Transverse Sound Velocities Research Articles

Computational prediction of Thermo-Elastic and charge carriers transport properties of Ba2MnReO6, Ba2NiReO6, and Sr2MnReO6 double Perovskite compounds

The present work involves a computational investigation of the elastic, thermal, and thermoelectric characteristics of Ba2MnReO6, Ba2NiReO6, and Sr2MnReO6 from the Double Perovskite family. The study verified the mechanical stability of the three compounds and investigated Young’s modulus, Poisson, bulk, and shear modulusin various stress orientations. We were also able to compute longitudinal, transverse, and average sound velocities (Vl, Vt, and Vm, in m/s), and the findings revealed that Sr2MnReO6 had a greater longitudinal velocity than the other two compounds. Thermodynamic characteristics revealed that Ba2MnReO6, Ba2NiReO6, and Sr2MnReO6exhibit low lattice thermal conductivity (Kl) at medium temperatures, strong heat absorption, and a moderate coefficient of thermal expansion.The analysis of the electron and hole charge carriers’ transport characteristics revealed that, when doped with an electron concentration close to 1020 cm−3, the two materials, Ba2MnReO6 and Sr2MnReO6, may have an excellent figure of merit surpassing 0.6 at temperatures over 600 K.

Computational study of some seismic observations through compounds (Mgx,Ca(1-x))O at PREM model pressures up to 135.75 GPa

This computational study aims to track the change of some seismic observations by (Mgx,Ca(1-x))O compounds, this was at the PREM model pressures representing of Earth’s material. Based on the link between seismology and metallurgy in addition the Hashin & Shtrikman relationships, with taking into the results of our previous study, especially magnesium and calcium oxides. We were able to study the change in the values of density, bulk and shear modulus, longitudinal, transversal and bulk sound waves velocity of these compounds, with the change of x from a percentage to a hundred thousand. We were able to identify the compounds that he evaluated for those parameters very close to that of the Earth’s material at the pressures of the PREM model, especially at the most important spacing between the Earth’s internal layers until to the limits of the Earth's outer core. But not a single compound has been found to match all values once, meaning that no compound can be found in Earth's deep layers.

Theoretical investigation of collective motion in some liquid metals using pseudopotential approach

The collective motions are studied using a recently created pseudopotential and some elastic constants. This paper involves the calculations of the collective motions like phonon dispersion curves (PDCs) for longitudinal and transverse frequencies ([Formula: see text] and [Formula: see text]), longitudinal sound velocity ([Formula: see text]), transverse sound velocity ([Formula: see text]), isothermal bulk modulus (B), modulus of rigidity (G), Young’s modulus (Y), Poisson’s ratio [Formula: see text], Debye temperature ([Formula: see text]) of some monovalent (Na), divalent (Mg) and polyvalent liquid metals (Al, Pb, Bi). This investigation is based upon the theory of pseudopotential of second-order approach via the equations of Hubbard and Beeby (HB). [Formula: see text] The pair correlation function is calculated from the different mean spherical approximation (MSA), one-component plasma (OCP) and optimized random phase approximation (ORPA) structure factors employed in this work. Three different types of local field correction (screening) functions proposed by Hartree (H), Taylor (T) and Nagy (N) are utilized in this paper. The current findings are found to be in qualitative accord with experimental and theoretical data.

Study of electronic, mechanical, thermoelectric, and optical aspects of K2AlAg(Br/I)6 for solar cells, and energy storage applications

Double perovskite materials exhibit considerable potential in addressing global energy challenges and advancing renewable energy technologies. This study focuses on K2AlAg(Br/I)6 and employs a comprehensive DFT approach to explore its structural, mechanical, thermodynamic, optical, and thermoelectric properties. The structural and thermodynamic stabilities of K2AlAg(Br/I)6 are accurately examined through tolerance factor (τF) and formation energy analysis. The mechanical stability and ductile characteristics are affirmed by studying elastic constants, Passion's, and Pugh's ratios. Additionally, insights into hardness, Debye temperature, as well as transverse and longitudinal sound velocities contribute to a deeper understanding of the material's thermodynamic response. The band gap of K2AlAgBr6 is identified as 2.71 eV, which undergoes a reduction to 1.17 eV when Br is substituted with I, attributed to the pd-hybridization of cations and anions. Exploring optical properties reveals valuable information through dielectric constants ε(ω), refractive index (n(ω)), absorption (α(ω)), and reflectivity (R(ω)). Notably, absorption in both visible and ultraviolet ranges underscores the material's significance for solar cell applications. Furthermore, the computed ultralow lattice thermal conductivity and higher figure of merit are noteworthy outcomes, driven by the substantial Seebeck coefficient and electrical conductivity of the material. These results collectively highlight the exclusive and promising characteristics of K2AlAg(Br/I)6 in the area of renewable energy materials.

