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^(27)Al MAS-NMR study of inorganic polymer formation at ambient temperature

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 182-187页

作者： Sang-Wook AHN Hee-Soo LEE Wan-Hee YANG Jung-Woo LEE Young-Keun JEONG National Core Research Center for Hybrid Materials Solution Pusan National University School of Material Science and Engineering Pusan National University INTChem Co. Ltd.

Inorganic polymers are a novel class of materials formed by the polymerization of silicon, aluminium and oxygen species to form an amorphous three-dimensional framework structure. The basis of this process is the alkaline solutions to induce a certain amount of Si and AI atoms to dissolve from a feedstock such as aluminosilicate. A study of 27A1 MAS-NMR was carried out in an attempt to understand the reaction mechanism of the inorganic polymerization at ambient temperature. Scanning electron microscopy （SEM） and X-ray diflYactometry （XRD） were also employed to establish the composition and microstructure of the inorganic polymerization. Specimens were prepared with different A1/Si mole ratios from the starting materials. The higher the AI content, the more sufficient the AI atoms that can combine with SiO4, and the longer the reaction time, the more the bonded Si--O--A1--O polymer structure, and then the higher the A1 content, the fewer the octahedral A1 with a uniform Si--O--A1--O structure in four directions, because four AI atoms are combined with SiO4, resulting in a uniform Si--O--AI--O structure in four directions. The results show that they have an amorphous microstructure.

关键词： inorganic polymer amorphous tetrahedral

Statistical mechanics of fuzzy random polymer networks

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Science China Mathematics 1995年第9期38卷 1095-1104页

作者：陈晓红 Department of Mechanics Peking University Beijing 100871 China

A statistical mechanics framework of fuzzy random polymer networks is established based on the theories of fuzzy systems. The entanglement effect is manifested quantitatively by introducing an entanglement tensor and membership function and the amorphous structure is treated as the fuzzy random network made up of macromolecular coils entangled randomly. A random tetrahedral entangled-crosslinked cell is chosen as an average representative unit of the fuzzy random polymer network structure. By making use of the theory of fuzzy probability and statistical mechanics, the expression for the free energy of deformation is given, which fits well with the experimental data on rubber elasticity under various deformation modes. Both classical statistical theory and Mooney-Rivlin equation can be taken as its special cases.

关键词： fuzzy random polymer network statistical mechanics entanglement tensor random tetrahedral entangled-crosslinked cell.

TEM observation of oxidation of CuZnAlMnNi shape memory alloy

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Chinese Science Bulletin 2001年第21期46卷 1837-1839页

作者： BAI Yujun LU Chengwei GENG Guili YIN Longwei Mechanical Department Shandong University of Science and TechnologyJi’nan 250031China Materials Science and Engineering Shandong UniversityJi’nan 250061China

The atmospheric oxidation of a quenched CuZnAlMnNi alloy after ion-polishing was examined by transmission electron microscopy (TEM). It was found that a lot of oxide grains with various sizes yield homogeneously on the surface of the alloy after exposure at room temperature for 90 d. The grains mainly form along the planes of stacking fault, meanwhile, they can also be observed at the stacking fault tetrahedrals or around the dislocation lines. The formation of the oxides gives rise to the reduction of the stacking faults, and even complete disappearance in some zones, which is partly responsible for the decrement of shape memory effect (SME) of the alloy quenched during long-term holding at room temperature.

关键词： shape memory alloy oxidation stacking fault tetrahedral dislocation line.

