Materials Literature
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The nanocrystalline hard magnetic Nd2Fe14B phase plays a crucial role in the development of exchange spring magnets. We report the hardening mechanism of nanocrystalline Nd2Fe14B, as well as the effect of small amounts of magnetic additions on the hardening behavior. It is shown that the hardening mechanism is of the…
By allowing interactions between electrons, a Harper's equation is derived to examine the effects of electron correlations on the Hofstadter energy spectra. It is shown that the structure of the Hofstadter butterfly for the system of correlated electrons is modified only in the band gaps and bandwidths, but not in the…
We apply ab initio quantum-chemical methods to calculate correlation effects on cohesive properties of GdN, thereby extending the recently proposed incremental method to rare-earth compounds. Our calculated values are in reasonable agreement with the experimental cohesive energy (86.0%) and the experimental lattice co…
The oxidation of an Al(111) single-crystal surface induced by 100 eV electron bombardment in water vapor at room temperature has been studied using x-ray photoemission spectroscopy and electron-energy-loss spectroscopy. Electron bombardment significantly increases the growth rate and changes the observed growth-rate l…
In a measurement of pulsed laser deposition of ${\mathrm{SrTiO}}_{3}$ on ${\mathrm{SrTiO}}_{3}(001),$ we demonstrate that the difference in relative reflectivity change $\ensuremath{\Delta}R/R$ between $s$- and $p$-polarized light can be used in a real-time monitor of thin film growth at the level of a single atomic l…
We present a procedure that locally determines the composition (from a given set of available materials) of a segmented or graded thermoelectric generator leg in order to maximize its output power to a matched load. The method is based on a new interpretation of the electrical output relation, which is organized to re…
Using deuteron NMR techniques two-, effective three-, and various four-time correlation functions were recorded for supercooled ortho-terphenyl at 10–15 K above the calorimetric glass transition in order to characterize the heterogeneous nature of its primary response. The experimental results could successfully be de…
The block copolymers of poly(butylene succinate) (PBS) and poly(butylene terephthalate) (PBT) were synthesized by melt processing for different times. The sequence distribution, thermal properties, and crystallization behavior were investigated over a wide range of compositions. For PBS/PBT block copolymers it was con…
Several junctions between different nanotubes have been constructed which preserve the C ${\mathrm{sp}}^{2}$ honeycomb lattice with the sole insertion of a pentagon and a heptagon. This construction bends the structure at an angle that depends on the distance between the pentagon and heptagon. The atomic structure of…
We present a theoretical result on the ordering of cylindrical morphology in diblock and triblock copolymers. The equilibrium morphology of A–B diblock and A–B–A triblock copolymer films is shown to have the cylinders oriented parallel or vertical to the surface, depending on the film thickness and surface tensions. A…
We present a model that describes grain-boundary-limited conduction in polycrystalline semiconductors, for thermally assisted ballistic as well as diffusive transport, both for degenerate and nondegenerate doping. In addition to bulk parameters (the carrier effective mass and mean free path) the model contains grain b…
The phase separation of ultrathin polymer blend films of deuterated poly(styrene)/poly(vinylmethylether) leads to a variety of film morphologies, depending on polymer composition. Phase-separation measurements are made at a constant temperature difference from the critical temperature, leading to a bicontinuous spinod…
The synthesis of the MCM-41 materials with novel hollow tubular morphology in high alkaline condition was studied in detail. The tubular structure can be obtained in a narrow range of water/C 16 TMAB molar ratio, in which lamellar membranes consisting of the hexagonal arrangement of rod micelles exist. Tubular structu…
We find a striking peak structure in the magnetoresistance of the quasi-two-dimensional conductors $\ensuremath{\beta}\ensuremath{-}{(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\ensuremath{-}\mathrm{T}\mathrm{T}\mathrm{F})}_{2}{\mathrm{I}}_{3}$ and $\ensuremath{\alpha}\ensuremath{-}{(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm…
Electronic structures of ten kinds of rare-earth sesquioxide single crystals ( R 2 O 3 ; R =La, Pr, Nd, Sm, Eu, Gd, Er, Tm, Yb and Lu) were investigated by 4 d -4 f resonant photoemission measurement. The information of the electronic structure, especially the relative binding energy of 4 f state and O 2 p valence ban…
A method is described for measuring the heat and rate of recrystallization following partial melting. The method uses a specific sequence of temperatures with a differential scanning calorimeter, and the melting and recrystallization processes were confirmed by optical observations. The method was applied to poly(buty…
The in situ formation of a compatibilizer, consisting of a copolymer of PA grafted onto a maleic anhydride (MA) containing polymer, is essential for the morphology and properties of the corresponding PA blends. In this study four blends, containing PA-6 or PA-6.6 and EPDM-g-MA or poly(styrene-co-maleic anhydride) (SMA…
We report the structure and magnetic studies of carbon coated nanocrystals of nickel and cobalt synthesized in a special low carbon to metal ratio arc chamber. Powder x-ray diffraction profiles show peaks associated with single phase of fcc nickel or cobalt and major peaks of graphite with no evidence of carbides or s…
We use the local spin-density approximation in density-functional theory to study the electronic structure of ${\mathrm{TiO}}_{2}$ and its (110) stoichiometric surface, as well as ${\mathrm{Ti}}_{2}{\mathrm{O}}_{3}$ and the reduced (110) surface, which are examples of reduced ${\mathrm{TiO}}_{2},$ in order to address…
In order to interpret the phonon-assisted optical transitions in semiconductor quantum dots, a theory is developed comprising the exciton interaction with both adiabatic and Jahn-Teller phonons and also the external nonadiabaticity (pseudo-Jahn-Teller effect). The effects of nonadiabaticity of the exciton-phonon syste…