1.181, and 0.907 eV, respectively. Chalcogen substitution significantly impacts their electronic structures, notably increasing the Density of States (DOS) width in the valence band from sulfur to tellurium, and shifting the dielectric function's real part, ε1(ω), toward lower energies. This change means that the optical activity and response to electric fields are better, with Tl2SnTe3 showing the best polarization response and light‐matter interaction abilities. Optical tests show that Tl2SnTe3 has very high optical absorption, peaking at ≈17 × 104 cm−1 along [010], and reflectivity levels above 90%, marking its suitability for high‐reflectivity applications. Moreover, loss energy function analysis also shows that Tl2SnTe3 has a strong electron loss resonance at lower energies, which means it has strong interactions with electrons. [ABSTRACT FROM AUTHOR]

Hydrogen storage in the solid state method focuses more on attraction and requires large-scale research. Ab initio calculations of zinc-based Alkali metal hydrides X2ZnH4 (X = K, Rb and Cs) were performed to analyse the structural, electronic, thermal, and elastic properties. Studied hydrides are stable in the orthorhombic phase with space group16- PP222. Phonon dispersion curves are calculated at ambient conditions reveals thermodynamic stability. Electronic band structures and density of states reveal that these hydrides are direct bandgap semiconductors. Also, thermoelectric properties like thermal conductivity, electrical conductivity, specific heat capacity, Seebeck coefficient, Hall coefficient and carrier concentration are investigated using BoltzTraP software. In addition, the elastic constants have been calculated, and the mechanical properties such as bulk modulus, shear modulus, Young's modulus and Poisson's ratio have been calculated using these elastic constants. According to well-known Born stability criteria, K2ZnH4 and Rb2ZnH4 are mechanically stable, while Cs2ZnH4 is unstable. These hydrides might be used in hydrogen storage applications due to moderate gravimetric hydrogen density, which is 2.7 wt%, 1.6 wt%, 1.2 wt% for K2ZnH4, Rb2ZnH4, Cs2ZnH4, respectively. [ABSTRACT FROM AUTHOR]

In this study, we investigate the structural, electronic, magnetic and mechanical properties of the Na-based half-Heusler alloys XYZ composed of X=Na ( p 0 atom); Y=K, Rb, Cs ( d 0 atoms) and a main body sp atom Z=C, Si, Ge, Sn, Pb by using the DFT based full-potential WIEN2k package. We compare the total energy vs volume of ferromagnetic, antiferromagnetic and non-magnetic half-Heusler structures to obtain the stable magnetic structure. Calculations show that compounds are stable in the half-Heusler β -phase and the ferromagnetic state. From 15 alloys under study, 13 of them showed half-metallic behavior in the minimum-energy half-Heusler phase at the optimized lattice constant. We show that all compounds have the same total magnetic moment equal to 2 μ B . The band structure and the density of states of half-Heusler alloys are obtained. The elastic constants C 11 , C 12 and C 44 of the single crystal and the related elastic moduli G, B, E, υ of the polycrystalline aggregates are also calculated and used to study the mechanical stability of these alloys. Furthermore, the average, transverse, longitudinal sound velocities and the Debye temperature for these compounds are calculated. Finally, the Curie temperatures T C of the half-Heusler alloys are estimated by using the mean field approximation. The estimated Curie temperatures shows that these compounds preserve the ferromagnetic state and magnetic polarization at temperatures much higher than the room temperature and may be suitable for spintronic applications. [ABSTRACT FROM AUTHOR]

First-principles calculations using Density Functional Theory (DFT) and the Wien2k package are used to analyze the structural, electrical, optical, and elastic characteristics of Li-based chloride perovskites LiXCl3 (X = Ca, Ba). The structural analysis demonstrates that these compounds are stable and have the space group pm-3m (no. 221). The calculations show that these materials possess an indirect band gap. For elastic properties, the Pugh's ratio (compound ductility), elastic constants, anisotropy factor, Poisson's ratio, and bulk modulus are analyzed. In 0–30 eV energy range, optical parameters such as dielectric function, extinction coefficient, reflectivity, absorption coefficient, refractive index, and optical conductivity, are measured. Optical properties, i.e. dielectric function, extinction coefficient, refractive index, absorption coefficient, reflectivity and optical conductivity, are evaluated in 0–30 eV energy range. The calculations show that these materials possess large band gap and are structurally anisotropic, making these better candidates for scintillator applications. [ABSTRACT FROM AUTHOR]

