Debye model

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

Modeling Human Head Tissues Using Fourth-Order Debye Model in Convolution-Based Three-Dimensional Finite-Difference Time-Domain

Abstract: A fourth order Debye model is derived using genetic algorithms to represent the dispersive properties of the 17 tissues that form the human head. The derived model gives accurate estimation of the electrical properties of those tissues across the frequency band from 0.1 GHz to 3 GHz that can be used in microwave systems for head imaging. A convolution-based three-dimensional finite-difference time-domain (3D-FDTD) formulation is implemented for modeling the electromagnetic wave propagation in the dispersive head tissues whose frequency dependent properties are represented by the derived fourth-order Debye model. The presented results show that the proposed 3D-FDTD and fourth-order Debye model can accurately show the electromagnetic interaction between a wide band radiation and head tissues with low computational overhead and more accurate results compared with using multi-pole Cole-Cole model.

Effect of cluster size on the chemical ordering in nanometer-sized Au-75at%Cu alloy clusters

Abstract: The effect of cluster size on the chemical ordering in nanometer(nm)-sized Au-75at%Cu alloy clusters has been studied by means of transmission electron microscopy (TEM). It was found that the chemically disordered high-temperature phase, i.e. solid solution, becomes more stable than the ordered (L12) low-temperature phase even at room temperature when the cluster diameter is reduced below approximately 5 nm. Simulation has revealed that when the lattice of these nm-sized Au-75at%Cu clusters is so soft that the Debye temperature of the clusters is depressed, the order-disorder transition temperature, Tc of nm-sized clusters falls below room temperature.

Thermoelastic property and high-pressure stability of Fe7C3: Implication for iron-carbide in the Earth’s core

Abstract: To investigate the physical property of Fe7C3, we carried out in situ X-ray diffraction experiments using a Kawai-type multi-anvil apparatus and a diamond anvil cell up to 71.5 GPa and 1973 K. The carbide was found to be stable under these experimental conditions. However, we found anomalous behavior in its isothermal compression and thermal expansivity. These anomalies could be due to the magnetic phase transition in Fe7C3 from a ferromagnetic ( fm ) to a paramagnetic ( pm ) phase. The Curie temperature of 523 K at 1 bar (Tsuzuki et al. 1984) decreases with pressure, and the pressure-induced magnetic transition is estimated to occur at ~18 GPa and 300 K. The pressure-volume-temperature ( P - V - T ) data set for the pm -Fe7C3 was fitted by the Mie-Gruneisen-Debye (MGD) equation of state (EOS) and the following parameters were obtained: unit-cell volume V = 184.2 ± 0.3 A3, bulk modulus K = 253 ± 7 GPa, the pressure derivative of bulk modulus K ′ = 3.6 ± 0.2, Gruneisen parameter γ = 2.57 ± 0.05, Debye temperature 𝛉 = 920 ± 140 K, and q = 2.2 ± 0.5, respectively, at zero pressure. The calculated density for Fe7C3 provides a good explanation for the density of the Earth’s inner core obtained from seismological observations.