Sound Wave Velocity Research Articles

Integrating Theoretical and Experimental Approaches to Unveil the Mechanical Properties of CuSbSe2 Thin Films

Abstract An exhaustive investigation of the mechanical characteristics of CuSbSe2 (CASe) thin films is conducted in this study by combining experimental nanoindentation methods with theoretical simulations. The Ab-initio Molecular Dynamics (AIMD) calculations are performed with the machine learning (ML) force fields. By employing the Vienna Ab-initio Simulation Package (VASP) based on Density Functional Theory (DFT), theoretical inquiries are carried out to identify crucial parameters, such as bonding characteristics, elastic constants, hardness, bulk modulus, shear modulus, Young’s modulus, and Poisson’s ratio. Experimental validation is conducted using nanoindentation to investigate load-dependent hardness and Young’s modulus in a manner that closely matches the theorized predictions. The anomalies between experimental and theoretical outcomes are ascribed to anisotropic behavior and grain boundaries. Furthermore, an investigation is conducted into the directional dependence of sound wave velocities in the CASe films, leading to the revelation of intricate elastic property details. By employing an integrated theoretical-experimental approach, the present attempt not only increases the knowledge concerning CASe films but also fortifies the relationship between theory and experiment, thereby bolstering the dependability of our results. The insights provided as a result of this paper facilitate the development of CASe film applications in a variety of technological fields in the future.

An analytical model of spatial correlation between vector fields of surface generated noise in a stratified ocean.

Traditionally, hydrophone-based acoustic pressure information has been utilized for underwater detection, but the advent of vector sensors has enabled the utilization of particle velocity of sound waves. A vector sensor adds three-axis particle velocity vector components to the conventional acoustic pressure sensor, representing spatial correlation not as a scalar function but as a matrix of four vector components. While analytical solutions exist for vector sensor spatial correlation in the case of simple isotropic noise, such noise fails to reflect the medium properties of the ocean, such as sound speed or density. Previous investigation reflecting the ocean environment derived a pressure spatial correlation model for surface generated noise in a stratified ocean, but this model is limited in the applicability to vector sensors. In this work, we extend the pressure spatial correlation model to vector fields, and by comparing with isotropic noise, we have confirmed that ocean environmental factors significantly influence the spatial correlation of vector sensors.

Study on sound wave kinematic characteristics and temperature sensing mechanism during the warming process of loose coals

Coal spontaneous combustion is a major threat for safe production. In order to achieve the application of sound wave technology to the monitoring and early warning of coal spontaneous combustion, clarify the propagation characteristics of sound waves in loose coal heating process, and illustrate the temperature sensing mechanism of the sound wave detection and early warning of coal spontaneous combustion, the present study built a test system of sound wave kinematic parameter for loose coals to survey the attenuation characteristics of sound wave propagation during loose coal heating. The elastic wave CT algorithm was used to reconstruct the sound wave velocity field, clarify the propagation path, and identify the temperature anomaly area. The results show that with the increase of temperature, the time for sound wave propagation reduces rapidly and then slowly, the velocity increases gradually, and the internal structure and pores of coals become enlarged. In the sound velocity field reconstructed on the basis of SIRT algorithm, the area with high value corresponds to the high temperature area of the coal, which better reflects the changes of the temperature anomaly area during coal heating.

Hydrostatic pressure response of semiconducting GaSb applying a semi-empirical approach

In addition to experimental investigations, semi-empirical approaches prove valuable for replicating experimental results and predicting material behavior under high-pressure conditions. This study investigates the variation of unit cell volume in cubic zinc blende Gallium antimonide (GaSb) up to the phase transition pressure, relying solely on structural parameters from literature measurements at ambient conditions. The research extends to inspect the impact of high pressure on various properties, including mass density, bulk modulus, bulk sound wave velocity, microhardness, first-order pressure derivative of the isothermal bulk modulus, Grüneisen parameter, and Debye temperature for the GaSb compound. The bulk modulus and microhardness show nearly linear increases with pressure, while sound wave velocity and Debye temperature exhibit nonlinear variations. The first-order pressure derivative of the bulk modulus and Grüneisen parameter gradually decreased in the material under study. Similar trends under pressure are found in literature for materials with different crystallographic structures. Additionally, the study predicts and analyzes extra physical parameters of GaSb, comparing them with existing literature data.

