Materials Literature
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Enhancement mode-type metal-semiconductor field effect transistors using diamond have been fabricated. The transistor operation is based on the control of surface p-type conduction of a hydrogen terminated homoepitaxial layer. Boron doping was not used for the conduction. An aluminum contact is used for the Schottky g…
In situ x-ray diffraction on Pd hydride under 5 GPa of hydrogen pressure show that lattice contraction due to vacancy formation occurs in 2-3 h at 700-800 \ifmmode^\circ\else\textdegree\fi{}C, and two-phase separation into PdH and a vacancy-ordered phase of ${\mathrm{Cu}}_{3}$Au structure (${\mathrm{Pd}}_{3}$${\mathrm…
We propose an extension of the van der Waals equation which is designed to incorporate, in an approximate fashion, the effects of the network of hydrogen bonds that exist in liquid water. The resulting model qualitatively predicts the unique thermodynamic properties of water, including those of the deeply supercooled…
Reversible γ-induced structural transformations in vitreous As2S3 are studied using ESR and differential IR Fourier-spectroscopy techniques. It is shown that the investigated low-temperature (T < 100 K) as well as high-temperature (T ≈ 300 K) radiation-structural transformations are associated with chemical bond break…
A pivotal role in the formation of lactam catenanes is attributed to macromonocycle 1. The synthesis of a monosubstituted catenane, in which 1 acts as host, provides evidence for the proposed mechanism. Three iso-meric disubstituted catenanes are also prepared.
This article describes the use of synchrotron radiation to study chemical and structural changes of catalysts during actual operating conditions. Described are techniques using x-ray absorption near edge structure, extended x-ray absorption fine structure, pre-edge x-ray absorption, and x-ray diffraction. Some of the…
Optical and electrical properties of the gallium telluride Ga2Te3 are reported. Lattice modes are investigated using far-infrared spectroscopy and polarized Raman scattering experiments. The farinfrared reflectivity spectrum which is analyzed using a Lorentzian-oscillator model and the Raman spectrum shows that this c…
Strong through-space interactions with the dendritic shell surrounding the chromophore are at the root of the unusual redox properties of the porphyrin unit in 1. Compound 1, measuring approximately 4 nm in diameter with a molecular weight of over 19 kDa, represents a new class of synthetic, densely packed, globular e…
We review the x-ray-diffraction and high-resolution transmission electron microscopy (HRTEM) data that Doll et al. [Phys. Rev. B 43, 6816 (1991)] used as evidence for the epitaxial growth of cubic boron nitride (cBN) on silicon (001) surfaces. The three reported x-ray-diffraction peaks do not provide unambiguous evide…
The Mott-type metal-insulator transition has been successfully realized in a misfit-layer compound system La 1.17 VS 3.17 by Sr substitution for La. The transport properties are found to exhibit anomalous behaviors which are very similar to those of high-T c oxides, indicating that they are commonly found in systems h…
Abstract Unrestricted Hartree–Fock calcuations coupled with second‐order Møller–Plesset correlation correction were performed to study the structures and energetics of microlusters. For (BN) 2 , linear and rhombus forms are almost isoenergetic, whereas cyclic forms are preferable for (BN) 3 and (BN) 4 clusters. As a g…
In this paper, we report the use of extended coupled cluster functional of Arponen, Bishop, and co-workers to implement a stationary biorthogonal response approach. The objective of this is to calculate nonlinear molecular properties like hyperpolarizability, etc. in a more convenient way.
We have studied the structure of the ${\mathit{Q}}_{1}$ charge-density wave (CDW) in pure and Ta-doped ${\mathrm{NbSe}}_{3}$ as a function of temperature using high-resolution x-ray scattering. The CDW's phase-phase correlation lengths are much greater than the impurity spacing, and in pure crystals can be comparable…
The authors present experimental results which indicate that a Dy3+-doped Ga:La:S glass fibre amplifier may be operated efficiently at 1.3 µm with an optimum device length significantly shorter than a comparable Pr3+-doped glass fibre amplifier. Moreover, the efficiency exceeds that obtained from the Pr3+-doped ZBLAN…
A model for small helical carbon tubules is presented. A heptagon-pentagon defect in a perfect fullerene tubule, which is made up entirely of hexagons formed by nearest-neighbor carbon-carbon bonds, bends the tubule at a 30\ifmmode^\circ\else\textdegree\fi{} angle, which is the angle between the axes of the two halves…
Cadmium diselenite, CdSe 2 O 5 , consists of an octahedrally coordinated Cd atom and a diselenite group that acts as a bidentate ligand. Cadmium hydrogenselenite selenite, Cd 3 (HSeO 3 ) 2 (SeO 3 ) 2 , has seven- and six-coordinated Cd atoms and two different selenite groups: hydrogenselenite and selenite
For a two-dimensional electron gas (2DEG) with a nonabrupt edge electron-density profile, edge modes, analogous to the higher-multipole surface modes of a 3DEG, are found in addition to the regular edge plasmon. Several simple model edge density profiles are investigated. For a linear edge profile the integral equatio…
The temperature dependence of the spin-lattice relaxation time for 7 Li has been measured in a single crystal of LiNaSO 4 over the temperature range of 450 K–770 K. The result can be explained by a mechanism of vacancy diffusion. The activation energies for the hopping of Li + and Na + vacancies are estimated to be E…
The electronic subband structure of periodically n-type \ensuremath{\delta}-doped silicon is calculated self-consistently within the local-density approximation. Two types of energy levels are distinguished, one due to valleys transverse to the superlattice axis, and the other due to longitudinal valleys. Minibands, p…
It is often suggested that the rate of interdiffusion at semiconductor heterostructure interfaces may be strongly dependent on elastic strain in the structure. Experimental and theoretical results show that strain does not, and should not, affect interdiffusion.