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Rahman et al. [International Journal of Mod. Phys. B 30, 1650199 (2016)] found that MgCu intermetallic compound with CsCl-type (B2) structure becomes unstable under pressure at about 15 GPa. This prediction has been made using an elastic instability condition for second-order elastic constants given by Born. They determined the elastic constants using Hooke's law for the linear stress–strain relationship which does not hold good at high pressures. It has been shown here that the values of elastic constants for MgCu at high pressures determined by Rahman et al. are not consistent with the values of bulk modulus computed from the Birch–Murnaghan equation of state (BM-EOS). We have used the Tallon formulation based on the thermodynamics of elastic deformation to estimate elastic constants which yields results for the bulk modulus of MgCu at different pressures in good agreement with those determined from the BM-EOS. It has been found that MgCu remains stable up to about 20 GPa which is significantly higher than the limit of elastic stability predicted by Rahman et al. [ABSTRACT FROM AUTHOR]

In this work, we have used the full-potential linearized augmented plane wave (FP-LAPW) method implemented in the WIEN2k code combined with the generalized gradient approximation (GGA) of the density functional theory (DFT) to study the structural, elastic, mechanical, electronic, magnetic, and thermodynamic properties of the parent ternary inverse Heusler compounds based on Titanium and Cobalt Ti2CoGa, Ti2CoCu in the Hg2CuTi-type structure and their quaternary alloys Ti2CoGa 1 − x Cux (x = 0. 2 5 , 0.5, 0.75) for the chosen concentrations using a supercell with 16 atoms. We have calculated the structural properties, such as the lattice parameters, bulk modulus, and its first derivative, which are in good agreement with those that have been obtained based on other published theoretical methods. Also, we calculated the elastic constants of the studied Heusler alloys, and we found that these materials are elastically stable, ductile, and anisotropic. Therefore, the electronic and magnetic properties indicate that Ti2CoGa exhibits a half-metallic (HM) ferromagnetic behavior, while Ti2CoCu shows a metal and a non-magnetic (NM) character. Their quaternary alloys are found to be nearly HM ferromagnetic materials, with a magnetic moment mainly due to the atom Ti. Furthermore, the quasi-harmonic Debye model, which incorporates the lattice vibrations, was used to estimate the thermodynamic effects on some macroproperties of the Ti2CoGa 1 − x Cux alloys. Successful results were achieved for the variations of the primitive cell volume, bulk modulus, heat capacities, and Debye temperature with pressure and temperature, respectively, in the ranges of 0–30 GPa and 0–1400 K. To our knowledge, no analogous investigations on the mechanical and thermodynamic properties of the Ti2CoGa 1 − x Cux (x = 0. 2 5 , 0.5 and 0.75) alloys have been performed to date. As a result, it is predicted that Ti2CoGa 1 − x Cux Heusler alloys will be promising candidates for actual applications in spintronic devices. [ABSTRACT FROM AUTHOR]

First principles calculations have been performed using full potential linearized augmented plane wave, FP‐LAPW, within Wien2k to elucidate structural, elastic, mechanical, phonon, electronic and optical properties of lead free halide perovskites AgXF3(X=Be,Ca)$$ {\mathrm{AgXF}}_3\left(\mathrm{X}=\mathrm{Be},\mathrm{Ca}\right) $$. The energy volume curve fitting is used to examine structural stability. For structural optimization and mechanical properties, we employed Perdew–Burke–Ernzerhof generalized gradient approximation and PBEsol, revised for solids, exchange and correlation functional. The optimized lattice constant of AgBeF3$$ {\mathrm{AgBeF}}_3 $$ and AgCaF3$$ {\mathrm{AgCaF}}_3 $$ is 3.631 and 4.349Å. The elastic constant C11$$ {\mathrm{C}}_{11} $$, C12$$ {\mathrm{C}}_{12} $$ and C44$$ {\mathrm{C}}_{44} $$ are computed to extract different mechanical parameters like Poisson's ratio, Pugh's ratio, bulk modulus, shear modulus, Young's modulus, anisotropic ratio, Cauchy pressure and shear constant. The mechanical parameters exhibit greater structural, mechanical and dynamical stability of AgBeF3$$ {\mathrm{AgBeF}}_3 $$ than AgCaF3$$ {\mathrm{AgCaF}}_3 $$. The electronic and optical properties are calculated by using TB‐mBJ and SCAN potentials in addition to PBEsol. The electronic band gap of AgBeF3$$ {\mathrm{AgBeF}}_3 $$ and AgCaF3$$ {\mathrm{AgCaF}}_3 $$ is 4.71 and 6.01 eV with TB‐mBJ and both perovskites are indirect band gap materials. The optical response of these perovskites against wide range of incident electromagnetic radiation is assessed by calculating absorption, reflection, optical conductivity, dielectric constant, energy loss function and refraction. Strong absorption, high optical conductivity and low reflectivity indicates that AgBeF3$$ {\mathrm{AgBeF}}_3 $$ and AgCaF3$$ {\mathrm{AgCaF}}_3 $$ are promising materials for photovoltaic applications. [ABSTRACT FROM AUTHOR]

The crystal structures of zirconium diboride have been thoroughly explored up to 200 GPa by applying the particle‐swarm optimization technique in company with first‐principles calculations. The hexagonal ZrB2 with space group of P6/mmm is always stable in the pressure region of 0–200 GPa. Structurally, this structure consists of the intriguing regular ZrB12 hexagonal column and the planar hexagonal B ring unit. In addition, the stable AlB2–ZrB2 configuration is mechanically and dynamically stable as confirmed by the respective calculations of elastic constants and phonon dispersion curves. The hardness values exhibit a shrinking variation upon further compression, which mainly originates from the decreasing brittleness and degree of the directionality of the covalent bonds with the growing pressure. Interestingly, the analyses of the Poisson's ratio, density of states, electron location function and Bader charge substantiate that a combination of covalent and ionic characters exists in the AlB2–ZrB2 crystalline with the formidable covalent interaction in the BB bonds, and partially covalent and partially ionic interactions in the ZrB bonds. The hardness value for this phase unexpectedly reaches 45.41 GPa under ambient pressure, higher than the lower limit of superhard materials. [ABSTRACT FROM AUTHOR]

The subsurface in situ stress fields significantly influence the elastic and anisotropic properties of rocks, yet traditional linear elastic theories often overlook the impact of stress on seismic response characteristics. Nonlinear acoustoelastic theory integrates third-order elastic constants (TOECs) to elucidate the influence of stress on changes in elastic and anisotropic properties of stressed rocks. A comprehensive examination of recent scholarly investigations on nonlinear acoustoelastic phenomena precedes the introduction of an innovative stress-dependent equation for the PP-wave reflection coefficient. This equation delineates the dependence of azimuthal seismic response on horizontal uniaxial stress in inherently vertical transversely isotropic (VTI) media, or those VTI formations induced by a single set of horizontal aligned fractures. Emphasis is placed on delineating stress-induced anisotropy and elucidating azimuthal PP-wave reflection characteristics in horizontally uniaxially stressed VTI media. Additionally, this discourse extends to more intricate scenarios involving horizontally biaxially and triaxially stressed VTI media, as delineated by nonlinear acoustoelastic theory. Subsequently, the reflection coefficient of horizontally uniaxially stressed VTI media is expressed in terms of azimuthal Fourier coefficients (FCs), revealing that the unstressed VTI background exhibits heightened sensitivity to zeroth-order FC, while the stress-induced anisotropy manifests greater sensitivity to second-order FC. Through the application of azimuthal FCs-based amplitude versus offset and azimuth (AVOAz) inversion method to both synthetic and field datasets, the proposed model and approach offer promising avenues for reservoir characterization in VTI media subject to horizontal uniaxial stress conditions. [ABSTRACT FROM AUTHOR]

