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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 the elastic constants and thermal expansion of PbTe have been made from 4.2° to 303.2 degrees K. The linear coefficient of thermal expansion was found to be 20.4±0.6/°C at room temperature, and the 0°K Debye temperature was calculated to be 176.7°± 0.5°K.
Abstract: Measurements of the elastic constants and thermal expansion of PbTe have been made from 4.2° to 303.2°K. The extrapolated 0°K values for C44, (C11−C12)/2, and (C11+2C12)/3, respectively, are 1.514±0.009, 6.184±0.066, and 4.560±0.042×1011 dyn/cm2. At 303.2°K these values are 1.344±0.008, 5.016±0.057, and 4.107±0.037×1011 dyn/cm2. Intermediate values are presented graphically, as are the thermal‐expansion data. The linear coefficient of thermal expansion is found to be 20.4±0.4×10−6/°C at room temperature. The 0°K Debye temperature is calculated to be 176.7°±0.5°K.
127 citations
TL;DR: The hyperfine structure in the Mossbauer spectrum of Fe57 in ferrocene and in related compounds shows that the bonding of the iron atom is not affected by ring substitution.
Abstract: The hyperfine structure in the Mossbauer spectrum of Fe57 in ferrocene and in related compounds shows that the bonding of the iron atom is not affected by ring substitution. The temperature dependence of the fraction of recoil‐free absorption events in these compounds indicates that the Debye temperature is low (∼150°K) and that the optical modes make only a minor contribution to the reduction of the recoil‐free fraction at low temperature.
127 citations
TL;DR: The Kapitza conductance between isotopically enriched synthetic diamond and Ti, Al, Au, and Pb has been studied using picosecond optical techniques and suggests the existence of a second conductance mechanism.
Abstract: The Kapitza conductance between isotopically enriched synthetic diamond and Ti, Al, Au, and Pb has been studied using picosecond optical techniques. For Ti and Al, which have Debye temperatures roughly 1/5 of that of diamond, the measured heat flow is in reasonable agreement with calculations of the phonon heat transport based on a simple lattice dynamical model. However, for Au and Pb, which have Debye temperatures 0.07 and 0.04 times that of diamond, the measured Kapitza conductances are as much as 100 times larger than expected, suggesting the existence of a second conductance mechanism.
126 citations
TL;DR: In this article, a family of bulk metallic glasses (BMG) with up to $3.3m diameter and a very low glass transition temperature was found to be the softest in elastic moduli in known BMG's due to their very low transition temperature.
Abstract: We find that a family of $\mathrm{CeAlNiCu}$ alloy system can be readily cast into bulk glassy rods with up to $3\phantom{\rule{0.3em}{0ex}}\mathrm{mm}$ diameter. The $\mathrm{Ce}$-based bulk metallic glasses (BMG's) exhibit a wide supercooled region up to $78\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, very low glass transition temperature $({T}_{g}=359\phantom{\rule{0.3em}{0ex}}\mathrm{K})$, and Debye temperature $({\ensuremath{\theta}}_{D}=144\phantom{\rule{0.3em}{0ex}}\mathrm{K})$. The glass formation, crystallization, glass transition, liquid behavior, and elastic and acoustic properties of the $\mathrm{CeAlNiCu}$ alloys are investigated. Ultrasonic measurements demonstrate that the $\mathrm{Ce}$-based BMG's are the softest in elastic moduli in known BMG's due to their very low glass transition temperature. The fragility parameter $(m)$ is determined to be 21, indicating the strong liquid behavior of the alloy concerning the temperature dependence of viscosity. A remarkable large softening of long-wavelength acoustic phonons in the BMG relative to its crystalline state is observed, and the phonon softening is attributed to its intrinsic microstructural features and strong liquid behavior.
126 citations
TL;DR: In this article, a transducer operated at the fundamental frequency of 4 MHz at room temperature was used to measure the velocities and elastic moduli of a borate glass containing tellurite.
Abstract: Sodium borate glass containing tellurite as TexNa2−2xB4−4xO7−5x with x=0, 0.05, 0.15, 0.25 and 0.35 have been prepared by rapid quenching. Ultrasonic velocity (both longitudinal and shear) measurements have been made using a transducer operated at the fundamental frequency of 4 MHz at room temperature. The density was measured by the conventional Archimedes method. The elastic moduli, the Debye temperature, Poisson's ratio, and the parameters derived from the Makishima–Mackenzie model and the bond compression model have been obtained as a function of TeO2 content. The monotonic decrease in the velocities and the elastic moduli, and the increase in the ring diameter and the ratio Kbc/Ke as a function of TeO2 modifier content reveals the loose packing structure, which is attributed to the increase in the molar volume and the reduction in the vibrations of the borate lattice. The observed results confirm that the addition of TeO2 changes the rigid character of Na2B4O7 to a matrix of ionic behaviour bonds (NBOs). This is due to the creation of more and more discontinuities and defects in the glasses, thus breaking down the borax structure.
126 citations