Influence of water on the thermoelastic properties of Fe bearing ringwoodite: A first-principles study

Using first-principles density functional theory (DFT), we model the thermoelastic properties of hydrated ringwoodite (γ-(Fe, Mg)2SiO4), a potential water reservoir in the Earth's mantle transition zone (MTZ). Our calculations indicate that hydration, in general, leads to a reduction in the sound wave velocity of ringwoodite. However, increased pressure tends to suppress this reduction. For our 1.56 wt% H2O containing ringwoodite model, we find that the suppression is so large that at pressure and temperature (P-T) conditions relevant to the lower part of the MTZ the sound wave velocities for the hydrous (1.56 wt% H2O) ringwoodite become very similar to that of the anhydrous ringwoodite. However, when the water concentration is increased to 3.3 wt%, the pressure-induced suppression of the velocity reduction due to hydration is not so significant. We have given a plausible explanation for the same on the basis of the electronic structure of the hydrous ringwoodite models. We conclude that in the lower part of the MTZ, seismic wave data is sufficiently robust to detect regions of very high-water content (∼3.3 wt%). However, if the water concentration is less than 1.56 wt%, sound wave velocities may not be able to precisely detect the state of hydration of the MTZ.

Coupled models for propagation of explosive shock waves in cylindrical and spherical geometries

The propagation of shock waves in different geometries is crucial in engineering and scientific applications. A comprehensive model is developed to elucidate the hydrodynamic growth and decay of shock waves in cylindrical and spherical geometries by using the strong shock wave assumption. This model takes into consideration the conservation equations governing mass, momentum, and energy, thereby allowing for an accurate description of the coupled behavior between the piston and shock wave propagation. In contrast to the localized analysis employed in previous self-similar methods, this model incorporates the finite sound wave velocity to introduce the concept of retarded pressure on the piston surface. Consequently, the proposed model offers a multitude of advantages by providing a complete set of dynamic information concerning the trajectories, velocities, and accelerations of both the piston and shock wave. Furthermore, an asymptotic analytical solution is derived to describe the decay of shock waves in cylindrical and spherical geometries. To validate the theoretical analysis and illustrate the propagation characteristics of shock waves in these specific geometries, thorough comparisons are conducted. These findings contribute to the advancement of our understanding of shock wave dynamics in various physical systems, particularly in the field of plasma physics.

Clarifying the Main Root Distribution of Trees in Varied Slope Environments Using Non-Destructive Root Detection

Tree stability relies on the characteristics of both root and crown structures. However, studying root systems is challenging due to their underground location, often requiring destructive methods for assessment. Non-destructive approaches offer potential solutions, such as the root detector tool. However, research in this area remains limited and requires further development. This study aims to evaluate the root detector tool by inspecting the radial root distribution in trees with different tree crown shapes, both excurrent (Agathis loranthifolia) and decurrent (Samanea saman), which grow in various soil slopes and soil slope positions. In addition, we establish correlations between tree morphometry, the physical properties of soil, root attributes, sound wave velocity, and their relationship. Based on the results, it was found that the root detector tool is effective in evaluating root distribution, including identifying the main root. The slope position of the tree in a slope class influences the radial distribution of the main roots. This is related to the crown growth as indicated by the direction of its crown. Principal Component Analysis (PCA) findings suggest that parameter morphometric and soil and root properties data clustering align with slope position rather than slope class.

