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In this work, explicit expressions to estimate all the transversely isotropic elastic constants of lamellar bone as a function of the volumetric bone mineral density (BMD) are provided. The methodology presented is based on the direct homogenization procedure using the finite element method, the continuum approach based on the Hill bounds, the least-square method and the mean field technique. Firstly, a detailed description of the volumetric content of the different components of bone is provided. The parameters defined in this step are related to the volumetric BMD considering that bone mineralization process occurs at the smallest scale length of the bone tissue. Then, a thorough description provides the details of the numerical models and the assumptions adopted to estimate the elastic behaviour of the forward scale lengths. The results highlight the noticeable influence of the BMD on the elastic modulus of lamellar bone. Power law regressions fit the Young's moduli, shear stiffness moduli and Poisson ratios. In addition, the explicit expressions obtained are applied to the estimation of the elastic constants of cortical bone. At this scale length, a representative unit cell of cortical bone is analysed including the fibril orientation pattern given by Wagermaier et al. (Biointerphases 1:1-5, 2006) and the BMD distributions observed by Granke et al. (PLoS One 8:e58043, 2012) for the osteon. Results confirm that fibril orientation arrangement governs the anisotropic behaviour of cortical bone instead of the BMD distribution. The novel explicit expressions obtained in this work can be used for improving the accuracy of bone fracture risk assessment.

We present results of resonant ultrasound spectroscopy (RUS) measurements applied to granular high explosive materials at different bulk pressing densities and degree of thermal conditioning. The material chosen in this study is a ubiquitously used explosive material known as pentaerythritol tetranitrate (PETN), which is used commercially in civil and defense applications both as a binderized plastic bonded explosive material and an unbinderized neat material. However, changes in granular PETN bulk elastic properties due to thermal conditioning, which could have implications for better understanding environmental aging-related effects, have not been well studied even though it is believed that elasticity may play an important role in explosive material initiation mechanisms. Furthermore, monitoring elastic property changes in granular explosive pressings has not yet been demonstrated using RUS, which is an appealing non-destructive characterization tool that requires only dry point contact with the explosive material. To this end, we report the first study using RUS to quantify the elastic properties of binderized and neat PETN pressings as well as to quantify changes in elastic properties as a function of both thermal conditioning and bulk pressing density. Elastic stiffness coefficients, sometimes more commonly referred to as elastic constants, calculated from the RUS measurements on the different PETN-based materials show a significant increase for the post-conditioned samples compared to the pre-conditioned samples. This trend of increasing elastic properties with thermal conditioning was consistent for different density pressings, different thermal exposure conditions, and even different neat PETN pressings of differing average crystal sizes and/or specific surface areas. [ABSTRACT FROM AUTHOR]

This work explores the investigation of tin monochalcogenides i.e. SnX (X: S, Se, Te) at room temperature (300 K). The mechanical, thermophysical and ultrasonic properties of SnX (X: S, Se, Te) have been evaluated using the computed values of second- and third-order elastic constants (SOECs and TOECs). The SOECs and TOECs have been obtained using Born–Mayer potential model at 0 K and 300 K. The brittleness behavior of tin monochalcogenides is detected by Pugh's ratio. It is observed that phonon–phonon interaction mechanism is dominant in tin monochalcogenides leading to high ultrasonic attenuation. The obtained temperature dependence behavior of tin monochalcogenides is validated via comparison with available works of literature data in previous works done experimentally as well as theoretically by others. [ABSTRACT FROM AUTHOR]

