Materials Literature
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On the basis of phase equilibria, the lowest temperatures, T min , above which at high pressures cubic boron nitride crystallization from melt solution is allowable in terms of thermodynamics have been found for a number of systems that include boron nitride.
The effect of various substituents on the hydrolysis and condensation reactions, the initial stages of the mechanism to form silsesquioxanes, are investigated with ab initio electronic structure theory including electron correlation effects. In addition, the role of water molecules on the mechanism is also discussed.
The synthesis of MCM-41-type materials functionalized with 3-mercaptopropyl(methyl) and/or methyl groups has been performed by co-condensation of the corresponding alcoxysilanes and tetramethoxysilane in the presence of CTAB and different amino acids. The presence of the organic moieties in the resulting material has…
The syntheses and structures of the novel Ce-Fe bimetallic complexes [[Fe(sal)2(bpy)]2Ce(NO3)(H2O)3].EtOH and [[Fe(sal)2(bpy)]4Ce2(H2O)11][salH]2.EtOH.3H2O (salH2 = salicylic acid) suggest Fe(3+)-sal2- units and Ce-OC(R)O-Fe bridging contribute to the formation of corrosion inhibitive layers on steel surfaces exposed…
Crystalline boron nanowires with tetragonal structure have been synthesized based on laser ablation of a B/NiCo target; the nanowires are sometimes single crystals and have a droplet at one end of the nanowire; the droplet contains B, Ni and Co elements, which indicates that the vapor-liquid-solid (VLS) mechanism may…
Depending on the number of dimethylsiloxane units in the spacer connecting two banana-shaped molecules either ferroelectric or antiferroelectric switchable polar smectic C phases have been obtained.
Ultrathin crystalline silica layers grown on a Mo(112) substrate have been shown to be a useful silica model oxide support in surface science model catalyst studies. As the oxide support material plays an important role in the catalytic process, a multitechnique surface science study is presented to characterize the m…
Two new mixed-valent triple perovskites, Ba(3)MRu(2)O(9) (M = Li, Na), were grown from reactive hydroxide fluxes. They crystallize in the hexagonal space group P6(3)/mmc, where Ru(V) and Ru(VI) are disordered on only one crystallographic site. Upon cooling, single crystals of Ba(3)NaRu(2)O(9) undergo a complex symmetr…
The degradation of polyethylene terephthalate (PET) in supercritical methanol was investigated with the aim of developing a process for chemical recycling of waste plastics. A batch reactor was used at temperatures of 573–623 K under an estimated pressure of 20 MPa for a reaction time of 2–120 min. PET was decomposed…
Abstract A novel design for 2D isotropic left‐handed metamaterials is presented. One of the main advantages of our proposal is that all the metallizations are placed at parallel stratified planes. Thus, this design can be realized by means of the well known, commonly used planar technology. An analytical model is prov…
Monodisperse silver nanoparticles with different sizes were synthesized by electrochemical reduction inside or outside zeolite crystals according to the silver exchange degree of compact zeolite film modified electrodes.
A new ion-pair complex, 1-benzyl-4-aminopyridinium bis(maleonitriledithiolato)nickelate(III) (1), has been synthesized. The variable magnetic susceptibility results of 1 show a discontinuity around 184 K, which is phenomenologically similar to that observed for first-row transition metal complexes undergoing a spin cr…
We investigate the origin of the Breit-Wigner-Fano line in the Raman spectra of individual single-walled carbon nanotubes and their bundles. Using confocal Raman microscopy and atomic-force microscopy we found that the Breit-Wigner-Fano line intensity increases strongly with the bundle thickness. We confirmed this res…
Tetrakis(trimethylsilyl)tetrahedrane 3 has been synthesized upon irradiation of tetrakis(trimethylsilyl)cyclobutadiene 8, which can be prepared either by thermal nitrogen elimination from trimethylsilyl[1,2,3-tris(trimethylsilyl)-2-cycloprop-1-enyl]diazomethane 7 or by mild oxidation of cyclobutadiene dianion 9 with 1…
In order to prepare bulk C 3 N 4 , high-pressure pyrolysis of melamine (C 3 N 6 H 6 ) at different temperatures was carried out. The products were characterized by C, N, H element analysis, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, and x-ray diffractometry. The results of the analysis…
To investigate the dielectric response of isolated single-walled carbon nanotubes, (SWCNTs), spatially resolved electron energy-loss spectroscopy measurements have been carried out using a scanning transmission electron microscope in a near-field geometry. Spectra have been compared with those acquired on multiwalled…
The syntheses and electrooptic properties of a new family of nonlinear optical chromophores are reported. These species feature an ethyne-elaborated, highly polarizable porphyrinic component and metal polypyridyl complexes that serve as integral donor and acceptor elements. Examples of this structural motif include ru…
Cellular solids inherit their macroscopic mechanical properties directly from the cellular microstructure. However, the characteristic material length scale is often not small compared to macroscopic dimensions, which limits the applicability of classical continuum-type constitutive models. Cosserat theory, however, o…
We study the linearized Fopl - von Karman theory of a long, thin rectangular elastic membrane that is bent through an angle $2 α$. We prove rigorous bounds for the minimum energy of this configuration in terms of the plate thickness $σ$ and the bending angle. We show that the minimum energy scales as $σ^{5/3} α^{7/3}$…
The microindentation hardness technique has been employed to examine the II → I polymorphic transformation of i -PBu1 taking place upon aging at room temperature. The hardness values of form I are shown to be remarkably higher than those of form II due to the denser packing of chains in the hexagonal crystal modificat…