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This study proposes a simple yet effective dynamic method that can nondestructively evaluate the elastic properties of homogeneous isotropic solid materials. Like some dynamic methods, such as resonance ultrasound spectrometry and impulse excitation technique, the proposed method consists of two steps: experimentally acquiring the specimen's natural frequencies and numerically calculating the elastic properties. Compared with the existing methods, the proposed method has much lower requirements on all four aspects of experimental operations: specimen preparation, specimen positioning, vibration excitation, and vibration detection. An inverse method based on finite element modal analysis is proposed to calculate the specimen's elastic properties, and it can deliver optimal estimations with high precision and accuracy. The performance of the proposed method was assessed using the well-established sound speed-based dynamic method, i.e., ultrasound pulse-echo testing. Taking a square aluminum specimen as an example, the differences in the measurements of Young's modulus and Poisson's ratio between these two methods are 2.25% and −2.07%, respectively; the differences in the measurements of shear modulus and bulk modulus are 0.01% and −1.46%, respectively. In summary, the proposed method provides a cheaper and experimentally simpler approach to determining the elastic properties of solid materials while maintaining accuracy and reliability similar to the established methods, which typically require sophisticated, costly equipment. [ABSTRACT FROM AUTHOR]

β-LiGaO2 with a wurtzite-like crystal structure is a direct ultra-wide bandgap semiconductor. Similar to many wide bandgap oxides, the valence band of LiGaO2 is predominantly composed of O-2p orbital, leading to a low valence band position, drastically limiting its applications. In this work, we employ first-principles calculations to demonstrate that adding a small amount of Bi into LiGaO2 to form the highly mismatched Li(Ga1−xBix)O2 alloys can dramatically modulate the valence band compositions. Compared to LiGaO2, the valence band maximum of the alloys is significantly elevated, and a fully occupied intermediate valence band appears, further raising the valence band positions. Despite the appearance of intermediate valence bands that significantly reduce the alloys' bandgap, the bandgap remains over 3.10 eV, ensuring visible light transparency. With increasing Bi composition in the alloys, the bulk modulus increases while the shear modulus gradually decreases, which improves the ductility. Moreover, the compliant elastic constants of the alloys indicate mechanical stability. These findings suggest that Li(Ga1−xBix)O2 alloys are promising flexible transparent conductive oxides, offering valuable insights for future applications. [ABSTRACT FROM AUTHOR]

To develop special insulating paper is of great significance to promote the service life of transformers. Using molecular simulation to guide the development of special insulating paper can greatly reduce the trial-and-error rate and waste of resources in traditional experiments. The effect of different types of polysilsesquioxane (POSS) on cellulose insulating paper was investigated by using molecular simulation. This paper investigated the thermal stability and mechanical properties and electrical characteristics of caged POSS, semi-caged POSS, and ladder-like POSS doped cellulose insulating paper. The results show that POSS with all types can enhance the performance of cellulose insulating paper, and ladder-like POSS possess the best modification effect. The glass transition temperature was increased by 58 K, and the bulk modulus, shear modulus, and elastic modulus of cellulose insulating paper doped with ladder-like POSS can improve up to 27.07%, 45.67%, and 41.28%, respectively. Meanwhile, the dielectric properties of ladder-like POSS modified insulating paper are also significantly improved. The findings of this paper propose a method for the preparation of ladder-like POSS modified insulating paper, which provides theoretical guidance for the experimental preparation of special insulating paper. [ABSTRACT FROM AUTHOR]

This work employs density functional theory calculations to investigate the structural, hydrogen storage, mechanical, electronic, optical, and bonding characteristics of perovskite hydrides KNaX 2 H 6 (X = Mg, Ca) for potential hydrogen storage applications. Negative formation energies, positive phonon dispersions, and appropriate tolerance factor values confirm the thermodynamic, dynamic, and cubic structural stability of these compounds. KNaMg 2 H 6 exhibits a promising gravimetric hydrogen storage capacity of 5.19%, while KNaCa 2 H 6 shows 4.09%. Both compounds display semiconducting behavior with indirect energy band gaps of 3.31 eV and 3.17 eV, respectively. Key mechanical properties, including bulk modulus, shear modulus, and Poisson's ratio, were evaluated using computed elastic constants. The desorption temperature for KNaMg 2 H 6 , determined to be 470.4 K, renders it suitable for practical applications. Partial Bader charge analysis reveals both ionic and slightly covalent bonding interactions. Optical analysis demonstrates strong ultraviolet absorption capabilities with a redshift in the absorption spectrum. The computed properties indicate these materials hold promise for hydrogen storage applications. • DFT study of KNaX 2 H 6 (Y Mg, Ca) perovskites for H 2 storage applications. • KNaX 2 H 6 (Y Mg, Ca) hydrides are mechanically and thermodynamically stable. • KNaX 2 H 6 (Y Mg, Ca) hydrides are semiconductors in nature. • The gravimetric ratios are found 5.19% for KNaMg 2 H 6 and 4.09% for KNaCa 2 H 6. [ABSTRACT FROM AUTHOR]

The strontium based hydrides XSrH 3 (X = Cs , Fr) are investigated in current study using first principles calculations for hydrogen storage applications. The obtained lattice constants for CsSrH 3 and FrSrH 3 are 4.88 Å and 4.74 Å respectively. The gravimetric hydrogen storage capacity ( C wt %) for CsSrH 3 and FrSrH 3 is 1.33% and 0.95%. The optimized lattice constants are utilized to compute elastic constants and mechanical parameters. The Young's modulus, bulk modulus and shear modulus for FrSrH 3 is larger than that of CsSrH 3 revealing the greater mechanical strength of FrSrH 3. The investigations of band structures and density of states indicating the semiconducting nature of with gaps 2.95 eV, 2.52 eV with PBE-GGA and 5.40 eV, 4.54 eV with TB-mBJ for CsSrH 3 and FrSrH 3 respectively. The dynamical stability for both hydrides is confirmed from phonon properties. The thermodynamic parameters are calculated under the variation of temperature and pressure. The heat capacities, volume, entropy and thermal expansion coefficient increase with temperature and decrease with pressure. • The gravimetric hydrogen storage of XSrH 3 (X = Cs, Fr) is explored for the first time. • The elastic, mechanical and transport properties of XSrH 3 (X = Cs, Fr) are investigated. • The PBE-GGA and TB-mBJ methods are used to explore band structures and optical properties. [ABSTRACT FROM AUTHOR]