This paper addresses an edge crack problem that originates at the interface of two bonded half-planes. The crack undergoes constant shear stress. We formulate the singular integral equation (SIE) with the unknown dislocation distribution function and traction as the right-hand term, using the modified complex potentials and the continuity conditions of traction and displacement. The curve length coordinate method is applied to transform the SIE of different edge crack configurations into the SIE for a straight line on the real axis with the interval [0, a], thus requiring fewer collocation points. A semi-open quadrature rule is used to solve the obtained SIE. The stress intensity factors (SIFs) of Mode I and Mode II at the crack's tip are analyzed. Some numerical examples are provided to demonstrate the behavior of SIFs for different edge crack configurations with different values of the elastic constant ratio. [ABSTRACT FROM AUTHOR]

The density functional theory (DFT) framework in the generalized gradient approximation (GGA) was employed to study the mechanical, dynamical, and thermodynamic properties of the ordered bimetallic Fe-Pt alloys with stoichiometric structures Fe3Pt, FePt, and FePt3. These alloys exhibit remarkable magnetic properties, high coercivity, excellent chemical stability, high magnetization, and corrosion resistance, making them potential candidates for application in high-density magnetic storage devices, magnetic recording media, and spintronic devices. The calculations of elastic constants showed that all the considered Fe-Pt alloys satisfy the Born necessary conditions for mechanical stability. Calculations on macroscopic elastic moduli showed that Fe-Pt alloys are ductile and characterized by greater resistance to deformation and volume change under external shearing forces. Furthermore, Fe-Pt alloys exhibit significant anisotropy due to variations in elastic constants and deviation of the universal anisotropy index value from zero. The equiatomic FePt showed dynamical stability, while the others showed softening of soft modes along high symmetry lines in the Brillouin zone. Moreover, from the phonon densities of states, we observed that Fe atomic vibrations are dominant at higher frequencies in Fe-rich compositions, while Pt vibrations are prevalent in Pt-rich. [ABSTRACT FROM AUTHOR]

In this work, the role of spin‐orbit coupling (SOC) in the physical properties of TlBi2${\rm TlBi}_2$ is reported. These electronic calculations reveal that the heavy elements Tl and Bi promote strong spin‐orbit coupling, lifting some of the degeneracies at the high‐symmetry points. The presence of SOC causes significant decreases in both elastic constants and elastic moduli, which in turn improve the compatibility of the calculated Debye temperature (ΘD$\Theta _D$ = 80 K) with the recent experimental data of 83 K. Furthermore, our quasi‐static harmonic approximation calculation, like this elastic constant calculation, confirms that taking SOC into account improves agreement with the experiment by decreasing value of Debye temperature from 95 to 85 K. Activating the SOC causes significant modifications in the phonon spectrum and the density of phonon states, as well as in the Eliashberg spectral function. As a result of these modifications, the electron–phonon coupling parameter (λ$\lambda$) increases from 1.178 to 1.259, by ≈7%$\approx 7\%$. The calculated values of λ$\lambda$ both with and without SOC imply that TlBi2${\rm TlBi}_2$ can be treated as phonon‐mediated superconductor with strong coupling. The SOC‐induced increase in λ$\lambda$ brings the superconducting transition temperature of TlBi2${\rm TlBi}_2$ from 6.076 to 6.211 K, which is almost equal to the recent experimental value of 6.2 K. [ABSTRACT FROM AUTHOR]

The elastic moduli and thermal expansion of MoAlB, Fe2AlB2, and Mn2AlB2 are investigated by first‐principles calculations, in particular to improve the density functional theory (DFT) prediction accuracy after clarifying the critical role of their lattice constants. By calculating the lattice constants and elastic moduli using the typical exchange‐correlation functionals, the observed positive correlation between the calculation errors of elastic moduli and those of cell volumes suggests a method to significantly improve the calculation accuracy for elastic moduli using the experimental cell volume to correct the input model (volume correction method), resulting in satisfactory results. Furthermore, a two‐step strategy is proposed for the precise high‐temperature elastic moduli with the help of quasi‐harmonic approximation for the most accurate high‐temperature cell volume using an exchange‐correlation functional in the first step, and another one used in the volume correction method in the second step. Similarly, the calculation accuracy of thermal expansion also heavily depends on that of cell volumes and configurations, where their thermal expansion is estimated with great accuracy by using the exchange‐correlation functional that well reproduces the lattice constants. [ABSTRACT FROM AUTHOR]

Abstract\nHIGHLIGHTSThis study explores the flexural behavior and free vibration analysis of sandwich plates including natural fiber-reinforced polymer composite faces and Polyethylene Terephthalate (PET) foam cores under a range of edge situations. ABAQUS is used to do numerical simulations with three-dimensional solid elements (C3D8R). To ascertain the natural frequencies of the plates, experimental procedures such as impact hammer testing and Fast Fourier Transform (FFT) analysis are carried out. The inference of different geometrical parameters on the natural frequencies is investigated through numerical simulation in ABAQUS. The study gives brief outlines regarding the sandwich plates for different engineering applications.Free vibration analysis of the Polyethylene Terephthalate (PET) foam and different natural fiber-reinforced polymer laminate composite faces-based sandwich plates under different edge conditions.The uniaxial tensile test and compression test are performed in the Universal Testing Machine (UTM) Instron 5967 is used to determine the elastic constants of the different natural fiber-reinforced laminated composite face layers and PET foam core.The obtained elastic properties from the tensile test and compression test of the face layers and PET foam core layer are used in the finite element software ABAQUS for the numerical simulation of the natural frequency of the sandwich plates.A set of experiments is conducted on different sandwich plates to capture the natural frequencies through an impact hammer test and Fast Fourier Transform (FFT) in the PulseLab software. The obtained natural frequency from the experimental technique and numerical simulation are compared and found to be highly consistence. [ABSTRACT FROM AUTHOR]

We analyse the volume dependence of the charge density wave phase transition temperature $T_{CDW}$ T CDW for 16 one and two dimensional materials such as the rare earth tritellurides $\hbox {TbTe}_3$ TbTe 3 , $\hbox {ErTe}_3$ ErTe 3 , $\hbox {TmTe}_3$ TmTe 3 $\hbox {DyTe}_3$ DyTe 3 , the transition metal dichalcogenide $\hbox {2H-NbSe}_2$ 2H-NbSe 2 , and the quasi-one dimensional conductors $\hbox {K}_{0.3}\hbox {MoO}_3$ K 0.3 MoO 3 , $\hbox {NbSe}_3$ NbSe 3 , $\lpar \hbox {TaSe}_4\rpar _2\hbox {I}$ (TaSe 4) 2 I . The volume dependence is taken in the form of the logarithmic derivative of $T_{CDW}$ T CDW in function of the strain components. We point out some characteristics of this parameter. This parameter is dimensionless with an absolute value of about 10 obtained from the measurements of the thermal expansion, the longitudinal elastic constants and pressure dependence for 11 one- and two-dimensional CDW systems. In contrast a huge positive value of about 100 is found at the lower charge density wave transition in $\hbox {TbTe}_3$ TbTe 3 , $\hbox {ErTe}_3$ ErTe 3 , $\hbox {TmTe}3$ TmTe 3 and $\hbox {DyTe}_3$ DyTe 3 . [ABSTRACT FROM AUTHOR]