This study investigates the impact of zirconium substitution on the structural, elastic and magnetic properties of CoCr2O4 nanoparticles. A series of CoCr2−xZrxO4 nanoparticles, x = 0.00, 0.05, 0.10, 0.15 and 0.20, are synthesized via the co-precipitation method. X-ray diffraction (XRD) patterns affirm the formation of single-phase cubic structure with the space group Fd3m. Special attention is given to accurately calculating the average crystallite size (D) and lattice parameter (a) using Williamson–Hall (W–H) analysis and the Nelson–Riley (N–R) extrapolation function, respectively. The increase in Zr4+ content leads to a reduction in crystallite size and an increase in the lattice parameter. Elastic properties are estimated from force constants and the lattice constant, determined from FTIR and XRD, respectively. The observed changes in the elastic constants are attributed to the strength of interatomic bonding. The stiffness constants decrease, while Poisson's ratio increases with increasing Zr4+ content, reflecting the increase in the ductility of the prepared samples. As the Zr4+ content increases, the stiffness constants decrease, and Poisson's ratio increases, reflecting enhanced ductility of the samples. Furthermore, as Zr4+ content rises, Young's modulus, the rigidity modulus and Debye temperature decrease. The magnetic hysteresis loop measurements are carried out at room temperature using a vibrating sample magnetometer (VSM) over a field range of 25 kg. Unsubstituted CoCr2O4 exhibits ferrimagnetic behavior. As Zr4+ content increases, saturation magnetization (Ms) and magnetic moment decrease, while remanent magnetization (Mr) and coercivity (Hc) initially decrease up to x = 0.10, then increase with further increases in x. The novel key of this study is how Zr4+ substitution in CoCr2O4 nanoparticles can effectively modify their elastic moduli and magnetic properties, making them suitable for various applications such as flexible electronics, protective coatings, energy storage components and biomedical implants. [ABSTRACT FROM AUTHOR]

Ab-initio simulations using density functional theory (DFT) were employed to investigate the structural, mechanical, electronic, magnetic, optical, and thermoelectric properties of halide perovskites (X = Cl, Br, I). Structural optimization and mechanical stability assessments confirm the reliability of these perovskites in a hexagonal P mc symmetry. The stability of the ferromagnetic phase was validated through total crystal energy minimization via Murnaghan's equation of state. Electronic band structures and density of states, derived from the generalized gradient approximation (GGA), reveal a semiconducting ferromagnetic nature in the spin up channel, spotlighting their potential in semiconductor spintronic applications. Phonon dispersion analysis of and revealed positive phonon modes throughout the entire Brillouin zone, confirming their dynamical stability. In contrast, demonstrated dynamical instability. The elastic constants confirm the mechanical stability and ductile nature of the perovskites. Optical and dielectric properties of these perovskites show significant UV absorption and photoconductivity, making them highly suitable for optoelectronic and solar cell applications. Finally, transport properties, such as the Seebeck coefficient, electrical conductivity, thermal conductivity, power factor, and figure of merit (ZT) unveil their exceptional thermoelectric performance. Combining half-metallic ferromagnetic traits with superior thermoelectric and optoelectronic performance positions compounds as exceptional candidates for applications in spintronics, optoelectronics, and thermoelectrics. This comprehensive investigation demonstrates their ability to excel across a diverse array of advanced technological applications. [ABSTRACT FROM AUTHOR]

Oxide-dispersion-strengthened (ODS) alloys generally exhibit extraordinary service performance under severe conditions through the formation of ultrafine nano oxides. Y2Ti2O7 has been characterized as the major strengthening oxide in Fe-based ODS alloys. First-principles energetic analyses were performed to investigate the structural, elastic and interface properties of Y2Ti2O7 in either Fe-based or Ni-based ODS alloys. Y2Ti2O7 has comparable elastic constants to bcc-Fe and fcc-Ni and similar elastic deformation compatibility in Y2Ti2O7-strengthened Fe-based and Ni-based ODS alloys is therefore expected. The Ni/oxide interface has generally better thermostability than Fe/oxide across the whole range of the concerned oxygen chemical potential. Further interface bonding and adhesion calculations revealed that Y2Ti2O7 can enhance the bonding strength of Ni/Y2Ti2O7 through d-d orbital interaction between the interfacial YTi layer and Ni layer, while the interface bonding between the Fe layer and YTi layer is weakened compared to the metal matrix. First-principles calculations suggest that Y2Ti2O7 can be a candidate for strengthening nano-oxides in either Fe-based or Ni-based ODS alloys with well-behaved mechanical properties for fourth-generation fission reactors and further experimental validations are encouraged. [ABSTRACT FROM AUTHOR]

