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Debye model

About: Debye model is a research topic. Over the lifetime, 7462 publications have been published within this topic receiving 133987 citations.


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TL;DR: In this paper, the role of P2O5 on the structure of the glass system was investigated using FT-IR spectroscopic studies and the results showed that the density and the molar volume increase as both sound velocities and the determined glass transition temperatures decrease with increasing the contents of P 2O5.
Abstract: Glasses in the system (95−x) [0.25 Na2O–0.75 B2O3]–x P2O5–5 Fe2O3 (0⩽x⩽15 mol%), have been prepared by the melt quenching technique. Elastic properties and FT-IR spectroscopic studies have been employed to study the role of P2O5 on the structure of the glass system. Elastic properties Poisson's ratio, micro-hardness and Debye temperature have been investigated using sound wave velocity measurements at 4 MHz (both longitudinal and shear) at room temperature. The results showed that the density and the molar volume increase as both sound velocities and the determined glass transition temperatures decrease with increasing the contents of P2O5. Infrared spectra of the glasses reveal that the borate network consists of diborate units and is affected by the increase in the concentration of P2O5 content as a second network former. These results are interpreted in terms of the replacement of the diborate units with B–O–B bridges by phosphate units with non-bridging oxygens (NBOs). Therefore, the elastic moduli are observed to decrease with the increase in P2O5 content.

47 citations

Journal ArticleDOI
TL;DR: In this paper, a joint frequency diffuse mismatch model (JFDMM) was proposed to estimate the thermal boundary conductance (hBD) at interfaces of materials with very different material properties.
Abstract: The accuracy of predictions of the thermal boundary conductance (hBD ) made using traditional models such as the diffuse mismatch model (DMM) varies depending on the types of material comprising the interface. At interfaces of materials with very different material properties, the discrepancy between the measured hBD and the DMM results has been associated with inelastic scattering. In this study, a new model, the joint frequency diffuse mismatch model (JFDMM), is derived under the assumption that the phonon flux approaching the interface is altered by phonons vibrating at joint frequencies around the interface affected by phonons on both sides of the interface. This model yields improved hBD predictions for a wide range of materials over a temperature range of several 100s of Kelvin, indicating that at these temperatures, substrate phonons are participating in interfacial thermal transport.

47 citations

Journal ArticleDOI
TL;DR: In this article, the elastic, electronic and thermodynamic properties of fluoro-perovskite KZnF3 have been calculated using the fullpotential linearized augmented plane wave (FP-LAPW) method.
Abstract: The elastic, electronic and thermodynamic properties of fluoro-perovskite KZnF3 have been calculated using the full-potential linearized augmented plane wave (FP-LAPW) method. The exchange-correlation potential is treated with the generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE). Also, we have used the Engel and Vosko GGA formalism (GGA-EV) to improve the electronic band structure calculations. The calculated structural properties are in good agreement with available experimental and theoretical data. The elastic constants C ij are calculated using the total energy variation with strain technique. The shear modulus, Young’s modulus, Poisson’s ratio and the Lame coefficients for polycrystalline KZnF3 aggregates are estimated in the framework of the Voigt-Reuss-Hill approximations. The ductility behavior of this compound is interpreted via the calculated elastic constants C ij . Electronic and bonding properties are discussed from the calculations of band structure, density of states and electron charge density. The thermodynamic properties are predicted through the quasi-harmonic Debye model, in which the lattice vibrations are taken into account. The variation of bulk modulus, lattice constant, heat capacities and the Debye temperature with pressure and temperature are successfully obtained.

47 citations

Journal ArticleDOI
TL;DR: In this article, surface thermodynamic quantities have been calculated as functions of temperature between 0°K and the melting temperature for the noble gas solids Ne, Ar, Kr, and Xe.
Abstract: Surface thermodynamic quantities have been calculated as functions of temperature between 0°K and the melting temperature for the (111), (100), and (110) surfaces of the noble‐gas solids Ne, Ar, Kr, and Xe. The method of calculation differs from the methods used in previous treatments of surface thermodynamic functions in that the atomic vibrations are taken into account, and the vibrational frequencies are properly calculated rather than obtained from a Debye model or an Einstein model. The quantities calculated are the static surface energy, vibrational surface energy, surface entropy, vibrational surface free energy, and surface specific heat. In addition, a surface frequency‐distribution function f8(ω) has been calculated; f8(ω) is positive at low frequencies, because of the presence of surface modes of vibration, and negative at higher frequencies. This behavior of f8(ω) produces a narrow peak in the graph of the surface specific heat as a function of temperature.

47 citations

Journal ArticleDOI
TL;DR: In this article, sound velocities and elastic constants were determined semi-continuously for two annealed polycrystalline titanium alloys between 4 and 300 K. A pulse-superposition technique was used.

47 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023178
2022346
2021303
2020242
2019285
2018304