Materials Literature
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Phase-change memory materials have stimulated a great deal of interest although the size-dependent behaviors have not been well studied due to the lack of method for producing their nanoscale structures. We report the synthesis and characterization of GeTe and Sb(2)Te(3) phase-change nanowires via a vapor-liquid-solid…
Raman spectra were acquired in situ during tensile straining of mechanically isolated fibers of spruce latewood. Stress-strain curves were evaluated along with band positions and intensities to monitor molecular changes due to deformation. Strong correlations (r = 0.99) were found between the shift of the band at 1097…
We use elastomeric polydimethylsiloxane substrates to strain single-walled carbon nanotubes and modulate their electronic properties, with the aim of developing flexible materials that can sense local strain. We demonstrate micron-scale nanotube devices that can be cycled repeatedly through strains as high as 20% whil…
Here, we report on an aqueous room temperature synthesis method for the production of gold nanoparticles that have a number (>4) of branches ultimately resembling the shape of sea urchins. The particles are synthesized in the presence of water soluble thiol terminated molecules, used as ligand molecules. These nano-ur…
Chalcopyrite-type CuInS 2 -based alloyed fluorescent nanocrystals (NCs), which contain no regulated heavy metal ions, were synthesized by heating an organometallic solution to demonstrate optical property tunability. Introduction of Zn into the CuInS 2 system enhanced their photoluminescence (PL) intensity. The result…
We present a nano-electromechanical system based on an individual single-walled carbon nanotube (SWNT) demonstrating their potential use for future displacement sensing at the nanoscale. The fabrication and characterization of the proposed nanoscaled transducer, consisting of a suspended metal cantilever mounted on to…
DFT methods are suitable for predicting both the geometries and spin states of EDDHA-Fe(III) complexes. Thus, extensive DFT computational studies have shown that the racemic-Fe(III) EDDHA complex is more stable than the meso isomer, regardless of the spin state of the central iron atom. A comparison of the energy valu…
Geometric effects influencing scanning tunnelling microscopy (STM) image formation of single wall carbon nanotubes (SWCNTs) were studied within the framework of a simple model potential. We focused on the geometrical effects which may influence the tunnelling probabilities and lead to discrepancies between the apparen…
Diffractive optics play an important role in a variety of fields such as astronomy, microscopy, and lithography. In the extreme ultraviolet region of the spectrum they have been difficult to make due to the extremely precise control required of their surface structure. We have developed a robust fabrication technique…
Commensurate-incommensurate change on the one-dimensional $S=1$ bilinear-biquadratic model $[\mathcal{H}(\ensuremath{\alpha})={\ensuremath{\sum}}_{i}{{\mathbf{S}}_{i}∙{\mathbf{S}}_{i+1}+\ensuremath{\alpha}{({\mathbf{S}}_{i}∙{\mathbf{S}}_{i+1})}^{2}}]$ is examined. The gapped Haldane phase has two subphases (the commen…
10.1088/0022-3727/39/13/002
Magnetic properties of polycrystalline ${\mathrm{Pr}}_{0.5}{\mathrm{Ca}}_{0.5}{\mathrm{Mn}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{O}}_{3}\phantom{\rule{0.3em}{0ex}}(x=0.015,0.03)$ samples have been investigated in the temperature range $1.5--300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, magnetic field up to $16\pha…
The endohedral fullerene structures of medium-sized ${\mathrm{Si}}_{\mathrm{N}}$ $(30\ensuremath{\leqslant}\mathrm{N}\ensuremath{\leqslant}39)$ clusters have been studied using the density functional theory (DFT) with gradient correction. For each cluster size, fullerene cages with different topologies and those fille…
We have generalized the McMillan theory of liquid crystalline smectic order in uniaxial particle fluids to biaxial particles. Upon varying the control parameter, a uniaxial nematic phase may: (i) order biaxially first, then smectically; (ii) order smectically first, then biaxially; and (iii) simultaneously order biaxi…
Ba 1− x Sr x TiO 3 ( x = 0.3, 0.5, 0.7) thin films have been prepared on (001) MgO substrates by pulsed laser deposition. Temperature-dependent permittivity and Raman spectra of the Ba 1 − x Sr x TiO 3 films are compared with those of the corresponding bulk samples. Raman spectra indicate that a tetragonal structure i…
A metal-ferroelectric-semiconductor structure has been developed by depositing Li-doped ZnO thin films (Zn1-xLixO, x = 0.25) on p-type Si substrates by the pulsed laser ablation technique. (002) preferential oriented films were deposited at a low growth temperature of 500 degrees C and 100 mTorr oxygen partial pressur…
Electrostatic layer-by-layer assembly (LBL) is a versatile method of fabricating ultrathin multilayer films, coatings, and microcapsules from materials in solution, notably, oppositely charged polyelectrolytes in water. Polypeptides, a special type of polyelectrolyte, have recently shown promise for a range of applica…
N5-carboxyaminoimidazole ribonucleotide (N5-CAIR) mutase (PurE) catalyzes the reversible interconversion of acid-labile compounds N5-CAIR and 4-carboxy-5-aminoimidazole ribonucleotide (CAIR). We have examined PurE from the acidophilic bacterium Acetobacter aceti (AaPurE), focusing on its adaptation to acid pH and the…
We seek to model the shock wave induced structural changes in silicate glass at the atomic scale. We use both direct shock propagation with nonequilibrium molecular dynamics (NEMD) and bulk simulations in the Hugoniot ensemble to characterize the structure and topology of the shocked glass. Despite the lack of long-ra…
We analyze the optical properties of $\ensuremath{\mu}\mathrm{m}$-sized rings of gold nanoparticles by the combination of extinction spectroscopy, surface enhanced Raman scattering (SERS) spectroscopy and microscopic dark field imaging in two variants. The imaging process relies on either SERS from methylene blue dye…