63 research outputs found
Phonon-phason coupling in icosahedral quasicrystals
From relaxation simulations of decoration-based quasicrystal structure models
using microscopically based interatomic pair potentials, we have calculated the
(usually neglected) phonon-phason coupling constant. Its sign is opposite for
the two alloys studied, i-AlMn and i-(Al,Cu)Li; a dimensionless measure of its
magnitude relative to the phonon and phason elastic constants is of order 1/10,
suggesting its effects are small but detectable. We also give a criterion for
when phonon-phason effects are noticeable in diffuse tails of Bragg peaks.Comment: 7 pages, LaTeX, uses Europhys Lett macros (included
Atomic scale study of the impact of the strain and composition of the capping layer on the formation of InAs quantum dots
Critical thickness for InAs quantum dot formation on (3 1 1)B InP substrates
We report on the critical thickness for InAs quantum dot (QD) formation on (3 1 1)B InP substrates. Firstly, critical thicknesses for InAs QD formation on InP surfaces have been measured by reflection high-energy electron diffraction. Large change of th
Phason softening in the AlPdMn icosahedral phase
The diffuse scattering located close to Bragg reflections has been
studied as a function of the temperature on a single grain of the AlPdMn
icosahedral phase. Between C and C there is a
reversible and continuous transition. When the temperature increases, the
diffuse scattering diminishes whereas high- reflections have
their intensity increased. All results are well interpreted within the
elasticity theory of quasi-crystals: the changes in diffuse scattering
shape and intensity when lowering the temperature are due to a softening
of the K1 phason elastic constant. The time decay of these
long-wavelength phason fluctuations is larger than 5 ns
Strain, size and composition of InAs quantum sticks, embedded in InP, determined via X-ray anomalous diffraction and diffraction anomalous fine structure in grazing incidence
Inflammatory pseudotumour of the liver: a variant rich in giant atypical reactive dendritic cells
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