Background: Cubic perovskite titanium stannous oxide (TiSnO3) is a promising material for various applications due to its functional properties. However, understanding how these properties change under external stress is crucial for its development and optimization. Method: This study employed density functional theory calculations to investigate the structural, electronic, optical, thermal, and mechanical properties of TiSnO3 under varying degrees of external static isotropic stress (0-120 GPa). Results: The study reveals a significant decrease in the bandgap of TiSnO3 with increasing stress due to lattice modifications and the formation of delocalized electrons. Partial density of states analysis indicates that Sn and O states play a key role in shaping the electronic band structure. TiSnO3 exhibits increased light absorption with stress, accompanied by a blue shift in absorption peaks, whereas, both polarizability and refractive index decrease with increasing stress. Mechanically, all elastic moduli (bulk, shear, and Young's) show an increase under stress, signifying a stiffening response of the material under stress. Similarly, the Pugh ratio suggests a transition from ductile to brittle behaviour at elevated stress levels. Phonon dispersion calculations indicate the instability of the cubic phase at 0 K. However, a phonon gap emerges at 30 GPa and widens with increasing stress. X-ray diffraction further supports these findings by demonstrating a shift in diffraction peaks towards higher angles with increasing stress, consistent with the applied stress. Conclusion: In conclusion, this computational study offers a thorough understanding of how external stress influences the properties of TiSnO3, providing valuable insights for potential applications in various fields. [ABSTRACT FROM AUTHOR]

This article investigates the effect of hydrostatic pressure on the optoelectronic characteristics of the InAsNBi/InAs quantum well (QW) system using an expanded version of the standard 8-band k dot p Hamiltonian. The effect of hydrostatic pressure on important structural and electronic parameters such as elastic constants, band gap, band offset, band structure, and effective masses are investigated in this manuscript. These factors assisted in the computation of optical gain spectra for different quantum well structures. Furthermore, this study is extended to several heterostructures by including diverse barrier materials such as GaAs, GaSb, and InP with InAsNBi QW. The optical analysis of these heterostructures can help the researchers to design and fabricate optoelectronic devices that can operate in LWIR regimes owing to the narrow bandgap of quaternary InAsNBi. Additionally, we examined the optical characteristics in TE mode for variations in hydrostatic pressure. [ABSTRACT FROM AUTHOR]

It is demonstrated that the substitution of Cl, B, and I at different concentrations in TlCaF3 significantly alters the phase, electronic band structure and optical, elastic, mechanical and anisotropic properties of the material. At 2.81% and 5.63% concentrations of all substituted elements, the cubic phase of TlCaF3 transforms into a pseudo-cubic tetragonal phase. With the addition of substitutional atoms, a systematic considerable narrowing of the bandgap is seen, and it can be either direct or indirect depending on the symmetrical positions. The bandgap shrinking can be addressed, in part, via the total/partial/elemental density of states (DOS) in line with structural variations. From the optical response, the refractive index rises with substitution atoms. According to the mechanical stability requirements for each substitution, the determined elastic constants for cubic and tetragonal structures match. Additionally, using elastic parameters, it is possible to estimate the unique mechanical features to evaluate the ductility and brittleness of pure and substituted compounds. Furthernore, Cl, Br and I-atoms' substitution would make them a suitable choice for improved optimisation in ultraviolet filters (UVF) due to the existence of their absorption spectra in the ultra-violet region and the modification in structural, electrical, optical, elastic and mechanical properties. [ABSTRACT FROM AUTHOR]

The catenary is a curve that has played a significant role in the history of mathematics, finding applications in various disciplines such as mechanics, technology, architecture, the arts, and biology. In this paper, we introduce some generalizations by applying the variational method to deformable strings. We explore two specific cases: (i) in the first case, we investigate the nonlinear behavior of an elastic string with variable length, dependent on the applied boundary conditions; specifically, this analysis serves to introduce the variational method and demonstrate the process of finding analytical solutions; (ii) in the second case, we examine a deformable string with a constant length; however, we introduce mass redistribution within the string through nonlinear elastic interactions. In the first scenario, the deformation state of the string always describes elongation, as compression states prove to be unstable for fully flexible strings. In contrast, in the second scenario, the finite length constraint induces compressive states in specific configurations and regions of the string. However, it is worth noting that the solution to this problem exists only for values of the elastic constant that are not too low, a phenomenon that is studied in detail. We conduct here both analytical and graphical analyses of various geometries, comparing the elastic behavior of the two aforementioned types of strings. Understanding the elastic behavior of deformable strings, especially the second type involving mass redistribution, is crucial for enhancing comprehension in the study of biological filaments or fibers and soft matter. For instance, these investigations can contribute to understanding the mechanisms employed by cells to sense gravity or other mechanical conditions. [ABSTRACT FROM AUTHOR]

In this paper, serial elastic actuators (SEAs) in conjunction with an accelerometer are proposed as force sensors to detect the intention of movement, and the SEA is proposed as a gentle actuator of a patient's upper-limb exoskeleton. A smooth trajectory is proposed to provide comfortable performance. There is an offset trajectory between the link and the motor, which increases safety by preventing sudden movements, and the offset is equivalent to the torsional elastic spring constant. The proposed control law is based on a backstepping approach tested in real-time experiments with robust results in a 2-DoF upper-limb rehabilitation exoskeleton. The experimental results showed a sensitivity of 100% and a positive predictive value of 97.5% for movement intention detection. [ABSTRACT FROM AUTHOR]

The elastic moduli and thermal expansion of MoAlB, Fe2AlB2, and Mn2AlB2 are investigated by first‐principles calculations, in particular to improve the density functional theory (DFT) prediction accuracy after clarifying the critical role of their lattice constants. By calculating the lattice constants and elastic moduli using the typical exchange‐correlation functionals, the observed positive correlation between the calculation errors of elastic moduli and those of cell volumes suggests a method to significantly improve the calculation accuracy for elastic moduli using the experimental cell volume to correct the input model (volume correction method), resulting in satisfactory results. Furthermore, a two‐step strategy is proposed for the precise high‐temperature elastic moduli with the help of quasi‐harmonic approximation for the most accurate high‐temperature cell volume using an exchange‐correlation functional in the first step, and another one used in the volume correction method in the second step. Similarly, the calculation accuracy of thermal expansion also heavily depends on that of cell volumes and configurations, where their thermal expansion is estimated with great accuracy by using the exchange‐correlation functional that well reproduces the lattice constants. [ABSTRACT FROM AUTHOR]

In this study, the dynamic properties of a mixture of granulated rubber and locally sourced Xiong'an clay are investigated, to promote the beneficial use of rubber–clay mixture (RCM) as a seismic isolation material in this area. A series of cyclic triaxial tests in the shear strain range of 10–4 ~ 10–2 is conducted, considering various scenarios of granulated rubber content, effective confining pressure, water content, dry density, cycle number, and consolidation time. The influences of these factors on the dynamic shear modulus and damping ratio of RCM are investigated and dominant factors are revealed. The results show that the shear modulus of RCM decreases with increasing rubber and water content whereas an opposite trend appears for the increased confining pressure, dry density, and consolidation time. Rubber content appears to be a dominant factor for the normalized shear modulus. The damping ratio of RCM is significantly related to the rubber content and effective confining pressure. A shear strain threshold of about 0.3% is observed concerning the influence of rubber content on the damping ratio. The G/Gmax ~ γ and D ~ γ curves of RCM can be well described by the Hardin–Drnevich model. Based on the test results, correlations of the parameters of the Hardin–Drnevich model with rubber content and effective confining pressure are developed. The proposed empirical formulas can provide a useful guide in the estimation of dynamic properties of RCM for the preliminary design calculations before detailed laboratory measurements have been performed in the study area. [ABSTRACT FROM AUTHOR]