Dynamic material constants obtained by wave-based methods are different from their static counterparts. Constraining rock's elastic constants' dynamic-to-static ratios (Rij) are important for understanding the geomechanical properties of earth's materials, particularly in the context of hydraulic fracturing that requires the knowledge of shale's static elastic constants. Conducting experiments with dynamic and elastic constants' anisotropy, on top of their pressure dependency, properly accounted for is challenging. Here, we measure suites of dynamic and static elastic constants, with anisotropy fully accounted for, on the shale samples extracted from the Duvernay unconventional reservoir; a comprehensive set of geochemical/petrophysical measurements are obtained too. We observe that the dynamic-to-static ratios are generally not sensitive to the increasing pressures at σ  > 50 MPa; we do not find a correlation with the samples' mineral contents either. However, we find that Rij strongly correlates to the dynamic elastic constants except for the R 11. The correlation between Rij , particularly Ri3, and the dynamic elastic constants can be explained by the sedimentary rocks' compactness and the horizontal void spaces parallel to the rock's laminated bedding planes. [ABSTRACT FROM AUTHOR]

Designing a particular change in a system structure to achieve the desired elastic properties of materials for a given task is challenging. Recent studies of purely geometrical atomic models have shown that structural modifications on a molecular level can lead to interesting and desirable elastic properties. Still, the result of such changes is usually difficult to predict. The present work concerns the impact of nanolayer inclusion ordering in hard sphere crystals on their elastic properties, with special attention devoted to their auxetic properties. Two sets of representative models, based on cubic crystals consisting of 6 × 6 × 6 unit cells of hard spheres and containing either neighboring or separated layers of spheres of another diameter, oriented orthogonally to the [001] direction, have been studied by Monte Carlo simulations in the isothermal–isobaric (NpT) ensemble. Their elastic constants have been evaluated using the Parinello–Rahman approach. The Monte Carlo simulations showed that introducing the layer inclusions into a pure face-centered cubic (FCC) structure leads to the system's symmetry changes from cubic symmetry to tetragonal in both cases. Essential changes in the elastic properties of the systems due to layer ordering were found both for neighboring and separated inclusions. It has been found that the choice of a set of layer inclusions allows one to tune the auxetic properties in two crystallographic directions ( [ 110 ] [ 1 1 ¯ 0 ] and [ 101 ] [ 1 ¯ 01 ] ). In particular, this study revealed that the change in layer ordering (from six separated layers to six neighboring ones) allows for, respectively: (i) enhancing auxeticity of the system in the [ 101 ] [ 1 ¯ 01 ] direction with almost loss of auxetic properties in the [ 110 ] [ 1 1 ¯ 0 ] direction in the case of six separated layers, while (ii) in the case of six neighboring layers, keeping the auxetic properties in both auxetic directions independently of the size of spheres constituting inclusions. [ABSTRACT FROM AUTHOR]

Highlights 2.5D woven composite material inevitably produces void defects in its production process, which will seriously reduce its mechanical properties and reduce its service life. In this paper, the effects of void defects on the mechanical properties of 2.5D woven composites were studied by multi‐scale analysis. An improved Halpin‐Tsai semi‐empirical model is proposed to calculate the elastic properties of yarns with porous defects and verified by finite element method. A microscale representative volume unit (RVE) for predicting the elastic constants of composites with pore defects is established. Theoretical analysis and finite element analysis were used to verify the micro scale, and finite element analysis and experiment were used to verify the micro scale. The effect of porosity on the elastic properties of micro‐scale RVE was studied in detail. The results show that the model is reasonable and accurate in predicting the mechanical properties of yarns and composites. In addition, the effect of porosity on the mechanical properties of 2.5D woven composites is significant. An improved Halpin‐Tsai semi‐empirical model is proposed, which makes the microscale theoretical analysis of 2.5D woven composites better consistent with the finite element analysis. The void position obstructs the stress transfer of the matrix, and the stress concentration phenomenon also occurs. The void content has an effect on the mechanical properties of composites at both micro and micro scales. [ABSTRACT FROM AUTHOR]