This study focuses on the relationship between porosity, surface roughness, microstructure, strength, and thermal properties, as well as their effect on the bioactivity and biodegradability of fabricated akermanite (AK; Ca 2 MgSi 2 O 7) bioceramic scaffolds. Firstly, we prepared the AK nanopowders using the mechanical activation method, mixed them with varying proportions of space-holder agent (NaCl), specifically 15, 20, 30, 40, and 50 vol%, and sintered them at 1200 °C to create porous scaffolds. We investigated the physical properties and microstructure using the Archimedes method and field emission scanning electron microscopy (FE-SEM), respectively. The mechanical properties in terms of microhardness, compressive strength, longitudinal modulus, Young's modulus, bulk modulus, and shear modulus were measured. The bioactivity and biodegradability of prepared scaffolds were assessed after soaking in simulated body fluid (SBF) for 10 days by FE-SEM and inductively coupled plasma-atomic emission spectroscopy (ICP-AES), respectively. The results revealed that porous scaffolds with suitable mechanical properties, bioactivity, and biodegradability were prepared. The porosity had a significant impact on the mechanical and biodegradability of the investigated scaffolds. It reduced mechanical properties slightly while improving bioactivity and biodegradability. The microstructure study displayed that all scaffolds formed apatite layer on their surfaces. This is because of good bioactivity and the suitable porosity level of AK. The obtained findings provide promising prospects for the future use of AK in bone tissue engineering. [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]

Semiconductor behavior has emerged as a promising substance for numerous advancements in natural energy production, storage, and conversion, as well as in medical technology due to exceptional properties and capabilities of the perovskites. Additionally, this property also presents a great opportunity for solar cells to serve as a substitute for conventional silicon‐based photovoltaic systems, as they provide greater efficiency and cost‐effective conversion of sunlight to electricity. Here, we are for the first time investigating lead‐free environment‐friendly cubic perovskites ASnX3 (A = Na and Li; X = Cl, Br, and I) under different hydrostatic pressures ranging from 0 to 5 GPa. Utilizing the GGA + PBE functional method with a space group of 221 (Pm3m), ASnX3 compounds (A = Na and Li; X = Cl, Br, and I) demonstrate direct bandgaps at 0 GPa, ranging from 0.790 to 0.282 eV for Li‐based halides and 0.760–0.296 eV for Na‐based halides, characterizing their semiconductor nature within the perovskite crystal lattice. Furthermore, our analysis revealed that the conduction band and the valence band intersect at a point above the Fermi level which influences the transition of semiconductor to metal or the creation of a half‐metallic state. The optical and structural properties of the compound were also examined, and as the pressure rose from 0 to 5 GPa, the absorption redshift occurred. The analysis of magnetic properties revealed that ASnX3 (A = Na and Li; X = Cl, Br, and I) compounds have diamagnetic behavior in both normal and under pressure conditions. Meanwhile, compounds that satisfy mechanical stability requirements up to certain pressures demonstrate alternations in bulk modulus, shear modulus, and Young's modulus. The compounds show ductile behavior as their Poisson's ratio values range between 0.28 and 0.44 for every compound. Increasing pressure increases the values of the compounds, but the compounds remain in the same range of ductile material and show better ductility. Finally, increasing pressure influences the characteristics of the compounds as I‐based compounds change phase transitions from semiconductor behavior to metallic behavior. On the other hand, Cl‐based and Br‐based compounds show semimetallic behavior for increased pressure. [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]

Unconsolidated porous media are distinct from consolidated porous rocks in the negligible bulk and shear moduli. This paper is motivated by resolving the control mechanism of P-wave attenuation in the media (represented by Toyoura sands and glass beads) saturated with water. The first model is Biot theory in which longitudinal friction (arising from velocity difference between the two phases) is quantified using dynamic permeability as a function of frequency. The first model simulates phase velocity (Vp) and the ultrasonically measured quality factor (Qp) well. A second model is the transverse squirt model in which squirt is induced by pressure differential between contact of grains (COG) and the main pore space. The second model outputs unrealistic Vp and Qp. The results reveal that P-wave attenuation in unconsolidated porous media (saturated with water) is governed by longitudinal friction rather than intrapore squirt. Remarkably, low-frequency dynamic permeability is much smaller than Darcy permeability, indicating that ultrasonic P-wave is surprisingly capable of indirectly detecting the very narrow gap at COG. [ABSTRACT FROM AUTHOR]

In this paper, the silicone rubber (SR)/thermoplastic polyurethane (TPU) composites and its compatibilizers were studied by molecule dynamics simulation and experiment. Three compatibilizers, fluorosilicone rubber (FSR), dendritic hydroxyl-terminated silicone oil (DHSO), and fluorinated modified tetraethyl orthosilicate grafted silicone rubber (FTEOS-g-SR) were introduced into the SR/TPU composites. The simulation results showed that the cohesion density of pure SR was 3.072 × 108 J/m3, the solubility parameter was 17.504 (J/cm3)0.5, the Young's modulus was 4.0139 GPa, the shear modulus was 1.4493 GPa, and the bulk modulus was 5.8061 GPa. Moreover, the cohesion density of SR/TPU/FSR and SR/TPU/DHSO increased to 4.693 × 108 and 3.459 × 108 J/m3, solubility parameter increased to 21.662 and 18.597 (J/cm3)0.5, the Young's modulus increased to 6.6399 and 6.0020 GPa, shear modulus increased to 2.4377 and 2.2060 GPa, and bulk modulus increased to 8.0148 and 7.1653 GPa, respectively. However, the cohesion density, solubility, and young's modulus of SR/TPU/FTEOS-g-SR decreased to 2.617 × 108 J/m3, 16.174 (J/cm3)0.5, 3.872 GPa, 1.7510 Gpa, and 1.6365 GPa. These results demonstrated that both FSR and DHSO can improve the mechanical properties of the SR/TPU composites, while the FTEOS-g-SR reduced their mechanical properties. The compatibility and mechanical properties of SR/TPU composites modified by FSR and DHSO were verified and compared. The factors such as blending temperature, blending ratio, and TPU types of SR/TPU composites were considered. Compared to composites cured at 185 °C, those cured at 175 °C exhibited better mechanical properties. The dynamically vulcanized SR/TPU (3:7, mass ratio) materials showed superior tensile strength and elongation at break when compared to the SR/TPU (5:5, mass ratio) composites. Moreover, the polyether type of TPU was found to be more favorable than the polyester type for obtaining a blended composite with good tensile properties. The experimental results demonstrated that both compatibilizers contributed to improving the mechanical properties of the composites to a certain extent. The scanning electron microscope (SEM) test revealed that FSR enhanced the dispersion of SR in the TPU matrix. Additionally, charge distribution simulation analysis indicated the presence of abundant intermolecular hydrogen bonds between FSR and TPU, which played a significant role in the excellent compatibility and mechanical properties observed in this blend system. [ABSTRACT FROM AUTHOR]