In this article, the proposed model analyzed shear wave propagation through an orthotropic strip with an edge crack. Dual integral equations have been developed for solution of the governing mixed boundary value problem with the aid of Hankel transform technique. Then, the dual integral equations have been transformed into a second kind Fredholm integral equation employing Abel's transformation. The numerical calculations of stress intensity factor and crack opening displacement are performed utilizing the Fox & Goodwin method and displayed graphically. Elastic constants of two orthotropic materials have been used to illustrate the influence of material orthotropy and normalized strip width on SIF and COD. [ABSTRACT FROM AUTHOR]

Background: Cubic perovskite titanium stannous oxide (TiSnO3) is a promising material for various applications due to its functional properties. However, understanding how these properties change under external stress is crucial for its development and optimization. Method: This study employed density functional theory calculations to investigate the structural, electronic, optical, thermal, and mechanical properties of TiSnO3 under varying degrees of external static isotropic stress (0-120 GPa). Results: The study reveals a significant decrease in the bandgap of TiSnO3 with increasing stress due to lattice modifications and the formation of delocalized electrons. Partial density of states analysis indicates that Sn and O states play a key role in shaping the electronic band structure. TiSnO3 exhibits increased light absorption with stress, accompanied by a blue shift in absorption peaks, whereas, both polarizability and refractive index decrease with increasing stress. Mechanically, all elastic moduli (bulk, shear, and Young's) show an increase under stress, signifying a stiffening response of the material under stress. Similarly, the Pugh ratio suggests a transition from ductile to brittle behaviour at elevated stress levels. Phonon dispersion calculations indicate the instability of the cubic phase at 0 K. However, a phonon gap emerges at 30 GPa and widens with increasing stress. X-ray diffraction further supports these findings by demonstrating a shift in diffraction peaks towards higher angles with increasing stress, consistent with the applied stress. Conclusion: In conclusion, this computational study offers a thorough understanding of how external stress influences the properties of TiSnO3, providing valuable insights for potential applications in various fields. [ABSTRACT FROM AUTHOR]

The microstructure and 650 °C tensile properties of a compositionally graded IN718-René41 (718-R41) superalloy fabricated by laser blown-powder directed energy deposition (DED-LB/M) are investigated to understand structure–property relationships and baseline tensile properties. Digital Image Correlation (DIC), in situ neutron diffraction, and conventional characterization techniques are performed to study the as-built and heat-treated states. The applied heat treatment generates static recrystallization and equiaxed grains in 718-rich compositions, while R41-rich compositions remain partially or un-recrystallized possibly influenced by a higher MC carbide fraction (>0.5%). The yield strengths of the 718 and R41 sections in the heat-treated state are comparable to wrought forms but the graded compositions show weakness due to unoptimized heat treatment. Diffraction elastic constants first decrease and then increase along the 718-R41 composition gradient, while a small difference is observed between the as-built and heat-treated states and γ, γ′ phases. Overall, the compositionally graded region shows a smooth transition in the elastic properties. Grain-level load transfer from the (220) to (200) grains shows compositional dependence, and qualitatively agrees with DIC-measured macroscopic yield strength. Within the (200) grains, the γ/γ′ phases deform elastically until the γ phase yields and afterwards, the γ′ phase takes load from the γ phase. [ABSTRACT FROM AUTHOR]

In this paper, theoretical investigations of structural, elastic and thermal properties of Zn3P2 material were done using Quantum ESPRESSO code based on density functional theory. The generalized gradient approximation (GGA) exchange correlation-functional helped to model the atomic interaction. First, the structural optimization procedure was carried out, and hence, the optimized structural parameters were utilized to obtain six independent elastic constants C 1 1 , C 1 2 , C 1 3 , C 3 3 , C 4 4 , and C 6 6 for the Zn3P2 tetragonal structure. Accordingly, these elastic constants were used to determine the elastic moduli such as the Bulk modulus, Young's modulus, and shear modulus, as well as other mechanical parameters such as Pugh's ratio, Poisson's ratio, anisotropic ratio, sound velocities and Debye temperature. Calculations of thermodynamic properties such as vibrational energies, vibrational free energies, and fixed volume heat capacities, were performed within the implementation of the Thermo_pw code. Elastic calculations confirmed that this compound is characterized by mechanical stability at zero pressure and 0K temperature, ionic bonding, a high degree of anisotropy, and typical ductility. An observable increase in Debye vibrational energies, entropies and constant volume heat capacities of this compound with increasing temperature was detected throughout the thermodynamic calculations, unlike vibrational free energy which revealed a pronounced decrease as temperature increased. [ABSTRACT FROM AUTHOR]

In this study, we have conducted a thorough investigation into the influence of the atomic radius of transition metals on the structural, electronic, and optical properties of nanolaminated borides MAlB (M = Cr , Mo, W) using first principles calculation. The validity and dependability of our calculation parameters are confirmed and compared with other available data sets. The calculated elastic constants reveal stronger resistance to deformation along the c direction as compared to the a- and b-directions. The mechanical properties of these borides increased in tandem with the atomic radius of transition metal. The chemical bonding within the borides is a mix of metallic and covalent bonds. Interestingly, there is a decrease in the boride metallicity concurrent with an increase in the atomic radius of the transition metal. Optical property analysis shows promise for these borides as absorbent materials. Furthermore, there is a correlation between the increase in the atomic nucleus of the transition metal and the increase in the maximum absorption coefficient. [ABSTRACT FROM AUTHOR]

The effect of CVI-induced porosity on mechanical behaviour of C f /SiC composites possessing 2.5D (woven) and 3D (NOOBed) architectures with multilayered (PyC/SiC) n=4 interphase has been investigated. X-ray computed micro-tomography has shown that inter-bundle and inter-fibre pore distribution is influenced by fibre architecture. Elastic constants measured by ultrasound phase spectroscopy have revealed greater anisotropy in 2.5D C f /SiC composite than 3D C f /SiC composite. Owing to negligible C f fraction and flattened inter-bundle pores distributed in thickness direction of 2.5D C f /SiC composite, the elastic constant, C 11 (∼15±0.03 GPa) is <1/6th of C 22 and C 33 obtained along fibre directions. Despite the flexural strength of 2.5D C f /SiC composite (∼335±8 MPa) being ∼24% higher than 3D C f /SiC composite, a more equitable distribution of C f along three mutually orthogonal directions leads to higher fracture toughness of 3D C f /SiC composites (∼19±1 MPa-m1/2) and greater damage tolerance. Porosity distributions having influence on crack paths, also affect both strength and fracture behaviour. [ABSTRACT FROM AUTHOR]

