Materials Literature
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Enzymatic copolymerization of lactones, divinyl esters, and glycols has been performed using lipase as catalyst to produce ester copolymers. The monomers used in this study were 12-, 13-, and 16-membered lactones, divinyl esters of adipic and sebasic acids, and alpha,omega-glycols. Candida antarctica and Pseudomonas c…
Triblock copolymer micelles have been used successfully as templates to form porous, highly uniform, and hollow MoO 3 nanospheres, with their diameter being equivalent to the micellar core size. By use of a combination of static and dynamic light scattering, small-angle X-ray scattering, and wide-angle X-ray diffracti…
In previous studies of capillary condensation of water between mica surfaces using the surface force apparatus (SFA) it has not been possible to obtain agreement with the Kelvin equation. The condensates in these studies exhibited refractive index values larger than that of bulk water and often deposited residues of i…
Organized mesoporous silica (OMS) constitutes new materials with many potential applications. These materials with very well organized pores can be obtained by lowering the pH of precursor systems, i.e., highly alkaline silicate solutions containing cationic surfactants such as cetyltrimethylammonium bromide (CTAB) or…
Reduction of a chiral cerium bisporphyrinate double-decker complex Ce(MOFPP) 2 (MOFPP = 5,15-bis(3,5-dimethoxyphenyl)- 10,20-bis(pentafluorophenyl)porphyrin dianion) with sodium anthracenide in dioxane at 20 °C resulted in acceleration of the porphyrin ligand rotation (= racemization) by a factor of more than 300. Pho…
Graphite, oxidized by HNO 3 and NaClO 3 to 25% (GO-25), 42% (GO-42), and 33% (GO-33), has been dispersed to partially exfoliated nanoplatelets and, along with poly(diallyldimethylammonium chloride) (PDDA) and poly(ethylene oxide) (PEO), layer-by-layer self-assembled to ultrathin S−(PDDA/GO) 10, S−PDDA/(GO/PEO) 10, and…
Nanocrystals or quantum dots of the IV-VI semiconductors PbS, PbSe, and PbTe provide unique properties for investigating the effects of strong confinement on electrons and phonons. The degree of confinement of charge carriers can be many times stronger than in most II-VI and III-V semiconductors, and lead salt nanostr…
The spin-state transition is an interesting and unresolved problem in layered perovskite La 2- x Sr x CoO 4 under doping, as it involves competition among different magnetic structures. Within the unrestricted Hartree-Fock approximation and using the real space recursion method we have studied the effect of Sr doping…
The crystal structure of chemically disordered lead scandium niobate, Pb(Sc 1/2 Nb 1/2 )O 3 , is studied by the high-resolution neutron powder diffraction method. The data, collected over the temperature range 2-653 K, are analysed using Rietveld refinement. From 653 K to 378 K, the symmetry of PSN is found to be cubi…
The crystal structure of DMABA has been determined at 293 and 180 K. It crystallizes in the monoclinic P 2 1 / c space group. The structure was refined to R 1 = 0.0466 for 1269 independent reflections at 293 K and R 1 = 0.038 for 1728 reflections at 180 K. DMABA is isomorphous with the chlorine analogue, DMACA. Its an…
We investigate the electron population dynamics in an ensemble of nearly isolated insulating nanoparticles, each nanoparticle modeled as an electronic two-level system coupled to a single vibrational mode. We find that at short times the ensemble-averaged excited-state population oscillates but has a decaying envelope…
Abstract The superplasticity exhibited by some fine-grained ceramics, notably 3-mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP), offers interesting possibilities to lower manufacturing costs by near net shape forming. Both glassy and crystalline materials have been added to pure 3 Y-TZP to limit grain…
The effect of niobium dopant and annealing (900°C, 8h) on the crystal structure, microstructure, and piezoelectric properties of 0.55Pb(Sc1/2Ta1/2)O3-0.45PbTiO3+xmass%Nb2O5 ceramics (Nb-doped PSTT) (x=1, 0.5%, 1.5%, 2%) were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and piezoelectric…
We analyzed the temperature dependence of the amplitude of modulated structures of [N(CH3)4]2ZnCl4 crystal in the incommensurate (INC) phase by measuring the EPR spectra for Mn2+ doped single crystal. The amplitude of the vibrational modulation linearly increased with decreasing temperature. Applying Frank and Van der…
Abstract Silicon dioxide is an important catalyst material, a mainstay insulator in microelectronics, and a widely distributed terrestrial and marine skeletal mineral. Geologically, it is found in one of a large number of polymorphic crystalline states, but can also be rendered “amorphous” by rapid cooling from the me…
Abstract It has been estimated that more than 90% of all scanning electron microscope (SEM) images ever published have been obtained using secondary electrons (SE) which are defined as being those electrons emitted with energies between 0 and 50eV. The properties of these secondary electron are therefore of considerab…
Abstract Focused Ion Beam (FIB) micromachining techniques have gained significant attention over the past few years as a promising method for the preparation of a variety of metallic and nonmetallic materials for subsequent characterization using transmission electron microscopy (TEM) The advantage of the FIB in terms…
Abstract Image analysis tools and statistical procedures have been developed to quantify particle shape. Three copper sulfate crystallization processes have been carried out and the effects of process operating parameters upon crystal morphology have been studied as well as the relationships between morphology and pow…
Abstract Most materials used in technology are polycrystalline. Therefore, the properties of the internal interfaces often control the properties of the materials (interface-controlled materials). In single phase polycrystalline materials, grain boundaries are the internal interfaces (homophase boundaries) of interest…
A short synthesis of tetramethyltetrathiafulvalene quadruply labeled with carbon-13 is described.