Materials Literature
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The difference between La-deficient and Sr-substituting effects for La in LaCoO${}_{3}$ has been investigated by using x-ray photoelectron spectroscopy (XPS). On the basis of the relationship between the intensity of the ${}^{2}{T}_{2}$ line and the amount of low-spin Co${}^{3+}$ ions in these compounds, it is pointed…
A genuine organic radical crystal 1,3,5-triphenyl-6-oxoverdazyl (TOV) has been revealed to be an S =1/2 two-dimensional (2D) weak-ferromagnetic Heisenberg antiferromagnet with the exchange interaction 2 J / k B =-9.0 K by the experiments of magnetic susceptibility, heat capacity, magnetization and electron paramagneti…
Poly(lactones) may be crosslinked by ring-opening polymerization of the corresponding cyclic esters in the presence of tetrafunctional bis(ϵ-caprolactone). The homopolymer of 1.5-dioxepan-2-one (DXO) has poor mechanical properties but also some very good properties, such as biocompatibility and degradability. Crosslin…
We have proposed a possible crystal structure for the cluster-assembled solid Al${}_{12}$C(Si), and its electronic structures and stability have been studied in the framework of density functional theory and ab initio molecular dynamics. We find that Al${}_{12}$C(Si) clusters are condensed by van der Waals force, with…
Phosphorus-containing polyurethanes are synthesized by reacting phosphorus-containing diisocyanates, bis (4-isocyanatophenoxy) phenyl phosphine oxide (BIPPO) and bis (3-isocyanatophenyl) phenyl phosphine oxide (BIPPPO), with various diols. The chemical structures of the obtained monomers and polymers are characterized…
In computing the volume occupied by atoms and the density in proteins, one is faced with the problem of intersecting spheres. To estimate either, the space between the atoms has to be divided according to the location of the atoms relative to each other. Various methods, based on Voronoi's idea of approximating the at…
Time-dependent excitation spectroscopy coupled with quantum chemical calculations is used to demonstrate that the photoluminescence (PL) resulting from the ultraviolet optical pumping of an etched porous silicon (PS) surface results from a silicon oxyhydride-like fluorophor bound to the PS surface. The time-dependent…
We present experimental x-ray-absorption spectra at the oxygen and $3d$ transition-metal $K$ edges of ${\mathrm{LaFeO}}_{3}$ and ${\mathrm{LaCoO}}_{3}$. We interpret the experimental results in terms of detailed theoretical calculations based on multiple-scattering theory. Along with providing an understanding of the…
A new mechanism of polarization switching and electron emission in ferroelectric cathodes is proposed. Surface flashover plasma of a ferroelectric origin was observed on a polar ferroelectric surface [D. Shur, G. Rosenman, and Ya. E. Krasik, Appl. Phys. Lett. 70, 574 (1997)]. Simultaneous measurements of switched char…
This article compares switching behaviors between negative (Nn) and positive (Np) dielectro-anisotropic nematic liquid crystals driven by an in-plane electric field which is generated with interdigital electrodes. Even for Np type liquid crystals, excellent viewing angle characteristics were obtained as expected. Theo…
Variations of optical absorption and especially of photoluminescence spectra of Cu 2 O with photoexcitation wavelength and temperature have been for the first time investigated in details. We have newly observed that the relation of the increase and decrease with temperature in the integrated intensity is complementar…
We study the lattice distortion in graphite ribbons of a nanometer width by taking account of the electron-phonon interaction in the tight binding model. In the ribbons with armchair edges, the typical Kekulé structure appears near the edges depending on the distribution of the bond orders. On the other hand, the zigz…
A model for the inelastic-scattering cross section of electrons in XPS experiments is presented. The calculation is analogous to a previous model for reflection-electron energy-loss spectroscopy by Yubero et al. [Phys. Rev. B 53, 9719 (1996)]. The model treats the general case of photoelectron creation at arbitrary de…
A new method for the determination of the interfacial tension coefficient between two immiscible fluids is proposed. The method is particularly useful for the binary polymer blends. The deformed drop retraction method, DDRM, makes it possible to determine the dynamic interfacial tension coefficient, ν, from the time e…
This article reports the fabrication of thin films of In2O3 from an aqueous sol and an organic solution. The stability of the aqueous sol with respect to the concentration of indium and pH are discussed. Thermo-gravimetric and differential thermal analysis were performed on the dried sol particles as well as the gel f…
We have studied the effects of hole doping on the electronic structure of La${}_{1\ensuremath{-}x}$Sr${}_{x}$CoO${}_{3}$ by photoemission and x-ray-absorption spectroscopy. The Co 2$p$ core-level and the valence-band spectra show charge-transfer satellites, which have been more obviously observed in 3$p$-3$d$ resonant…
Fragmentation tests in the uniaxial mode were performed on poly(ethylene terephthalate) (PET) films coated with a 100 nm thin silicon oxide layer. The coating's fragmentation process was analyzed in light of the mechanical behavior of the polymer substrate. It was shown that, upon unloading samples strained to less th…
In this paper we report the results of an extensive investigation of the La${}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{Mn}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}{\mathrm{O}}_{3}$ system. Substitution of Mn by Co dilutes the double-exchange (DE) mechanism and changes the long range ferromagnetic order of ${\mathrm{La}}_{0.7}{\m…
In spite of the enormous amount of theoretical and experimental work on conducting polymers, the actual mechanism involved in the transition to a metallic regime is still an open and polemical question. Recently, Galv\~ao et al. have proposed, based on the study of long, disordered, one-dimensional chains, that disord…
For the last two decades, mixtures of D- and L-lactides, the DD and LL cyclic dimers of lactic acid enantiomers, were polymerized under various conditions of temperature, time, and initiators. Consequences of the dimeric structure of lactide molecules on the distribution of chiral units and on the properties of result…