Determination of elastic constants for scots pine wood using ultrasound

Elastic constants of Scots pine (Pinus sylvestris L.) wood grown in Turkey were investigated using non-destructive ultrasound tests. Elastic modulus in longitudinal and perpendicular directions (EL, ER, ET), shear modulus in principal planes (GLR, GLT, GRT) and Poisson ratios (ʋLR, ʋRL ʋLT, ʋLT, ʋRT, ʋTR) were calculated using cubic samples (20 mm) which were conditioned at 65 % relative humidity and 21 °C. Longitudinal and transverse ultrasonic sound velocities in fiber (L), radial (R) and tangential (T) directions were measured using 2.25 MHz and 1 MHz sensors, respectively. Transverse sound wave velocities at an angle of 45° to the L, R and T directions were also measured with a 1 MHz sensor in order to calculate the Poisson ratios. The predicted elastic modulus based on ultrasound in L, R, T directions were 10600, 1300 and 470 N/mm2, respectively. The predicted shear modulus based on ultrasound in LR, LT, RT planes were 1180, 1050 and 350 N/mm2, respectively. Poisson ratios varied between 0.04 to 0.95. Comparing the data available in the literature, elastic constants of scots pine determined using ultrasonic method were within the acceptable values.

Inversion method for soil moisture content based on a distributed fiber optic acoustic sensing system.

The traditional measurement method can't achieve real-time monitoring of soil moisture content (SMC) within a two-dimensional area. To solve the above problems, we propose a rapid SMC monitoring method for two-dimensional area based on distributed acoustic sensing (DAS). DAS demodulates the backward Rayleigh scattering signal containing seismic wave sound velocity information from the active seismic source. The folding ruler approximation is employed to calculate the sound velocity of the soil, which is then inverted to determine the soil moisture content. The experiment measured the soil within a two-dimensional area formed by the seismic source and the acoustic sensing optical cable. The sensing optical cable and the active seismic source are organized into a two-dimensional area and the measurement range is 3 × 10 m with 33 points. The SMC ranges from 15% to 40%. The experiment shows that the absolute error between the measured values obtained by DAS and the water cut meter is 7%. This experiment verifies the feasibility of using the Rayleigh scattering properties to invert SMC and provides a new method for real-time monitoring of SMC in a large area.

NbSbO4 Kristalinin Yapısal, Elastik ve Piezoelektrik Özelliklerinin İncelenmesi

The structural, elastic, and piezoelectric properties of the NbSbO4 crystal were calculated based on the density functional theory. These properties were calculated using the ABINIT package program under both the generalized gradient approximation and the local density approximation. The elastic stiffness tensor and the elastic compliance tensor for the NbSbO4 crystal were calculated in the ground state. Voigt Bulk Modulus, Reuss Bulk Modulus, Hill Bulk Modulus, Voigt Shear Modulus, Reuss Shear Modulus, Hill Shear Modulus, Young Modulus, Poisson Ratio, Flexibility Coefficient, Debye temperature, Longitudinal sound wave velocity for NbSbO4 crystal using elastic stiffness and elastic compliance tensor, Transverse sound wave velocity and Average speed of sound were calculated. Then, the ground state piezoelectric tensor of the NbSbO4 crystal was calculated. Accordingly, 2D longitudinal surfaces and 3D representation surfaces of the piezoelectric tensor were obtained using MTEX software. The properties obtained with both the generalized gradient approximation and the local density approximation are compared. As a result of the calculations, it was understood that the material was a flexible and formable material in both approximations.

Elastic moduli and refractive index of γ-Ge3N4.

Germanium nitride, having cubic spinel structure, γ-Ge3N4, is a wide band-gap semiconductor with a large exciton binding energy that exhibits high hardness, elastic moduli and elevated thermal stability up to approximately 700°C. Experimental data on its bulk and shear moduli (B0 and G0, respectively) are strongly limited, inconsistent and, thus, require verification. Moreover, earlier first-principles density functional calculations provided significantly scattering B0 values but consistently predicted G0 much higher than the so far available experimental value. Here, we examined the elasticity of polycrystalline γ-Ge3N4, densified applying high pressures and temperatures, using the techniques of laser ultrasonics (LU) and Brillouin light scattering (BLS) and compared with our extended first-principles calculations. From the LU measurements, we obtained its longitudinal- and Rayleigh wave sound velocities and, taking into account the sample porosity, derived B0 = 322(44) GPa and G0 = 188(7) GPa for the dense polycrystalline γ-Ge3N4. While our calculations underestimated B0 by approximately 17%, most of the predicted G0 matched well with our experimental value. Combining the LU- and BLS data and taking into account the elastic anisotropy, we determined the refractive index of γ-Ge3N4 in the visible range of light to be n = 2.4, similarly high as that of diamond or GaN, and matching our calculated value. This article is part of the theme issue 'Exploring the length scales, timescales and chemistry of challenging materials (Part 1)'.

