74 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
Purification and characterization of a glucoamylase secreted by <i>Sclerotinia sclerotiorum</i>
International audienc
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
Preventable deaths in a French regional trauma system: A six-year analysis of severe trauma mortality
International audienc
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