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.

Determination of the Mechanical Characteristics of the Ideal Ceramic (Diamond–Silicon Carbide Composite

In this paper, a new diamond–silicon carbide ceramic composite material—Ideal—is studied and its mechanical characteristics are determined. For the first time, a comprehensive determination of Poisson’s ratio, shear modulus, bulk modulus, and transverse sound velocity is carried out. Poisson’s ratio is in the region of 0.008 to 0.01, which, in turn, indicates the absolutely brittle nature of the failure of the Ideal ceramic under loading. The criteria that allow evaluating different materials used for body armor are calculated.

Optical generation and detection of GHz longitudinal and transverse acoustic waves in solids assisted by two-dimensional metallic grating structure

Absorption of laser pulses with picosecond temporal width in a two-dimensional nano-scale metallic grating deposited on a transparent substrate launches both longitudinal and transverse acoustic waves in to the sample. The periodic metallic structure makes the generated acoustic waves propagate several different directions. The propagating acoustic waves are monitored optically by the delayed light pulses (probe light) as the transient reflectivity change which is known as the Brillouin oscillation. The probe light is also diffracted by the metallic grating, allowing the detection of the acoustic waves propagating in the multiple directions efficiently. The analysis of the Brillouin oscillation frequencies brings the longitudinal and transverse sound velocities and the optical refractive index simultaneously from a single measurement. We verify the above mentioned scheme using a sample with two-dimensional square lattice (period 380 nm) of aluminum square islands of lateral dimension 200 × 200 nm2 and thickness of 50 nm on a fused silica substrate of thickness 1 mm. From the obtained Brillouin oscillation frequencies in several tens GHz, the acoustic and optical properties of the substrate material are successfully retrieved. The technique would be applicable to investigate the acoustic and optical properties of more complicated systems, such as anisotropic and/or inhomogeneous medium.

Lattice Vibration, Optical and Mechanical Properties of AlP Semiconductor under the Influence of Pressure

The lattice vibrations, optical, and mechanical properties of zinc-blende AlP semiconductor have been investigated. Research has been carried out to determine how pressure affects various properties, including the refractive index, optical and static dielectric constants, longitudinal and transverse sound velocities, reflectivity, susceptibility, phonon frequencies, ionicity, transverse effective charge, and micro-hardness. The pseudo-potential method (EPM) was used to perform the computations in this article. A fair degree of agreement is seen when comparisons are made with the available experiment and other theoretical calculations.

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.

Theoretical investigation on the structural and vibrational properties of some alkali liquid metals: A pseudopotential approach

Along with a few elastic constants, a recently created pseudopotential is employed to examine the vibrational properties of some simple alkali metals, i.e. Li, Na, K, Rb and Cs. The phonon dispersion curves (PDC) are computed in the text. (ωL and ωT), longitudinal sound velocity (vl), transverse sound velocity (vt), isothermal bulk modulus (B), modulus of rigidity (G), Young’s modulus (Y ), Debye temperature (θD) of some liquid alkali metals. The second order technique used in the current work, using Hubbard and Beeby (HB) equations, is based on pseudopotential theory. The various Percus-Yevick hard sphere (PYHS) and one-component plasma (OCP) structure factors used in the current investigation are used to construct the pair correlation function g(r). The current paper makes use of three distinct forms of local field correction functions developed by Hartree (H), Taylor (T), and Nagy (N). The current findings are found to qualitatively agree with the experimental and theoretical data that is currently available.

How Ultrasonic Pulse-Echo Techniques and Numerical Simulations Can Work Together in the Evaluation of the Elastic Properties of Glasses

This paper presents the numerical simulation of the ultrasonic wave transmittance utilizing the elastodynamic finite integration technique (EFIT). With this methodology, it is possible to simulate the propagation of the ultrasound in a medium with a relatively low computational cost. The capability of this technique for determining the elastic properties of fluorophosphate and the aluminosilicate glasses is described in detail. The elastic constants of the glasses were calculated from the theoretically predicted longitudinal and transversal sound velocities and compared with the corresponding experimental data. Furthermore, the calculated and experimental elastic properties of the fluorophosphate and aluminosilicate glasses were correlated with the structural peculiarities of these glasses. This simulation technique is also suitable for unveiling the existence of possible defects in the glasses by comparing the experimental and simulation data. The EFIT technique is shown to be a very useful tool in order to provide fast and easy-to-acquire data regarding also the structural characteristics of various glassy systems. This can be used in conjunction with other spectroscopic techniques which can prove to be extremely useful for the non-destructive testing of vitreous materials. The latter can prove very important when vitreous materials used in optical or optoelectronic applications need continuous monitoring in order to ensure their optimum operation and functionality with limited intervention. The main contribution of this paper is the treatment of numerical time-domain modeling of 2D acoustic wave propagation in a viscoelastic medium by implementing the elastodynamic finite integration technique (EFIT).

