Materials Literature
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Abstract Polypyrrole–PMMA composite films have been prepared with the chemical oxidative polymerization by spreading the water‐insoluble solvent solution of pyrrole and PMMA mixture on the surface of the aqueous solution containing K 2 S 2 O 8 , the oxidizing agent. The conductivity of the films increases rapidly, pas…
A photoelectron hologram is a two-angle photoelectron diffraction pattern: Direct photoemission plays the role of the reference wave and the scattered waves are the object waves. When the hologram is created from the core-level photoemission of single emitting species on an ordered surface, a complete three-dimensiona…
Transmission electron diffraction and imaging are applied to derive a proposal for the tilt scheme of the perovskite based structure of silver niobate (AgNbO3). Electron diffraction data enable a reduction of the possible spacegroups down to two, each compatible with a number of tilt schemes for the octahedra in the p…
Characteristic features of the dislocation structure developed in the first stage of deformation of single-glide oriented crystals of concentrated f.c.c. alloys like α-CuZn are extended multipoles in the primary slip planes. Their various configurations are explained by considering their formation in the case that the…
It is found with TEM that there is a new phase, called M phase, coexisting with the normal P and Q phases at room temperature. All kinds of ferroelectric domains in the Q phase and antiferroelectric domains in the P phase are observed. They are in good agreement with the results given by the symmetry theory on domains…
Raman scattering measurements were performed to investigate optical modes of scheelite-type double molybdates XY(MoO 4 ) 2 (X=Li, Na and Y=La, Nd). In the polarized Raman scattering measurements, we have found four modes in NaLa(MoO 4 ) 2 , one in low frequency region (with B g symmetry) and three in high frequency re…
We have observed a new, strong feature at 47 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ in the first-order Raman spectrum of ion-implanted GaAs, prior to any anneal. It is not present in the Raman spectrum of either amorphous or single-crystal GaAs. The peak is strong between excitation photon energies \ensuremath{\si…
Vapor-grown carbon fibers possessing a high degree of preferential orientation have been prepared using either a catalyzed substrate or a fluidized catalytic method, yielding fibers with diameters of about 10 and 1 μm, respectively. After heat treatment at 2600–2960 °C, the fibers were used as a host material for brom…
Cristallisation dans R3c avec affinement jusqu'a 0,017. L'angle O−Sc−O vaut 92,8° indiquant une faible elongation trigonde des octoedres formes d'atomes O
A method is presented to analyze complex glow curves composed of several, possibly overlapping, peaks from thermally stimulated processes of general kinetic order and is applicable when the process studied is activated using any arbitrary temperature profile. A theoretical analysis is given to determine the properties…
Lone-pair electrons on S or Se interacting with each other were proposed as a new type of electrically neutral gap states in amorphous chalcogenides based on energy-band calculations using a simple tight-binding method. Much attention was focused on the ``molecular'' systems such as amorphous S, Se, and ${\mathrm{As}}…
A method is discussed to analyze multifractal properties of spectra and wave functions by means of an entropy function. The method is exemplified on a model for lattice vibrations in an incommensurate crystal phase. It is shown that the model has a spectrum with scaling properties. Moreover, it is probably singular co…
A $p\ensuremath{-}n$ transition in the electronic conduction in Bi-doped bulk amorphous semiconductors ${\mathrm{Ge}}_{20}{\mathrm{Te}}_{80\ensuremath{-}x}{\mathrm{Bi}}_{x}$ at about $x=3.5$ has been observed for the first time. $n$-type conduction has been established by the measurement of thermoelectric power that b…
A quantitative low-energy electron diffraction (LEED) intensity analysis shows that the room-temperature reaction of Pd atoms with a Cu{001} surface produces a surface alloy, Cu{100}c(2\ifmmode\times\else\texttimes\fi{}2)-Pd, analogous to Cu{001}c(2\ifmmode\times\else\texttimes\fi{}2)-Au. The structure of Cu{001}c(2\i…
We report here a comprehensive study of the bulk electronic structure of single-crystal ${\mathrm{Ti}}_{2}$${\mathrm{O}}_{3}$ and ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ using both angle-integrated and angle-resolved photoemission and synchrotron radiation. The electronic structure of these materials is of particular int…
Exact eigenstates of a tight-binding model on a two-dimensional Penrose lattice are investigated. Several exact eigenfunctions are found for certain transfer matrices, and a method to obtain more general exact solutions is proposed. The fractal dimension of self-similar non-normalizable eigenfunctions is defined, and…
Distinct antiphase domain structures in GaAs epitaxial layers grown on a Si/SiO2/Si-substrate structure by metalorganic chemical vapor deposition have been revealed by using a silicon etchant (HF/HNO3). The antiphase is characterized by the [011]-oriented etching textures which rotate 90° between adjacent domains. The…
A soft optic phonon which is neither Raman nor infrared active has been directly observed for the first time in the higher-symmetry phase above ${T}_{a}$ (221.5 K) of hexagonal BaTi${\mathrm{O}}_{3}$ by an experiment of hyper-Raman scattering. The underdamped feature of the soft-phonon mode even close to ${T}_{a}$ all…
We have investigated the variation of the structural energy along two transition paths from the layered to the highly condensed phases of BN using the first-principles total-energy pseudopotential method. Along the structural paths considered, the symmetries of the initial layered phases have been maintained, leading…
We have measured the thermal conductivity of two diamond films grown by a chemical vapor deposition process. At room temperature the thermal conductivity is of the order of 10 W cm−1 K−1, i.e., as high as naturally occurring (type Ia) single-crystal diamonds. This value exceeds the thermal conductivity of copper at ro…