The basic structural, optical, elastic, and electronic properties are investigated in this research for QZnCl3 (Q = Li and Na) ternary centrosymmetric chloroperovskites compounds utilizing the DFT approach. The integrated TB-mBJ exchange–correlation potential within the WIEN2K computational simulation package serves for precise outcomes. The structural optimization is done by fitting the Birch-Murnaghan equation of state (EOS) for the primitive unit cell energy versus primitive unit cell volume. The parameters from the optimized fitted curves, Goldsmith's tolerance factor (tG), and octahedral coefficient predict the stable cubic structure of QZnCl3 (Q = Li and Na) centrosymmetric ternary chloroperovskites compounds. The elastic parameters which include cubic elastic constants (ECs), elastic moduli (E), Poisson's ratio (v), anisotropy factor (A), and the Pugh ratio (B/G) investigated through IRelast code display the mechanical stability, ductility, and toughness of interested centrosymmetric compounds. Predicted electronic band structures and densities of states (DOS) display that LiZnCl3 and NaZnCl3 possess an indirect (R-Γ) band gap of 3.82 eV and of 3.91 eV respectively, confirming that both the materials are wide band gap semiconductors. In optical properties, the spectral curves of several parameters are observed from 0 eV up to 15 eV incident photons energy, and it is revealed that the centrosymmetric chloroperovskites QZnCl3 (Q = Li and Na) are optically effective at high absorption coefficients (α(ω)), optical conductivity (σ(ω)), optical reflectivity (R(ω)), and energy loss (L(ω)) functions. The potential energy applications can be deemed for these materials, influencing electromagnetic radiation in the ultraviolet (UV) spectrum ranges. In a nutshell, the research on QZnCl3 (Q = Li and Na) demonstrate that these centrosymmetric materials are noteworthy and can be applied as energy storage systems, scintillators, and many other components of present electronic devices. [ABSTRACT FROM AUTHOR]

Background: Advanced ceramic matrix composites (CMC) are aimed at highly demanding thermo-mechanical environments, such as space or hypersonic applications. Their design and manufacturing require a reliable, cost-effective method for estimating and quantifying CMC mechanical properties. Objective: CMC composite materials present orthotropic mechanical properties. Different tests are often conducted to measure all independent elastic properties. These variety of tests are expensive and demand significant time and effort. Therefore, it is highly desirable to have one mechanical test that can generate all or most of the elastic properties. Method: This study proposes a single Brazilian disc (BD) test setup. It investigates an efficient inverse problem to evaluate the Young's and shear moduli of an orthotropic Liquid Silicon Infiltrated (LSI) C/C–SiC CMC. A combined BD test and Digital Image Correlation (DIC) technique were used for this purpose. The BD test employs a circular disc compressed diametrically in varying orientations of the tested multi-layered CMC 0°/90 o woven carbon fibers. The BD introduces a multi-axial stress and strain field highly affected by these primary elastic moduli. DIC enables full-field multi-axial strain calculations in large spatial variations. Results: A numerical study resulted in a unique iterative inverse-mechanics test procedure based on BD tests conducted on orthotropic materials at two material orientations. This approach was applied to measure C/C-SiC material properties, showing an efficient and reliable appraisal of major elastic moduli. Conclusions: The presented approach may drive down both the duration and cost of the mechanical evaluation, thereby potentially improving future process designs. [ABSTRACT FROM AUTHOR]