Suppressing the metal-metal interaction by CoZn_(0.5)V_(1.5)O_(4)derived from two-dimensional metal-organic frameworks for supercapacitors

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Science China Materials 2022年第1期65卷 105-114页

作者： Fang Yuan Guohua Gao Xiaodi Jiang Wenchao Bi Yixuan Su Jingwen Guo Zhihao Bao Jun Shen Guangming Wu Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and EngineeringTongji UniversityShanghai 200092China College of Science University of Shanghai for Science and TechnologyShanghai 200093China

Co_(2)VO_(4) with Co tetrahedrons and octahedrons of transition metal oxides has achieved progress in electrocatalysts and ***,high metal-metal interactions make it challenging to maintain high reactivity as well as increase the conductivity and stability of *** this work,spinel-structured CoZn_(0.5)V_(1.5)O_(4) with a high specific surface area was synthesized through an ion-exchange process from the metal-organic frameworks of *** functional theory calculations indicate that the replacement of transition metal by Zn can decrease the interaction between the transition metals,leading to a downshift in the π^(∗)-orbitals(V-O)and half-filled a_(1g) orbitals near the Fermi level,thus increasing the conductivity and stability of CoZn_(0.5)V_(1.5)O_(4).As a supercapacitor electrode,CoZn_(0.5)V_(1.5)O_(4) exhibits high cycling durability(99.4% capacitance retention after 18,000 cycles)and specific capacitance(1100mFcm^(-2) at 1mAcm^(-2)).This work provides the possibility of designing octahedral and tetrahedral sites in transition metal oxides to improve their electrochemical performance.

关键词： supercapacitors metal-metal interaction octahedral tetrahedral metal-organic frameworks

First-Eutectic Features of Polar Metals in Double Systems

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Journal of Crystallization Process and Technology 2017年第3期7卷 55-63页

作者： Alexander L. Shimkevich Inessa Yu. Shimkevich NRC Kurchatov Institute Moscow Russia

It is known that the dense part of any liquid metal consists of ramified clusters of almost regular tetrahedrons (triangular pyramids with atoms in their vertexes) that are connected into chains by faces. Any metal additive as a second component of liquid alloy can be both beyond these clusters as separated atoms and into them as inherent clusters. The liquid-metal alloy transfers into the second state, at the first eutectic of the solvent. This polymorphic transition of liquid matrix is discovered in the systems, Pb-K and Na-Pb, by molecular-dynamic simulating their microstructure and in experiments on scattering slow neutrons by these alloys of different compositions. In the first system, the obtained results identify both the homogeneous alloy at low concentrations of potassium in liquid lead and the alloy clustering, (Pb4K)n, at potassium concentrations following the eutectic, Pb0.91K0.09. In the second one at the concentrations of lead more than 2%, just the second state is discovered with the clusters, (Na4Pb)n. One can expect the same polymorphic transition in the eutectic, Na0.93Tl0.07, with the micro-inhomogeneity, (Na6Tl)n, and with the melting point of 64 C. This eutectic maintained by the oxygen-free technology and enriched by the isotope, 205Tl, can become the best coolant for fast nuclear reactors due to the depressed chemical activity of sodium and composition stability.

关键词： tetrahedral Cluster Liquid-Metal Eutectic Lead and Potassium Sodium and Thallium Polymorphic Transition

Electronic and Structural Properties of Li3AlP2and Li3AlAs2from First Principles

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Journal of Modern Physics 2011年第9期2卷 929-933页

作者： Mehrdad Dadsetani Shirin Namjoo 不详

A detailed analysis of the electronic and structural properties of the filled tetrahedral semiconductors Li3AlP2 and Li3AlAs2 has been performed, using the full potential linearized augmented plane wave method within the density functional theory. Experimental results about the structural properties, involves the positions of the elements Al and P(As). Since there were not any other efforts about the positions of the Li elements in these compounds, so to our knowledge there was no theoretical study about them till now. In the first step the interactional forces between atoms were minimized. The calculated internal coordinations of atoms agree well with the experimental results. Using these positions we obtained the equilibrium lattice constants, bulk modulus and their pressure derivative. In the second step the electronic properties of Li3AlP2 and Li3AlAs2 have been studied. The study of total and partial electronic DOS indicate the main contribution of DOS consists of P(As) 3p(4p) and P(As) 3s(4s) states. Our band structure calculation verifies that Li3AlP2 is an indirect gap semiconductor with a value of about 2.36 eV between valance band maximum occuring at H point and conduction band minimum occuring at Г point;though the difference between the direct (2.38 eV) and indirect (2.36 eV) is very small. We also found that Li3AlAs2 is a direct band gap (1.49 eV) in the center of BZ.