The structural, mechanical, optical, thermo-physical, and electronic properties of the monoclinic XGaH 5 (X = Ba, Ca, and Mg) used as hydrogen storage material were investigated in detail using the ab initio technique. Gravimetric hydrogen densities (5.1 wt % for the MgGaH 5 , 4.4 wt % for the CaGaH 5 , and 2.38 wt % for the BaGaH 5), hydrogen desorption temperatures (29.05 K for the MgGaH 5 , 175.56 K for the CaGaH 5 , and 218.36 K for the BaGaH 5) and enthalpies of formation (−0.039 eV/atom for the MgGaH 5 , -0.237 eV/atom for the CaGaH 5 and -0.296 eV/atom for the BaGaH 5) of these compounds were also calculated. As a result of electronic band structure calculations, band gap values for BaGaH 5 , CaGaH 5 , and MgGaH 5 were obtained as 3.08 eV, 4.05 eV, and 3.61 eV, respectively. It is clear from the high band gap values that all three materials have insulator character. The second-order independent elastic constant values, which provide information about the hardness and mechanical stability of the materials, were calculated. The elastic constant values showed that XGaH 5 is mechanically stable. Hardness parameters such as bulk modulus, shear modulus, B/G ratio (1.19 for the MgGaH 5 , 1.11 for the CaGaH 5 , and 1.68 for the BaGaH 5), Young's modulus, and Poisson's ratio were also calculated using elastic constant values. According to the B/G ratio, all three structures were found to be brittle materials. From Poisson's ratio (0.17 for the MgGaH 5 , 0.15 for the CaGaH 5 , and 0.25 for the BaGaH 5), the atoms in XGaH 5 compounds are connected by covalent bonds. Besides, the formation enthalpies of the materials were calculated, and it was concluded that all three compounds could be synthesized in the laboratory. In addition, some optical properties of XGaH 5 such as dielectric function, conductivity, reflectivity, and absorption were also calculated. Finally, thermo-physical properties were calculated for XGaH 5 compounds. • First-principles calculations to investigate XGaH 5 materials for hydrogen storage applications. • XGaH 5 (X = Ba, Ca, and Mg) compounds are found to be mechanically stable and brittle. • The desorption temperature values for MgGaH 5 , CaGaH 5 , and BaGaH 5 are 29.05 K, 175.56 K, and 218.36 K, respectively • MgGaH 5 5.1 wt % has a higher gravimetric hydrogen densities. [ABSTRACT FROM AUTHOR]

In this study, the mechanical characteristics of Cu2ZnSnS4 are investigated under varying pressures. The correlations between pressure and elastic constants Cij, bulk modulus B, shear modulus G, and Young's modulus E, are obtained. The thermal properties of Cu2ZnSnS4 were studied, including Debye temperature, heat capacity CV and CP, thermal expansion coefficient a, Grüneisen constant and entropy S at temperatures (0, 200, 400, 600, 800, 1000, 1200K) and pressures (0, 2, 4, 6, 8, 10 GPa), are also obtained and analyzed. [ABSTRACT FROM AUTHOR]

A comprehensive examination of the crystal structure, as well as elastic and thermal properties, of the recently created Zintl phase CsGaSb2 has been carried out using ab initio density functional theory pseudo-potential plane-wave calculations. All the provided facts presented are newly forecasted, with the exception of the structural properties under normal conditions. The calculated lattice parameters and interatomic bond lengths of the investigated material closely correspond to the actual values, indicating a high level of accuracy. Forecasts have been generated for the elastic parameters and related characteristics of both single-crystal and polycrystalline phases of CsGaSb2. The parameters encompassed in this list are elastic constants, shear modulus, bulk modulus, Poisson's ratio, Young's modulus, anisotropy indices, elastic wave velocities, Pugh's criterion, and Debye temperature. The mechanical and dynamic stability of CsGaSb2 as well as its elastic anisotropy have been established. The temperature dependence of various macroscopic properties, including bulk modulus, unit cell volume, volumetric thermal expansion coefficient, isochoric and isobaric thermal capacities, Debye temperature, Grüneisen parameter, and entropy function, was evaluated at specific pressures using Debye's quasi-harmonic approach in combination with ab initio calculations. [ABSTRACT FROM AUTHOR]