PiCUS Sonic Tomograph: A Case Study of Crimson Bottlebrush Tree (Melaleuca citrina (Curtis) Dum.Cours)

Trees with a decreasing level of health and structure can become a threat to life and property if they are not properly managed. Thus, a regular visual tree assessment (VTA) is essential to monitor the trees’ conditions. A recent assessment, July 2022, by VTA on an existing Melaleuca citrina in the Forest Research Institute Malaysia (FRIM) showed poor canopy growth colonised by parasitic plants with the emergence of fruiting bodies (conk or mushroom) on its trunk, indicating internal wood decay. Tree inspection using an advanced approach of PiCUS Sonic Tomograph (PiCUS) was performed to evaluate the severity of the decayed trunk. As a non-invasive method, PiCUS measures the wood deterioration in trees using sound wave velocity that moves through the density of the wood. The thicknesses of the residual wall of trees with internal defects were recorded as colour-coded tomograms. The results were then compared with previous observations in the year 2017. The soil penetration test, pH and “The Jar Test” were also adopted to analyse soil properties and condition around the tree. The tomogram images showed an increased percentage of decay from 2017 to 2022 of approximately 2 to 78%, respectively. The sound wood also decreased from 82 to 14% for the respective period. The soil is categorised as silt loamy with pH value of 5.6 to 6.4 while the soil penetration test exceeds a value of 2.06 MPa, which restricts the root growth. This information is vital for further maintenance of urban trees and very useful for managerial decisions.

DFT Insights into Noble Gold-Based Compound Li5AuP2: Effect of Pressure on Physical Properties.

In this study, the Li5AuP2 compound is investigated in detail due to the unique chemical properties of gold that are different from other metals. Pressure is applied to the compound from 0 to 25 GPa to reveal its structural, mechanical, electronic, and dynamical properties using density functional theory (DFT). Within this pressure range, the compound is optimized with a tetragonal crystal structure, making it mechanically and dynamically stable above 18 GPa and resulting in an increment of bulk, shear, and Young's moduli of Li5AuP2. Pressure application, furthermore, changes the brittle or ductile nature of the compound. The anisotropic elastic and sound wave velocities are visualized in three dimensions. The thermal properties of the Li5AuP2 compound are obtained, including enthalpy, free energy, entropy × T, heat capacity, and Debye temperature. The electronic properties of the Li5AuP2 compound are studied using the Perdew-Burke-Ernzerhof (PBE) and Heyd-Scuseria-Ernzerhof (HSE) functionals. The pressure increment is found to result in higher band gap values. The Mulliken and bond overlap populations are also determined to reveal the chemical nature of this compound. The optical properties, such as dielectric functions, refractive index, and energy loss function of the Li5AuP2 compound, are established in detail. To our knowledge, this is the first attempt to study this compound in such detail, thus, making the results obtained here beneficial for future studies related to the chemistry of gold.

