排序方式: 共有100条查询结果,搜索用时 15 毫秒
41.
Yang XY Tian G Chen LH Li Y Rooke JC Wei YX Liu ZM Deng Z Van Tendeloo G Su BL 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(52):14987-14995
Preparation and characterization of well-organized zeolitic nanocrystal aggregates with an interconnected hierarchically micro-meso-macro porous system are described. Amorphous nanoparticles in bimodal aluminosilicates were directly transformed into highly crystalline nanosized zeolites, as well as acting as scaffold template. All pores on three length scales incorporated in one solid body are interconnected with each other. These zeolitic nanocrystal aggregates with hierarchically micro-meso-macroporous structure were thoroughly characterized. TEM images and (29)Si NMR spectra showed that the amorphous phase of the initial material had been completely replaced by nanocrystals to give a micro-meso-macroporous crystalline zeolitic structure. Catalytic testing demonstrated their superiority due to the highly active sites and the presence of interconnected micro-meso-macroporosity in the cracking of bulky 1,3,5-triisopropylbenzene (TIPB) compared to traditional zeolite catalysts. This synthesis strategy was extended to prepare various zeolitic nanocrystal aggregates (ZSM-5, Beta, TS-1, etc.) with well-organized hierarchical micro-meso-macroporous structures. 相似文献
42.
Quintana M Montellano A del Rio Castillo AE Van Tendeloo G Bittencourt C Prato M 《Chemical communications (Cambridge, England)》2011,47(33):9330-9332
Graphene sheets have been functionalized with a PAMAM dendron, finding that graphene can be efficiently functionalized all over the surface, or only at the edges, depending on the reactions used in the functionalization process. 相似文献
43.
Dr. Anastasia M. Alekseeva Prof. Dr. Artem M. Abakumov Dr. Andreas Leither‐Jasper Dr. Walter Schnelle Dr. Yuri Prots Prof. Dr. Gustaaf Van Tendeloo Prof. Eugene V. Antipov Prof. Dr. Yuri Grin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(52):17860-17870
The crystal structures of Mg11Rh18B8 and Mg3Rh5B3 have been investigated by using single‐crystal X‐ray diffraction. Mg11Rh18B8: space group P4/mbm; a=17.9949(7), c=2.9271(1) Å; Z=2. Mg3Rh5B3: space group Pmma; a=8.450(2), b=2.8644(6), c=11.602(2) Å; Z=2. Both crystal structures are characterized by trigonal prismatic coordination of the boron atoms by rhodium atoms. The [BRh6] trigonal prisms form arrangements with different connectivity patterns. Analysis of the chemical bonding by means of the electron‐localizability/electron‐density approach reveals covalent B? Rh interactions in these arrangements and the formation of B? Rh polyanions. The magnesium atoms that are located inside the polyanions interact ionically with their environment, whereas, in the structure parts, which are mainly formed by Mg and Rh atoms, multicenter (metallic) interactions are observed. Diamagnetic behavior and metallic electron transport of the Mg11Rh18B8 and Mg3Rh5B3 phases are in agreement with the bonding picture and the band structure. 相似文献
44.
Christophe Lepoittevin Sylvie Malo Gustaaf Van Tendeloo Maryvonne Hervieu 《Solid State Sciences》2009,11(3):595-607
The Fe2(Sr2 ? xAx)FeO6.5 ? δ/2 systems have been investigated, by doping the iron rich 2201-type parent structure with Ba2+, La3+ and 5d10 post-transition cations. The syntheses have been carried out up to the limit of the 2201-type solid solutions, in order to test the role of the double iron layer Fe2O2.5 ? δ/2. The localisation of the charge carriers in these compounds is consistent with their strong antiferro-magnetism. The investigation was then carried out in the transition part of the diagram up to the formation of stable phases. The study of structural mechanisms was carried using high resolution electron microscopy (transmission and scanning transmission), electron diffraction and energy dispersive spectroscopy. Different non-stoichiometry mechanisms are observed, depending on the electronic structure and chemical properties of the doping elements. The specific behavior of the modulated double iron layer is discussed. 相似文献
45.
Pieter Samyn Gustaaf Schoukens Dirk Stanssens Leo Vonck Henk Van den Abbeele 《Journal of nanoparticle research》2012,14(8):1-24
Quantum dots (QDs) are routinely employed for bioimaging applications and detection of pathogens and toxins. Their use as surrogates to study the fate and transport of non-fluorescent nanoparticles is limited due to high cost, detection of limit issues, and lack of sufficient data related to health effects. Systematic studies on the impact of QDs on environment and health may facilitate its safe use for environmental applications. This review summarizes the studies conducted with QDs with a focus on environmental applications and provides toxicity data important to human health. 相似文献
46.
