56 research outputs found

    Crystals springing into action : metal–organic framework CUK-1 as a pressure-driven molecular spring

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    Mercury porosimetry and in situ high pressure single crystal X-ray diffraction revealed the wine-rack CUK-1 MOF as a unique crystalline material capable of a fully reversible mechanical pressure-triggered structural contraction. The near-absence of hysteresis upon cycling exhibited by this robust MOF, akin to an ideal molecular spring, is associated with a constant work energy storage capacity of 40 J g(-1). Molecular simulations were further deployed to uncover the free-energy landscape behind this unprecedented pressure-responsive phenomenon in the area of compliant hybrid porous materials. This discovery is of utmost importance from the perspective of instant energy storage and delivery

    A genetic modifier screen identifies chromosomal intervals harboring potential midline interacting genes

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    This work investigates the growth of B-C-N layers by chemical vapor deposition using methylamine borane (MeAB) as single-source precursor. MeAB has been synthesized and characterized, paying particular attention to the analysis of its thermolysis products, which are the gaseous precursors for B-C-N growth. Samples have been grown on Cu foils and transferred onto different substrates for their morphological, structural, chemical, electronic and optical characterizations. The results of these characterizations indicate a segregation of h-BN and Graphene-like (Gr) domains. However, there is an important presence of B and N interactions with C at the Gr borders, and of C interacting at the h-BN-edges, respectively, in the obtained nano-layers. In particular, there is significant presence of C-N bonds, at Gr/h-BN borders and in the form of N doping of Gr domains. The overall B:C:N contents in the layers is close to 1:3:1.5. A careful analysis of the optical bandgap determination of the obtained B-C-N layers is presented, discussed and compared with previous seminal works with samples of similar composition.Comment: 35 pages, 7 figure

    Chemical vapor deposition growth of boron-carbon-nitrogen layers from methylamine borane thermolysis products

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    This is the Accepted Manuscript version of an article accepted for publication in Nanotechnology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-6528/aa9c07This work investigates the growth of B-C-N layers by chemical vapor deposition using methylamine borane (MeAB) as the single-source precursor. MeAB has been synthesized and characterized, paying particular attention to the analysis of its thermolysis products, which are the gaseous precursors for B-C-N growth. Samples have been grown on Cu foils and transferred onto different substrates for their morphological, structural, chemical, electronic and optical characterizations. The results of these characterizations indicate a segregation of h-BN and graphene-like (Gr) domains. However, there is an important presence of B and N interactions with C at the Gr borders, and of C interacting at the h-BN-edges, respectively, in the obtained nano-layers. In particular, there is a significant presence of C-N bonds, at Gr/h-BN borders and in the form of N doping of Gr domains. The overall B:C:N contents in the layers is close to 1:3:1.5. A careful analysis of the optical bandgap determination of the obtained B-C-N layers is presented, discussed and compared with previous seminal works with samples of similar compositio

    In situ Synchrotron X-ray Thermodiffraction of Boranes

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    International audienceBoranes of low molecular weight are crystalline materials that have been much investigated over the past decade in the field of chemical hydrogen storage. In the present work, six of them have been selected to be studied by in situ synchrotron X-ray thermodiffraction. The selected boranes are ammonia borane NH 3 BH 3 (AB), hydrazine borane N 2 H 4 BH 3 (HB), hydrazine bisborane N 2 H 4 (BH 3) 2 (HBB), lithium LiN 2 H 3 BH 3 (LiHB) and sodium NaN 2 H 3 BH 3 (NaHB) hydrazinidoboranes, and sodium triborane NaB 3 H 8 (STB). They are first investigated separately over a wide range of temperature (80-300 K), and subsequently compared. Differences in crystal structures, the existence of phase transition, evolutions of unit cell parameters and volumes, and variation of coefficients of thermal expansion can be observed. With respect to AB, HB and HBB, the differences are mainly explained in terms of molecule size, conformation and motion (degree of freedom) of the chemical groups (NH 3 , N 2 H 4 , BH 3). With respect to LiHB, NaHB and STB, the differences are explained by a stabilization effect favored by the alkali cations via M¨¨¨H interactions with four to five borane anions. The main results are presented and discussed herein
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