Sound velocities and single-crystal elasticity of hydrous Fo90 olivine to 12 GPa

Nominally anhydrous minerals (NAMs) may contain significant amounts of water and constitute an important reservoir for mantle hydrogen. The colloquial term ‘water’ in NAMs is related to the presence of hydroxyl-bearing (OH−) point defects in their crystal structure, where hydrogen is bonded to lattice oxygen and is charge-balanced by cation vacancies. This hydrous component may therefore have substantial effects on the thermoelastic parameters of NAMs, comparable to other major crystal-chemical substitutions (e.g., Fe, Al). Assessment of water concentrations in natural minerals from mantle xenoliths indicates that olivine commonly stores ∼0–200 ppm of water. However, the lack of samples originating from depths exceeding ∼250 km coupled with the rapid diffusion of hydrogen in olivine at magmatic temperatures makes the determination of the olivine water content in the upper mantle challenging. On the other hand, numerous experimental data show that, at pressures and temperatures corresponding to deep upper mantle conditions, the water storage capacity of olivine increases to 0.2–0.5 wt%. Therefore, determining the elastic properties of olivine samples with more realistic water contents for deep upper mantle conditions may help in interpreting both seismic velocity anomalies in potentially hydrous regions of Earth's mantle as well as the observed seismic velocity and density contrasts across the 410-km discontinuity.Here, we report simultaneous single-crystal X-ray diffraction and Brillouin scattering experiments at room temperature up to 11.96(2) GPa on hydrous [0.20(3) wt% H2O] Fo90 olivine to assess its full elastic tensor, and complement these results with a careful re-analysis of all the available single-crystal elasticity data from the literature for anhydrous Fo90 olivine. While the bulk (K) and shear (G) moduli of hydrous Fo90 olivine are virtually identical to those of the corresponding anhydrous phase, their pressure derivatives K′ and G′ are slightly larger, although consistent within mutual uncertainties. We then defined linear relations between the water concentration in Fo90 olivine, the elastic moduli and their pressure derivatives, which were then used to compute the sound velocities of Fo90 olivine with higher degrees of hydration. Even for water concentrations as high as 0.5 wt%, the sound wave velocities of hydrous and anhydrous olivines were found to be identical within uncertainties at pressures corresponding to the base of the upper mantle. Contrary to previous claims, our data suggest that water in olivine is not seismically detectable, at least for contents consistent with deep upper mantle conditions. In addition to that, our data reveal that the hydration of olivine is unlikely to be a key factor in reconciling seismic velocity and density contrasts across the 410-km discontinuity with a pyrolitic mantle.

Examinations of mechanical, and shielding properties of CeO2 reinforced B2O3–ZnF2–Er2O3–ZnO glasses for gamma-ray shield and neutron applications

The glass system 75B2O3 - 4.5ZnF2 – 0.5 Er2O3–(20−x) ZnO- x CeO2, x = (0 ≤ x ≤ 1 mol. %) was manufactured using a melt quenching process, with CeO2 substituted for ZnO in the glass matrix in concentrations ranging from 0 to 1 mol %. The Makishima–Mackenzie model and sound wave velocity measurements were used to evaluate the mechanical parameters and elastic characteristics of the examined glass system, respectively. The results showed that increasing CeO2 doping ratio from 0 to 1 mol% increased density, sound velocities, elastic properties, and microhardness from 5.80 to 9.01 GPa. Phy-X/PSD software was employed to assess the effect of replacing ZnO with CeO2 on shielding capacity. The obtained results revealed that replacing ZnO with CeO2 enhances shielding characteristics and the manufactured glass may be useful in shielding applications.

Modeling the Composition of the Earth’s Liquid Outer Core

The paper suggests expressions, coherent with experimental data, for the calculation of the sound velocity and the temperature of a condensed medium under pressures in the Earth’s liquid outer core through parameters of the shock Hugoniot of the medium. Additives to the Earth’s liquid outer iron-nickel core were fitted so that the calculated pressure, density and sound wave velocity corresponded to geophysical values and the temperature did not exceed the admissible limits. It was established that the iron carbide Fe3C containing (4.0 ± 0.5) wt.% carbon with additives of FeS2 and SiC with a total content of Si and S up to 1.5 wt.% meets the required criteria as the main light additive in the upper layers of the Earth’s core. Less probable is the additive of carbon in the diamond phase up to 0.5 wt.%. In the Earth’s outer core, at the boundary with the solid inner core, among the possible light additives are the iron carbide Fe3C with (3.5 ± 0.4) wt.% carbon or diamond phase carbon of (4.0 ± 0.5) wt.%. Additives at the bottom of the Earth’s liquid outer core, containing significant amounts of Si, S, are hardly probable. The content of H in the Earth’s liquid outer core can be significant at the minimum possible core temperatures. The content of O is insignificant.

