We report phonon densities of states (DOS) of iron measured by nuclear resonant inelastic x-ray scattering to 153 gigapascals and calculated from ab initio theory. Qualitatively, they are in ...agreement, but the theory predicts density at higher energies. From the DOS, we derive elastic and thermodynamic parameters of iron, including shear modulus, compressional and shear velocities, heat capacity, entropy, kinetic energy, zero-point energy, and Debye temperature. In comparison to the compressional and shear velocities from the preliminary reference Earth model (PREM) seismic model, our results suggest that Earth's inner core has a mean atomic number equal to or higher than pure iron, which is consistent with an iron-nickel alloy.
Phonons in Wurtzite Aluminum Nitride Schwoerer-Böhning, M.; Macrander, A. T.; Pabst, M. ...
physica status solidi (b),
September 1999, Letnik:
215, Številka:
1
Journal Article
Recenzirano
We present data obtained with inelastic X‐ray scattering measurements of the phonon dispersions in hexagonal aluminum nitride along all three high‐symmetry directions. These are the first such data ...for AlN. Presently available single crystals are large enough to perform an inelastic X‐ray scattering experiment. The results are compared with first‐principles calculations. We find excellent agreement between the data and the calculations.
Quasi-reversible current maxima at low voltage, leading to N-type current-voltage characteristics with negative differential resistance, have been observed in different types of organic ...light-emitting devices including conjugated polymer LEDs, dye-doped polymeric LEDs and LEDs from evaporated small molecules. We have investigated the dependence of this phenomenon on different external parameters, like layer thickness, temperature and time. We found that the usual explanations, e.g. by tunneling, cannot satisfactory explain our observations. Instead, our experiments indicate that spatially local effects are responsible for the anomalous high current flow at low voltage. The implications for device operation and lifetime are discussed.
Dynamic diffuse scattering of X-rays in fcc 4He Venkataraman, C. T.; Schwoerer-Böhning, M.; Simmons, R. O.
Physica Status Solidi (b),
February 2004, Letnik:
241, Številka:
2
Journal Article
PDF
