The Magnetic Spin Ladder (C_{5}H_{12}N)_{2}CuBr_{4}: High Field Magnetization and Scaling Near Quantum Criticality

The magnetization, $M(H \leq 30$ T, 0.7 K $\leq T \leq 300$ K), from single crystals and powder samples of (C$_{5}$H$_{12}$N)$_{2}$CuBr$_{4}$ has been used to identify this system as an $S=1/2$ Heisenberg two-leg ladder in the strong coupling limit, $J_{\perp} = 13.3$ K and $J_{\parallel} = 3.8$ K, with $H_{c1} = 6.6$ T and $H_{c2} = 14.6$ T. An inflection point in $M(H, T = 0.7$ K) at half-saturation, $M_{s}/2$, is described by an effective \emph{XXZ} chain. The data exhibit universal scaling behavior in the vicinity of $H_{c1}$ and $H_{c2}$, indicating the system is near a quantum critical point.Comment: 4 pages, 4 figure

LiBH4@Carbon Micro-Macrocellular Foams: Tuning Hydrogen Release through Varying Microporosity

Microporous-macroporous carbononaceous monolith-type materials, prepared through a hard template method using silica as exo-templating matrices, have been impregnated by an etheric solution of LiBH4 to prepare LiBH4@Carbon samples. It has been shown that the amorphous character of LiBH4 is largely favoured when developing the carbon microporosity (pores smaller than 2 nm) and that LiBH4 dehydrogenation is strongly enhanced at low temperatures. The onset temperature of dehydrogenation can be decreased to 200°C and hydrogen capacity reaching 4.0 wt.% is obtained at 300°C with the carbon having the largest microporous volume, whereas the hydrogen release for bulk LiBH4 is negligible at the same temperature. In addition to some irreversible reactions with carbon surface groups the explanation for such modification could lie in the LiBH4 destabilization through confinement to the nanoscale range and associated amorphization

Chimie intégrative : un outil pour la synthèse rationnelle de matériaux avancés

Dossier Techniques de l'Ingénieur RE 173Les sciences chimiques, en perpétuelle évolution, sont associées à des synthèses de plus en plus complexes et transdisciplinaires. Dans ce contexte, nous montrons comment la chimie intégrative parvient à compartimentaliser les réacteurs chimiques au travers de réactions déclenchées aux interfaces huile/eau d'émulsions diluées (réacteurs chimiques dispersés) et concentrées (réacteurs chimiques en contact). Pour illustrations, quelques exemples non exhaustifs de morphosynthèses de matériaux fonctionnels avancés sont donnés dans les domaines de la biocatalyse hétérogène, de la conversion d'énergie et du relargage thermostimulé de substances d'intérêt encapsulées

Chimie intégrative : un outil pour la synthèse rationnelle de matériaux avancés

11 pagesDossier Techniques de l'Ingénieur RE 173Les sciences chimiques, en perpétuelle évolution, sont associées à des synthèses de plus en plus complexes et transdisciplinaires. Dans ce contexte, nous montrons comment la chimie intégrative parvient à compartimentaliser les réacteurs chimiques au travers de réactions déclenchées aux interfaces huile/eau d'émulsions diluées (réacteurs chimiques dispersés) et concentrées (réacteurs chimiques en contact). Pour illustrations, quelques exemples non exhaustifs de morphosynthèses de matériaux fonctionnels avancés sont donnés dans les domaines de la biocatalyse hétérogène, de la conversion d'énergie et du relargage thermostimulé de substances d'intérêt encapsulées

Gold nanoparticles spontaneously generated in onion-type multilamellar vesicles. Bilayers-particle coupling imaged by Cryo-TEM

We report the spontaneous, in-situ synthesis of gold nanoparticles within onion-type multilamellar vesicles (MLV) using a simple and mild strategy. Monoolein, one of the MLV components, was used as reductant, without any additional chemical. Two different preparative pathways were employed that resulted in gold particle formation as asserted by UV-vis spectroscopy and transmission electron microscopy (TEM). When onions were prepared from a lamellar phase containing gold ions, nanoparticles with a rice grain shape and narrow size distribution (6 × 10 nm*nm) were formed, suggesting synthesis within the vesicles. When preformed onions were dispersed in a KAuCl4 solution, TEM and cryogenic temperature-transmission electron microscopy (cryo-TEM) analysis reveal that both extra- and intravesicular syntheses took place. Cryo-TEM imaging evidences the insertion of gold nanoparticles between MLV leaflets and the close coupling between particle morphology and the lamellar phase. A simple mechanism of particle growth within a lamellar phase is proposed that could explain the differences in nanoparticle size and shape observed between both preparative pathways

: Advanced functional cellular materials bearing multiscale porosity

With this mini review we show through the sol-gel and emulsion-based Integrative Chemistry how it is possible to trigger materials dimensionality and beyond their functionalities when reaching enhanced applications. In here we focus on 3D macrocellular monolithic foams bearing hierarchical porosities and applications thereof. We first depict the general background of emulsions focusing on concentrated ones, acting as soft templates for the design of PolyHIPE foams, HIPE being the acronym of High Internal Phase Emulsions while encompassing both sol-gel and polymer chemistry. Secondly we extend this approach toward the design of hybrid organic-inorganic foams, labeled Organo-Si(HIPE), where photonics and heterogeneous catalysis applications are addressed. In a third section we show how inorganic Si(HIPE) matrices can be employed as sacrificial hard templates for the generation carbonaceous foams, labeled Carbon(HIPE). These foams being conductive we show applications when employed as electrodes for Li-S battery and as hosts for Li(BH4)-based hydrogen storage

Macrocellular Silica Monoliths Hierarchically Textured: Mesostructured Si-HIPE Materials

ABSTRACTInterface between sol-gel process and soft matter appears recently as a very nice tool to generate new materials with complex textures or/and structures extended at various length scales. In this general context, hierarchical inorganic porous monoliths have been prepared using a double templates procedure, namely concentrated emulsion as a macroscopic pattern and mesoscopic micellar templates. The texture of those monoliths can vary dramatically playing either with the oil volume fraction, synthetic pH conditions or the emulsification process. These materials show interconnected macroporosity associated to vermicular-type mesostructuration with an average mesoporosity of 800 m2/g associated to bulk density as low as 0.08 g cm-3 which is comparable to values obtained for silica aerogel.</jats:p

Molecular design of nanostructured boron nitride

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