The porosity dependence of sound velocities in ceramic materials

The porosity dependence of transverse and longitudinal sound wave velocities is studied in statistically isotropic porous ceramics. Based on the model relations for elastic moduli six model relations are constructed for the prediction of the porosity dependence of these velocities. All of them predict a decrease of sound wave velocities with increasing porosity, but the Maxwell / Mori-Tanaka / MMT model leads to unrealistic predictions for high porosity. A velocity ratio function is defined which contains the porosity dependence of the effective Poisson ratio and enables the prediction of longitudinal wave velocities. A comparison with literature data shows that most data lie below the exponential prediction and above the numerical prediction for concave pores. The correlation of the normalized longitudinal wave velocities and relative transverse wave velocities shows that essentially all values are above the highest lower bound and are reasonably predicted by the differential, exponential and self-consistent models.

Nonlinear Equivalent Circuit of High-Power Sandwich Piezoelectric Ultrasonic Transducer.

In the theoretical design and analysis of the sandwich piezoelectric ultrasonic transducer, the transducer is considered to be an ideal linear system, where the dielectric, piezoelectric, and mechanical losses are neglected. However, when the transducer is driven at high power, the losses are becoming several times higher comparing them to low signal measurements, and the transducer works in a nonlinear state. In order to predict the performance of the transducer at high power, the nonlinear parameters (complex constants) of the piezoelectric materials are introduced. The corresponding nonlinear equivalent longitudinal wave sound velocity and the nonlinear equivalent longitudinal wavenumber of the piezoelectric ceramics are derived. Then, the nonlinear equivalent circuit (NEC) and the nonlinear resonance frequency equation of the high-power sandwich piezoelectric ultrasonic transducer that related with the losses are deduced. Then, the nonlinear finite element model (NFEM) of the transducer is constructed. The performance parameters of the transducer obtained by the NEC method and the finite element (FE) method are compared with each other, and consistent results have been achieved by two methods. Finally, the contribution of various losses is obtained through theoretical calculation, simulation, and experimental measurement, and the correctness of the theoretical model in this article is verified.

Thermal equation of state of Fe3O4 magnetite up to 16 GPa and 1100 K

Abstract Fe3O4 magnetite is an important mineral commonly found in various geological settings, including the planet Mars, whose thermoelastic properties at high pressure and temperature are still poorly constrained. We performed X-ray diffraction measurements on natural magnetite using resistive-heated diamond-anvil cells up to 16 GPa and 1100 K. We fitted a thermal equation of state (EoS) to the collected data resulting in K0 = 182(1) GPa, K0′ = 4, θD = 660 K, γ = 1.8(1), and q = 2.7. Moreover, it was possible to explore the structural evolution of magnetite in detail using single-crystal measurements. Over the studied pressure and temperature range, we found no evidence of a transformation from an inverse to a normal spinel structure. The EoS parameters obtained in this study will be implemented into currently available databases for self-consistent thermodynamic modeling. In particular, our results are used to model and compare the sound wave velocities of a magnetite-bearing and magnetite-free martian upper mantle assemblage. We observe that the incorporation of magnetite reduces the sound wave velocities; however, the magnitude of the effect is below the current seismic detection limit of the InSight mission on Mars at the low abundance of magnetite expected in the martian mantle.

First‐Principles Calculations of the Thermal Expansion Path of the Co7Mo6 μ‐Phase

The thermal expansion path is calculated for the Co7Mo6 compound, with the structure of μ‐phase, from T = 0 to 1500 K which is below its decomposition temperature. The method allowing to reduce the problem to a 1D case and considering the energy as depending on only one variable, the volume, is used. The thermodynamic properties of Co7Mo6 are studied using first‐principles‐based quasiharmonic Debye–Grüneisen approximation and by comparing the free energies calculated along different paths of thermal expansion. The electronic, vibrational, and magnetic energy contributions to the free energy are accounted. The thermal expansion of Co7Mo6 is not isotropic. The influence of electronic, magnetic, and vibrational entropy on the stability of Co7Mo6 is analyzed. The isobaric heat capacity, thermal expansion, elastic constants, bulk modulus, sound wave velocities, and Debye and Curie temperatures are reported. The calculated results are analyzed and are in agreement with the available experimental and theoretical data.