Materials Literature
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Using density-functional-theory calculations, we have identified new stable configurations for tri-, tetra-, and penta-vacancies in silicon. These new configurations consist of combinations of a ring-hexavacancy with three, two, or one interstitial atoms, respectively, such that all atoms remain fourfold. As a result,…
Orbital-free density functional theory as an extension of traditional Thomas-Fermi theory has attracted a lot of interest in the past decade because of developments in both more accurate kinetic energy functionals and highly efficient numerical numerical methodology. In this paper, we developed a new conjugate-gradien…
We demonstrate the exchange coupling of a ferromagnetic semiconductor (Ga1-xMnxAs) with an overgrown antiferromagnet (MnO). Unlike most conventional exchange biased systems, the blocking temperature of the antiferromagnet (T_B = 48 +- 2 K) and the Curie temperature of the ferromagnet (T_C = 55.1 +- 0.2 K) are comparab…
Electronic structures of homogeneous bulk samples of Zn0.9Co0.1O which do not exhibit diluted ferromagnetic semiconducting (DMS) behavior have been investigated using photoemission spectroscopy and x-ray absorption spectroscopy. We have found that the Co ions in Zn1−xCoxO are in the divalent Co2+(d7) states under the…
Shell cross-linked nanoparticles (SCKs) presenting surface- and bioavailable biotin functional groups were synthesized via a mixed micelle methodology, whereby co-micellization of chain terminal biotinylated poly(acrylic acid)-b-poly(methyl acrylate) (PAA-b-PMA) and nonbiotinylated PAA-b-PMA were cross-linked in an in…
A new multistep approach was developed to synthesize atomically ordered intermetallic nanocrystals, using AuCu and AuCu(3) as model systems. Bimetallic nanoparticle aggregates are used as precursors to atomically ordered nanocrystals, both to precisely define the stoichiometry of the final product and to ensure that a…
We derive a t-J model with electron-phonon coupling from the three-band model, considering modulation of both hopping and Coulomb integrals by phonons. While the modulation of the hopping integrals dominates, the modulation of the Coulomb integrals cannot be neglected. The model explains the experimentally observed an…
As an introductory lecture to the workshop an overview is given over continuum models for homoepitaxial surface growth using partial differential equations (PDEs). Their {\em heuristic derivation} makes use of inherent symmetries in the physical process (mass conservation, crystal symmetry, ...) which determines their…
The effect of finite deformed length is demonstrated by squashing an armchair (10,10) single-walled carbon nanotube with two finite tips. Only when the deformed length is long enough, an effectual metal–semiconductor–metal heterojunction can be formed in the metallic tube. The effect of finite deformed length is expla…
Unpurified carbon nanotubes were introduced to silicone elastomer to investigate their effect on the thermal conductivity. Microstructure studies by a scanning electron microscope showed that the carbon nanotubes (CNTs) can be well dispersed in the matrix by the grinding method. No notable agglomerates or phase separa…
Individual carbon nanotubes were immersed and removed from various organic liquids using atomic force microscopy. The carbon nanotube-liquid interactions could be monitored in situ, and accurate measurements of the contact angle between liquids and the nanotube surface were made. These wetting data were used to produc…
A core−shell hybrid nanostructure, possessing a hard backbone of multiwalled carbon nanotube (MWNT) and a soft shell of brushlike polystyrene (PS), was successfully prepared by in situ atom transfer radical polymerization (ATRP), using Cu(I)Br/ N, N,N ‘,N ‘ ‘,N ‘ ‘ -pentmethyldiethylenetriamine (PMDETA) as the catalys…
Ab initio calculations show that the band gap of boron nitride (BN) nanotubes can be greatly reduced by a transverse electric field. This gap reduction arises from a mixing of states within the highest occupied molecular orbital and lowest unoccupied molecular orbital complexes and leads to a spatial separation of ele…
In this study, hyaluronic acid (HA) was electro-spun and electro-blown to prepare nonwoven nanofibrous membranes. Critical parameters for processing and corresponding effects on the membrane morphology were investigated using the methods of rheology and scanning electron microscopy (SEM). During electro-spinning, the…
A poly(3-hexylthiophene) containing an interacting amino chain end enhances the performance of P3HT/CdSe solar cells by increasing the dispersion of CdSe nanocrystals and improving the morphology of the nanocomposite without introducing insulating surfactants.
A layered p-type thermoelectric module of AgSbTe/sub 2/-(Bi,Sb)/sub 2/Te/sub 3/ was fabricated by a Spark Plasma Sintering (SPS) process and its' performances was evaluated with both calculation and measurement. Each powder of AgSbTe/sub 2/ and (Bi,Sb)/sub 2/Te/sub 3/ was consolidated by the SPS process. Various tempe…
We examined the magnetic field effects on thermoelectric properties, aiming to enhance the thermoelectric power generation. Here, we propose the "Nernst-Seebeck" element, which uses the hybrid electric field of the Seebeck effect and the Nernst effect in the magnetic field. The thermoelectric properties of the polycry…
In order to achieve high thermoelectric conversion efficiency, it is necessary to make use of materials with a maximal figure of merit Z = S/sup 2//spl times//spl sigma//k (S is the Seebeck coefficient, /spl sigma/ and k are the electrical and thermal conductivity, respectively) over a wide temperature range. A/sup IV…
One of the most promising applications of thermoelectricity is the recovery of waste heat for the production of electrical energy. Nowadays, several thermoelectric companies manufacture commercial thermoelectric modules (TEMs) based on Bi/sub 2/Te/sub 3/ compounds specially designed to perform as Seebeck modules.. Thi…
Semiconductor clathrate compounds are energetically being studied as a new class of thermoelectric material based on the concept of Phonon Glass and Electron Crystal, since the materials combine glasslike low thermal conductivity and relatively good carrier mobility. These fascinating properties of clathrate compounds…