Sound velocities in liquids near freezing: Dependence on the interaction potential and correlations with thermal conductivity

We present systematic investigation of sound velocities in various fluids at the fluid–solid phase transition. First, theoretical estimates indicating that quasi-universal values of sound velocities at freezing can be expected are presented. Then, this prediction is verified on three model systems with quite different interactions (inverse power law, screened Coulomb, and Lennard-Jones pairwise potentials) and 15 real atomic and molecular liquids. It is documented that the ratio of the sound velocity to the thermal velocity tends to a quasi-universal value (cs/vT∼10) in many systems considered, but exceptions also exist. In particular, extremely soft interactions can result in indefinitely large ratios cs/vT. Complex hydrocarbon liquids also demonstrate high ratios cs/vT. On the other hand, liquids composed of light elements, such as hydrogen and neon, demonstrate lower ratios cs/vT. For model systems, we discuss relations between the thermodynamic sound velocity and instantaneous longitudinal, transverse, and bulk sound velocities. It is found that these relations are greatly affected by the potential softness. Finally, correlations between the thermal conductivity coefficient and the sound velocity are briefly discussed in the context of Bridgman's formula.

Influence of Halides on Elastic and Vibrational Properties of Mixed-Halide Perovskite Systems Studied by Brillouin and Raman Scattering.

The relationship between halogen content and the elastic/vibrational properties of MAPbBr3-xClx mixed crystals (x = 1.5, 2, 2.5, and 3) with MA = CH3NH3+ has been studied using Brillouin and Raman spectroscopy at room temperature. The longitudinal and transverse sound velocities, the absorption coefficients and the two elastic constants C11 and C44 could be obtained and compared for the four mixed-halide perovskites. In particular, the elastic constants of the mixed crystals have been determined for the first time. A quasi-linear increase in the sound velocity and the elastic constant C11 with increasing chlorine content was observed for the longitudinal acoustic waves. C44 was insensitive to the Cl content and very low, indicating a low elasticity to shear stress in mixed perovskites regardless of the Cl content. The acoustic absorption of the LA mode increased with increasing heterogeneity in the mixed system, especially for the intermediate composition where the Br and Cl ratio was 1:1. In addition, a significant decrease in the Raman-mode frequency of the low-frequency lattice modes and the rotational and torsional modes of the MA cations was observed with decreasing Cl content. It clearly showed that the changes in the elastic properties as the halide composition changes were correlated with the lattice vibrations. The present findings may facilitate a deeper understanding of the complex interplay between halogen substitution, vibrational spectra and elastic properties, and may also pave the way for optimizing the operation of perovskite-based photovoltaic and optoelectronic devices by tailoring their chemical composition.

Mechanical, optical, and lattice vibrational properties of gallium antimonide (GaSb) semiconductor under the influence of temperature

We have determined the optical, mechanical, and lattice dynamic features of the zinc-blende GaSb compound. It has been investigated how temperature affects longitudinal and transversal sound velocities, reflectivity, phonon frequencies, micro-hardness, and transverse effective charge. Additionally, the dependences of the effective charge, ionicity, bending, stretching force constants, susceptibility, Cauchy, and Born ratios on the temperature of zinc-blende GaSb material, have been calculated. The pseudo-potential method (EPM) has been used to perform the computations in this paper. Comparative analysis with the existing experiment and other theoretical calculations reveals a respectable degree of agreement.

The First-Principles Investigation of Structural Stability, Mechanical, Vibrational, Thermodynamic, and Optical Properties of CaHfS3 for Optoelectronic Application

In this study, the structural, electronic, elastic, phonon vibration, thermodynamic features, and optical properties of the orthorhombic phase of (space group Pnma) C a H f S 3 were examined by first-principles calculations utilizing the plane wave ultrasoft pseudopotentials in generalized gradient approximations (GGAs) and with Hubbard on-site correction (DFT + U). To improve the value of the band gap, the exchange correlation potential is also approximated with Hubbard correction (GGA + U). The equilibrium state properties such as lattice parameters, unit cell volume, bulk modulus, and its derivative were calculated and are in good agreement with the existing data. The mechanical properties such as bulk modulus, shear modulus, Young’s modulus, and elastic anisotropy were determined from the obtained elastic constants. The ratio of bulk modulus to shear modulus confirms that the orthorhombic phase of C a H f S 3 is a ductile material. In addition, the longitudinal sound velocity, transverse sound velocity, and Debye temperature for C a H f S 3 have been computed. The absence of negative frequencies in the phonon dispersion curve and the phonon density of states confirm that C a H f S 3 in the orthorhombic phase is dynamically stable. The thermodynamic parameters such as free energy, entropy, and heat capacity were examined with variations in temperature. Finally, the absorption coefficient, dielectric constant, energy loss function, reflectivity, and refractive index are discussed in detail in the spectral range 0–1.6 Ry (21.77 eV). The polarizations along (100), (010), and (001) directions significantly show different optical responses.

