Materials Literature
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We present valence effective Hamiltonian (VEH) calculations on the optical absorptions of a series of phthalocyanine compounds: the metal-free phthalocyanine molecule, a model system for the lithium phthalocyanine molecule, the metal-free phthalocyanine dimer, and model systems for the lutetium diphthalocyanine and th…
Electron emitters in vacuum microelectronic devices need sharp tips in order to permit electron emission at moderate voltages. A method has been found for preparing uniform silicon tips with a radius of curvature less than 1 nm. These tips are formed by oxidation of 5-μm-high silicon cones through exploitation of a kn…
Abstract Owing to enthalpy relaxation, values of the glass transition temperature ( T g ) for partially reacted polymers may depend on the thermal history of samples and the heating rate used for measurements. Use of theoretical relations between T g and the extent of reaction ( x ) of a thermoset must take this fact…
The first measurements are reported for the frequency-dependent (ac) conductivity (real as well as imaginary parts) for various compositions of the bismuth-vanadate glassy semiconductors in the frequency range ${10}^{2}$--${10}^{5}$ Hz and in the temperature range 77--420 K. The behavior of the ac conductivity is broa…
The occurrence of ferroelectricity in smectic-C liquid crystals is discussed and it is suggested that, for this phenomenon to occur, the requirement that the molecules must be chiral is an over-constraint.
Magnesium fluoride(MgF2) and Magnesium aluminate spinel(MgA1204) ceramics for 3-5 micron IR transmission have been developed by a powder processing technique. Their optical, physical, mechanical, and thermal properties have been measured and compared with each other. The transmittance and flexural strength related wit…
In order to provide an accurate basis for the interpretation of the physical properties of this complex incommensurate system, the structure of the room temperature quasi-commensurate phase of barium sodium niobate is determined by taking into account, for the first time, the satellite reflections present in the diffr…
We have measured the effect of pressure on the solid phase epitaxial growth rate of Ge(100) into self-implanted amorphous Ge by using in situ time-resolved infrared interferometry in a high-temperature, high-pressure diamond anvil cell. In the temperature range 300–365 °C, a rate enhancement of more than a factor of 1…
We have imaged for the first time the atomic structure of a quasicrystal using a scanning tunneling microscope. The structure of the decagonal ${\mathrm{Al}}_{65}$${\mathrm{Co}}_{20}$${\mathrm{Cu}}_{15}$ quasicrystal is described by a pentagon-center-decorated pentagonal quasilattice giving strong evidence for a tilin…
In shape-memory alloys a first-order martensitic phase transition is responsible for pseudo-elastic and for ferro-elastic stress-strain relations. To describe this behaviour a modified Landau theory is proposed in which the free energy of the crystal depends on the temperature and on the full strain tensor. The energy…
Abstract Effects of E / P ratio of the EPDM rubber on the flow behavior and morphology of the crosslinkable polyethylene and EPDM blends have been studied as a function of shear rate and processing temperature. High‐ E / P ‐ratio EPDM rubber exhibits high viscosities within the temperature range studied but the extrud…
Abstract New thermoplastic elastomers (TPEs) consisting of a central rubbery polyisobutylene (PIB) and glassy outer cyclopolyisoprene (cy‐PIP) segments have been prepared by living carbocationic polymerization by sequential monomer addition. First the homopolymerization of isobutylene (IB) and isoprene (IP) have been…
Abstract Polylactide (PLA)‐poly(ethylene glycol) (PEG) copolymers were synthesized from polyethylene glycol and D , L ‐lactide using low toxic stannous octoate as catalyst at 180°C by bulk polymerization. The copolymers were characterized by GPC, IR, and 13 C‐NMR. A full assignment NMR spectrum is presented. The physi…
The characteristics of Forbush decreases of cosmic ray caused by solar flares in March 1989 are analysed in this paper. The anisotropy for μ-meson component are also analysed beside neutron component, and the relationship between the cosmic ray intensity variation and the characteristics of solar flares and geomagneti…
This paper deals with the ion wind of SF6 gas which is generated by partial discharges at a tip of a needle electrode at dc fields. The velocity measurements of the ion wind are performed by a hot wire annemometer, using a needle(φ0.2, length 10) -plate(φ120) set in compressed SF6 gas (3_??_5 atm). The velocity of the…
This paper clarifies two matters, the source of equation of Ω and the nature of current vector T, of T-Ω method in magnetostatic field analysis. First, we derive a new formula including T0 (T0 obtained from exciting current density Js is expressed as T0) from the Biot-Savart formula by dyadic operator. From this new f…
Abstract Some sulfur concretes have been shown to expand excessively under moist conditions. The deterioration is accompanied by a decrease in dynamic modulus of elasticity with time. The durability of sulfur concretes containing glycerin and crude oil admixtures was slightly improved, but expansions were still unacce…
It is well known that segregation of Ti and formation of TiN occurs when active brazing alloys such as Ag-Cu-Ti were used for Si3N4 joining. Si3N4-Si3N4 joining was carried out using several glass solders containing oxides of active metal, 1A group elements and 2A group elements without applying pressure. Si3N4-glass…
The X-ray diffraction (XRD) and scanning electron microscopy (SEM) study was carri-ed out for an amorphous Cu+ conductor 0.4CuI-0.3 Cu2O-0.3P2O5 with the simultaneous conductivity measurement in the isothermal heat treament process. The results indicated that the initial amorphous material was phase-separated. In the…
By using carbide nucleation-heat-treated SUS304 stainless steel specimens, the effect of various type of stresses applied during 500°C isothermal heat treatment on Low Temperature Sensitization (LTS) was examined. The Degree of Sensitization (DOS) was detected by means of the Electrochemical Potentionkinetic Reactivat…