• The modified energy method evaluated the elastic properties of SWBNNT, and the inversion energy term was considered. • Temperature's impact on BNNT's elastic properties was explored by incorporating it as an independent variable. • MSM and continuum mechanics models are used to evaluate the changes in different bonds, bond angles, and reaction angles. The elastic properties of boron nitride nanotubes (BNNTs) were investigated utilizing an enhanced energy method. By considering small deformations and applying the principle of minimum potential energy, the variations in atomic bonds and bond angles within the nanotube structure were determined. The modified model incorporated the contribution of inversion energy to the overall potential energy of the system, leading to the derivation of analytical expressions for the Young's modulus, shear modulus, and strain energy of both armchair and zigzag BNNTs under varying temperatures. The results indicate that compared to zigzag BNNTs, the impact of inversion energy on the elastic constants of armchair BNNTs is more significant, especially at small diameters (<1 nm). In thermal environment, this study demonstrates that the change in Young's modulus of BNNTs is lower than that of carbon nanotubes (CNTs), confirming the superior thermal stability of BNNTs over CNTs. Furthermore, molecular structure mechanics (MSM) and continuum mechanics models were employed to analyze the strain energy of BNNTs. The effects of different bonds, bond angles, and inversion angles on strain energy were analyzed in a thermal environment, revealing distinct differences between the two types of BNNTs. These findings provide more accurate theoretical guidance for thermal applications based on the stretching of BNNTs. [ABSTRACT FROM AUTHOR]

Using state-of-the-art first-principles electronic-band-structure calculations alongside density functional theory, we investigated the structural, elastic, electronic, and magnetic properties of LiMnZ2 (Z = Se, Te) compounds with a trigonal structure. Initially, we determined the equilibrium lattice structure and atomic positions, which aligned well with experimental values. Ferromagnetism was shown to be more favorable than the non-magnetic state. The elastic constants, cohesive energies, and formation energies indicated that the studied compounds were mechanically stable in the experimentally determined trigonal lattice. The analysis of spin-polarized band structures and density of states revealed that both LiMnZ2 compounds exhibited perfect half-metallic characters. The total spin magnetic moment per formula unit adhered to the Slater–Pauling rule, being exactly 4 μΒ, mainly concentrated at the Mn atoms due to the strong spin polarization of the Mn d orbitals. We anticipate that our results will prompt further experimental and computational studies for the application of these layered materials in practical devices. [ABSTRACT FROM AUTHOR]

The temperature dependent mechanical, thermo-physical and nonlinear ultrasonic properties of europium monopnictides EuX (X: N, P, As and Sb) were studied in this exploration. The 2nd and 3rd order elastic constants (SOECs and TOECs) of EuX were computed with the help of Coulomb and Born-Mayer potential applying two fundamental indicators i.e., the nearest neighbour distance and the hardness parameter in the temperature span 100-300K. Further the SOECs are applied to enumerate the mechanical variables such as elastic moduli, Zener anisotropic ratio, Poisson's ratio and Pugh's index using Voigt-Reuss-Hill (VRH) approach at T=300K. The results derived from elastic and mechanical properties confirm the mechanical stability and brittle nature of EuX. The acoustical velocities have been enumerated using the SOECs and density of EuX along <100>, <110> and <111> directions at T=300K. All above physical parameters have been utilized to compute the direction dependent Grüneisen parameter and Debye characteristic temperature of EuX at T=300K. The achieved values of this exploration are discussed and equated with materials of similar characteristics. [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]

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]

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]

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]

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]

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]

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]

The structural, microstructural, optical, and elastic properties of polycrystalline perovskite series, Ca1+xCu3–xTi4O12; x = 0–1.0, have been investigated employing X-ray powder diffractometry, scanning electron microscopy, UV–Vis spectroscopy, and ultrasonic pulse-echo selection technique at 300 K. The primary structural parameter and ultrasonic parameters; longitudinal wave velocity (V1), the amplitude of transmitted and reflected pulses ao/an were used to calculate porous values of various elastic parameters such as shear wave velocities Vs, mean sound velocity Vm, elastic moduli L, B, G, E, Debye temperature θ, Poisson's ratio σ, acoustic impedance Z, internal friction Q–1, absorptivity A, adiabatic compressibility Ba, Lame's constant λL, and Vickers micro-hardness Hv. The elastic constants were emended to a void-free state using eight distinct semi-empirical methods. These models are principally relying on the pore morphology in the material. Depending upon the correction model employed, Lo is found to decrease from ~21.5 to ~39.5%, Bo from ~17.4 to 45.6%, while Eo and Go are found to decrease from ~22 to 34% on Ca2+ substitution (x = 0–0.5) in the system. Besides, the observed increase in different elastic moduli for x = 1.0 composition is found to vary from 0.3 to 7%. The compositional dependency of elastic moduli has been explained in terms of the change in interatomic bonding strength produced by variations in interatomic distances, microstructure, and electronic configuration. The values of Pough's ratio Bo/Go, Frantsevich's ratio Go/Bo, and Poisson's ratio σo suggest the brittle nature of prepared ceramics. [ABSTRACT FROM AUTHOR]

