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排序方式: 共有6111条查询结果,搜索用时 15 毫秒
981.
982.
SHEN Yi ZHU Hua HUANG Rong ZHAO Li & YAN ShaNing Faculty of Material Science Chemical Engineering China University of Geosciences Wuhan China Faculty of Materials Science Engineering Hubei University Wuhan 《中国科学B辑(英文版)》2009,(5)
Tungsten trioxide powder with the novel morphology was prepared via the hydrothermal method with oxalic acid as the organic inducer, the structure and shape of which were detected by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET. Furthermore, photochromic properties of the as-prepared powder samples were tested by an ultraviolet-visible spectrophotometer combined with a color difference meter. The corresponding results indicated that the induced product was still hexagonal WO3, made up... 相似文献
983.
984.
Richard M. Ibberson Dr. Amelia J. Fowkes Dr. Matthew J. Rosseinsky Prof. William I. F. David Prof. Peter P. Edwards Prof. 《Angewandte Chemie (International ed. in English)》2009,48(8):1435-1438
Metal lite : High‐resolution neutron powder diffraction data reveals that the body‐centered cubic crystal structure of lithium(0)tetraamine transforms to a simple cubic structure below 22 K. The detailed structure determinations will allow new insights into the coupled structural and electronic properties of the lightest metal.
985.
Various TiO2 nanostructures, such as nanorings, nanorods were synthesized via potentiostatic anodization of titanium powder under different conditions. The morphology of the obtained TiO2 nanostructures can be easily tuned by varying applied voltage. The crystal structure, compositional information and morphological structures were characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectra (XPS) and field emission scanning electronic microscopy (FESEM). XRD and XPS analysis confirmed the anodization products were TiO2. A possible formation mechanism was suggested on the basis of the shape evolution of TiO2 nanostructures observed by FESEM. The results revealed that the applied voltage played an important role in the formation of various nanostructures. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
986.
M. Hari Prasad Reddy J. F. Pierson S. Uthanna 《Crystal Research and Technology》2011,46(12):1329-1336
Thin films of Ag2Cu2O3 were formed on glass substrates by RF magnetron sputtering technique under different oxygen partial pressures in the range 5 × 10‐3 – 8 × 10‐2 Pa using mosaic target of Ag70Cu30. The influence of oxygen partial pressure on the core level binding energies, crystallographic structure, and electrical and optical properties of the deposited films was studied. The atomic ratio of copper to silver in the films was 0.302. The oxygen content was in correlation with the oxygen partial pressure maintained during the growth of the films. The films formed at oxygen partial pressures < 2 × 10‐2 Pa was mixed phase of Ag2Cu2O3 and Ag. The films deposited at 2 × 10‐2 Pa were single phase of Ag2Cu2O3. The crystallite size of the films formed at 2 × 10‐2 Pa was 12 nm, while those films annealed at 473 K was 16 nm. The nanocrystalline Ag2Cu2O3 films formed at oxygen partial pressure of 2 × 10‐2 Pa showed electrical resistivity of 8.2 Ωcm and optical band gap of 1.95 eV. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
987.
P. Narayana Reddy A. Sreedhar M. Hari Prasad Reddy S. Uthanna J. F. Pierson 《Crystal Research and Technology》2011,46(9):961-966
Nano‐crystalline silver oxide films were deposited on glass and silicon substrates held at room temperature by RF magnetron sputtering of silver target under different oxygen partial pressures. The influence of oxygen partial pressure on the structural, morphological, electrical and optical properties of deposited films was investigated. Varying oxygen partial pressure during the sputter deposition leads to changes of mixed phase of Ag2O and Ag to a single phase of Ag2O and to AgO. The X‐ray diffraction and X‐ray photoelectron spectroscopy results showed the formation of single phase Ag2O with cubic structure at oxygen partial pressures of 2x10‐2 Pa while the films deposited at higher oxygen partial pressure of 9x10‐2 Pa showed the formation of single phase of AgO with monoclinic structure. Raman spectroscopic studies on the single phase Ag2O showed the stretching vibration of Ag‐O bonds. Single‐phase Ag2O films obtained at oxygen partial pressure of 2x10‐2 Pa were nano‐crystalline with crystallite size of 20 nm and possessed an electrical resistivity of 5.2x10‐3 Ωcm and optical band gap of 2.05 eV. The films deposited at higher oxygen partial pressure of 9x10‐2 Pa were of AgO with electrical resistivity of 1.8x10‐2 Ωcm and optical band gap of 2.13 eV. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
988.
Zhang L Ai Z Jia F Liu L Hu X Yu JC 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(15):4185-4190
Various nanostructured films of copper and silver tellurides were hydrothermally grown on the corresponding metal substrates through reactions between metal foils and tellurium powder in different media. Interesting morphologies including nanowires, nanorods, nanobelts, nanosheets, and hierarchical dendrites were obtained. The nanostructured films were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). A growth mechanism was proposed based on the characterization results. This study provides a low-temperature, solution-phase approach to grow low-dimensional, nanostructured metal tellurides with controllable morphologies. 相似文献
989.
Novel mu(5)-eta(1),eta(1),eta(1),eta(1),eta(2) and mu(5)-eta(1),eta(1),eta(1),eta(2),eta(2) coordination modes of alkyl and aryl ethynide moieties are found in silver(I) complexes 1-5, and the metal-ligand distances can be classified into sigma, pi and mixed (sigma,pi) types. With the consistent square-pyramidal capping Ag(5) baskets of the ethynide moiety as supramolecular synthons, a series of two- and three-dimensional coordination networks are obtained. 相似文献
990.
Gonsior M Krossing I Matern E 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(6):1703-1714
The first condensed-phase preparation of ternary P-Ch-X cations (Ch=O-Te, X=F-I) is reported: [P5S3X2]+, [P5S2X2]+, and [P4S4X]+ (X=Br, I). [P5S3X2]+ is formed from the reaction of the Ag+/PX3 reagent with P4S3. The [P5S3X2]+ ions have a structure that is related to P4S5 by replacing P=S by P+--X and S in the four-membered ring by P(X). We provide evidence that the active ingredient of the Ag+/PX3 reagent is the (H2CCl2)Ag-X-PX2+ cation. The latter likely reacts with the HOMO of P4S3 in a concerted HOMO-LUMO addition to give the P5S3X2+ ion as the first species visible in situ in the low-temperature 31P NMR spectrum. The [P5S3X2]+ ions are metastable at -78 degrees C and disproportionate at slightly higher temperatures to give [P5S2X2]+ and [P4S4X]+, probably with the extrusion of 1/n (PX)n (X=Br, I). All six new cage compounds have been characterized by multinuclear NMR spectroscopy and, in part, by IR or Raman spectroscopy. The [P5S2X2]+ salts have a nortricyclane skeleton and were also characterized by X-ray crystallography. The structure of the [P4S4X]+ ion is related to that of P4S5 in that the exo-cage P=S bond is replaced by an isoelectronic P+--X moiety. 相似文献