Search results for "Honeycomb structure"
showing 8 items of 8 documents
Slow Relaxation of the Magnetization in Anilato-Based Dy(III) 2D Lattices.
2021
The search for two- and three-dimensional materials with slow relaxation of the magnetization (single-ion magnets, SIM and single-molecule magnets, SMM) has become a very active area in recent years. Here we show how it is possible to prepare two-dimensional SIMs by combining Dy(III) with two different anilato-type ligands (dianions of the 3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone: C6O4X22−, with X = H and Cl) in dimethyl sulfoxide (dmso). The two compounds prepared, formulated as: [Dy2(C6O4H2)3(dmso)2(H2O)2]·2dmso·18H2O (1) and [Dy2(C6O4Cl2)3(dmso)4]·2dmso·2H2O (2) show distorted hexagonal honeycomb layers with the solvent molecules (dmso and H2O) located in the interlayer space and…
The pore structure of compacted and partly saturated MX-80 bentonite at different dry densities
2014
Compacted MX-80 bentonite is a potential backfill material in radioactive-waste repositories. Pore space in MX-80 has been the subject of considerable debate. 3D reconstructions of the pore space based on tomographic methods could provide new insights into the nature of the pore space of compacted bentonites. To date, few such reconstructions have been done because of problems with the preparation of bentonite samples for electron microscopy. The nanoscale intergranular pore space was investigated here by cryo-Focused Ion Beam nanotomography (FIB-nt) applied to previously high-pressure frozen MX-80 bentonite samples. This approach allowed a tomographic investigation of the in situ microstru…
The influence of the rubber carboxyl functionality on the processability and properties of solid rubber modified epoxy mixtures
2005
A high molecular weight, carboxyl functionalised solid rubber was added to an epoxy resin-aromatic amino system developed for autoclave curing of honeycomb core composite structures. The achievement of an optimal balance of viscous flow and viscoelasticity of the resin, by controlling the nature and extent of cross-linking of the functionalised rubber, was proposed as a route to void-free honeycomb skins. The aim of the present investigation is to understand how the concentration of carboxylic groups of the rubber, prereacted with one of the epoxy monomers, affects the matrix resin flow properties. The concentration of carboxyl groups was changed by reacting them with a monofunctional epoxy…
Topological Insulators in Ternary Compounds with a Honeycomb Lattice
2010
One of the most exciting subjects in solid state physics is a single layer of graphite which exhibits a variety of unconventional novel properties. The key feature of its electronic structure are linear dispersive bands which cross in a single point at the Fermi energy. This so-called Dirac cone is closely related to the surface states of the recently discovered topological insulators. The ternary compounds, such as LiAuSe and KHgSb with a honeycomb structure of their Au-Se and Hg-Sb layers feature band inversion very similar to HgTe which is a strong precondition for existence of the topological surface states. In contrast to graphene with two Dirac cones at K and K' points, these material…
Highly textured boron/nitrogen co-doped TiO2 with honeycomb structure showing enhanced visible-light photoelectrocatalytic activity
2020
International audience; In this work, we report a novel photocatalyst based on boron and nitrogen co-doped TiO2 rutile (1 1 0) honeycomb structures. The photocatalyst has been prepared by simultaneously oxidizing and doping a Ti-foil substrate at 750 degrees C. The unit cell volume and the crystallite size of grown TiO2 films were measured by Rietveld refinement analysis. The co-doping by boron and nitrogen was achieved simultaneously with the oxidation of the titanium, resulting in a rutile (1 1 0) textured TiO2 film. X-ray photoelectron spectroscopy analysis revealed the presence of Ti-O-N and Ti-O-B-N bonds, and the presence of crystal defects in the lattice was detected and displayed by…
Two-Dimensional Carbon: A Review of Synthesis Methods, and Electronic, Optical, and Vibrational Properties of Single-Layer Graphene
2019
Graphite has been widely used by humans for a large part of their history. Nevertheless, it has only recently been possible to isolate its basic unit: carbon atoms arranged in a honeycomb structure on a single plane, namely graphene. Since its discovery, many techniques have been developed and improved to properly synthesize graphene and its derivatives which are part of the novel class of two-dimensional materials. These advanced materials have imposed themselves in nanotechnology thanks to some outstanding physical properties due to their reduced dimensions. In the case of graphene, its reduced dimension gives rise to a high electrical mobility, a large thermal conductivity, a high mechan…
Synthesis, Structure, and Magnetic Properties of [(S)-[PhCH(CH3)N(CH3)3]][Mn(CH3CN)2/3Cr(ox)3]·(CH3CN)_(solvate), a 2D Chiral Magnet Containing a Qua…
2008
The synthesis, structure, and magnetic properties of a novel oxalate-based bimetallic magnet obtained by using the chiral (S)-trimethyl-(1-phenyl-ethyl)-ammonium, ((S)-[PhCH(CH3)N(CH3)3](+)), cation as template is reported. This compound can be formulated as [(S)-[PhCH(CH3)N(CH3)3]][Mn(CH3CN)2/3Cr(ox)3] x (CH3CN)_(solvate), and it crystallizes in the chiral trigonal space group P3. It shows a distorted two-dimensional honeycomb structure formed by Mn(II) and Cr(III) ions connected through oxalate anions with [(S)-[PhCH(CH3)N(CH3)3](+) cations and solvent molecules intercalated between the oxalate layers. Two-thirds of the Mn(II) ions of the honeycomb anionic network are heptacoordinated. Th…
Out-of-plane elastic constants of curved cell walls honeycombs
2021
International audience; The work describes the out-of-plane properties of a curved wall honeycomb structure evaluated using analytical models and finite elements techniques. Out-of-plane properties are calculated using a theoretical approach based on energy theorems and validated using a fullscale<br>finite element technique to simulate transverse shear tests. The effects of the curvature of the walls and the depth of the honeycomb cells on the out-of-plane elastic constants are evaluated and excellent agreement is observed between theoretical and numerical models. These curved cell wall honeycombs feature specific (i.e., relative density weighted) highly tailorable upper shear bounds tha…