A Theoretical Framework of Mechanical Properties of the Monolayer Graphene

For decades, scientists and researchers believed that two-dimensional (2D) crystals are thermodynamically unstable. Graphene was the first two dimensional material that has successfully been exfoliated from bulk graphite in 2004. We derive interatomic potentials for Graphene for two dimensional lattice structure and using Quasi-harmonic approximations, Mechanical Properties of monolayer Graphene were investigated. The compressibility, hardness, ductility, toughness, brittleness and bonding nature of the Graphene are too well connected with the SOECs. Thus, comprehensive studies on elastic properties are important to show the potential of Graphene in engineering applications. Present studies of monolayer Graphene have been carried out to investigate the elastic constants such as Young’s modulus, Poisson’s ratio, bulk modulus and shear modulus. With the help of elastic constants, the values longitudinal and transverse sound velocities have been computed. We, at present also find the phonon group velocities at Г points along symmetry directions by PYTHON Program. Mechanical Properties were calculated by PYTHON program is agreed very close with the result of other researchers.

Theoretical Prediction of Mechanical Properties of BxAl1−xSb Ternary Semiconducting Alloys

Abstract The present work aims to predict the elastic constants and other significant properties of ordered BxAl1-xSb (0 ≤ x ≤ 1) ternary semiconducting alloys. We report the initial results of the elastic stiffness constants, the bulk modulus, the aggregate shear modulus, the Cauchy ratio, the aggregate Young’s modulus, the Born ratio, the isotropy factor, the fracture toughness and the longitudinal, transverse and average sound velocities. The Debye temperature and the melting point were also predicted using two different empirical expressions. Except the Cauchy ratio, which decreases with enhancing boron content x, all other physical quantities of BxAl1-xSb alloys increase gradually and monotonically with increasing of boron concentration x in the range 0-1. Our obtained data for BSb and AlSb binary semiconducting compounds are discussed and analyzed in comparison with experimental and other theoretical values of the literature. Generally, our data for BSb and AlSb are in good agreement with other results reported previously in literature. Indeed, our obtained value (335.82 K) of the Debye temperature for AlSb compound overestimates the result (328.6 K) reported by Salehi et al. by around 2.03%, while that (1520 K) of the melting point for BSb overestimates the result (1500 K) reported recently by Bioud et al. by around 1.34%. Furthermore, to the best of our knowledge, no theoretical or experimental data were reported in the literature on the elastic constants and other properties for BxAl1-xSb alloys to compare with them.

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.

Boson peak: Damped phonon in solids

The boson peak has long been considered an exclusive fingerprint of structural glasses, attributed to the disordered structure nature of glass. However, numerous studies also revealed the existence of boson peaks in many crystalline materials. The paradox is an unsolved knot in condensed matter physics. Here, we systematically explore the boson peaks in various disordered materials via a low-temperature specific heat perspective. A linear relationship between the boson peak temperature and the transverse sound velocity is well established, which indicates the phonon nature of the boson peak. Further analysis reveals that the boson peak is a ubiquitous hallmark of all solids that originates from the transverse mode damping, and glasses with disordered structures could enhance the phonon damping and result in the distinct boson peak phenomenon. The results have benefits for a better understanding of the structural origins of boson peaks.

In situ laser-ultrasonic monitoring of Poisson’s ratio and bulk sound velocities of steel plates during thermal processes

We demonstrate the in situ measurement of zero-group-velocity Lamb waves and thickness-resonances in steel sheet samples using laser-based ultrasound, while changing the sample temperature from ambient to 1000 ∘C. The ratio of resonance frequencies yields the temperature dependent Poisson’s ratio of its material without requiring knowledge on the sheets’ thickness. Changes in the temperature derivative of the determined Poisson’s ratio reflect changes in the microstructural constituents. We show that additional resonances present in the response spectrum can be used to cross-check the evaluation. With additional knowledge on the thickness, longitudinal and transverse sound velocities are determined as well. We find good qualitative agreement between the temperature dependence of the measured quantities and reference data obtained from dilatometry and thermodynamic material simulations. The determination of the Poisson’s ratio and transverse sound velocity complements previous investigations limited to the longitudinal sound velocity. This is particularly evident above the Curie temperature during the ferrite to austenite transformation and could be beneficial to disentangle transformations with more than two microstructural constituents involved. Finally, the limitations posed by elastic anisotropy introduced by rolling texture, and experimental uncertainties due to temperature inhomgeneities are discussed. We conclude that the laser-ultrasonic measurement of plate resonances provides a robust, contact-free, non-destructive, and in situ determination of Poisson’s ratio.