Materials Literature
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Effects of oxygen adsorption on the structural and transport properties of single wall carbon nanotubes (SWCN's) are investigated in detail using ab initio and generalized tight-binding molecular-dynamics methods. We find that the oxygen-SWCN interaction depends strongly on the spin configuration which, in turn, speci…
Electrical conduction behaviors of bismuth titanate (BiT) and vanadium-doped bismuth titanate (V-BiT) single crystals were investigated by the complex impedance method at high temperatures. Oxygen partial pressure dependence of the electrical conductivity revealed that both BiT and V-BiT showed oxide ionic and p -type…
Protocols for modifying gold nanoparticles with peptide-bovine serum albumin (BSA) conjugates are described within. The resulting constructs were characterized using a number of techniques including static fluorescence spectroscopy and time-correlated single photon counting spectroscopy (TCSPC) in order to quantify pe…
High-density ceramic samples of NaNbO 3 (NN) have been successfully fabricated by spark plasma sintering (SPS), which is a process that uses microscopic electrical discharge between particles under pressure. The obtained NN ceramic shows a hysteresis loop characteristic of ferroelectrics. The coercive electric field,…
Molecular Dynamics (MD) simulations have been used to obtain a molecular insight into the origins of the twist, bend, and helix pitch of the tape-like and ribbon (double tape)-like β-sheet aggregates formed by the self-assembling peptides P 11 -I (CH 3 CO-QQRQQQQQEQQ-NH 2 ) and P 11 -II (CH 3 CO-QQRFQWQFEQQ-NH 2 ). P…
Using first-principles density functional calculations, we show that hexagonal metallic silicon nanotubes can be stabilized by doping with 3d transition metal atoms. Finite nanotubes doped with Fe and Mn have high local magnetic moments, whereas Co-doped nanotubes have low values and Ni-doped nanotubes are mostly nonm…
The significance of orientation control on ferroelectric polarization and electromechanical displacement properties was studied by comparing the difference in growth behavior among Bi 4- x Pr x Ti 3 O 12 films (BPT, x =0.3, 0.5, and 0.7, nominal) deposited on both Pt and Ir sputter-grown bottom electrode layers on Si…
We report total-energy electronic-structure calculations that provide energetics and electronic structures of fullerenes encapsulated in zigzag carbon nanotubes (so-called peapods). It is found that the space between the nanotube and the encapsulated fullerenes is a decisive factor to determine the energetics for the…
The diffusion of intrinsic defects in 3C-SiC is studied using an ab initio method based on density functional theory. The vacancies are shown to migrate on their own sublattice. The carbon split-interstitials and the two relevant silicon interstitials, namely the tetrahedrally carbon-coordinated interstitial and the <…
In this paper we study the twist disclination within the elastoplastic defect theory. Using the stress function method, we found exact analytical solutions for all characteristic fields of a straight twist disclination in an infinitely extended linear isotropic medium. The elastic stress, elastic strain and displaceme…
Ab initio methods are used for investigating structural and electronic properties of silicon−carbon nanotubes (SiCNTs). Tubes with different Si to C ratios were tested and the trend from C-rich to Si-rich SiCNTs is examined. Our results show that SiCNTs lose stability when the ratio of Si over C increases. Nevertheles…
The influence of positive and negative chemical pressure on the magnetic behavior of the compound, Ce2RhSi3, crystallizing in a AlB2-derived hexagonal structure and ordering antiferromagnetically around (TN = 7 K), is investigated by studying electrical resistivity (rho) and magnetic susceptibility (chi) behavior of t…
The results of x-ray diffraction, and ac and dc magnetization as a function of temperature are reported for a new class of spin-chain oxides, Ca3Co1+xIr1-xO6. While the x= 0.0, 0.3, 0.5 and 1.0 are found to form in the K4CdCl6-derived rhombhohedral (space group R-3c) structure, the x= 0.7 composition is found to under…
The results of ac susceptibility (chi) measurements for Ca3CoXO6 (X = Rh, Ir and Co) compounds, containing spin-chains separated by Ca ions, are presented. All these compounds exhibit an unusually large frequency dependence of ac chi, in the vicinity of respective magnetic ordering temperatures, which is normally not…
The annealing kinetics of mobile intrinsic defects is investigated by an ab initio method based on density functional theory. The interstitial-vacancy recombination, the diffusion of vacancies and interstitials to defect sinks (e.g. surfaces or dislocations) as well as the formation of interstitial-clusters are consid…
The structural, vibrational, energetic and electronic properties of hydrogen at the stoichiometric RuO2(110) termination are studied using density functional theory. The oxide surface is found to stabilize both molecular and dissociated H2. The most stable configuration in form of hydroxyl groups (monohydrides) at the…
We have fabricated 5nm-high Fe(110) stripes by self-organized (SO) growth on a slightly vicinal R(110)/Al2O3(11-20) surface, with R=Mo, W. Remanence, coercivity and domain patterns were observed at room temperature (RT). This contrasts with conventional SO epitaxial systems, that are superparamagnetic or even non-magn…
Barium titanate (BaTiO 3 ) crystallites with various particle sizes from 17 to 100 nm were prepared by the 2-step thermal decomposition method of barium titanyl oxalate (BaTiO(C 2 O 4 ) 2 ·4H 2 O). The crystal structure of these BaTiO 3 particles was assigned to cubic m-3m by a X-ray diffraction (XRD) measurement whil…
The thermoelectric properties of filled gallium-germanium clathrates are analyzed from a band-structure point of view. Using the virtual crystal approximation the undoped clathrates are calculated to be semiconductors with band gaps around 0.6--0.9 eV. The conduction bands hybridize with the unoccupied d states of the…
A broad visible and infrared photoluminescence continuum is detected from surface-plasmon-enhanced transitions in gold nanostructures. We find that the ratio of generated infrared to visible emission is much stronger for gold nanostructures than for smooth gold films. While visible emission is well explained by interb…