Pieter Samyn Marlies Deconinck Gustaaf Schoukens Dirk Stanssens Leo Vonck Henk Van den Abbeele 《先进技术聚合物》2012,23(3):311-325
Organic nanoparticles are synthesized by partial imidization of high‐molecular weight styrene(maleic‐anhydride) with 26 to 34 mol% maleic anhydride, in aqueous environment and presence of ammonium hydroxide. The nanoparticle dispersions have a maximum solid content of 35 wt% and good stability that critically depends on the ratio of imidized and ammonolyzed maleic anhydride moieties. The deprotonated residual maleic anhydride moieties provide dispersion stability at pH > 4, while protonation at pH < 4 causes nanoparticle sedimentation. After presentation of the synthesis conditions, the imidization reaction is characterized by FT‐IR and Raman spectroscopy, followed by thermal analysis (TGA, DSC), and morphological characterization (DLS, SEM, TEM, AFM). The reaction conditions were optimized by physical characterization of various dispersions, and finally nanoparticles could be obtained with a maximum degree of imidization of 77% in dispersed conditions, or 90 to 95% after drying that are favorable for coating applications. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
47.
De Palma R Laureyn W Frederix F Bonroy K Pireaux JJ Borghs G Maes G 《Langmuir : the ACS journal of surfaces and colloids》2007,23(2):443-451
Tantalum pentoxide (Ta2O5) is a promising material for the realization of biological interfaces because of its high dielectric constant, its high chemical stability, and its excellent passivating properties. Nevertheless, the deposition of highly organized silane SAMs to realize well-defined and tailored Ta2O5-based (bio)interfaces, has not been studied in great detail as of yet. In this work, we have investigated the formation of a highly ordered, dense monolayer of trichlorosilanes on Ta2O5 surfaces. Specifically, two different cleaning procedures for Ta2O5 were compared and (n-decyl)trichlorosilane (DTS) was used to study the effect of both cleaning methods on the silanization of Ta2O5. Both types of cleaning allowed the formation of complete and crystalline DTS monolayers on Ta2O5, in contrast with the incomplete, disordered silane layer assembled on uncleaned Ta2O5. The deposited self-assembled monolayers were studied by means of contact angle goniometry, Brewster angle FTIR, X-ray photoelectron spectroscopy, cyclic voltammetry, and ellipsometry. Infrared analysis exhibited a highly ordered DTS silane film on Ta2O5 and indicated a larger tilt angle of the alkyl chains on this substrate by comparison to DTS on SiO2. Furthermore, with use of ellipsometry and XPS, the silane film thickness on Ta2O5 was determined to be substantially smaller than that reported in the literature for DTS on SiO2, supporting the observations of an increased tilt angle (approximately 45 degrees ) on Ta2O5 than on SiO2 (approximately 10 degrees ). By means of cyclic voltammetry, the formation of a dense, essentially pinhole-free, silane film was observed on the cleaned samples. In conclusion, the fully characterized and optimized procedure for the silanization of Ta2O5 surfaces with trichlorosilanes will allow the formation of well-defined, reproducible, and controllable chemical interfaces on Ta2O5. 相似文献
48.
Lidia Armelao Dr. Davide Barreca Dr. Gregorio Bottaro Dr. Alberto Gasparotto Dr. Chiara Maccato Dr. Eugenio Tondello Prof. Oleg I. Lebedev Dr. Stuart Turner Gustaaf Van Tendeloo Prof. Cinzia Sada Dr. Urška Lavrenčič Štangar Prof. 《Chemphyschem》2009,10(18):3249-3259
The present work is devoted to the preparation of Ag/TiO2 nanosystems by an original synthetic strategy, based on the radio‐frequency (RF) sputtering of silver particles on titania‐based xerogels prepared by the sol–gel (SG) route. This approach takes advantage of the synergy between the microporous xerogel structure and the infiltration power characterizing RF‐sputtering, whose combination enables the obtainment of a tailored dispersion of Ag‐containing particles into the titania matrix. In addition, the system′s chemico‐physical features can be tuned further through proper ex situ thermal treatments in air at 400 and 600 °C. The synthesized composites are extensively characterized by the joint use of complementary techniques, that is, X‐ray photoelectron and X‐ray excited Auger electron spectroscopies (XPS, XE‐AES), secondary ion mass spectrometry (SIMS), glancing incidence X‐ray diffraction (GIXRD), field emission scanning electron microscopy (FE–SEM), transmission electron microscopy (TEM), electron diffraction (ED), high‐angle annular dark field scanning TEM (HAADF–STEM), energy‐filtered TEM (EF–TEM) and optical absorption spectroscopy. Finally, the photocatalytic performances of selected samples in the decomposition of the azo‐dye Plasmocorinth B are preliminarily investigated. The obtained results highlight the possibility of tailoring the system characteristics over a broad range, directly influencing their eventual functional properties. 相似文献
49.
50.
Idrissi H Turner S Mitsuhara M Wang B Hata S Coulombier M Raskin JP Pardoen T Van Tendeloo G Schryvers D 《Microscopy and microanalysis》2011,17(6):983-990
Focused ion beam (FIB) induced damage in nanocrystalline Al thin films has been characterized using advanced transmission electron microscopy techniques. Electron tomography was used to analyze the three-dimensional distribution of point defect clusters induced by FIB milling, as well as their interaction with preexisting dislocations generated by internal stresses in the Al films. The atomic structure of interstitial Frank loops induced by irradiation, as well as the core structure of Frank dislocations, has been resolved with aberration-corrected high-resolution annular dark-field scanning TEM. The combination of both techniques constitutes a powerful tool for the study of the intrinsic structural properties of point defect clusters as well as the interaction of these defects with preexisting or deformation dislocations in irradiated bulk or nanostructured materials. 相似文献