The inversion of parameters characterizing reservoir property based on rock physics model is an important content in seismic exploration, while the strong nonlinearity between basic parameters and seismic attributes makes it challenging in practice or computationally expensive. This study focuses on the issue of wave propagation in porous media saturated with two immiscible fluids and proposes to utilize deep neural network (DNNs)-based surrogate model to conduct forward analysis and parameter inversion. First, three classical rock physics models were employed to generate the dataset for training DNNs. Among them, five basic parameters (the porosity, bulk modulus and shear modulus of rock matrix, the solid density, and the saturation) were sampled within each reasonable range, and then, the corresponding phase velocity and inverse quality factor of seismic wave were calculated based on the three models. Next, DNNs were trained as surrogate models of the three rock physics models for sensitivity analysis. Then, such approach was applied to parameter inversion and different scenarios with different provided information and unknown quantities were designed to investigate the feasibility. The results showed the sensitivity of different models to basic parameters determines the corresponding inversion accuracy. When providing the information on the compressional wave, the porosity can be well inferred in most cases, while the accuracies of inverting saturation based on different models vary. Furthermore, it was found that adding the information of the shear wave can improve the performance of parameter inversions to a high level. From the obtained results, it was concluded that the DNNs-based surrogate models can serve as efficient tools for forward and inverse problems. [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]

Context: To estimate the influence of temperature on properties of 2,4,6,8,10,12-hexanitro- 2,4,6,8,10,12-hexaazaisowurtzitane/1,4-dinitroimidazole (CL-20/1,4-DNI) cocrystal explosive, the supercell crystal of CL-20/1,4-DNI cocrystal model was established. The mechanical properties, sensitivity, and stability of cocrystal model under different temperatures (T = 225 K, 250 K, 275 K, 300 K, 325 K, 350 K) were predicted. Results show that mechanical parameters, including bulk modulus, tensile modulus and shear modulus are the lowest when temperature is 300 K, while Cauchy pressure is the highest, indicating that CL-20/1,4-DNI cocrystal model has better mechanical properties at 300 K. Cohesive energy density (CED) and its components energies decrease monotonically with the increase of temperature, illustrating that the CL-20 and 1,4-DNI molecules are activated and the safety of cocrystal explosive is worsened with the increase of temperature. Cocrystal model has relatively higher binding energy when the temperature is 300 K, implying that the CL-20/1,4-DNI cocrystal explosive is more stable under this condition. Methods: The CL-20/1,4-DNI cocrystal model was optimized and the properties were predicted through molecular dynamics (MD) method. The MD simulation was performed with COMPASS force field and the ensemble was set as NPT, external pressure was set as 0.0001 GPa. [ABSTRACT FROM AUTHOR]

DFT calculation is used to investigate the structural, electronic, optical, and elastic properties of AgCuSe and AgCuS. The calculations are performed using the ATK with generalized gradient approximation (GGA) in combination with Hubbard U correction parameters for both structures. The calculated band gap energies and partial density of state reveal that AgCuS has semiconductor properties unlike this AgCuSe has a metallic nature. The optical properties, real and imaginary parts of dielectric function are obtained for the energy range of 0 to 5 eV. Elastic stiffness coefficients (Cij), bulk modulus (B), shear modulus (G), and Young modulus (E) have been calculated. [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 evaluation of rock hydraulic fracturing tendency plays a crucial role in the selection of fracturing layers within reservoirs and the evaluation of post-compression capacity. The sandstone reservoirs in the Yihuang New Area have poor physical properties and are deeply buried. It is necessary to increase the production of oil and gas by hydraulic fracturing. Regarding the sandstones in the region, the following parameters were considered: combined compressive strength, bulk modulus, shear modulus, fracture index, horizontal-stress difference coefficient, and fracture toughness. In accordance with the catastrophe theory, a multi-level structure was established for the hydraulic fracturing-tendency evaluation of sandstone reservoirs, consisting of a target layer, a guide layer, and an indicator layer. A catastrophic model for evaluating the hydraulic fracturing tendency of sandstone reservoirs was established. The results are consistent with those obtained from the Analytic Hierarchy Process. However, the catastrophe theory significantly reduces subjective interference. The results indicate that when the hydraulic fracturing-tendency evaluation value is greater than 0.8, the reservoir can be fractured well; when the hydraulic fracturing-tendency evaluation value is between 0.7 and 0.8, the fracture reservoir is moderate; and when the hydraulic fracturing-tendency evaluation value is less than 0.7, the fractured reservoir is poor. The optimal fracture intervals for the Yi 70 well are 1320–1323 m, 1350–1355 m, and 1355–1360 m. The optimal fracture planes for the Yi 76 well are 1921–1925 m and 1925–1930 m. The optimal fracture planes for the Yi 10-1-26 well are 2487–2495 m, 2585–2587 m, and 2589–2591 m. The hydraulic fracturing-tendency model developed in this study has been applied to several well sections of sandstone reservoirs in the Yihuang New Area. Additionally, the model was compared with existing hydraulic fracturing-tendency evaluation models. The evaluation results are in agreement with the post-pressure capacity-monitoring data. The accuracy of the model presented in this study has been verified, as has its applicability to other sandstone reservoirs. [ABSTRACT FROM AUTHOR]

Structural, electronic, optical, thermoelectric ,and elastic properties of Mo- and W-based group-V compounds, TMX (TM = Mo and W; X = N, P, and As) have been studied by using the full-potential linear augmented plane wave method. Local spin density approximation (LSDA) has been used for exchange–correlation potentials. Pressure-dependent lattice constants and bulk moduli have been obtained using LSDA. Volume optimization, with and without spin-polarization, reveal that the WC-type hexagonal phase (MoN, MoP, and WN) and MoAs and WP in MnP-type orthorhombic phase are energetically stable in a non-magnetic phase. The electronic properties show that all these materials are metallic in nature, while the optical properties showed high reflectivity and low transmission. The thermoelectric properties have also been elaborated, and, as these materials have zero band gap values, they showed high thermal conductivity at high temperatures with low Seebeck and almost constant electrical conductivity. Moreover, the elastic properties of these two phases are surprising with their high bulk and shear moduli. All the materials fall in the category of super-hard materials with ductile and brittle characteristics. [ABSTRACT FROM AUTHOR]

The study used Density Functional Theory to simulate the properties of single-walled and double-walled boron nitride nanotubes. The cohesive energy calculations suggest that double-walled nanotubes are more stable than single-walled nanotubes. Double-walled nanotubes have a narrower bandgap than single-walled nanotubes. The smaller diameter of the nanotubes reduces available energy for vibrational modes. Double-walled nanotubes have larger Young's modulus, shear modulus, and bulk modulus than single-walled nanotubes. Both single-walled and double-walled nanotubes perform like auxetic materials in some directions. The group velocity of acoustic phonons in SWBNNTs (6, 0) is higher than in SWBNNTs (12, 0). [ABSTRACT FROM AUTHOR]