Influence of Gd substitution on the structural, microstructure, dielectric, elastic and magnetic properties of Mg–Cu–Zn ferrites with the compositions Mg 0.3 Cu 0.2 Zn 0.4 Gd x Fe 2.1 - x O 4 (where x = 0.0, 0.01, 0.02 and 0.04) have been reported in this study. The structural property has been performed with an X-ray diffraction technique. It shows a single-phase cubic spinel structure for x ≤ 0.01, while a small peak of GdFeO 3 is seen with the spinel structure for x > 0.01. The surface morphology study indicates that the grain growth of Mg–Cu–Zn ferrites depends on the Gd content. It reveals that the average grain size is found to be larger for x = 0.01, which could be attributed to the densification of the sample. The magnetic hysteresis loop has been investigated for all the prepared samples. It shows that the saturation magnetization is found to be larger for x = 0.01, which is also correlated to the grain size. The dielectric constant of the prepared samples has been studied at 300 K as a function of frequency. An enhancement of the dielectric constant is observed for Gd-substituted Mg–Cu–Zn ferrites. The Cole–Cole plots have displayed a single semicircular arc, which indicates that the conduction mechanism occurred through a grain effect. The elastic constants such as bulk modulus, Young's modulus, rigidity modulus and Poisson's ratio have been calculated for all the studied samples. It reveals that all the synthesized samples are in ductile nature. It is expected that Gd substituted Mg–Cu–Zn ferrites with the composition Mg0.3Cu0.2Zn0.4Gd0.01Fe2.09O4 is a potential material for high-frequency operation. [ABSTRACT FROM AUTHOR]

In this study, we have investigated a range of structural, elastic, electronic, optical, and thermoelectric properties of halide double perovskites Cs2BʹGeCl6 (Bʹ: Zn, Cd). Our analysis was conducted using the full potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) and the modified Becke–Johnson (mBJ) potential. Structural parameters were determined through optimization and analytical schemes, allowing us to precisely define the crystal structure. Elastic properties, including elastic constants, shear modulus, Young's modulus, anisotropy factor, and Poisson's ratio, were calculated to assess the materials' mechanical characteristics. The electronic properties of these double perovskites reveal their semiconductor nature, characterized by an indirect energy band gap (Xv-Lc). Optical properties, including as the dielectric function, absorption coefficient, refractive index, extinction coefficient, reflectivity, electron energy loss, and optical conductivity, were computed across a photon energy range up to 13.0 eV to elucidate the optical response of the materials. Additionally, we predicted the thermoelectric properties of Cs2BʹGeCl6 (Bʹ: Zn, Cd) by calculating key thermoelectric coefficients, including the Seebeck coefficient and power factor. Our findings suggest the potential suitability of Cs2BʹGeCl6 (Bʹ: Zn, Cd) double perovskites for applications in photovoltaic and thermoelectric devices. [ABSTRACT FROM AUTHOR]

[Display omitted] For the first time, the elastic constants c 11 , c 12 , and c 44 of disordered cubic titanium monoxide TiO y were determined depending on the oxygen content y in the homogeneity region from TiO 0.80 to TiO 1.25. It has been established that the values of the elastic moduli depend on the oxygen content y and the crystallographic direction [ hkl ]. Large changes in the elastic characteristics of TiO y depending on the [ hkl ] direction indicate a strong anisotropy of the elasticity of disordered cubic titanium monoxide. [ABSTRACT FROM AUTHOR]

The temperature-dependent characterization of full tensor properties of single-domain relaxor-based single crystals (SCs) is important for understanding the influence of temperature on the properties of their multidomain SCs. However, no relevant results have been published because characterization is difficult to achieve using the traditional electric resonance method. In this Letter, the temperature-dependent elastic and piezoelectric properties of single-domain [111]c poled Mn-doped 28Pb(In1/2Nb1/2)O3-43Pb(Mg1/3Nb2/3)O3-29PbTiO3 SCs were investigated in the range of 20–80 °C by resonant ultrasound spectroscopy (RUS) using a rectangular parallelepiped sample. The temperature-dependent dielectric constants were calculated from the measured capacitances of the sample. The results are self-consistent because they were obtained from the same sample. The elastic constants obtained using the ultrasonic pulse-echo method agree closely with those obtained using RUS. Moreover, the experimental results of electric impedance spectrum agree closely with those simulated using the material constants characterized herein, indicating that the characterization is reliable. [ABSTRACT FROM AUTHOR]

