Debye model

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

Electron screening in d(d, p)t for deuterated metals : temperature effects

Abstract: The electron screening in the d(d, p)t reaction has been studied for the deuterated metal Pt at a sample temperature T = 20 °C–340 °C and for Co at T = 20 °C and 200 °C. The enhanced electron screening decreases with increasing temperature, where the data agree with the plasma model of Debye applied to the quasi-free metallic electrons. The data represent the first observation of a temperature dependence of a nuclear cross section. We also measured the screening effect for the deuterated metal Ti (an element of group 4 of the periodic table) at T = −10 °C–200 °C: above 50 °C, the hydrogen solubility dropped to values far below 1 and a large screening effect became observable. Similarly, all metals of groups 3 and 4 and the lanthanides showed a solubility of a few per cent at T = 200 °C (compared to T = 20 °C) and a large screening also became observable. Within the Debye model, the deduced number of valence electrons per metallic atom agrees with the corresponding number from the Hall coefficient, for all metals investigated.

Low-temperature specific heats of titanium, zirconium, and hafnium

Abstract: The specific heats of titanium, zirconium, and hafnium were found to obey the relation $c=\ensuremath{\gamma}T+\ensuremath{\beta}{T}^{3}$ from 1.1 to 4.5\ifmmode^\circ\else\textdegree\fi{}K within the experimental error. As in other transition metals, the electronic term is large and for the Group IV-A metals decreases with increasing atomic number indicating a progressively larger degree of electronic interaction in the sequence titanium, zirconium, and hafnium. The Debye temperatures decrease with increasing atomic mass as would be expected from the central-force model; however, the ratio of the Debye temperatures indicate that the average atomic force constant for hafnium is some 50% larger than for titanium and zirconium in agreement with the unusually small atomic volume of hafnium.

FP-APW + lo study of the elastic, electronic and optical properties of the filled skutterudites CeFe4As12 and CeFe4Sb12

Abstract: Using a full-relativistic version of the full-potential augmented plane wave plus local orbitals (FP-APW + lo) method within the local density approximation (LDA), we have studied the elastic, electronic and optical properties of the filled skutterudites CeFe4As12 and CeFe4Sb12. Structural parameters, including lattice constant, internal free parameters and, bulk modulus and its pressure derivative were calculated. We have determined the full set of first-order elastic constants, Young’s modulus, Poisson’s ratio and the Debye temperature of these compounds. Band structures, density of states, pressure coefficients of energy band gaps are also given. It is found that both CeFe4As12 and CeFe4Sb12 are indirect band gap semiconductors. The valence band maximum (VBM) is located at Γ point, whereas the conduction band minimum (CBM) is located at N point. Optical constants, including the dielectric function, optical reflectivity, refractive index and electron energy loss were calculated for radiation up to 30 eV. This is the first quantitative theoretical prediction of the elastic and optical properties for these compounds, and it still awaits experimental confirmation.

Temperature Dependence of the Thermal Properties of Optical Memory Materials

Abstract: We have measured the temperature dependence of the thermal conductivities of Ge2Sb2Te5 (GST) and ZnS–SiO2 using a nano second thermoreflectance measurement system from room temperature to 500–600 °C. The specific heat capacities of these materials also have been determined from -130 to 500 °C for GST and from room temperature to 600 °C for ZnS–SiO2. The Debye temperature was obtained from specific heat capacity measurement. Using the obtained temperature dependence of the thermal conductivities, a temperature simulation inside a simple structured optical disk with and without considering its temperature dependence was carried out, and the difference in maximum temperature was approximate 80 °C.