Acoustic velocities and elasticity of high P-T synthesized new (VNbTaTi)C high-entropy carbides (HECs) are reported at high pressure using large volume press (LVP)-based ultrasonic interferometry technique. Using the finite-strain equation approach, the bulk modulus and shear rigidity, and their pressure dependences, are derived from the current experimental data, yielding B 0 = 261.6(2) GPa, G 0 = 191.4(3) GPa, ∂B/∂P = 4.34(18), and ∂G/∂P = 1.83(6). Interestingly, the (VNbTaTi)C HECs is more incompressible than the superhard γ-B (∼213.9 GPa), and almost as incompressible as superhard PcBN (∼254 GPa). Meanwhile, its shear rigidity (∼191.4 GPa) is comparable to the superhard B 6 O-B 4 C composite (G = 202 GPa), and as stiff as the (TiZrNbTa)C (193 ∼ 195 GPa) HECs. More strikingly, the fracture toughness is enhanced up to ∼4.6(3) MPa·m1/2, and the Vickers hardness of (VNbTaTi)C HECs is ∼22.6(2) GPa, which are significantly stronger than other high-entropy carbides. These new findings and results may be very important for its applications in extreme environments. [ABSTRACT FROM AUTHOR]

Sound velocities and densities of Al‐bearing superhydrous phase B (Al‐bearing SuB) were investigated up to 24 GPa and 1300 K by synchrotron X‐rays combined with ultrasonic interferometry techniques in a multi‐anvil apparatus. We found that Al + H incorporation decreases the adiabatic bulk modulus and shear modulus of SuB. Our results however suggest that this effect is less important than that of temperature. The presence of hydrous pyrolite with ∼10 wt.% Al‐bearing SuB in cold subducting slabs could explain up to ∼2% high velocity anomalies at the bottom of the mantle transition zone (500–660 km) while it turns into ∼7.7% low velocity anomalies below 660 km. Al‐bearing SuB is reportedly stable at mantle temperatures, where it could account for ∼12.2% low velocity anomalies beneath subduction zones in the uppermost lower mantle. Plain Language Summary: Among dense hydrous magnesium silicates, Superhydrous phaseB (SuB) is believed to hold large amount of water and transport it to the deep mantle. Recent studies showed that Al can largely increase the thermal stability region of SuB, suggesting this phase may also be an important carrier of water in the mantle transition zone (MTZ) and uppermost lower mantle (ULM). Here we investigated the sound velocities of Al‐bearing SuB up to 24 GPa and 1300 K using ultrasonic interferometry combined with synchrotron X‐ray techniques in a multi‐anvil apparatus. We found that Al + H incorporation decreases adiabatic bulk modulus and shear modulus of SuB. Our results however suggest that this effect is less important than that of temperature. Based on our elasticity data, we calculated velocity of a hydrated pyrolite composition, containing up to 10% of Al‐SuB along temperature profiles corresponding to cold slab and hot mantle at the depths of the MTZ and the ULM. We found that the presence of hydrous pyrolite may explain high velocity anomalies up to 660 km depth at MTZ while low velocity anomalies appear below 660 km along cold slab geotherm. Nevertheless, low velocity anomalies are generated in the whole depth range along a normal geotherm. Key Points: We constrained the Al + H incorporation on sound velocities of superhydrous phase B (SuB) up to 24 GPa and 1300 KAl + H incorporation which promoted by increased temperature significantly affect velocities of SuBAccumulation of Al‐bearing SuB can explain velocity contrast with various magnitude owing to the change of Al + H content with temperature [ABSTRACT FROM AUTHOR]

In this paper, we will investigate the structural, electronic, mechanical, magnetic and optical properties of Heusler Mn2NiAl (MNA) compound using the Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA) of the full potential linearized augmented plane-wave method for exchange and use correlations, modified Becke–Johnson and GGA+U Hubbard parameter. The calculated band structure (BS) and density of states (DOS) of MNA showed a metallic (GGA), nearly half-metallic (mBJ) and half metallic (GGA+U) behavior. Moreover, the magnetic computed magnetic moments by GGA+U are higher compared to GGA and mBJ results. Bulk modulus, shear modulus, Voigt and Reuss polycrystalline elastic modulus, Debye temperature, sound velocities, the melting temperatures, B / G ratio, Young's modulus and Poisson's ratio were obtained. The elastic anisotropy of MNA alloy was analyzed using 2D and 3D figures of directional dependence of Poisson's ratio, shear modulus, linear compressibility and Young's modulus. Studies have shown that the Heusler material MNA has magnetic and anisotropic properties and is mechanically stable. [ABSTRACT FROM AUTHOR]

We present structural, electronic, magnetic, elastic and transport properties of tetragonal Mn2PtSn (MPS) bulk material in stannite (ST) phase, we will use a FP-LAPW method based on DFT under GGA, TB-mBJ and GGA+U as implemented in the WIEN2k code. From the ferromagnetic state, band structure (spin-down/spin-up channel) calculations reveal an indirect bandgap/zero-bandgap. Mn2PtSn shows inverse tetragonal crystal structures with ferromagnetic spin order at zero temperature. The elastic stability criterion shows that the MPS crystal satisfies the mechanical stability under applied at 0 GPa. The related mechanical properties such as bulk modulus (B), shear modulus (G), Young's modulus (E), and Poisson's ratio (ν) are also studied for polycrystalline of MPS; the calculated B/G value (B/ G = 2. 9 6) shows that MPS behaves in a ductile manner. Hence, this study of transport properties suggests their potential thermoelectric applications at high temperatures. To our knowledge, the results obtained show that this ternary alloy is advantageous for materials employed in spintronic devices. [ABSTRACT FROM AUTHOR]