Various active materials exhibit strong spatio-temporal variability of their orientational order known as active turbulence, characterised by irregular and chaotic motion of topological defects, including colloidal suspensions, biofilaments, and bacterial colonies.In particular in three dimensions, it has not yet been explored how active turbulence responds to changes in material parameters and chirality.Here, we present a numerical study of three-dimensional (3D) active nematic turbulence, examining the influence of main material constants: (i) the flow-alignment viscosity, (ii) the magnitude and anisotropy of elastic deformation modes (elastic constants), and (iii) the chirality. Specifically, this main parameter space covers contractile or extensile, flow-aligning or flow tumbling, chiral or achiral elastically anisotropic active nematic fluids. The results are presented using time- and space-averaged fields of defect density and mean square velocity. The results also discuss defect density and mean square velocity as possible effective order parameters in chiral active nematics, distinguishing two chiral nematic states—active nematic blue phase and chiral active turbulence. This research contributes to the understanding of active turbulence, providing a numerical main phase space parameter sweep to help guide future experimental design and use of active materials. Active turbulence is a dynamic state of active nematics that is in three dimensions realized as a network of reconfiguring and proliferating disclination lines. This work explores the scaling properties of active turbulence with material constants and the chirality-driven transition from a chiral active turbulence to an active blue phase. [ABSTRACT FROM AUTHOR]

Lead‐free double perovskites are unique materials for transport and optoelectronic applications that use clean resources to generate energy. Using first‐principle computations, this study thoroughly investigates the structural, thermoelectric, and optical attributes of A2TlAgF6 (A = Rb, Cs). Tolerance factor and formation energy estimates are used to verify that these materials exist in the cubic phase. Elastic constants with high melting temperature values are ductile when evaluated for mechanical stability using the Born stability criterion. The optical absorption band is adjusted from 2 to 4 eV via band gaps of 1.88 and 1.99 eV, as indicated by band structures. Analysis of optical properties reveals perfect absorption in the visible spectrum, whole polarization, and low optical loss. Furthermore, thermoelectric properties are assessed at 300, 500, and 700 K in the range of −0.5 to 3 eV for chemical potential (μ). The materials exhibit significant improvements in the Figure of Merit scale due to their elevated electrical conductivity, Seebeck coefficient, and extremely low thermal conductivity values. [ABSTRACT FROM AUTHOR]

In this paper we report on a computationally cost-effective method designed to estimate the thermal conductivity of optical materials based on cubic oxide including mixed ones, i.e. solid solutions of different oxides. The proposed methodology take advantage from Density Functional Theory (DFT) calculations to extract essential structural parameters and elastic constants which represent the inputs for revised versions of Slack and Klemens equations relating thermal conductivity to elastic constants. Slack equation is modified by the introduction of a corrective factor that incorporates the Grüneisen parameter γ, while in the revised Klemens equation a distortion parameter d accounting for the impact of point defects on lattice symmetry is added, which is a critical factor in determining thermal conductivity in optical materials with mixed compositions. The theoretical results were found in good agreement with experimental data, showing the reliability of our proposed methodology. [ABSTRACT FROM AUTHOR]

The research explores new compounds with structures similar to square‐octagonal beryllium oxide, commonly known as Haeckelites. The goal is to identify semiconducting variations compounds that can be synthesized and show promising potential in optoelectronic devices. Start with 1083 binary Haeckelite structures, and to test the synthesis potential of these materials quickly, develop new descriptors and use machine learning techniques. As a result, it identifies a subset of 350 materials with suitable properties in terms of phase stability and electronic perspective. These materials are further investigated to analyze their electronic structure and phase stability, which are determined through density functional theory calculations. The phase stabilities of the predicted semiconducting Haeckelites are also compared to other binary compounds using an evolutionary structure search algorithm. The comprehensive methodology also includes examining the dynamic stabilities through phonon calculations and mechanical properties through elastic constant calculations. Eventually, 13 new Haeckelite compounds are discovered, demonstrating exceptional stability and performance in electronic tests. Among these compounds, eight have shown remarkable absorption coefficients and are considered promising candidates with high reflectivity. Additionally, they have exhibited high electron mobility. These findings strongly suggest the potential of these compounds for synthesis and their application in optoelectronic devices. [ABSTRACT FROM AUTHOR]

In order to predict the effects of different fiber orientations on the elastic constants of composites, this paper takes carbon fiber reinforced polypropylene composites as an example, and adopts the Mori-Tanaka method to establish the Random Volume Element (RVE) model of fiber composites with five different fiber orientations, namely, 0°, 30°, 45°, 60°, and 90°, and investigates the effects of the fiber The effects of fiber orientation and fiber volume fraction on their elastic constants were investigated to obtain the required data by this method instead of experiment. By improving the Halpin-Tsai model, the value of the orientation factor was determined on the basis of the random orientation factor, and the original shape factor was modified to an exponential shape factor, the orientation degree factor was introduced, and finally, the relationship equations between the modified exponential shape factor and the volume fraction and orientation degree were obtained. The results show that for the same fiber orientation and volume fraction, the smaller the value of shape factor, the higher the elastic modulus. The fitting errors of the four values of elastic constants were also analyzed, and it was found that the improved Halpin-Tsai model could be used to predict the elastic constants of carbon fiber-reinforced polypropylene composites in a certain range, thus providing a method to study the prediction of the elastic constants of composites by fiber orientation. [ABSTRACT FROM AUTHOR]

The utilization of recycled iron in durable concrete production has gained attention for enhancing sustainability and resource efficiency. Simultaneously, incorporating nanoparticles as supplementary cementitious materials (SCMs) offers significant benefits. Introducing nano-sized iron particles (Fe2O3) into the cement paste results in a compact microstructure, improving strength, and durability. In this study, we investigate the bending behavior of concrete slabs reinforced with Fe2O3 nanoparticles using the non-local quasi-3D shear deformation theory based on Eringen's non-local differential constitutive relations. To characterize the elastic material properties of the nanocomposite, we employ Eshelby's homogenization model. In order to extend the applicability of our findings, we assume that the concrete plate rests on Kerr's foundation, which includes a shear layer connected to upper and lower springs. By deriving the equations of motion using the principle of virtual work, we establish a comprehensive framework for analyzing the bending of the concrete plate. To solve the equilibrium equations for a simply supported concrete plate, we present Navier's analytical solutions. Our investigation considers various influential parameters, such as the concentration of Fe2O3 nanoparticles in the concrete matrix, the elastic constants of the soil medium, different types of bending loads, and size-dependent nonlocal parameters. One of the most captivating findings of this study is that the incorporation of 30 wt% of iron nanoparticles in concrete leads to a remarkable improvement of 60% in the elastic properties of the material. Additionally, this same amount of iron nanoparticles has shown the potential to reduce the deflection of thin plates by over 60%. [ABSTRACT FROM AUTHOR]

Incorporating metal cations into V2O5 has been proven to be an effective method for solving the poor long-term cycling performance of vanadium-based oxides as electrodes for mono- or multivalent aqueous rechargeable batteries. This is due to the existence of a bilayer structure with a large interlayer space in the V2O5 electrode and to the fact that the intercalated ions act as pillars to support the layered structure and facilitate the diffusion of charged carriers. However, a fundamental understanding of the mechanical stability of multi-ion-co-intercalated bilayered V2O5 is still lacking. In this paper, a variety of pillared vanadium pentoxides with two types of co-intercalated ions were studied. The root-mean-square deviation of the V-O bonds and the elastic constants calculated by density functional theory were used as references to evaluate the stability of the intercalated compounds. The d-band center and electronic band structures are also discussed. Our theoretical results show that the structural characteristics and stability of the system are quite strongly influenced by the intercalating strategy. [ABSTRACT FROM AUTHOR]

