421 research outputs found
On a mixed problem for the parabolic Lam'e type operator
We consider a boundary value problem for the parabolic Lam\'e type operator
being a linearization of the Navier-Stokes' equations for compressible flow of
Newtonian fluids. It consists of recovering a vector-function, satisfying the
parabolic Lam\'e type system in a cylindrical domain, via its values and the
values of the boundary stress tensor on a given part of the lateral surface of
the cylinder. We prove that the problem is ill-posed in the natural spaces of
smooth functions and in the corresponding H\"older spaces; besides, additional
initial data do not turn the problem to a well-posed one. Using the Integral
Representation's Method we obtain the Uniqueness Theorem and solvability
conditions for the problem
Variability of structural and electronic properties of bulk and monolayer Si2Te3
Since the emergence of monolayer graphene as a promising two-dimensional
material, many other monolayer and few-layer materials have been investigated
extensively. An experimental study of few-layer Si2Te3 was recently reported,
showing that the material has diverse properties for potential applications in
Si-based devices ranging from fully integrated thermoelectrics to
optoelectronics to chemical sensors. This material has a unique layered
structure: it has a hexagonal closed-packed Te sublattice, with Si dimers
occupying octahedral intercalation sites. Here we report a theoretical study of
this material in both bulk and monolayer form, unveiling a fascinating array of
diverse properties arising from reorientations of the silicon dimers between
planes of Te atoms. The lattice constant varies up to 5% and the band gap
varies up to 40% depending on dimer orientations. The monolayer band gap is 0.4
eV larger than the bulk-phase value for the lowest-energy configuration of Si
dimers. These properties are, in principle, controllable by temperature and
strain, making Si2T3 a promising candidate material for nanoscale mechanical,
optical, and memristive devices.Comment: 9 pages, 4 figure
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