The scarcity of research on the shielding properties of spinel ferrites underscores the necessity for more rigorous investigations. Consequently, this study introduces a facile synthesis method for Co, Cu, and Sm spinel nanoferrites (referred to as CCS nanoferrites) using the citrate combustion technique. The investigation focuses on their mechanical, dielectric, and gamma-ray shielding parameters. Gamma-ray shielding features are obtained theoretically via the Phy-X database. The particle size, nature, and distribution of the present CCS nanoferrites were analyzed using HR-TEM microscopy. HR-TEM results reveal both the spherical shapes and the aggregation of nanoparticles. These observations can be attributed to the interplay of high surface energy and magnetic interactions among the components of the CCS nanoferrites. The Co 0.5 Cu 0.5 Sm 0.15 Fe 1.85 O 4 nanoferrite exhibits an optimal dielectric constant value of 4587, with an enhanced ratio of 1618% compared to the pristine CCS0 sample. Additionally, it demonstrates an optimal conductivity of 38.59 μ (Ω·m)−1, with an enhanced ratio of 1105%. Furthermore, the loss is reduced to 2.65, showing an improvement ratio of 54% compared to the pristine nanoferrite at room temperature and 50 Hz. Moreover, the longitudinal modulus, shear modulus, Young's modulus, and bulk modulus of the nanoferrite Co 0.5 Cu 0.5 Sm 0.15 Fe 1.85 O 4 were increased from 1.79 to 4.96 GPa, 0.32–0.93 GPa, 0.88–2.56 GPa, and 1.37–3.73 GPa, respectively, when compared to the pristine sample. The comparative study of half-value layers at 0.662 MeV revealed that CCS nanoferrites exhibit smaller half-value layers than common radiation shielding materials. Additionally, the study highlighted the enhanced radiation shielding performance of the nanoferrites. Concerning the dielectric, mechanical, and ionizing radiation shielding properties of the CCS spinel nanoferrites, the CCS5 (with the highest Sm content) has the optimum ionizing radiation shielding ability with the highest dielectric and mechanical parameters compared to the other samples. The implications of these findings extend to potential applications in biomedicine, radiation protection, and the optimization of electronic devices operating in radiation fields. [ABSTRACT FROM AUTHOR]

This study proposes two lattice metamaterials (FS and HCS) inspired by a variation of face-centered cubic structure combined with the cross-section of horsetail grass. Under uniaxial compression and shear loading, the mechanical properties, deformation behavior, and energy absorption capacity of the structure were evaluated by varying the geometric parameters to improve the relative density of the structure by finite element method and experiment. The results show that the two structures differ little in mechanical properties when the volume density is low and converge when the volume density reaches 0.4. At the same time, when compared with their original structure, the new structures are improved in Young's modulus by 1.5 to 3.8 times, shear modulus by two times when the volume density is low, bulk modulus by 1.25 to 1.4 times, and total stiffness by 2.75 times. In addition, research shows that the two structures are highly isotropic when the Zener anisotropy ratio approaches 1. Finally, to evaluate the energy absorption ability of the two structures when improving the parameter geometric value, the research shows that increasing the number of unit cells greatly affects the structure's ability to absorb energy. When improving the diameter of the truss, the deformability of the structure decreases as the maximum compression force increases, while the effect of improving the thickness of cells on the special energy absorption capacity (SEA) tends to decrease. With good mechanical properties and energy absorption capacity, the structure is proposed for potential engineering applications. [ABSTRACT FROM AUTHOR]

The mechanical properties of the half-Heusler alloy C2CaNa using density functional theory approach as installed in Quantum Espresso software was examined. We observed that C2CaNa will be easily compressed due to the small value of its bulk modulus. The values of the lattice constant a0, elastic constants (C11, C12, C14), Young's modulus E, Piosson's ratio ν, Shear modulus G, Zener anitropy A, pressure derivative B′, and band-gap Eg were obtained. Also the Voigt approximation, Reuss approximation and the Voigt–Reuss–Hill average of the approximation were gotten. Calculated values of G/B ratio is 0.581; this shows that C2CaNa has low resistance opposed to shear deformation. The B/G ratio evaluated for C2CaNa is 1.72. This implies that C2CaNa is "brittle" in nature at ambient condition. Our calculated elastic constants (C11, C12, and C44) for C2CaNa satisfied the following mechanical stability conditions for cubic structure: C11 – C12 > 0, C44 > 0, and C11 + 2C12 > 0. The value of C12 is an indication that C2CaNa is mechanically stable. This examination gives important experiences into the primary dependability and mechanical way of behavior of this material, this will empower advance material plan and application. [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]

The first high damage resistant ultra-high temperature ceramic ScB 2 C 2 with excellent hydrolysis resistance was successfully prepared through boron carbon thermal reduction and hot pressing sintering using Sc 2 O 3 , B 4 C and graphite as raw materials. The Vickers hardness, flexural strength, fracture toughness, Young's modulus, shear modulus, bulk modulus and Poisson's ratio of as-prepared ScB 2 C 2 ceramic are 6.0 ± 0.2 GPa, 246 ± 17 MPa, 4.11 ± 0.18 MPa·m1/2, 240 GPa, 101 GPa, 127 GPa and 0.18, respectively. In the a - b plane (B 2 C 2 sheet) and along the c -axis direction, ScB 2 C 2 exhibits extremely strong anisotropy of chemical bonds and elastic properties. The high residual strength, damage tolerance factor D t and fracture toughness to strength ratio K Ic /σ f indicates that ScB 2 C 2 has excellent damage tolerance. In addition, ScB 2 C 2 displayed remarkable thermal shock resistance and hydrolysis resistance. These unique features endow ScB 2 C 2 with significant potential for future ultra-high temperature applications. [ABSTRACT FROM AUTHOR]

This study examines the physical, optical and mechanical characteristics of BWP glasses. The density and molar mass increase as the WO3 concentration rises, resulting in a denser and more substantial glass sample. However, the molar volume decreases, indicating a reduction in volume due to the increased density caused by WO3. The inclusion of WO3 also leads to a tighter spacing between atoms. The optical basicity of the glass increases with higher WO3 concentrations. The electronegativity decreases, suggesting the glass becomes more electron-donating. The electronic polarizability and cross-link density increase, resulting in a stiffer and more robust glass network. The mechanical moduli, including Young's modulus, bulk modulus, shear modulus, and longitudinal modulus, also increase with higher WO3 concentrations, indicating improved mechanical characteristics and reduced deformation. The Poisson's ratio shows a larger transverse deformation tendency with increasing WO3 concentration. Micro-hardness values increase with WO3 content, indicating enhanced durability and mechanical robustness. The mean free path values indicates that the higher WO3 content, or lower P2O5 content, improves the shielding ability. [ABSTRACT FROM AUTHOR]