Quantum‐mechanical calculations based on the density functional theory (DFT) enable an effective characterization of a variety of properties of materials at the atomistic level, although at a high computational cost. Here, we fully exploit parallel computing to apply such methods to the study of lattice dynamics and mechanical response of the major oxide constituents of Portland cement clinker: C3S${\rm {C}}_3{\rm {S}}$, C2S${\rm {C}}_{2}{\rm {S}}$, C3A${\rm {C}}_{3}{\rm {A}}$, and C4AF${\rm {C}}_4{\rm {AF}}$. Raman spectra and the evolution of the elastic tensor (and associated mechanical properties) with pressure are predicted for all oxide systems. We devote much attention to the assessment of dynamical and mechanical stability of the many previously proposed polymorphic forms of the most abundant oxide: C3S${\rm {C}}_3{\rm {S}}$. Specifically, five different crystalline models of C3S${\rm {C}}_3{\rm {S}}$ are analyzed: only two turn out to be dynamically stable. The mechanical response of C3S${\rm {C}}_3{\rm {S}}$ is further analyzed as a function of temperature through a quasi‐harmonic description of its lattice dynamics. [ABSTRACT FROM AUTHOR]

This paper contains the solution to the problem of a semi-infinite moving crack situated in an orthotropic strip bonded between two identical strips. The crack moves with a constant velocity, and the surface is under shear wave disturbance. We first examine the equations of elasticity, which include equilibrium equations and stress and displacement constitutive relations with the model-specific continuity and boundary conditions. Using the Fourier integral transform, the standard form for the Wiener–Hopf (W-H) equation is obtained, which is solved using the W-H method. The analytical expressions for the considered crack problem have been obtained for stress intensity factor (SIF), normalized stress intensity factor (NSIF), and stress magnification factor (SMF). The behavior of NSIF has been graphically presented for particular cases of composite materials for different crack propagation velocities and various depth ratios of the strips. The novelty of this paper lies in the analytic solutions using the W-H method for the semi-infinite moving crack problem under the influence of anti-plane shear waves. The pictorial presentations of normalized SIF clearly show their dependency on strip depths, crack propagation velocities and elastic constants. [ABSTRACT FROM AUTHOR]

Due to high thermal conductivity and higher fissile density, one of the most options being pursued for accident-tolerant fuels is U–Si fuels. Unfortunately, the data available for U–Si fuels are rather limited now. Based on a few assumptions regarding geometry structures, electronic properties, elastic constants and hardness are predicted systematically for U–Si compounds using density functional theory (DFT) in this work. The calculation results show that the U3Si2, β-U3Si and γ-U3Si compounds are metallic and brittle, which is in good agreement with the previous experimental results. The Si-rich USi1.84 compound presents the ductile. By analyzing shear anisotropy factors, it is found that the U3Si2, β-U3Si and Si-rich USi1.84 have the anisotropic characteristics, while the γ-U3Si is isotropic. Moreover, among the U3Si2, β-U3Si, γ-U3Si and Si-rich USi1.84 compounds, the γ-U3Si is hardest and Si-rich USi1.84 is softest, then U3Si2 is much harder than that of β-U3Si by the Voigt hardness calculations. The hardness value of U3Si2 is overestimated in our calculation than experimental data, mainly because the model may be ideal without considering defects and microstructure. The theoretical investigation of this work will be expected to provide parameters for the physical models in the advanced fuel rod performance analysis. [ABSTRACT FROM AUTHOR]

This study uses density functional theory calculations to study the impact of pressure on the structural, elastic, and thermodynamic properties of CaRh2P2 and BaRh2P2 compounds. The equilibrium structural parameters closely match the experimental values. CaRh2P2 shows a greater reduction in lattice parameter "a" under pressure, while BaRh2P2 shows the opposite trend. The single-crystal elastic constants calculated for both compounds meet the criteria for mechanical stability under varying pressures up to 18 GPa. The study extends to polycrystalline elastic properties, including bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and related properties, under pressures up to 18 GPa. The Pugh ratio, Cauchy pressure, and Poisson's ratio indicate the ductile behavior of the title compounds. BaRh2P2 exhibits superconducting characteristics, unlike CaRh2P2, confirmed by interlayer PP bond length calculations. Debye's quasi-harmonic model explores the temperature dependencies of various properties, with results that align well with elastic constant data, thus validating the results. [ABSTRACT FROM AUTHOR]

Perovskites represent distinctive materials suitable for both transport and optoelectronic applications, harnessing renewable resources to produce energy. In this study, the perovskite Li2SnI6 has been explored, focusing on a comprehensive analysis of its physical properties under strain. The encompassed investigation of the structural, elastic, electronic, optical, and thermoelectric characteristics of the studied compound. Utilizing density functional theory (DFT) implemented in the Wien2k package, we employed the LSDA+mBJ approximation to determine the exchange-correlation potential. The elastic constants and related parameters have been reported such as bulk modulus, shear modulus, Young's modulus, anisotropy factor, Poisson's ratio, and internal strain parameter for Li2SnI6 in its cubic structure. The electronic part reveals the semiconductor behavior of the studied compound and a decrease in gap energy with increasing pressure, reaching Eg = 0.2 eV for P = 12 GPa. Additionally, the absorption of optical factors lies in the ultra-violet (UV) region, noted at P = 12 GPa, with an intensity of 230 × 104 cm−1, which makes this material suitable for photovoltaic devices. Furthermore, we delved into the electrical conductivity, Seebeck coefficient, and electronic part of thermal conductivity. The results indicated that the compound demonstrates p-type behavior, as evidenced by positive values for the Seebeck coefficient with the highest value of 240 µV/K observed for P = 4 GPa. The analysis of thermoelectric and optical properties suggests that the studied perovskite is well-suited for applications in renewable energy. [ABSTRACT FROM AUTHOR]

This article introduces and examines a new type of lead-free double perovskites, K2InSbX6 (X = Cl, Br) for their potential use in optoelectronic and thermoelectric devices. The investigation is conducted through theoretical exploration. The physical features of the materials were investigated using density functional theory. Both compounds are found stable in their cubic structure. Elastic constants and negative formation energies computed for K2InSbX6 demonstrate its mechanical and thermodynamic stability. According to the computed Poisson, Pugh's ratio, and anisotropy, both materials are brittle and show anisotropic behavior. Furthermore, the calculated findings show that K2InSbCl6 and K2InSbBr6 have direct bandgap values of 1.31 and 1.22 eV, respectively. Optical analysis reveals a notable ability to absorb visible and near-UV radiation. Perovskite K2InSbX6's excellent light absorption capabilities and narrow band gap make it a great choice for utilization in solar cell applications and other optoelectronic devices. Furthermore, the findings of transport characteristics indicate that the materials possess exceptional electrical and thermal conductivity and are projected to exhibit optimal thermoelectric capabilities at a temperature of 300 K. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations were executed for the titled features of hitherto unreported Rb2XS3 (X = Si, Ge, Sn) chalcogen compounds. All compounds were found to be in semiconducting character where they demonstrate high-k dielectric properties, high optical conductivity, high refractivity and reasonable absorbance. In addition, obtained phonon dispersion curves of all compounds with positive phonon frequencies stipulate the dynamical stability. Also, computed elastic stiffness constants prove mechanical stability and bilateral agreement between Pugh ratio analyses with Poisson ratio results confirms the ductile mechanical feature of all addressed compounds. Overall, with satisfactory optical, elastic and mechanical aspects, Rb2XS3 (X = Si, Ge, Sn) chalcogenides can be promising materials for recent optoelectronics and microelectronics with diverse applications. [ABSTRACT FROM AUTHOR]

