排序方式: 共有66条查询结果,搜索用时 15 毫秒
61.
M. Pugaczowa-Michalska 《Solid State Communications》2006,140(5):251-255
A computational study of the pressure and thermal behaviour of NiMnSb within the framework of density functional theory and the Debye-Grüneisen model is reported. The theoretical values of equilibrium lattice parameter, bulk modulus, its pressure derivative, Debye temperature, Grüneisen constant and coefficient of thermal expansion are estimated from electronic structure calculated by the full-potential nonorthogonal local-orbital minimum basis method (FPLO). The bulk modulus and its pressure derivative have been computed using the Murnaghan form of the equation of states. The volume-temperature dependence was obtained by minimisation of the free energy as a sum of the total energy of the rigid lattice and the free energy of the vibration lattice. The thermal expansion coefficient for the studied NiMnSb, obtained within the Debye theory including anharmonicity, is in good agreement with experimental results. 相似文献
62.
Single-walled carbon nanotubes (SWNTs) have many interesting properties; they may be metallic or semiconducting depending on their diameter and helicity of the graphene sheet. Hydrostatic or quasi-hydrostatic high pressures can probe many electronic features. Resistance-temperature measurements in SWNTs from normal condition and under 0.4 GPa of quasi-hydrostatic pressures reveal a semiconducting-like behavior. From 0.5 to about 2.0 GPa, the resistance changes to a Kondo-like feature due to magnetic impurities used to catalyse the nanotube formation. Above 2.0 GPa, they become metallic and at about 2.4 GPa, the resistance decreases dramatically around 3 K suggesting a superconducting transition. 相似文献
63.
G.G.N. Angilella G. Balestrino P. Cermelli P. Podio-Guidugli A.A. Varlamov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(1):67-74
We propose a Ginzburg-Landau phenomenological model for the dependence of the critical temperature on microscopic strain in
tetragonal high-T
c
cuprates. Such a model is in agreement with the experimental results for LSCO under epitaxial strain, as well as with the
hydrostatic pressure dependence of T
c
in most cuprates. In particular, a nonmonotonic dependence of T
c
on hydrostatic pressure, as well as on in-plane or apical microstrain, is derived. From a microscopic point of view, such
results can be understood as due to the proximity to an electronic topological transition (ETT). In the case of LSCO, we argue
that such an ETT can be driven by a strain-induced modification of the band structure, at constant hole content, at variance
with a doping-induced ETT, as is usually assumed.
Received 1st October 2001 and Received in final form 5 December 2001 相似文献
64.
R. Lewis 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):409-414
Inclusive electron scattering cross-sections in the quasielastic and resonance regions for few GeV electrons are well represented
in terms of scaling functions and scaling variables, the so-called superscaling analysis (SuSA). The concepts of scaling of
the first and second kinds and superscaling are discussed, as are several mechanisms which are known to yield scaling violations.
Given the high quality of scaling for cross-sections at appropriate kinematics, it is shown how the ideas can be turned around
to provide predictions for both charge-changing and neutral current neutrino reactions with nuclei at comparable kinematics. 相似文献
65.
First principle calculations of elastic properties under pressure of the filled tetrahedral semiconductors LiZnN, LiZnP and LiZnAs are presented, using the pseudo-potential plane-waves approach based on density functional theory, within the local density approximation. Elastic constants, bulk modulus, Young’s modulus and Poisson’s ratio are calculated at zero pressure. A linear dependence of the bulk modulus and elastic constants with applied pressure is found. As the experimental elastic constants are not available for LiZnX, we have also calculated the elastic constants of GaN, GaP and GaAs, the binary analogues of LiZnN, LiZnP and LiZnAs, respectively, for checking the reliability and accuracy of our predicted results for LiZnX. The obtained results agree well with the available experimental data. 相似文献
66.
Fernando L. Primo Leandro Michieleto Marcilene A.M. Rodrigues Patrícia P. Macaroff Paulo C. Morais Zulmira G.M. Lacava Maria Vitória L.B. Bentley Antonio C. Tedesco 《Journal of magnetism and magnetic materials》2007
In this work, we performed the synthesis and in vitro characterization of a new class of drug delivery system (DDS) denominated magnetic nanoemulsion (MNE). The association of colloidal nanoparticles with biocompatible magnetic fluids results in a new DDS for application in photodynamic therapy (PDT) and magnetic hyperthermia treatment. It works in a synergic manner with an expected enhancement in tumor damage after minimum drug doses, based on heat dissipation and/or light photosensitization. For this purpose, we investigated the permeation and retention in vitro model using Foscan® as a photosensitizer incorporated in MNE using a Franz diffusion cell and a biological skin model in biomimetic conditions. 相似文献