Silicon Sheets By Redox Assisted Chemical Exfoliation

In this paper, we report the direct chemical synthesis of silicon sheets in gram-scale quantities by chemical exfoliation of pre-processed calcium di-silicide (CaSi2). We have used a combination of X-ray photoelectron spectroscopy, transmission electron microscopy and Energy-dispersive X-ray spectroscopy to characterize the obtained silicon sheets. We found that the clean and crystalline silicon sheets show a 2-dimensional hexagonal graphitic structure.Comment: Accepted in J. Phys.: Condens. Matte

Etude cristallographique et spectroscopique de quelques phases nouvelles du systeme K2O-Sb2O5-P2O5

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Self-Assembly of Cluster-Based Nanoscopic Supramolecules into One-Dimensional Coordination Polymers

Octahedral metal clusters [Nb6Cl12(CN)6]4−, (Mn(Salen))+ (or (Mn(7-MeSalen))+) (Salen = N,N′-ethylene-bis-(salicylidene)iminate) and ditopic organic linkers (4,4′-bpe (trans-1, 2-bis(4-pyridyl)-ethylene) or 4,4′-dpyo (4,4′-dipyridyl N,N′-dioxide)) self-assemble to form three cluster-based 1D coordination polymers: [Mn(Salen)(MeOH)2]2{(4,4′-dpyo) [(Mn(Salen))2(Nb6Cl12(CN)6)]}·2MeOH (1), {(4,4′-bpe)[(Mn(7-MeSalen))2(Mn(7-MeSalen)(H2O))2(Nb6Cl12(CN)6)]}·1.5MeCN·8H2O (2), and [(4,4′-bpe)(Mn(Salen)(H2O))2]{(4,4′-bpe)2[(Mn(Salen)(MeOH))2(Mn(Salen))2(Nb6Cl12(CN)6)][(Mn(Salen))2(Nb6Cl12(CN)6)]}·16H2O (3). Single crystal X-ray diffraction analyses show that the frameworks of the three coordination polymers are built of heterotrimeric and/or heteropentameric supramolecular species linked by ditopic organic ligands. The framework of 1 consists of anionic chains built of heterotrimeric dianions [(Mn(Salen))2(Nb6Cl12(CN)6)]2− (T) linked by 4,4′-dpyo. The chains run along two directions ([0 2 −2] and [0 3 3]) leading to the formation of channels along the crystallographic (a) direction where the cations [Mn(Salen)(S)2]+ and solvent molecules are located. Also, 2 was reported earlier, it possesses a neutral 1D chain built of neutral heterpentameric supramolecules: [(Mn(7‐MeSalen))2(Mn(7‐MeSalen)(S))2(Nb6Cl12(CN)6)] (P) linked by 4,4′-bpe ligands. Hydrogen bonds between non-bridging cyanide ligands and coordinated solvent molecules connect the chains into 2D hydrogen-bonded frameworks. Finally, 3 features an anionic chain, built of alternating heterotrimers [(Mn(Salen))2(Nb6Cl12(CN)6)]2− and heteropentamers [(Mn(Salen)(S))2(Mn(Salen))2(Nb6Cl12(CN)6)] linked by the organic spacer 4,4′-bpe. The anionic charge is compensated by the in situe-assembled [Mn(Salen)(S)(4,4′‐bpe)Mn(Salen)(S)]2+ dimers. Magnetic measurements reveal that the Mn(III) ions are well isolated and only weak magnetic interactions are observed. The thermal stability of the three compounds was investigated

Silicon Sheets By Redox Assisted Chemical Exfoliation

In this paper, we report the direct chemical synthesis of silicon sheets in gram-scale quantities by chemical exfoliation of pre-processed calcium disilicide (CaSi2). We have used a combination of x-ray photoelectron spectroscopy, transmission electron microscopy and energy-dispersive x-ray spectroscopy to characterize the obtained silicon sheets. We found that the clean and crystalline silicon sheets show a two-dimensional hexagonal graphitic structure. © 2013 IOP Publishing Ltd

Silicon Nanoparticles Synthesis From Calcium Disilicide By Redox Assisted Chemical Exfoliation

We report the preparation of single-crystal silicon nanoparticles with 15 to 22 nm diameter from calcium disilicide (CaSi2) by redox assisted chemical exfoliation using solution phase synthesis route. Silicon nanoparticles are found to be highly oriented with a predominant size of 18 nm. X-Ray diffraction, as well as transmission electron microscopy studies, confirm that the silicon nanoparticles are a diamond type and highly crystalline

A New Crystalline LiPON Electrolyte: Synthesis, Properties, and Electronic Structure

The new crystalline compound, Li2PO2N, was synthesized using high temperature solid state methods starting with a stoichiometric mixture of Li2O, P2O5, and P3N5. Its crystal structure was determined ab initio from powder X-ray diffraction. The compound crystallizes in the orthorhombic space group Cmc2(1) (# 36) with lattice constants a = 9.0692(4) angstrom, b = 53999(2) angstrom, and c = 4.6856(2) angstrom. The crystal structure of SD-Li2PO2N consists of parallel arrangements of anionic chains formed of corner sharing (PO2N2) tetrahedra. The chains are held together by Li+ cations. The structure of the synthesized material is similar to that predicted by Du and Holzwarth on the basis of first principles calculations (Phys. Rev. B 81,184106 (2010)). The compound is chemically and structurally stable in air up to 600 degrees C and in vacuum up to 1050 degrees C. The Arrhenius activation energy of SD-Li2PO2N in pressed pellet form was determined from electrochemical impedance spectroscopy measurements to be 0.6 eV, comparable to that of the glassy electrolyte LiPON developed at Oak Ridge National Laboratory. The minimum activation energies for Li ion vacancy and interstitial migrations are computed to be 0.4 eV and 0.8 eV, respectively. First principles calculations estimate the band gap of SD-Li2PO2N to be larger than 6 eV. (C) 2013 Elsevier B.V. All rights reserved