Ordinary nematic liquid crystals have a uniform director field as ground state. However, there are relevant examples of spontaneously twisted nematic states, not only in chiral, but also in achiral materials. Different twist configurations can be found, with the director modulation along the twist axis, as in the cholesteric and in the twist-bend nematic phase, or perpendicular to it, as in blue phases and in skyrmion structures. Here, we develop a generalised Maier–Saupe theory to calculate the thermodynamic and elastic properties, included saddle-splay, of nematics made of particles whose shape can be described as a distorted rod. This turns out to be a powerful approach for screening the relation between the molecular shape and the formation of modulated nematic phases. Application to the paradigmatic models of banana-shaped and helical particles allows us to identify the role of distinct shape features, such as curvature and chirality, and the distinct mechanisms by which these promote twisted configurations. [ABSTRACT FROM AUTHOR]

In our previous works we have shown that the elastic properties of the intercalated SmAb phase formed by bent-shaped dimers are governed by the nematic-like behaviour of the secondary director m that is associated with the projection of the molecular axes of the monomers on the plane of the smectic layer. From the experiment, the corresponding three Frank-like moduli $K_{11}^m$ K 11 m , $K_{22}^m$ K 22 m and $K_{33}^m$ K 33 m related to the secondary director demonstrate the usual behaviour of the Frank moduli of the nematics formed by rod-like molecules: monotonously increase with decreasing temperature. This is contrary to the temperature dependence of the elastic moduli for the primary director of N and NTB phases formed by bent-shaped dimers (for which the bend elastic constant decreases with temperature to zero). However, the values of the Frank-like moduli for SmAb were found to be smaller than their nematic-phase equivalents, and demonstrate a strong and unusual anisotropy, with $K_{11}^m$ K 11 m : $K_{22}^m$ K 22 m : $K_{33}^m$ K 33 m ratio being approximately 30 : 1 : 10. Here we present a theoretical model based on the assumption of the nematic-like order within the smectic layers that provides a qualitative explanation of the experimental results. [ABSTRACT FROM AUTHOR]

In the current investigation, we have explored the structural, electrical, optical, thermoelectric, and elastic features of potassium(K) based halide double perovskite K2MBiBr6 (M = Na, Ag, Cu) using the WIEN2k code under the framework of density functional theory. Various factors, including negative formation energy, structural optimization, tolerance, and octahedral factors, verify the stability of perovskites. The generalized gradient approximation has been employed to investigate the structural phase and elastic properties. The Tran-Balaha modified Becke-Johnson function has been utilized to precisely evaluate the electronic, optical, and thermoelectric properties. The electronic parameters, such as band gap and density of states revealed that K2NaBiBr6, K2AgBiBr6, and K2CuBiBr6 are semiconductors, with indirect bandgaps of 4.01, 2.36, and 1.26 eV, respectively. For optical properties, the current study has examined characteristics such as energy loss, refractive index, light energy absorption, and polarization through the entire energy spectrum, which ranges from 0 to 8 eV. The BoltzTraP code is used to examine thermoelectric characteristics, revealing maximum ZT values of 0.75, 0.77, and 0.78, respectively. This study further emphasizes the elastic constants of cubic symmetry to figure out the variation between ductile and brittle nature, anisotropy, and the large melting temperature of these materials. The theoretical findings given in the present article have substantial impacts on the future renewable energy sector especially solar cells and electron transport applications. [ABSTRACT FROM AUTHOR]

