Showing 114 results for Author: Raphael P. Hermann
Apr, 2016
Journal
An overview is presented on the variation of electrical conductivity, oxygen permeation, oxygen surface exchange and thermal expansion coefficient as a function of the composition of perovskites in the quasi-ternary system LaFeO3-LaCoO3-LaNiO3. Powders of thirteen nominal perovskite compositions were synthesized under identical conditions by the Pechini method. The powder…
Mar, 2016
Journal
The room temperature magnetocaloric material MnFe4Si3 was investigated with nuclear inelastic scattering (NIS) and resonant ultrasound spectroscopy (RUS) at dierent temperatures and applied magnetic fields in order to assess the in uence of the magnetic transition and the magnetocaloric effect on the lattice dynamics. The NIS data give access to phonons with energies abov…
Mar, 2016
Journal
The lattice dynamics and thermoelectric properties of sintered phosphorus-doped nanostructured silicon- germanium alloys obtained by gas-phase synthesis were studied. Measurements of the density of phonon states by inelastic neutron scattering were combined with measurements of the elastic constants and the low- temperature heat capacity. A strong influence of nanostructur…
Nov, 2015
Journal
Using a combination of first-principles calculations and experimental transport measurements, we study the electronic and magnetic structure of the unfilled skutterudite FeSb3. We employ the hybrid functional approach for exchange-correlation. The ground state is determined to be anti-ferromagnetic with an atomic magnetic moment of 1.6 μB/Fe. The N ́eel temperature TN is e…
Sep, 2015
Journal
he crystallinity and the lattice dynamics in elemental modulated Sbinline imageTeinline image films are investigated microscopically using high energy synchrotron radiation diffraction combined with inline imageSb nuclear inelastic scattering. The correlation length is found to be finite but less than 100 Å. The element specific density of phonon states is extracted. A com…
Jun, 2015
Journal
A high-pressure study of the lattice dynamics in the filled skutterudite Eu0.84Fe4Sb12 was carried out by means of x-ray powder diffraction and nuclear inelastic scattering. The anharmonicity of particular phonon modes was characterized by mode and element specific Gr¨uneisen parameters. The large anharmonicity of the rattling optical mode that is hybridized with the acous…