Double perovskite halides Cs2TlGaCl6 and Cs2TlGaBr6 are promising for photovoltaic applications due to their optoelectronic properties. The first-principles density functional theory (DFT) with the HSE06 hybrid functional was applied to systematically investigate their structural stability, electronic structure, optical absorption, and mechanical properties. The calculated tolerance and octahedral factors confirm stable crystal structures. The indirect band gaps of 2.50 eV (Cs2TlGaCl6) and 1.54 eV (Cs2TlGaBr6) are suitable for visible-light harvesting. Strong visible-light absorption and low reflectivity are observed. Elastic constant calculations based on the Voigt–Reuss–Hill approximation validate mechanical stability. The Spectroscopic Limited Maximum Efficiency (SLME) estimates promising photovoltaic efficiencies of 12.41% for Cs2TlGaCl6 and 29.73% for Cs2TlGaBr6 perovskite. These findings highlight the potential of Cs2TlGaCl6 and Cs2TlGaBr6 for low-cost, high-efficiency solar cells, warranting further experimental investigations. [ABSTRACT FROM AUTHOR]

The rare earth-based perovskite oxides are vastly studied for optoelectronic and photovoltaic applications. Here in this manuscript, the structural, mechanical, thermodynamic, electronic, and optical properties of AcXO3 (X = Al, Ga, In) are addressed by density functional theory (DFT) based WIEN2k code. The optimized parameters are reported from the Birch–Murnaghan equation of states in terms of lattice constant and bulk modulus. The elastic constants C11, C12, and C44 for the cubic phase satisfy the Born–Huang stability conditions. The Poisson and Pugh's ratios discriminate that the Ac(Al/Ga)O3 have brittle and AcInO3 ductile nature. The thermodynamic parameters like melting temperature, Debye temperature, and lattice thermal conductivity have also been explained in terms of elastic constants and moduli. The electronic behavior is explained by the band structures and density of states which is mainly contributed by Ac-d, X-p, and O-p states. The replacement of Al with Ga, and In reduces the bandgap from 4.1 to 2.2 eV. The optical characteristics are studied in terms of dielectric constants, absorption coefficient, reflection, refractive index, optical loss, and their dependent parameters. The absorption region shifts from ultraviolet to the visible region making them significant for diverse optoelectronic applications. [ABSTRACT FROM AUTHOR]

Dense environmental barrier coatings (EBCs) are urgently needed to protect SiC-based ceramic matrix composites (SiC CMCs) in future gas turbine engines, and multi-component rare-earth (Re) disilicates are attracting attention due to their excellent thermal-mechanical properties and chemical compatibility. In this paper, first-principles calculations were performed on ten different crystal structures and elastic constants of (Re 0.5 Yb 0.5) 2 Si 2 O 7 (Re Sc, Y, Ho, Er, Tm, Yb, Lu) and (Sc x Yb 1-x) 2 Si 2 O 7 (x = 0, 0.25, 0.5, 0.75, 1.00) disilicate materials. Meanwhile, five bulk disilicate ceramics of Yb 2 Si 2 O 7 , (Sc 0.5 Yb 0.5) 2 Si 2 O 7 , (Er 0.5 Yb 0.5) 2 Si 2 O 7 , (Sc 0.33 Er 0.33 Yb 0.34) 2 Si 2 O 7 , and (Sc 0.25 Ho 0.25 Er 0.25 Yb 0.25) 2 Si 2 O 7 were prepared and tested for thermal-mechanical properties. The prepared bulk ceramics exhibit superior thermal stability at 1823 K, with no phase transformation or grain coarsening occurring. Compared to Yb 2 Si 2 O 7 , (Sc 0.5 Yb 0.5) 2 Si 2 O 7 exhibits a smaller unit cell volume, average Re–O bond length, grain size, and thermal conductivity. It also shows increased ion mass disorder, lattice distortion, ion radius disorder, coefficient of thermal expansion (CTE), microhardness, and Young's modulus. However, (Er 0.5 Yb 0.5) 2 Si 2 O 7 mainly exhibits opposite behaviors. Most of the thermal-mechanical properties of (Sc 0.33 Er 0.33 Yb 0.34) 2 Si 2 O 7 and (Sc 0.25 Ho 0.25 Er 0.25 Yb 0.25) 2 Si 2 O 7 are intermediate between those of (Sc 0.5 Yb 0.5) 2 Si 2 O 7 and (Er 0.5 Yb 0.5) 2 Si 2 O 7. These findings of this study may accelerate the development of medium-entropy or high-entropy disilicates with controlled polymorphic phases and customized thermal-mechanical properties. [ABSTRACT FROM AUTHOR]

The secant shear modulus is an important parameter in several geotechnical engineering models and calculation approaches. The characteristics of this parameter are very complex due to the hysteretic behavior of cyclically loaded soils. Its characteristics primarily depend on the mean effective confining stress and the void ratio. In this paper, the characteristics of the secant shear modulus of sand under large shear strain amplitude are investigated in detail based on the results of several cyclic triaxial and simple shear tests under drained and undrained conditions. The evaluation of the secant shear modulus based on the shape of the open stress–strain hysteresis loop is then discussed. Under certain loading conditions, the secant shear modulus defined from the reloading and unloading branches of the loop obviously differ. The evolution of the stiffness index, which measures the change in the secant shear modulus due to cyclic loading, shows that the drainage conditions play an essential role in the behavior of the secant shear modulus. [ABSTRACT FROM AUTHOR]

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This study investigates the structural, mechanical, optical, thermal, and electronic properties of the ionic semiconducting materials XZrS3 (X = Ca, Ba) within the framework of density functional theory (DFT). Here, the elastic constants, modulus (bulk, shear, Young's), ratios (Pugh, Poisson) and elastic anisotropy for XZrS3 (X = Ca, Ba) are studied. Furthermore, the electronic, optical, and thermal properties for XZrS3 (X = Ca, Ba) are regenerated and designed using the values obtained with Cambridge Serial Total Energy Package (CASTEP) software. The calculated lattice parameters show excellent agreement with theoretical and experimental values. The elastic stiffness constants confirm the mechanical stability of both compounds. Although XZrS3 (X = Ca, Ba) is elastically anisotropic, it has little optical anisotropy. The electronic band structures of the material exhibit direct-bandgap semiconducting behavior, with values of 1.3 eV (CaZrS3) and 1.1 eV (BaZrS3) using the generalized gradient approximation (GGA), respectively, which is ideal for solar cell (0.9–1.56 eV) and optoelectronic device applications. Bandgap values of 1.9 eV and 1.6 eV are found for CaZrS3 and BaZrS3, respectively, using the Heyd–Scuseria–Ernzerhof HSE06 functional, which is consistent with previous theoretical and experimental bandgap results. The optical properties including dielectric function, refractive index, absorption coefficient, reflectivity, and loss function are characterized using the GGA of Perdew–Burke–Ernzerhof (GGA-PBE) and HSE06 methods and are discussed in detail. Because of the relatively low Debye temperature (D), thermal conductivity of the lattice (kph), and minimum thermal conductivity (Kmin), the studied materials can be used as thermal barrier coating (TBC) materials. The capacity of heat, Debye temperature, and thermal coefficient of expansion are all computed. [ABSTRACT FROM AUTHOR]

