نتایج جستجو برای: phonon dispersion
تعداد نتایج: 76044 فیلتر نتایج به سال:
Single-crystal diffuse scattering data have been collected at room temperature on synthetic titanite using both neutrons and high-energy x-rays. A simple ball-and-springs model reproduces the observed diffuse scattering well, confirming its origin to be primarily due to thermal motion of the atoms. Ab initio phonons are calculated using density-functional perturbation theory and are shown to re...
Raman spectra of isotopically pure CuBr (Cu Br) were measured under hydrostatic pressures up to 10 GPa at 10 K. The anomalous line shape of the longitudinal-optic ~LO! scattering in the zinc-blende phase ~CuBr-III, 0–4 GPa!, consisting of a broad structure between 155 and 177 cm, exhibits a continuous change with pressure and develops into a narrow LO phonon peak near 4 GPa. The disappearance o...
Micrometre-sized MgB2 crystals of varying quality, synthesized at low temperature and autogenous pressure, are compared using a combination of Raman and infra-red (IR) spectroscopy. These data, which include new peak positions in both spectroscopies for high quality MgB2, are interpreted using DFT calculations on phonon behaviour for symmetry-related structures. Raman and IR activity additional...
We consider the impurity-induced polariton local states in a dipole-active medium. These states present the local optical vibrations which are coherently coupled with the induced electromagnetic field. We show that the crossover between the polariton and phonon local states takes place within the relativistically narrow interval near the bottom of the polariton gap. However, the resonant phonon...
Single crystals of Ba1-xKxBiO3 compound for 0 < x <0.6 from insulator to superconducting region have been grown by electrochemical method. The crystals have been characterized by powder x-ray diffraction and Laue x-ray to determine the crystal structure, formed phases and potassium concentration. Inelastic x-ray scattering spectrum of the crystals has been studied to investigate the phonon pro...
We report a comprehensive investigation of the lattice dynamics of URu2Si2 as a function of temperature using Raman scattering, optical conductivity, and inelastic neutron scattering measurements as well as theoretical ab initio calculations. The main effects on the optical phonon modes are related to Kondo physics. The B1g ( 3 symmetry) phonon mode slightly softens below ∼100 K, in connection ...
To better understand thermal transport at nanoscale point contacts such as the tip-sample contact of a scanning probe microscope and at the contact between a nanotube and a planar surface, we have used a nonequilibrium molecular dynamics MD method to calculate the temperature distribution and thermal resistance of a nanometer scale constriction formed between two planar silicon substrates of di...
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