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171.
Josefina M. Silveyra Javier A. Moya Victoria J. Cremaschi Du?an Jani?kovi? Peter ?vec 《Hyperfine Interactions》2010,195(1-3):173-177
FINEMET type ribbons (Fe73.5Si13.5Nb3???xMoxB9Cu1, x = 1.5, 2 at.%) were produced by the planar flow casting technique and subsequently heat treated at 823 K to induce nanocrystallization and to optimize its soft magnetic properties. The coercivity, measured by conventional fluxmetric method, resulted in H C?=?0.53 ±0.10 and 0.41±0.05 A/m for x?=?1.5 and 2 respectively. A correlation between magnetic properties and the amorphous and nanocrystalline phases when Nb was partially substituted with Mo was studied by means of Mössbauer spectroscopy and X-ray diffraction. 相似文献
172.
Oscar A. Douglas-Gallardo Maxi A. Burgos-Paci Rubén Mendoza-Cruz Karl G. Putnam M. Josefina Arellano-Jiménez Miguel José-Yacamán Marcelo M. Mariscal Vicente A. Macagno Cristián G. Sánchez Manuel A. Pérez 《Journal of nanoparticle research》2018,20(3):85
A novel strategy to synthesize photoluminescent silicon nanocrystals (SiNCs) from a reaction between tetraethylorthosilicate (TEOS) and trimethyl-hexadecyl-ammonium borohydride (CTABH4) in organic solvent is presented. The formation reaction occurs spontaneously at room temperature in homogeneous phase. The produced silicon nanocrystals are characterized by using their photoluminescent properties and via HRTEM. In addition, theoretical calculations of the optical absorption spectrum of silicon quantum dots in vacuum with different sizes and surface moieties were performed in order to compare with the experimental findings. The new chemical reaction is simple and can be implemented to produce silicon nanocrystal with regular laboratory materials by performing easy and safe procedures. 相似文献
173.
Preparation of functionalized platinum nanoparticles: a comparison of different methods and reagents
Liu Guangliang Arellano-Jiménez M. Josefina Carter C. Barry Agrios Alexander G. 《Journal of nanoparticle research》2013,15(6):1-13
Au–Pd core–shell nanocubes and triangular nanoparticles were systematically synthesized from a few Pd layers up to fully grown morphologies by a modified seed-mediated growth method. The shape evolution of Au–Pd core–shell nanoparticles from single crystal and singly twinned seed to final concave nanocube and triangular plates are presented at atomic level by Cs-corrected scanning transmission electron microscopy (STEM). The growth mechanism of both morphologies was studied throughout different sizes. It was found that the concave nanocubes grew from octahedral Au seeds due to fast growth along 〈111〉 directions; while the triangular nanoparticles grew from singly twinned Au seeds, growing twice as fast in 〈110〉 directions along the twin boundary; compared to the 〈111〉 direction perpendicular to the twin boundary. Both the concave nanocubes and triangular nanoparticles presented high index facet (HIF) surfaces that will increase the catalytic activity of different reactions. 相似文献
174.
Amo-Ochoa P Delgado S Gallego A Gómez-García CJ Jiménez-Aparicio R Martínez G Perles J Torres MR 《Inorganic chemistry》2012,51(10):5844-5849
The synthesis and characterization of compound [Rh(2)(O(2)CEt)(4)(H(2)O)(2)] (1) and one-dimensional heterobimetallic polymers K(n){Rh(2)(O(2)CEt)(4)[Au(CN)(2)]}(n) (2) and K(n){Rh(2)(O(2)CMe)(4)[Au(CN)(2)]}(n)·4nH(2)O (3), constructed from dirhodiumtetracarboxylato units, [Rh(2)(O(2)CR)(4)](+), and dicyanoaurate, [Au(CN)(2)](-), fragments are described. In both compounds 2 and 3 the resulting polymeric chains are nonlinear and have in common similar structural parameters, although the solid state supramolecular arrangement is very different. These structural differences explain the fact that complex 2 displays aurophilic interactions while this type of interactions are absent in complex 3. As a result, compound 2 shows rich blue luminescent properties whereas compound 3 is not luminescent. The electrical conductivity in solid state of compounds 2 and 3 is also studied. 相似文献
175.