Some soil characteristics, such as the shear wave velocity, the shear modulus, the Poisson ratio, and the porosity, affect how clay soils behave. The soil design parameters under loading, such as soil liquefaction induced by dynamic earthquake loading, employ the shear wave velocity and shear module with modest stress. In order to understand the pore saturation, the Poisson ratio and seismic velocity ratio are also utilized. Additionally, one of the most crucial physical characteristics for assessing permeability at the base of any engineering structure, resolving consolidation issues that may arise at the foundation of an engineering structure, and influencing the deformation behavior of soils is soil porosity. Predicting the porosity of clay soils is a crucial first step in tackling engineering and environmental issues that may arise in the soil after an earthquake or not. With the use of dynamic soil metrics such as seismic velocities, shear modules, bulk modules, seismic velocity ratios, and Poisson ratios, the current work aims to estimate soil porosity. Seismic refraction was used by various studies in the past to conduct in-situ geophysical research. The lithological characteristics of the soil (such as the grain size, shape, type, compaction, consolidation, and cementation of the grains) and the physical characteristics of the soil (such as porosity, permeability, density, anisotropy, saturation level, liquid–solid transition, pressure, and temperature), as well as the elasticity characteristics of the soil (such as shear modulus (G), bulk modulus (K), Young modulus (E), Poisson ratio (μ) and Lamé constants (λ )) all have an impact on seismic waves passing through a medium. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the effective behaviour of a micro-cracked material whose matrix bulk and shear moduli are ruled by a linear viscoelastic Burgers model. The analysis includes a detailed study of randomly oriented and distributed cracks displaying an overall isotropic behaviour, as well as aligned cracks resulting in a transversely isotropic medium. Effective material properties are approximated with the assumption that the homogenized equivalent medium exhibits the characteristics of a Burgers model, leading to the identification of short-term and long-term homogenized modules in the Laplace–Carson space through simplified formulations. The crucial advantage of this analytical technique consists in avoiding calculations of the inverse Laplace–Carson transform. The micromechanical estimates are validated through comparisons with FE numerical simulations on 3D microstructures generated with zero-thickness void cracks of disc shape. Intersections between randomly oriented cracks are accounted for, thereby highlighting a potential percolation phenomenon. The effects of micro-cracks on the material's behaviour are then studied with the aim of providing high-performance creep models for macrostructure calculations at a moderate computation cost through the application of analytical homogenization techniques. [ABSTRACT FROM AUTHOR]

Multiscale modeling (MM) has broadened its scope to encompass the calculation of mechanical properties, with a particular focus on investigating how the dimensions of single-walled carbon nanotubes (SWCNTs), specifically their diameters, affect the mechanical properties (Longitudinal and Transverse Young’s modulus) of simulated nanocomposites through Molecular Dynamics (MD) simulations. The MD method was employed to construct nanocomposite models comprising five different SWCNTs chiralities: (5, 0), (10, 0), (15, 0), (20, 0), and (25, 0), serving as reinforcements within a common Polymethyl methacrylate (PMMA) matrix. The findings indicate a correlation between the SWCNT diameter increase and enhancements in mechanical and physical properties. Notably, as the diameter of SWCNTs increases, the density, Longitudinal Young’s modulus, Transvers Young’s Shear modulus, Poisson’s ratio, and Bulk modulus of the simulated nanocomposite transition from (5, 0) to (25, 0) by approximately 1.54, 3, 2, 1.43, 1.11, and 1.75 times, respectively. To corroborate these results, stiffness matrices were derived using Materials Studio software. [ABSTRACT FROM AUTHOR]

The elastic properties, electronic structure, and optical properties of X (X = B , Al, Ga) atomic substitution for arsenene are calculated based on density functional theory. The results show that, at the same concentration, B-substituted arsenene shows the best structural stability, followed by Ga-substituted arsenene, with Al-substituted arsenene being the least. Arsenene and its substitution systems possess excellent mechanical stability. The substitution of X atoms leads to a reduction in the bulk modulus, shear modulus, and Young's modulus of arsenene systems, while simultaneously increasing the Poisson's ratio. For the substitution systems, the four parameters all gradually increase as the substitution concentration increases. The substitution of X (X = B , Al, Ga) atoms into arsenene can facilitate the transformation from an indirect to direct bandgap (except for Al and Ga substitution at a concentration of 3.13%) with a narrower bandgap for increasing substitution concentration. The B–As bond shows the strongest covalency, followed by the Ga–As bond, while the Al–As bond exhibits the strongest ionicity. Arsenene substituted with X atoms shows anisotropy of optical properties in both the xy-plane and along the z-axis direction. The static dielectric constant increases with higher substitution concentration. The imaginary part of the dielectric function shows the extent of excited electron transitions between bands. After X atom substitution, arsenene exhibits a redshift in its absorption edge, which is wider with the higher substitution concentrations. The peak reflectance and valley transmittance values of arsenene and its substitution systems are located in the ultraviolet region in both xy-plane and z-axis. [ABSTRACT FROM AUTHOR]

Auxetic materials have a negative Poisson's ratio and are of significant interest in applications that include impact mitigation, membrane separations and biomedical engineering. While there are numerous examples of structured materials that exhibit auxetic behavior, the examples of engineered auxetic structures is largely limited to periodic lattice structures that are limited to directional or anisotropic auxetic response. Structures that exhibit a three-dimensionally isotropic auxetic response have been, unfortunately, slow to evolve. Here we introduce an inverse design algorithm based on global node optimization to design three-dimensional auxetic metamaterial structures from disordered networks. After specifying the target Poisson's ratio for a structure, an inverse design algorithm is used to adjust the positions of all nodes in a disordered network structure until the desired mechanical response is achieved. The proposed algorithm allows independent control of shear and bulk moduli, while preserving the density and connectivity of the networks. When the angle bending stiffness in the network is kept low, it is possible to realize optimized structures with a Poisson's ratios as low as −0.6. During the optimization, the bulk modulus of these networks decreases by almost two orders of magnitude, but the shear modulus remains largely unaltered. The materials designed in this manner are fabricated by dual-material 3D-printing, and are found to exhibit the mechanical responses that were originally encoded in the computational design engine. The approach proposed here provides a materials-by-design platform that could be extended for engineering of optical, acoustic, and electrical properties, beyond the design of auxetic metamaterials. [ABSTRACT FROM AUTHOR]

Novel halide double perovskites CsKAgSbX6 (X = Cl, Br) have been theoretically investigated in the current study to determine their optoelectronic, elastic, and thermoelectric properties. The Density Functional Theory based on the GGA-PBE and HSE functionals using the Quantum Espresso code was applied. The optimization of the cubic structure of the perovskites resulted in the optimized lattice constants of about 10.78 Å and 11.31 Å for CsKAgSbCl6 and CsKAgSbBr6, respectively. The results also revealed that both materials are stable in the cubic structure and are mechanically stable as well as ductile in nature. The anisotropy of CsKAgSbX6 (X = Cl, Br) has been investigated by evaluating the highest and lowest values of the shear modulus, Bulk modulus, and the Young's modulus. Moreover, the investigation of their electronic properties indicated that they are semiconductors with energy gap values found to be 1.36 eV for CsKAgSbCl6 and 0.87 eV for CsKAgSbBr6 using the GGA approximation and 2.49 eV and 1.81 eV for the respective perovskites using the HSE functional. Regarding their optical properties, these materials show an excellent UV light absorption, low reflectivity and high-power conversion efficiency, making them promising for solar cell applications. Finally, with a reasonably high figure of merit, CsKAgSbX6 (X = Cl, Br) double perovskites also have potential for thermoelectric devices. [ABSTRACT FROM AUTHOR]