This article employed a first-principles calculation method based on density functional theory to optimize the geometric structure of the ternary layered nitride M2 AlN (M = Ti, Zr). The structural, mechanical, electronic and optical properties of the ternary layered nitride M2 AlN (M = Ti, Zr) under high pressure were investigated. The study of structural and mechanical properties reveal that Ti2 AlN exhibits superior compressibility compared to Zr2 AlN. The elastic constants further validate its mechanical stability under high pressure. Ductility and elastic anisotropy enhance under increasing pressure, with Zr2 AlN demonstrating heightened sensitivity to these pressure conditions. Research on electronic properties reveals that both ternary layered nitrides exhibit metallic behavior, and their covalent character strengthen with increasing pressure. Investigations into the optical properties reveal that the polycrystalline nature and static dielectric functions ε1 (0), along with the static refractive index n(0) of Ti2 AlN and Zr2 AlN along various axes, demonstrate relatively low anisotropy in their optical characteristics. Both ternary nitrides exhibit pronounced capabilities for light absorption and reflectivity. Theoretical inquiries in this study clarified the relevant characteristics of the ternary layered nitrides Ti2 AlN and Zr2 AlN under the elevated pressure, establishing a robust theoretical framework for subsequent experimental investigations. [ABSTRACT FROM AUTHOR]

The structural, electronic, mechanical, and optical properties of pseudo-cubic CH3NH3PbI3 perovskite have been studied within the framework of density functional theory, in line with solar cell applications. The computed values of lattice and elastic constants concurred with the available theoretical and experimental data. This compound has a semi-conducting behavior, with a direct band gap of about 1.49 eV. Note that the solar radiation spectrum has a maximum energy intensity value of approximately 1.50 eV. Thus, semiconductors with such gaps are preferred for photovoltaic applications. Its elastic parameters reveal that it is a ductile material that is mechanically stable. Optical descriptors such as refractive index, reflectivity, extinction, energy loss, and absorption have been explored with the aim of establishing the optical features of the material. Our findings demonstrate that this perovskite is suitable for solar cell applications based on the size and nature of the band gap, as also supported by the obtained upper limit value of simulated power conversion efficiency via the spectroscopic limited maximum efficiency mathematical model. [ABSTRACT FROM AUTHOR]

This work investigates the structural, mechanical, and electrical properties of the superhard semiconductor carbon BC14 under pressure, based on density functional theory (DFT). BC14 formed by sp3 hybridization still maintains good mechanical stability and dynamic stability under 100 GPa pressure. The relative enthalpy of BC14 increases gradually at a slower rate and is always much lower than that of BC12, C96, T-carbon, TY-carbon, and Y-carbon. The elastic constant, elastic modulus, and ratio of bulk modulus (B) to shear modulus (G) increase with pressure, while the hardness exhibits a decreasing tendency. BC14 is anisotropic in elastic mechanics, and its Young's modulus (E) is isotropic in the (111) direction. Increasing pressure leads to the anisotropy of elastic modulus becoming stronger. From 0 GPa to 100 GPa, the band gap increases from 5.56 eV to 6.07 eV, and inherits indirect characteristics. No obvious effect of pressure is observed with regard to the number of diffraction peaks in the XRD pattern, but the diffraction peaks are slightly shifted. [ABSTRACT FROM AUTHOR]

In this paper, the applicability of machine learning for predicting the elastic properties of binary and ternary bcc Ti and Zr disordered alloys with 34 different doping elements is explored. The original dataset contained 3 independent elastic constants, bulk moduli, shear moduli, and Young's moduli of 1642 compositions calculated using the EMTO-CPA method and PAW-SQS calculation results for 62 compositions. The architecture of the system is made as a pipeline of a pair of predicting blocks. The first one took as the input a set of descriptors of the qualitative and quantitative compositions of alloys and approximated the EMTO-CPA data, and the second one took predictions of the first model and trained on the results of the PAW-SQS calculations. The main idea of such architecture is to achieve prediction accuracy at the PAW-SQS level, while reducing the resource intensity for obtaining the training set by a multiple of the ratio of the training subsets sizes corresponding to the two used calculation methods (EMTO-CPA/PAW-SQS). As a result, model building and testing methods accounting for the lack of accurate training data on the mechanical properties of alloys (PAW-SQS), balanced out by using predictions of inaccurate resource-effective first-principle calculations (EMTO-CPA), are demonstrated. [ABSTRACT FROM AUTHOR]

