Materials Literature
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Anharmonic effects in crystals typically result in the symmetric broadening of the single-phonon Lorentzian line shape. However, a simple model, based on consideration of a highly anharmonic potential, shows that anharmonicity can lead not only to asymmetric line shapes but also to line shapes composed of multiple sub…
Surface modification of a P2 beam-exposed InGaAs surface and an As2 beam-exposed InP surface was studied in situ using reflection high energy electron diffraction during gas source molecular beam epitaxy. It is revealed that the InP surface remained stable under As2 beam exposure after forming an InAs surface layer a…
We report the fabrication of high aspect ratio, sub-10 nm size, structures in silicon without involving any wet chemical etching. A 50 nm thick double layer of low and high molecular weight polymethylmethacrylate resist was exposed with an 80 kV electron beam of diameter smaller than 5 nm. After exposure the resist wa…
This letter is aimed at understanding the intergranular conduction in zinc oxide varistors. In particular, we have studied current-voltage and Arrhenius plots of the resistive current for the prebreakdown conduction. A current-temperature (I-T) relation has been found to present two breaks at ∼370 and ∼240 K. Although…
Optical second-harmonic and sum-frequency spectra of clean and oxidized Si(100) and Si(111) samples reveal a strong resonance band at 3.3 eV photon energy. It is concluded that the resonance arises from direct transitions between valence and conduction band states in a few monolayers of strained silicon at the Si-${\m…
The electromagnetic levitation technique is applied to undercool melts of quasicrystal-forming alloys of Al-Cu-Co and Al-Cu-Fe. Undercooling with respect to the solidification of the decagonal phase (quasiperiodic in two dimensions) is measured in situ by contactless temperature measurements. The undercoolings are ana…
An amorphous carbon network generated by quenching high-density high-temperature liquid carbon using tight-binding molecular-dynamics simulation is found to contain a large fraction of tetrahedral bonding sites. Investigations of the structural, vibrational, and electronic properties of the theoretical model provide f…
The structure of molten lithium nitrate at 573 K has been investigated by applying the technique of neutron diffraction to five isotopically enriched samples: NLiNNO3, 0LiNNO3, 7LiNNO3, 7Li15NO3 and 0Li15NO3. The ion-ion and ion-counterion partial structure factors relating to g Li-Li(r), g Li-N(r), g Li-O(r) partial…
As determined by quantitative differential thermal analysis, the enthalpies of fusion of forsterite and spinel, are ΔH f = 142 ± 14 and 107 ± 11 kJ/mol at 2174 and 2408 K, respectively. Significant premelting has been observed for forsterite, beginning about 100 K below the congruent melting point. When heated in grap…
Abstract A survey by X‐ray diffractometry was carried out to confirm the two crystalline phase Iα/Iβ(triclinic/monoclinic) system of native celluloses. We have investigated cellulose samples from 12 different origins and measured the d ‐spacings with reasonable precision. The samples were then subjected to the hydroth…
Among the mechanisms suggested to account for degradation of varistor materials, ion migration has strong support. Mobile, positively charged ions in the depletion layer would be the key element in degradation. In this context, the authors discuss the consequences of an electrical stressing on the current-temperature…
Abstract We review the theory of the isotropic—nematic phase transition for solutions of thin hard rods and semi-flexible chain molecules along with the extensions to polydisperse systems and soft interactions. The occurrence of more highly ordered liquid crystal phases (smectic, columnar) in concentrated solutions of…
Oxidation of pure titanium was carried out at room temperature under different oxygen pressures (10 -8 -10 -6 torr). The kinetics for each pressure was determined. Measured film thicknesses were larger for higher pressures. Deconvolution of XPS spectra showed than TiO was the major oxide present and TiO 2 the minor co…
A set of hydrogenated amorphous silicon oxide (a-SiOx:H) films have been fabricated by plasma enhanced chemical vapor deposition. Some of the films exhibit strong room-temperature photoluminescence and others do so only after annealing at high temperature. The variation of photoluminescence after different annealing t…
Ordered phases of O on W(110) entail compressive surface stress, the manifestations of which are directly observed for different coverages using scanning tunneling microscopy. Low coverage adsorption results in a gas phase with disordered persistent structures. At higher coverage, ordered phases condense with disorder…
Magnetic polarons in magnetically disordered systems (for brevity, spin-glass polarons) are in one respect very unlike other polarons: Usual polaron hopping at low T proceeds via tunneling, and these polarons do not affect the T dependence of the hopping rate, while the spin-glass polaron tunneling is suppressed by th…
Polystyrene (PS)-polyisoprene (PI) diblock copolymers dissolved in n-decane aggregate into spherical micelles with a PS core and a corona of tethered PI chains. The PI corona may be considered as a brush on the surface of a sphere or as the outer part of a many-armed polymer star. The thermal density fluctuations of t…
The E(V) phase diagram of different crystal structures of indium nitride is studied theoretically, using density functional theory, pseudopotential and full-potential LMTO methods. The high-pressure phase is identified as rocksalt and is found to be semiconducting. The transition pressure is predicted, and the lattice…
Electrochromic niobium oxide thin films were prepared by a radio-frequency magnetron sputtering method. Amorphous Nb2O5 thin films deposited at radio-frequency power 100 W showed the electrochromic behavior: Reduction and oxidation of the films in 0.1 M Na2CO3+0.1 M NaHCO3 buffer solution resulted in coloration and bl…
Experimentally observed stress-strain characteristics in yield deformation of Si, GaAs, and InP crystals are discussed in terms of the dynamic processes of dislocations on a microscopic scale. It is shown that experimental observations are satisfactorily reproduced by calculation on a theoretical model using empirical…