M.?C.?ArenasEmail author Gabriela?Sánchez M.?E.?Nicho Josefina?Elizalde-Torres V.?M.?Casta?o 《Applied Physics A: Materials Science & Processing》2012,106(4):901-908
Conducting Polyaniline films (Pani) on Corning glass substrates, produced using either an in-situ doping process or a co-doping
process, were prepared by the oxidative polymerization of aniline in N,N,dimethylformamide. Bicyclic aliphatic camphorsulfonic
acid (CSA), aromatic toluenesulfonic acid (TSA) and carboxylic trifluoroacetic acid (TFA) were employed as doping agents,
and CSA mixed with TSA and CSA mixed with TFA were employed as the co-doping materials. The topography of the Pani films was
analyzed by atomic-force microscopy (AFM), and their doping and oxidizing states were characterized by Fourier-transform infrared
(FT-IR) spectroscopy and optical (UV-Vis) spectroscopy. Flower-like clusters, microfibers, and nanofibers were obtained by
doping with CSA, TSA, and the mix of both (CSATSA), respectively. The flower-like morphology limits the conductivity of the
film while the microfiber morphology leads to a highly conductive film. The conductivity of the films increases with the doping
level, coil-like conformation of the chain and the protonation of the imine in quinoid units. The codoped process reduces
the roughness of the CSA-doped films by 50%, but the conductivity depends on the acid type used for this process (TSA or TFA).
The optical gas sensor response of the films is related to both the morphology and the degree of protonation. In this study,
Pani with a microfiber morphology obtained from TSA-doping is the most sensitive to ammonia gas sensing, and Pani with flower-like
morphology is the least sensitive. 相似文献
176.
Ramírez-Fernández J Botubol JM Bustillo AJ Aleu J Collado IG Hernández-Galán R 《Natural product communications》2011,6(4):443-450
The asymmetric synthesis of key fragments of the phytotoxic toxins botcinolide/botcinin is reported. The synthesis of 1 and 1a are based on a convergent route via esterification and alkene metathesis of fragments A, B or C, B, which were obtained by Evans aldol condensation and stereoselective crotylation, respectively. 相似文献
177.
García-Álvarez J Díez J Gimeno J Seifried CM 《Chemical communications (Cambridge, England)》2011,47(22):6470-6472
Carbonyl rhenium(I) complexes are efficient catalysts for the regioselective isomerization of terminal propargylic alcohols into α,β-unsaturated aldehydes or ketones which can be used as an unprecedented recyclable catalytic system (up to 10 consecutive runs) in the ionic liquid [BMIM][PF(6)]. 相似文献
178.
Roselló-Merino M Díez J Conejero S 《Chemical communications (Cambridge, England)》2010,46(48):9247-9249
Pyridinium 2-carboxylates decompose thermally in the presence of a variety of late transition metal precursors to yield the corresponding 2-pyridylidene-like complexes. The mild reaction conditions and structural diversity that can be generated in the heterocyclic ring make this method an attractive alternative for the synthesis of 2-pyridylidene complexes. IR spectra of the Ir(i) carbonyl compounds [IrCl(NHC)(CO)(2)] indicate that these N-heterocyclic carbene ligands are among the strongest σ-electron donors. 相似文献
179.
180.
Crystal and Molecular Structure of Tris(1,1-diethyl-3-benzoyl-thioureato)ruthenium(III) The crystal and molecular structure of tris(1,1-diethyl-3-benzoyl-thioureato)-ruthenium(III) has been determined by an X-ray structure analysis. The compound crystallizes in the trigonal space group P3 with a = 16.556, c = 8.476 Å and Z = 2. The structure was solved by Patterson methods and refined to a final R value R = 0.074 for 801 observed reflections. The molecule has the symmetry C3. The coordination polyhedron is an octahedron with facial arrangement of the ligator atoms. The Ru? S and Ru? O distances are 2.293 Å and 2.047 Å, respectively. 相似文献