Poisson's ratio is one of the fundamental characteristics in the material models that are used. In engineering practice, its values are assumed to be constant in the elastic and in the plastic region. In this paper, the conventionally used values of this number for steel materials and aluminum alloys are confronted with experimental results. By using non-contact strain measurements with the DIC (digital image correlation) method, the evolution of the Poisson ratio value in the regions of transition from the elastic to the plastic region as well as in the regions of large plastic deformations was documented. The obtained experimental results are graphically compared using the proposed strain scaling. The gradient of the Poisson ratio changes in the vicinity of the yield stress is significant, indicating the need for a refinement of the material models in this region. Deviations from the conventionally used value of this number were found in the large plastic deformation region. In conclusion, a possible approach for improving the accuracy of simulations in FEM softwares was formulated. [ABSTRACT FROM AUTHOR]

Novel tetragonal (P42/mnm) boron pnictides BX (X = N, P, As, Sb, Bi) with chromium boride (crb) topology exhibiting a square B2X2 motif with resulting edge- and corner-sharing tetrahedra were predicted from crystal chemistry and extensively characterized by density functional theory (DFT) calculations. All new BX phases were found to be cohesive with decreasing cohesive energy along the series. Mechanically stable with positive sets of elastic constants, all crb phases exhibit slightly lower hardness than other BX polymorphs due to increased openness of the crystal structures. All-positive phonon frequencies characterize the crb BX family except for X = Bi, which shows a slight acoustic instability; also, the shape of the phonon spectra changes from band-like for X = N, P, As to flat bands for the heavier elements. The electronic band structures reveal insulating to semiconducting properties for crb BX, depending on the pnictogen nature along the series. [ABSTRACT FROM AUTHOR]

A transferable force‐field of HMX/Estane interface is derived by first‐principles calculation and least square optimization. Based on the force‐field, the plastic bonded explosive consists of HMX and Estane is simulated by molecular dynamics. The polycrystal structure is obtained, and a set of thermodynamic properties are calculated, including the heat capacity, thermal expansion coefficients, bulk modulus, elastic constants and Hugoniot curve. We find that the mixture explosive has higher thermal expansion coefficient than single crystal, because the interface is debonding at high temperature condition. [ABSTRACT FROM AUTHOR]

Considering the spring-type imperfect interfaces, the effective elastic properties of one-dimensional (1D) hexagonal quasicrystal (QC) are investigated systematically. The spring-type imperfect interface between QC matrix and inclusion is an ultra-thin, soft and weakly conductive interface. The Mori–Tanaka method is presented to determine the effective elastic constants of phonon, phason and phonon–phason coupling field. The numerical results are provided to show that the existence of imperfect interfaces reduces the effective elastic constants to some extent. It indicates that the interface plays an important role in the elastic properties of QC composites. Besides, the effective elastic constants are also subject to the aspect ratio and the volume fraction of inclusions. [ABSTRACT FROM AUTHOR]

We calculated the structural, electronic, mechanical and thermoelectric properties of the iridium-based, newly proposed Heusler alloys Ir2V (In, Sn). Both alloys have an indirect bandgap at the Fermi level in the spin-down channel, with metallic overlap in the spin-up channel, indicating the presence of half-metallic behavior. The Hubbard interactions contribute to the half-metallic behavior of these alloys. The magnetic moments are estimated using the Slater–Pauling formula, indicating large values of magnetic moments in all alloys with predominant contribution from the V atom. The stability of these alloys is established by their phonon frequencies, as well as formation and cohesive energies. Elastic constants such as Poisson's ratio, Pugh's ratio and various types of moduli affirm their mechanical stability and strength. Further, the effect of temperature on spin transport is also reported. These materials are prospective candidates for high-temperature thermoelectric applications, according to an analysis of high Curie temperatures and various transport coefficients. [ABSTRACT FROM AUTHOR]