The family of ternary Chalcogenides systems has been investigated for their potential applications in optoelectronic devices. We present first-principles calculations of structural, elastic, magnetic, optical properties, and the effective mass of the Sulvanite compounds NbTu2S4 (Tu = Fe, Rh) is determined by GGA + U. The electronic band gaps are NbFe2S4 (2.4 eV (up)/1.8 eV (dn) and NbRh2S4 (2.07 eV (up)/1.6 Ev (dn), which are comparable to other computed results. Optical properties such as absorption coefficient, dielectric function, energy loss function, reflectivity function, refractive index, and extinction coefficient have been calculated for the first time. There is no difference between the materials regarding transparency in the visible range. The low hole effective mass and high valence band indicate a P-type material with photovoltaic applications. Plasma frequencies are observed around 13 eV for both investigated crystals. Sulvanite crystals have effective masses computed from high symmetry points varying non-linearly. The elastic parameter was used to study elastic properties. It is observed that both crystals show an anisotropic nature and ductility. The optical properties suggest that these crystals could be suitable for optoelectronic devices. [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]

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]

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]

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]

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]

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]

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]

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]

In this work, we report on a comparative study of the structural, optical, and elastic properties of SrTiSe3 and SrZrSe3 compounds using the DFT method. The lattice constants of the compounds are calculated using the GGA-PBE approximation and the hybrid functional Heyd, Scuseria, and Ernzerhof (HSE). The properties of the SrTiSe3 and SrZrSe3 materials in relation to electronic composition, elastic constants, and optical characteristics are deduced and analyzed. Both compounds display magnetic behavior, according to electronic calculations. SrTiSe3 shows metallic behavior, as the calculated bandgap value is zero. SrZrSe3, on the other hand, has a bandgap of 0.347 eV, which demonstrates its semiconducting nature. We have demonstrated that the plasma frequency of SrTiSe3 is around 1.77836. Using density functional theory, we report on the electronic characteristics of the compounds under mechanical stress. For SrZrSe3, the gap energy values rise with compressive stress and decrease with increasing tensile stress to zero. In addition, the study includes the extinction coefficient, optical conductivity, dielectric tensor, electron energy loss, and refractive index. [ABSTRACT FROM AUTHOR]

First-principles calculations are carried out to investigate the effect of pressure (up to 40 GPa) on electronic, optical and elastic properties of the scintillator material calcium iodide, CaI2, by using Perdew–Burke–Ernzerh of generalized gradient approximation (PBE-GGA). The electronic band structure reveals an indirect band gap of 3.89 eV and a direct band gap of 4.35 eV for zero pressure. We have also calculated the pressure dependence of optical properties. The elastic constants and elastic moduli increase nonlinearly with pressure. Decreasing Pugh's ratio and increasing hardness with pressure indicate a cross-over from ductile to brittle nature at 5 GPa. Analyses of elastic properties show that CaI2 is mechanically stable up to the applied pressure of 40 GPa. The calculated light yield increases linearly with pressure yielding a pressure coefficient of 1327 ph/MeV per GPa due to the decreasing band gap. Light yield increases as much as 62% at 40 GPa. [ABSTRACT FROM AUTHOR]

In this paper, we studied the magnetic stability, structural, elastic and electronic properties of Ir2FeAl full Heusler compound in the regular phase (Cu2MnAl, prototype L2 1) , by using the first principle of density functional theory, with the generalized approximation of the GGA gradient. We found that the ferromagnetic state of Ir2FeAl is more stable than the nonmagnetic configuration at their lattice parameters equilibrium. This result was confirmed by the calculation of the cohesive energy. The stability is asserted by the elastic constants and the conditions of the mechanical stability criterion. The band structure and the calculated densities of states (DOS) of this alloy show a semi-metallic behavior. The ferromagnetic performance of Ir2FeAl is confirmed by the total magnetic moment of 4.28 μ B , where its major contribution comes from Fe atoms. We estimated the Debye temperature of Ir2FeAl from the average speed of sound. This is the first quantitative theoretical prediction of the elastic properties of the Ir2FeAl compound, and it still awaits experimental confirmation. [ABSTRACT FROM AUTHOR]

Here, we report time-resolved broadband transient reflectivity measurements performed in a single crystal of SnS2. We made use of time-domain Brillouin scattering and a broadband probe to measure the out-of-plane longitudinal sound velocity, υ L = (2950 ± 100) m s – 1 , in this semiconducting two-dimensional metal dichalcogenide. Our study illustrates the potential of this non-invasive all-optical pump–probe technique for the study of the elastic properties of transparent brittle materials and provides the value of the elastic constant c 33 = (39 ± 3) GPa. [ABSTRACT FROM AUTHOR]