This study explored the structural stability, elastic properties, structural transformation, and critical concentration of Ni3Al and Ni3M (M = Ti, Ta, Nb) using L12, D024, and DO22 structures, along with three-dimensional supercells featuring stacking faults along [ 10 1 ¯ ] , [ 01 1 ¯ ] , [111] directions. First-principles calculations revealed that the most stable structures for Ni3Al, Ni3Ti, Ni3Ta, and Ni3Nb are L12, D024, DO22, and DO22, respectively. Notably, the bulk modulus, Young′s modulus, shear modulus, and isotropy of Ni3Ti, Ni3Ta, and Ni3Nb surpassed those of Ni3Al, with increased ductility, except for Ni3Ti. By substituting Al atoms with 0–8 Ti, Ta, and Nb atoms in a 32-atom Ni3Al structure, the critical concentration for the transformation from L12 to D024 or DO22 ranged between 18.75 at. % and 21.88 at. %, and between 15.63 at. % and 18.75 at. %, respectively. This critical concentration was influenced by the dynamic interplay among Ti, Ta, Nb, and Al atoms interacting with Ni atoms. The structural transformation from L12 to D024 or DO22 can be attributed to the reduction in the superlattice extrinsic stacking fault energies or the anti-phase boundary energies, respectively, a consequence of the redistribution of charge density between Ti, Ta, Nb atoms and Ni atoms. [ABSTRACT FROM AUTHOR]

The structural, elastic, piezoelectric, and electronic properties of Li-doped K0.5Na0.5NbO3 (K0.5−xNa0.5−yLix+yNbO3, KNN-L) are calculated. The properties of KNN-L are related to the Li-doping content and the replaced K or Na atoms. The bulk modulus, the shear modulus, and Young's modulus of KNN-L are mostly higher than those of KNN, and the hardness value increases. The Poisson ratio of KNN-L is lower than that of most KNN, and the ductility is reduced. All doped structures are direct band gap semiconductors. K0.5Na0.375Li0.125NbO3 has the largest piezoelectric charge constant, d33 = 44.72 pC/N, in the respective structures, which is 1.5 fold that of K0.5Na0.5NbO3 (29.15 pC/N). The excellent piezoelectric performance of Li-doping KNN-L was analyzed from the insights of elastic and electronic properties. [ABSTRACT FROM AUTHOR]

Experimental data describing the uniaxial compression and relaxation of brain tissue are compared to the predictions from a rheological model developed by Yarin and Kosmerl ["Rheology of brain tissue and hydrogels: A novel hyperelastic and viscoelastic model for forensic applications," Phys. Fluids 35, 101910 (2023)]. A qualitative agreement between the model and experiments with swine brain tissue is confirmed, and the uniformly valid values (i.e., valid in all rheometric experiments without any change) of the rheological parameters are established. These are the values of the following four parameters: G (the shear modulus), κ (the bulk modulus), α (the dimensionless degree of hyperelasticity), and θ (the viscoelastic relaxation time). In addition, the present rheological model with the established rheological parameters is incorporated into a dynamic model of bullet penetration into brain tissue after a short-range shooting, when muzzle gases and/or air fill the bullet channel leading to its widening, wave propagation, fragmentation, and backspatter of brain tissue. This problem is of significant interest in forensic science because there is an urgent need to provide physics-informed models to reconstruct and analyze crime scenes. [ABSTRACT FROM AUTHOR]

Context: Based on first principles, the structure, elasticity, mechanics, electronics, and optical properties of cubic K2Pb2O3 were studied. The structural parameters calculated by this method are close to the previous theoretical results. The elastic constant, bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and mechanical stability are studied, and it is shown that cubic K2Pb2O3 is mechanically stable, isotropic, and brittleness. The electrical conductivity and chemical bonding of cubic K2Pb2O3 were analyzed based on the calculated band structure, density of states (DOS), and bond populations. The dispersion of optical functions, including the dielectric function, refractive index, extinction coefficient, reflectivity, absorption coefficient, and loss function, is displayed and analyzed. Methods: All computations have been carried out based on density functional theory (DFT) as implemented in the CASTEP code. The norm conservation pseudopotential method is used to exchange correlation functionals within the generalized gradient approximation (GGA). [ABSTRACT FROM AUTHOR]

A new formulation of the bismuth-zinc-borate glass system has been fabricated using the conventional melt-quenching method. The amorphous phase of the glass sample has been confirmed by the nonexistent of any crystalline peak presented by X-ray diffraction patterns. The Fourier-transform infrared spectroscopy result displays several bands associated with the Zn–O and B–O–B bonding. The glass samples exhibited a density increase from 3.19 to 4.28 g/cm3 and the molar volume increased from 23.48 to 31.00 cm3/mol. The density of the glasses increases due to the addition of Bi2O3 which has a higher atomic mass compared to the other elements in glass compositions. The addition of Bi2O3 contributes more mass to the glass structure, leading to an increase in overall density. The incorporated Bi2O3 reduced the longitudinal (6134.41–5121.94 ms−1) and shear (3310.50–2848.15 ms−1) velocities. The elastic moduli resulted in a decreasing behavior when Bi2O3 concentration increased, and the values ranged from 120.04 to 112.21 GPa for longitudinal modulus, 34.96–34.69 GPa for shear modulus, 73.43–65.95 GPa for bulk modulus, and 90.52–88.56 GPa for Young's modulus. The Poisson's ratio presents the same trend as the modulus, while the microhardness shows an inversely proportional trend. The BiZnB4 sample demonstrates the lowest Poisson's ratio (0.276) and highest microhardness (5.18 GPa) values. These findings show that the physio-elastic properties are composition-dependent, suggesting potential applications as flexible glass panels for dynamic building glass design. [ABSTRACT FROM AUTHOR]

In order to design Cu-Sn alloys with excellent overall performance, the structural stability, mechanical properties, and electronic structure of X-doped Cu-Sn alloys were systematically calculated using first-principles calculations. The calculation results of the cohesive energy indicate that the Cu-Sn-X structures formed by X atoms (X = Ag, Ca, Cd, Mg, Ni, Zr) doping into Cu-Sn can stably exist. The Cu-Sn-Ni structure is the most stable, with a cohesive energy value of −3.84 eV. Doping of X atoms leads to a decrease in the bulk modulus, Possion's ratio and B/G ratio. However, doping Ag and Ni atoms can improve the shear modulus, Young's modulus, and strain energy of the dislocation. The doping of Ni has the highest enhancement on shear modulus, Young's modulus, and strain energy of the dislocation, with respective values as follows: 63.085 GPa, 163.593 GPa, and 1.689 W/J· m − 1 . The analysis of electronic structure results shows that the covalent bond between Cu and X is the reason for the performance differences in Cu-Sn-X structures. [ABSTRACT FROM AUTHOR]