Self-healing microcapsules in the asphalt pavement must be kept intact under vehicle load to ensure there is enough rejuvenator in capsules when cracks appear in asphalt pavement. In this paper, the crack resistance of self-healing microcapsules in asphalt pavement was evaluated. Firstly, an expanding multi-scale analysis was conducted based on proposed mesoscopic mechanical models with the aim to determine the mechanical parameters for the following contracting multi-scale analysis. Secondly, the periodic boundary condition was introduced for the contracting multi-scale analysis and the stress field of the capsule wall was obtained. Finally, the effects of the design parameters of the microcapsule on its crack resistance in asphalt pavement were investigated. The results showed that the incorporation of microcapsules has almost no effect on the elastic constants of the asphalt mixture. The core could be simplified as an approximately incompressible solid with the elastic constants determined by the proposed mesoscopic mechanical model. With the increase of the modulus of the capsule wall, the mean maximum tensile stress of the capsule wall increased from 0.372 MPa to 0.465 MPa, while with the decrease of the relative radius of the capsule core, the mean maximum tensile stress of the capsule wall increased from 0.349 MPa to 0.461 MPa. The change in the mean maximum tensile stress of the capsule wall caused by the change of capsule diameter was within 5%. The relative radius of the capsule core and the elastic modulus of capsule wall were two key parameters in capsule design. Besides, the microcapsules with the wall made of resin would not crack under the vehicle load before microcracks occurred in asphalt pavement. [ABSTRACT FROM AUTHOR]

First-principles were employed to research the hydrogen storage capacities and structure, mechanic, electronic, optical, dynamical, thermodynamic properties of XAlH 3 (X = Na, K) compounds. The investigation of elastic constants, formation energy and phonon dispersion curve reveals that the XAlH 3 compounds possesses mechanical, thermodynamic and dynamic stability. By calculating the B/G, it is evident that NaAlH 3 has ductility and KAlH 3 has brittleness. Moreover, the chemical bonding of XAlH 3 compounds is ionic. According to the results obtained from the electronic property analysis, these compounds are metal nature. Additionally, the internal charge transfer of the two compounds was studied by Bader partial charge analysis. The optical properties show that the NaAlH 3 hydride has higher static dielectric function than that of KAlH 3. The thermodynamic properties of these hydrides have been studied, including energy, heat capacity, free energy, and the entropy variation with temperature. Furthermore, NaAlH 3 and KAlH 3 have high hydrogen storage capacities, which are 5.40 wt% and 4.19 wt%, respectively. This study has revealed for the first time the characteristics of XAlH 3 hydrides, bringing new potential options for hydrogen storage materials. • XAlH 3 (X = Na, K) perovskite have been investigated firstly using first-principles. • XAlH 3 hydrides exhibit thermodynamically, mechanically and dynamically stable. • The gravimetric hydrogen storage capacity is found to be 5.40 and 4.19 wt%, respectively. [ABSTRACT FROM AUTHOR]

Determining the mechanical properties of a composite material represents an important stage in its design and is generally a complicated operation. These values are influenced by the topology and geometry of the resulting composite and the values of the elastic constants of the components. Due to the importance of this subject and the increasing use of composite materials, different calculation methods have been developed over the last fifty years. Some of the methods are theoretical, with results that are difficult to apply in practice due to difficulties related to numerical calculation. In the current paper, using theoretical results offered by the homogenization theory, values of engineering elastic constants are obtained. The finite element method (FEM) is used to determine the stress and strain field required in these calculations; this is an extremely powerful and verified calculation tool for the case of a material with any type of structure and geometry. In order to minimize errors, the paper proposes the method of least squares, a mathematical method that provides the best estimate for the set of values obtained by calculating FEM. It is useful to consider as many load cases as possible to obtain the best estimates. The elastic constants for a transversely isotropic material (composite reinforced with cylindrical fibers) are thus determined for a real case. [ABSTRACT FROM AUTHOR]