Depending on the 3D-printing orientation, the anisotropy of the elastic characteristics of the Inconel 625 alloy generated with selective laser sintering from powders is investigated. The impact of the original powder combination and the following heat treatment (post-printing treatment) on the anisotropy of the alloy elastic characteristics is assessed. As demonstrated, the suggested treatments can lessen the anisotropy of the alloy elastic characteristics. Based on knowledge of the elastic constants of the single crystal and x-ray texture features, the results of a theoretical estimation of the elastic and shear moduli, Poisson's ratio, and their anisotropy in the horizontal and vertical directions of 3D printing are provided. As demonstrated, the obtained theoretical values differ by 6-10% from the corresponding experimental values. The calculated stress-strain state can be more accurately calculated with the use of the estimated elastic characteristics and their anisotropy. The strategy for 3D-printing complicated components from Inconel 625 alloy may be made more effective. [ABSTRACT FROM AUTHOR]

This study employs first-principles calculations to examine structural, elastic, and mechanistic relationships of Mg2Ni alloys under varying conditions of pressure. The investigation encompasses Young's modulus, bulk modulus, shear modulus, Poisson's ratio, and anisotropy index, as well as sound velocity, Debye temperature, and related properties. Our findings indicate that the lattice parameters of Mg2Ni in its ground state are in agreement with values obtained experimentally and from the literature, confirming the reliability of the calculated results. Furthermore, a gradual decrease in the values of the lattice parameters a / a 0 and c / c 0 is observed with increasing pressure. Specifically, the values for C 13 and C 33 decrease at a hydrostatic pressure of 5 GPa, while C 11 and C 13 increase when the external hydrostatic pressure exceeds 5 GPa. All other elastic constants exhibit a consistent increasing trend with increasing pressure between 0 and 30 GPa, with C 11 and C 12 increasing at a faster rate than C 44 and C 66 . In the 0–30 GPa pressure range, Mg2Ni satisfies the mechanical stability criterion, indicating its stable existence under these conditions. Additionally, the Poisson's ratio of Mg2Ni consistently exceeds 0.26 over a range of pressures from 0 to 30 GPa, signifying ductility and demonstrating consistency with the value of B / G . The hardness of Mg2Ni increases within the pressure range of 0–5 GPa, but decreases above 5 GPa. Notably, the shear anisotropy of Mg2Ni exhibits greater significance than the compressive anisotropy, with its anisotropy intensifying under higher pressures. Both the sound anisotropy and the Debye temperature of Mg2Ni demonstrate an increasing trend with rising pressure. [ABSTRACT FROM AUTHOR]

The temperature dependent thermophysical, mechanical and ultrasonic properties of B2 structured ferromagnetic materials MTi (M: Fe, Co, Ni) have been evaluated in present study. The Coulomb and Born-Mayer potential model has been applied to calculate second and third order elastic constants in the temperature range 0-300K. The values of second order elastic constants have been used to find the mechanical and thermophysical properties. The chosen materials have been found ductile as the value of Pugh's indicator for MTi has been found greater than 1.75. The FeTi has been found more stable than CoTi and NiTi. The mechanical constants have been found highest for FeTi. Again, the values of elastic stiffness constants have been used to compute the ultrasonic velocities, Debye average velocities, Debye temperatures, thermal conductivities and Grüneisen parameters along <100>, <110> and <111> directions for the longitudinal and shear modes of wave propagation. The ultrasonic velocities have been observed more for longitudinal mode than shear mode. The ultrasonic velocities and Debye temperatures are found to be highest along <100> direction for all chosen materials. Hence <100> direction would be most suitable for the wave propagation in case of MTi. The obtained values of elastic, mechanical, thermophysical and ultrasonic properties have been compared with existing literatures and discussed. [ABSTRACT FROM AUTHOR]

AbstractOrigami metamaterials exhibit abnormal mechanical properties through artful structural design. To further explore the mechanical behavior of reentrant metamaterials, a multi-directional auxetic origami metamaterial (AOMM) was designed, and its negative Poisson’s ratio effect was analyzed through the diagram of load bearing and deformation. Theoretical models related to geometric parameters, relative density, folding rate, equivalent elasticity and load plateau were established to reveal the deformation transformation mechanism, and the influence of size parameters on the equivalent elastic constants was drawn. Using thermoplastic polyurethane (TPU) as the substrate, two types of multi-directional AOMMs were fabricated by 3D printing, and quasi-static compression experiments were performed. The results show that the TPU AOMMs has a reusable compressive capacity, whose compressive mechanical behaviors are mainly contributed by the buckling instability and large deformation of sidewall. There is a coupling effect between the cross connection boundaries, which results in the difference in mechanical properties of AOMM with different geometric sizes. The prediction results of relative density, load plateau and yield strain through equivalent theories approximate that of experimental results. Simultaneously, finite element analyses were conducted, which agrees well with the experiments. These foundings may provide reference for the design and application of novel auxetic or origami metamaterials. [ABSTRACT FROM AUTHOR]

Hybrid organic-inorganic lead halide perovskites (LHPs) have emerged as a highly significant class of materials due to their tunable and adaptable properties, which make them suitable for a wide range of applications. One of the strategies for tuning and optimizing LHP-based devices is the substitution of cations and/or anions in LHPs. The impact of Cs substitution at the A site on the structural, vibrational, and elastic properties of MAxCs1−xPbCl3-mixed single crystals was investigated using X-ray diffraction (XRD) and Raman and Brillouin light scattering techniques. The XRD results confirmed the successful synthesis of impurity-free single crystals, which exhibited a phase coexistence of dominant cubic and minor orthorhombic symmetries. Raman spectroscopy was used to analyze the vibrational modes associated with the PbCl6 octahedra and the A-site cation movements, thereby revealing the influence of cesium incorporation on the lattice dynamics. Brillouin spectroscopy was employed to investigate the changes in elastic properties resulting from the Cs substitution. The incorporation of Cs cations induced lattice distortions within the inorganic framework, disrupting the hydrogen bonding between the MA cations and PbCl6 octahedra, which in turn affected the elastic constants and the sound velocities. The substitution of the MA cations with smaller Cs cations resulted in a stiffer lattice structure, with the two elastic constants increasing up to a Cs content of 30%. The current findings facilitate a fundamental understanding of mixed lead chloride perovskite materials, providing valuable insights into their structural and vibrational properties. [ABSTRACT FROM AUTHOR]

In this work, we explore the physical properties of RbXH3 (X=Cr, Zr) perovskite hydrides for solid‐state hydrogen storage. The structural, mechanical, electronic, optical, and hydrogen storage properties were theoretically investigated using density functional theory and CASTEP software. The selected candidates were fully relaxed and optimized in the cubic phase space group Pm‐3 m. The structural phase stability was verified by means of thermodynamic, dynamic and mechanical stabilities. Mechanical analyses based on Poisson's ratio (ν), G/B ratio, and Cauchy pressure show that RbCrH3 and RbZrH3 exhibit brittle behavior with preference of ionic bonding. The electronic structures unveil half‐metallicity in RbCrH3 compound and metallic‐like behavior in RbZrH3. Furthermore, optical calculations were also conducted to gain additional insights into the physical properties of RbXH3 compounds. The gravimetric hydrogen storage (Cwt %) capacities have been calculated as 2.09 wt % and 1.64 wt % for RbCrH3 and RbZrH3, respectively. The hydrogen desorption temperatures have been obtained as 545.11 K and 548.15 K for RbCrH3 and RbZrH3, respectively. Our calculation propose RbCrH3 hydride as potential material for hydrogen storage application. [ABSTRACT FROM AUTHOR]