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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 article, measurements of low-temperature specific heats in a number of binary and ternary amorphous PdSi and Pd-Si-Cu alloys were reported.
Abstract: Measurements are reported of low-temperature specific heats in a number of binary and ternary amorphous Pd-Si and Pd-Si-Cu alloys. The results indicate that the linearterm temperature coefficient, $\ensuremath{\gamma}$, changes with electron concentration and shows a pronounced maximum near $\frac{e}{a}=1.6$. The glassy alloys are also characterized by a large ${T}^{5}$-term coefficient and a relatively low limiting Debye temperature. The hypothesis of a minimum in the density of states at the Fermi level within the glassy range has not been confirmed.
57 citations
TL;DR: In this article, the specific heat of polymethyl methacrylate and polystyrene has been measured using the heat pulse method between 0.5 and 4.3°K.
Abstract: Measurements of the specific heat of polymethyl methacrylate and polystyrene have been performed using the heat pulse method between 0.5 and 4.3°K. Above 2°K the specific heat is about double that expected on the basis of the Debye theory and acoustic measurements. Below 2°K the experimental data approach the Debye value. The excess specific heat can be fit by two Einstein modes. For polymethyl methacrylate the Einstein temperatures are 4.9 and 17.5°K containing 0.014% and 1.0% of all modes, respectively. For polystyrene the corresponding modes are 5.5 and 16°K with strengths of 0.038% and 1.8% respectively. The data support a model of pendant side groups near voids capable of independent low frequency torsional oscillations. The barrier to internal rotation of the pendant group is estimated.
57 citations
TL;DR: In this paper, a finite difference time domain model based on efficient two-pole Debye dispersion was proposed to analyze the electromagnetic interaction between a whole human body and ultra wide band radiation having a wide frequency spectrum.
Abstract: We have successfully developed a human body finite difference time domain model based on efficient two-pole Debye dispersion, and analyzed for the first time the electromagnetic interaction between a whole human body and ultra wide band radiation having a wide frequency spectrum. The two-pole Debye dispersion model is obtained for 50 individual human tissue properties from Gabriel's Cole-Cole data by least squares fitting over a wide frequency range from 100 MHz to 6 GHz. For validation, the model is exposed to radiation of a spread spectrum signal modulated by typical binary phase shift keying. Local energy absorption in a human body has been compared between the two-pole Debye model and a conventional model with frequency-independent permittivity and conductivity.
57 citations
TL;DR: In this paper, the stability and elastic properties of Mg2Pb are investigated by the first principles method, using the method of ultrasoft pseudopotential within the generalized gradient approximation based on density functional theory.
Abstract: The stability and elastic properties of Mg2Pb are investigated by the first principles method, using the method of ultrasoft pseudopotential within the generalized gradient approximation based on density functional theory. Cohesive energy and formation enthalpy show that Mg2Pb is stable. Similar result is also obtained by the energy band structure and density of states (DOS) analysis. The thermal data of Mg2Pb are calculated using Debye's quasi-harmonic approximation, such as heat capacity and Gibbs free energy. Based on the CV, we found that the Debye temperature of Mg2Pb is 247.2 K. Young's modulus and shear modulus for Mg2Pb are 68.6 and 27.9 GPa calculated from the theoretical elastic constants by Voigt–Reuss–Hill averaging scheme.
57 citations
20 Dec 2008-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the effects of temperature and strain rate on the mechanical properties of a Ni 60 Pd 20 P 17 B 3 BGA were investigated and the mechanism reflecting changes in the maximum compressive stress and plastic strain with temperature was discussed.
Abstract: Little is known about mechanical properties of bulk glassy alloys (BGAs) at cryogenic temperatures. In this study, we investigated the effects of temperature and strain rate on the mechanical properties of a Ni 60 Pd 20 P 17 B 3 BGA. Compression tests were performed at temperatures of 295, 223, 173 and 77 K and at strain rates from 5 × 10 −5 to 5 × 10 −3 s −1 . Measurements of the elastic parameters were also made at temperatures from 91 to 371 K. It is found that both the maximum compressive stress and plastic strain to failure increase with decreasing testing temperature. The Young and shear moduli, and Debye temperature monotonically increase with decreasing temperature, while Poisson’s ratio decreases, indicating that the BGA becomes rigid and the effective atomic distance decreases at cryogenic temperatures. The mechanism reflecting the changes in the maximum compressive stress and plastic strain with temperature is discussed.
56 citations