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排序方式: 共有178条查询结果,搜索用时 31 毫秒
121.
Dr. Jingwei Hou Dr. Zhiliang Wang Dr. Peng Chen Prof. Vicki Chen Prof. Sir Anthony K. Cheetham Prof. Lianzhou Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(44):19602-19617
This Review examines how the intermarriage of perovskite and metal-organic framework crystals brings new paradigms for material design and functionality. The strategic combination of halide perovskites and metal–organic frameworks (MOFs) has generated a new family of porous composite materials that will enable new applications, including optoelectronic, catalysis, sensing, and data encryption. This Review surveys the current progress of this exciting new area. Fundamental aspects, including perovskite nucleation and growth, heterojunction electron–hole transfer, electronic structure, and luminescence within confined spaces, are highlighted, with suggestions of approaches by which guest confinement within MOFs can be synthetically designed. We further address the underlying principles and discuss the new insights and tools for the manipulation of these composite materials for the development of synthetic microporous semiconducting composites, as well as new strategies for host–guest interfacial engineering. 相似文献
122.
Zhang Z. Rayner J. Cheetham A. Lund T. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1997,25(1):27-36
This paper develops a fuzzy model to simulate the behaviour of a nonlinear system, in particular a plasma source, with a view to developing a control system for processing plasmas employing a helicon source. Genetic algorithms are employed to optimize fuzzy rules related to the parameters of the fuzzy model which contain a set of variable zeros and poles of the nonlinear system as well as its time delay. A practical application of the fuzzy model is to estimate the electron number density of a low-temperature plasma. Based on the membership functions of the input and output, a set of fuzzy rules by which the variable zeros and poles are identified is derived and optimized using a genetic algorithm. The principal reason for investigating the proposed fuzzy model is the subsequent computer-aided design of a fuzzy controller to control the nonlinear system. Two experimental results are presented to validate the fuzzy model method. One shows a computer simulation and the other predicts the real-time behaviour of the plasma source as its input parameters are varied 相似文献
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124.
Solid solutions of vanadates of formula BixLn1−xVO4 (Ln=Y, Gd) doped with Eu3+ or Sm3+ ions have been synthesized by solid-state reactions. Intense red/orange-red luminescence is obtained in these samples on excitation in the broad charge-transfer band in the near UV. The excitation in the Eu3+ levels leads to much less intense red emission. These materials could find applications as red phosphors for solid-state white lighting devices utilizing GaN-based excitation in the near UV. 相似文献
125.
126.
Cyclodextrin [2] and [3]rotaxanes have been synthesised by use of a metal-driven ligand formation methodology. The kinetically stable cobalt(III) complexes formed act as either linking or capping groups, the function being selected by manipulation of the reaction conditions to promote the formation of either 2:1 or 1:1 complexes, respectively. In all cases, mixtures of isomers containing different alpha-cyclodextrin orientations were observed. All three orientational isomers of the [3]rotaxane were isolated and structurally characterized by 2D NMR. 相似文献
127.
We report the synthesis and crystal structures of two transition metal-based coordination polymers comprising ligand molecules not included in the original reaction mixtures but instead formed in situ during hydrothermal treatment. Zinc meso-iminodisuccinate hydrate (I), Zn(2)(C(8)H(7)NO(8)).0.57H(2)O, formed from zinc acetate and L-aspartic acid, and tetraaquanickel(II) 5,10-dioxo-5,10-dihydro-4,9-dioxa-pyrene-2,7-dicarboxylate (II), Ni(H(2)O)(4)(C(16)H(4)O(8)), formed from nickel acetate and 5-hydroxyisophthalic acid. We show that the formation of I takes place via a fumaric acid intermediate, while the formation of II requires the formation of a new C-C bond. The structure of I consists of weakly interacting sheets, while the structure of II consists of strongly hydrogen-bonded chains. Crystal data: for I, P2(1)/n (14), a = 10.073 A, b = 9.894 A, c = 12.053 A, beta = 105.605 degrees, V = 1156.87(13) A(3), Z = 4; for II, P1 (2), a = 5.011 A, b = 6.526 A, c = 12.305 A, alpha = 76.868 degrees, beta = 84.988 degrees, gamma = 87.619 degrees, V = 390.3(4) A(3), Z = 1. 相似文献
128.
Extreme Flexibility in a Zeolitic Imidazolate Framework: Porous to Dense Phase Transition in Desolvated ZIF‐4 下载免费PDF全文
Dr. Michael T. Wharmby Dr. Sebastian Henke Dr. Thomas D. Bennett Dr. Sneha R. Bajpe Inke Schwedler Dr. Stephen P. Thompson Dr. Fabia Gozzo Dr. Petra Simoncic Dr. Caroline Mellot‐Draznieks Prof. Haizheng Tao Prof. Yuanzheng Yue Prof. Anthony K. Cheetham 《Angewandte Chemie (International ed. in English)》2015,54(22):6447-6451
Desolvated zeolitic imidazolate framework ZIF‐4(Zn) undergoes a discontinuous porous to dense phase transition on cooling through 140 K, with a 23 % contraction in unit cell volume. The structure of the non‐porous, low temperature phase was determined from synchrotron X‐ray powder diffraction data and its density was found to be slightly less than that of the densest ZIF phase, ZIF‐zni. The mechanism of the phase transition involves a cooperative rotation of imidazolate linkers resulting in isotropic framework contraction and pore space minimization. DFT calculations established the energy of the new structure relative to those of the room temperature phase and ZIF‐zni, while DSC measurements indicate the entropic stabilization of the porous room temperature phase at temperatures above 140 K. 相似文献
129.
F. Poineau E. E. Rodriguez P. F. Weck A. P. Sattelberger P. Forster T. Hartmann E. Mausolf G. W. C. Silva G. D. Jarvinen A. K. Cheetham Kenneth R. Czerwinski 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(2):605-609
The chemistry of technetium is being explored at the University of Nevada Las Vegas. Our goal is to investigate both the applied and fundamental aspects of technetium chemistry, with a special emphasis on synthesis, separations, and materials science. The synthetic chemistry focuses on metal–metal multiple bonding, oxides and halides. Synthesis and characterizations of (n-Bu4N)2Tc2X8, Tc2(O2CCH3)4X2 (X = Cl, Br), TcO2, Bi2Tc2O7, Bi3TcO8, TcBr3 and TcBr4 have been performed. The applied chemistry is related to the behavior of Tc in the UREX process. Separation of U/Tc has been conducted using anion exchange resin and metallic Tc waste form synthesized and characterized. 相似文献
130.
Rayner J. P. Cheetham A. D. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2010,38(2):62-72