Materials Literature
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Paths of tetragonal states between two phases of a material, such as bcc and fcc, are called Bain paths. Two simple Bain paths can be defined in terms of special imposed stresses, one of which applies directly to strained epitaxial films. Each path goes far into the range of nonlinear elasticity and reaches a range of…
We have calculated formation energies and position of the defect levels for all native defects and for a variety of donor and acceptor impurities employing first-principles total-energy calculations. An analysis of the numerical results gives direct insight into defect concentrations and impurity solubility with respe…
The diffusivity of Ga and Al adatoms on the (2x4) reconstructed GaAs(001) surface are evaluated using detailed ab initio total energy calculations of the potential energy surface together with transition state theory. A strong diffusion anisotropy is found, with the direction of fastest diffusion being parallel to the…
We present a method for the controlled fabrication of stable nanostructures under ambient conditions. The surfaces under consideration, WSe2, are imaged by an atomic force microscope. By applying a voltage between the tip and the sample, we can control an etching process at the surface: different voltage thresholds fo…
A substantial difference in the angular distributions of $2p$ photoelectrons from polarized oxygen atoms was found for two antiparallel atomic polarizations. This magnetic dichroism was studied as a function of photon energy from 25 to 52 eV. Our method extends traditional photoelectron angular distribution measuremen…
We report an absolute measurement of the tensor analyzing powers ${T}_{20}$ and ${T}_{22}$ in elastic electron-deuteron scattering at a momentum transfer of $1.6{\mathrm{fm}}^{\ensuremath{-}1}$. The novel approach of this measurement is the use of a tensor polarized ${}^{2}\mathrm{H}$ target internal to an electron st…
A simple fabrication method is described to produce reliable and robust (self-repairing) field emission sources from randomly aligned carbon nanotubes. The sources display stable and reproducible current–voltage characteristics with sharp turn on near 100 V and emission currents up to 400 mA/cm2 at 200 V. Two successf…
The vibrational properties of carbon monoxide adsorbed to the copper (100) surface are explored within density functional theory. Atoms of the substrate and adsorbate are treated on an equal footing in order to examine the effect of substrate--adsorbate coupling. This coupling is found to have a significant effect on…
Strains of nearly 0.2% have been induced along [001] in unstressed crystals of Ni2MnGa with magnetic fields of 8 kOe applied at 265 K. These stains are associated with the superelastic motion of twin boundaries in the martensitic phase that is stable below about 274 K.
It is shown in this paper that the wetting behavior of n-alkanes on a water surface can be predicted using the wetting theory of Cahn, together with experimental results for n-alkane vapor adsorption on water which are readily available in the literature. The evolution of the wetting behavior with the carbon number of…
Structural relaxation in viscous glycerol has been followed from 5.9 ps to 3.7 ns by coherent neutron scattering around the structure factor maximum. In a 100 K interval, the line shape of the decay function shows no significant temperature dependence; the mean relaxation time scales accurately with viscosity. Interpa…
The anomalies of supercooled water in thermodynamic response functions at atmospheric pressure, the phase transition between low and high density amorphous ices (LDA and HDA), and a predicted fragile–strong transition are accounted for in a unified manner by reconciling an idea due to Stanley and co-workers introducin…
噴出起源の異なる幾つかの北海道粗粒火山灰土について, 排水・非排水三軸圧縮, 平面ひずみ圧縮及び繰返し非排水せん断試験を実施し, それらの力学特性を調べた. 一連の実験と考察から, 1) せん断中に有効平均主応力が増加するような応力条件では構成粒子の破砕が確実にもたらされるものの, 繰返し非排水せん断過程で液状化に向かうような場合は粒子破砕はほとんど生じない, 2) 破砕性の卓越する火山灰土の応力―ひずみ―強度特性は有効拘束圧 (あるいは平均主応力) に強く依存するとともに, 通常の密度の砂ではみられない特異なダイレイタンシー挙動を示す, 3) 降下生成物で構成されている火山灰地盤の静的・動的力学特性にはクリーンな砂よりもはるかに…
Metal–porphyrin π bonds such as those in 1 and 2 were hitherto unknown modes of coordination in porphyrin complexes. However, arene complexes of this kind were recently synthesized by Rauchfuss et al. (Angew. Chem. Int. Ed. Engl. 1996, 35, 1833). Metal – porphyrin interactions of this type may also play a role in reac…
In only a few picoseconds the photoinduced electron transfer in the noncovalently linked complex between zinc porphyrin 1 and the quinone 2 is complete. Transient absorption spectra show the zinc porphyrin cation radical as typical intermediate of the electron transfer.
Trivacant polyoxotungstates such as α-A-[PW9O34]9− ions react with tBuSiCl3 to afford the anion 1. This can react further with other trichlorosilanes to give α-A-[PW9O34(tBuSiO)3(RSi)]3− ions (R = H, Me, Et, CHCH2, CH2CH2CH2Cl). Similar arsenic compounds are also reported.
Many liquids with vastly different properties can form glasses upon cooling. Although this phenomenon has been known since ancient times, no complete general understanding of the glass transition is available. In his Perspective, Sokolov reviews recent theoretical and experimental progress in unraveling the mysteries…
Fine tuning of the magnetic properties can be achieved in [Ni(tren)]3[Fe(CN)6]2·6 H2O (1, section of structure shown on the right; tren = tris(2-aminoethyl)amine), the first example of a three-dimensional bimetallic network of a Prussian blue analogue containing organic groups. The compound orders as a bulk ferrimagn…
Broad-band dielectric spectroscopy (10 −2 Hz–10 7 Hz) is employed to study the molecular dynamics of three low-molecular-weight glass-forming H-bonded liquids being confined in (dielectrically inactive) porous glasses with pore sizes of 2.5 nm, 5.0 nm and 7.5 nm. From the relaxation time distribution of the dielectric…
Zinc porphyrin/pyridine coordination interactions have been used to assemble complexes containing two different chromophore arrays. These undergo photoinduced electron transfer (see picture) and energy transfer reactions, which mimic some of the primary events in photosynthesis.