1,213 research outputs found
Negative thermal expansion in the Prussian Blue analog Zn3[Fe(CN)6]2: X-ray diffraction and neutron vibrational studies
The cubic Prussian Blue (PB) analog, Zn3 [Fe(CN)6]2, has been studied by
X-ray powder diffraction and inelastic neutron scattering (INS). X-ray data
collected at 300 and 84 K revealed negative thermal expansion (NTE) behaviour
for this material. The NTE coefficient was found to be -31.1 x 10-6 K-1. The
neutron vibrational spectrum for Zn3[Fe(CN)6]2.xH2O, was studied in detail. The
INS spectrum showed well-defined, well-separated bands corresponding to the
stretching of and deformation modes of the Fe and Zn octahedra, all below 800
cm-1.Comment: 4 pages, 3 figure
First principles calculations and experiments to determine the hydrogenation process of Cu-Li-Mg
Density Functional Theory (DFT) calculations were performed. They were firstly implemented to optimize the structure and refine the stoichiometry of the only ternary compound, CuLi0.08Mg1.92 of the Cu-Li-Mg system. Furthermore using DFT, several possible structures of CuMg2Hx were optimized. Since most of the hydrides are cubic structures or can be considered as distortions of a cubic structure, we have started calculations for CuMg2Hx (x = 4 - 6)with tetragonal and monoclinic structures, similar to those of the hydrides formed by the nearest neighbors of Cu and Mg in the periodic table: NiMg2H4 and CoMg2H5 (e.g. monoclinic C2/c and tetragonal P4/nmm, respectively). It can be concluded that the most stable configuration corresponds to CuMg2H5 with C2/c structure. We have performed several neutron scattering experiments that are in agreement with the first principles calculations.</jats:p
KLEIN: A New Family of Lightweight Block Ciphers
Resource-efficient cryptographic primitives become fundamental for realizing both security and efficiency in embedded systems like RFID tags and sensor nodes. Among those primitives, lightweight block cipher plays a major role as a building block for security protocols. In this paper, we describe a new family of lightweight block ciphers named KLEIN, which is designed for resource-constrained devices such as wireless sensors and RFID tags. Compared to the related proposals, KLEIN has advantage in the software performance on legacy sensor platforms, while in the same time its hardware implementation can also be compact
Anharmonicity of flux lattices and thermal fluctuations in layered superconductors
We study elasticity of a perpendicular flux lattice in a layered
superconductor with Josephson coupling between layers. We find that the energy
contains ln(flux displacement) terms, so that elastic constants cannot be
strictly defined. Instead we define effective elastic constants by a thermal
average. The tilt modulus has terms with ln(T) which for weak fields, i.e.
Josephson length smaller than the flux line spacing, lead to displacement
square average proportional to T/ln(T). The expansion parameter indicates that
the dominant low temperature phase transition is either layer decoupling at
high fields or melting at low fields.Comment: 15 pages, 2 eps figures, Revtex, submitted to Phys. Rev. B.
Sunj-class: superconductivit
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