Using first-principles calculations, the mechanical properties of orthorhombic phase Al1-xTMxP (x = 0.0625, 0.125, 0.25; TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) crystals were studied. By analyzing the mechanical stability, it was found that Al0.75Zn0.25P is mechanical unstable, and the rest all mechanical stable. The mechanical properties of Al1-xTMxP were studied, including Bulk modulus, shear modulus, Young's modulus, Poisson's ration, ductility, Vickers hardness, and elastic anisotropy. It was found that Al0.75Ni0.25P has the largest Bulk modulus, the largest Poisson's ratio. Al0.75Ni0.25P has the smallest shear modulus, the smallest Young's modulus and the smallest Vickers hardness. The Al0.75Ni0.25P has the best ductility. Al0.75Ni0.25P and Al0.75Cu0.25P show strong elastic anisotropy, and the Al0.75Cu0.25P has the largest elastic anisotropy. Through the study of the mechanical properties of Al1-xTMxP, it was found that doping Ni into AlP is an effective means to tune its mechanical properties. [ABSTRACT FROM AUTHOR]

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

The issue of fixed Poisson's ratio is a critical problem plaguing bond–based peridynamic (BB–PD) models. The popular approach of introducing the bond's tangential stiffness cannot completely remove Poisson's ratio limitation, but instead leads to some additional troubles, such as negative tangential stiffness and bond force density misalignment in finite rigid body rotation problems. To address the issue of fixed Poisson's ratio thoroughly, a unified bond–based peridynamics (UPD) was originally proposed. In the proposed model, a novelty pairwise force density function has been developed, in which dilatation and distortion are distinguished, and the model assigns different stiffnesses to the two deformation components. Arbitrary and reasonable values of Poisson's ratio can be achieved by adjusting the PD parameters that control the bulk and shear moduli of the material. The theoretical range of Poisson's ratio in the proposed model is (-1, 0.5], which is consistent with those in continuum mechanics. In addition, the absence of tangential stiffness prevents the proposed model from misalignment of bond force density due to rigid body rotation. Several numerical examples, including four two–dimensional and three–dimensional deformation analyses and three quasi–static fracture analyses, were implemented to verify the accuracy and reliability of the proposed model. The results show that the proposed model can accurately simulate the elastic properties of the material and obtain the deformation with high accuracy. The numerical examples also demonstrate the fracture prediction capability of the proposed model. • The problem of fixed Poisson's ratio is addressed without introducing tangential stiffness. • The proposed model distinguishes between dilatation and distortion in deformation. • The proposed model avoids misalignment of bond force due to rigid body rotation. • The proposed model can accurately predict fractures in various modes. [ABSTRACT FROM AUTHOR]

To describe the evolution of residual stresses in epoxy resin during the curing process, a more detailed characterization of its viscoelastic properties is necessary. In this study, we have devised a simplified apparatus for assessing the viscoelastic properties of epoxy resin. This apparatus employs a confining cylinder to restrict the circumferential and radial deformations of the material. Following the application of load by the testing machine, the epoxy resin sample gradually reduces the gap between its surface and the inner wall of the confining cylinder, ultimately achieving full contact and establishing a continuous interface. By recording the circumferential stress–strain on the outer surface of the confining cylinder, we can deduce the variations in material bulk and shear moduli with time. This characterization spans eight temperature points surrounding the glass transition temperature, revealing the bulk and shear relaxation moduli of the epoxy resin. Throughout the experiments, the epoxy resin's viscoelastic response demonstrated a pronounced time-temperature dependency. Below the glass transition temperature, the stress relaxation response progressively accelerated with increasing temperature, while beyond the glass transition temperature, the stress relaxation time underwent a substantial reduction. By applying the time-temperature superposition principle, it is possible to construct the relaxation master curves for the bulk and shear moduli of the epoxy resin. By fitting the data, we can obtain expressions for the constitutive model describing the viscoelastic behavior of the epoxy resin. In order to validate the reliability of the test results, a uniaxial tensile relaxation test was conducted on the epoxy resin casting body. The results show good agreement between the obtained uniaxial relaxation modulus curves and those derived from the bulk and shear relaxation modulus equations, confirming the validity of both the device design and the testing methodology. [ABSTRACT FROM AUTHOR]

The thermoelastic properties and thermal expansion of natural single-crystal zircon without detectable radiation damage were determined in the temperature range between 100 and 1650 K on five samples from Cambodia, Sri Lanka, and Tanzania. Up to about 1500 K, the results are in excellent agreement and fully reversible. The average adiabatic elastic stiffness coefficients at room temperature in GPa are c11 = 426.8(6), c12 = 68.1(4), c13 = 152.0(4), c33 = 490.8(9), c44 = 113.1(2), and c66 = 49.0(1). Polycrystalline averaging for the aggregate bulk and shear modulus (Voigt-Reuss-Hill average) yields K = 229.3(4) GPa and G = 109.3(1) GPa. From 293 to 1573 K, the elastic stiffnesses soften almost linearly with the temperature coefficients in MPa/K: dc11/dT = –45.36(7), dc12/dT = –2.03(7), dc13/dT= –9.59(7), dc33/dT = –42.85(12), dc44/dT = –9.60(3), and dc66/dT = –2.19(1). Below room temperature, the behavior of the cij is nonlinear, with decreasing absolute values of the temperature coefficients. Above about 1500 K, a temperature- and time-dependent irreversible elastic stiffening accompanied by an increasing ultrasound dissipation was observed in all samples. These anomalies are interpreted to be the consequence of increased dislocation densities. [ABSTRACT FROM AUTHOR]

To improve the mechanical properties of casting aluminum-copper alloy, the mixed rare earth (RE) was added to ZL206 and its properties and the enhanced mechanism of alloy were researched. The results showed that the strength and hardness of the composite were improved by 10.2% and 6.2%, respectively. After adding mixed RE, which was led by the heterogeneous enrichment area blocking the growth of the α-Al phase and making grain refinement during the solidification process. The simulation results of RE surface adsorption models by first principles also showed that the elastic constant calculation improved the bulk modulus, shear modulus, and Young's modulus of the material. The addition of mixed RE enhances the strength and hardness, although it adversely affects toughness and reduces the machining index. Also, the work function decreased, and the Fermi level increased, reflecting that the electron locality on each band was strong and the bonding state of the alloy system was covalent, which showed that the corrosion resistance was enhanced after adding mixed RE. It provides a new method for the mechanism of RE-modified aluminum-copper alloys and expands the direction of cast aluminum-copper alloy modification. [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]