关键词： Filled tetrahedral Semiconductors Electronic Properties FP-LAPW DFT

A STUDY OF BENT BONDS IN C_4R_4 AND Li_4R_4 MOLECULES

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Chinese Science Bulletin 1987年第3期32卷 171-175页

作者：邱文元杜奇石彭周人李俊清 Department of Chemistry Lanzhou University Department of Modern Chemistry University of Science and Technology of China Hefeihe C_4R_4 and Li_4R_4 type molecules which have come into notice recently have a distinctive tetrahedral configuration (see Fig. 1). Their syntheses and specific properties have been reported by many authors. We were interested in studying the bending

The C4R4 and Li4R4 type molecules which have come into notice recently have a distinctive tetrahedral configuration （see Fig. 1）. Their syntheses and specific properties have been reported by many authors. We were i... 详细信息

关键词： interested tetrahedral distinctive notice listed representing bending hydrophilic bonding melting

APPLICATIONS OF THE DSCPCF MODEL: EQUILIBRIUM CONFIGURATION AND d-d TRANSITION BANDS FOR MX_4^(n-) TYPE COMPLEXES

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Chinese Science Bulletin 1982年第7期27卷 743-747页

作者：杨频黎乐民 Department of Chemistry Shanxi University Taiyuan Department of Chemistry Peking Universityy the aid of the double sphere coordination point charge field model (DSCPCF) we have investigated the variation of the d-orbital level of the complex ion MX_4~(n-) with that of the bond angle and predicted its equilibrium configuration and the d-d transition bands.

By the aid of the double sphere coordination point charge field model （DSCPCF） we have investigated the variation of the d-orbital level of the complex ion MX4n- with that of the bond angle and predicted its equilib... 详细信息

关键词： bands orbital figuration distorted tetrahedral perturbation Slater rigid minima bases

TEMPERATURE DEPENDENCE OF MSS-BAUER SPECTRA OF Y-Ca-In-Ge IRON GARNET

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Chinese Science Bulletin 1985年第5期30卷 593-597页

作者：李士李国栋 Institue of High Energy Physics Academia Sinica Beijing Institute of Physics Academia Sinica Beijing? INTRODUCTION The M?ssbauer spectra (MS) of a Ca~(2+) In~(2+) and Ge~(4+) substituted yttrium iron garnet (YIG)-Y_(2.78)Ca_(0.25)In_(0.60)Ge_(0.25)Fe_(4.11)O_(12)(Y-Ca-In-GeIG) cannot be resolved simply into two sets of octahedral(a) and tetrahedral (d) subspectra since the nonequivalent environment (NE) resulting from random distribution of nonmagnetic ions can influence the MS. If the probabilities P_n~(m) of NE which is less than 8% were neglected then the (a) and (d) subspectra each can be again resolved into two and three sets of

Ⅰ. INTRODUCTION The M?ssbauer spectra （MS） of a Ca2+, In2+ and Ge4+ substituted yttrium iron garnet （YIG）-Y2.78Ca0.25In0.60Ge0.25Fe4.11O12（Y—Ca—In—GeIG） cannot be resolved simply into two sets of octahedral（a） and tetrahedral （d） subspectra, since the nonequivalent environment （NE） resulting from random distribution of nonmagnetic ions can influence the MS. If the probabilities Pnm of NE which is less than 8％, were neglected, then the （a） and （d） subspectra each can be again resolved into two and three sets

关键词： octahedral tetrahedral substituted neglected garnet resolved yttrium magnetization simply again