Materials Literature
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Carbon nanofibers have been grown at room temperature using a combination of radio frequency and microwave assisted plasma-enhanced chemical vapor deposition. The nanofibers were grown, using Ni powder catalyst, onto substrates kept at room temperature by using a purposely designed water-cooled sample holder. Branched…
A mathematical model is presented to analyze the kinetics of solid-state polymerization of bisphenol A polycarbonate. The reaction kinetic model incorporated in the solid-state polymerization model is a hybrid of a molecular species model and a functional group model derived from the original model developed by Flory.…
We present neutron and synchrotron powder-diffraction investigations as well as ab initio calculations to elucidate delicate structural features in doped skutterudites. Samples with assumed Fe doping were investigated (FeyCo4Sb12, y=0.4, 0.8, 1.0, and 1.6), as well as samples with formal Ni substitution (Co4−xNixSb12,…
The chainlike silicon nanowires SiNWs have been synthesized by fluctuating the pressure of the carrier gas in the growth process. The chainlike SiNWs comprise crystalline Si nanoparticles interconnected by amorphous silicon oxide wires. In addition to the sphere, other interesting shapes such as rectangular and triang…
Domain structure changes in (1-x)Pb(Mg1∕3Nb2∕3)O3-xPbTiO3 have been studied by polarized optical microscopy. In the zero-field-cooled condition, increasing the x revealed systematic changes in the domain morphology from polar nanodomains for x<0.25, to fine crosshatched domains near the morphotrophic phase boun…
Abstract Surface‐enhanced Raman scattering (SERS) spectra of 3‐ and 4‐benzoylpyridine (BP) adsorbed on silver hydrosols were compared with the FTIR and normal Raman spectra in bulk and in solution. With a small fractional change in adsorbate concentration, the SER spectra of isomeric BPs show significant changes in th…
The structural and magnetic properties of the melt-spun Pr2Fe14B∕α-Fe nanocomposite powders consolidated via shock-wave compression and subjected to postshock thermal treatment were investigated. Shock compression results in grain refinement, which leads to a reduction of an effective anisotropy and therefore an incre…
Neutron irradiation effects on highly oriented antiferroelectric PbZrO3 (PZ) thin films are investigated in view of their possible application as a temperature sensitive element in an alternative bolometer system for fusion devices such as the International Thermonuclear Experimental Reactor (ITER). All films were pre…
A continuous CO2 laser is focused to locally anneal small fused silica spots. A noncontact radiometry diagnostic enables us to follow surface temperature variation that occurs from site to site. A “steady state” dispersion of surface temperature is observed across our sample. We show that nonhomogeneous silica thermal…
Crystallization of amorphous data marks in crystalline Ga15Sb85 and Ge,In doped SbTe phase-change material was studied in situ in a Transmission Electron Microscope (TEM). Electron irradiation induced crystallization was obtained at room temperature using a 120kV beam. In general, electron beam (e−-beam) induced cryst…
Ab initio theoretical evidence of hexacoordinate planar main group atoms centered in hexagonal hydrocopper complexes Cu(6)H(6)X (X = Si, P, As) is presented at the density functional theory level in this work. The results obtained extend the bonding capacity of silicon, phosphorus, and arsenic to planar hexacoordinati…
With the use of a newly developed spin-polarized scanning electron microscope, we have succeeded in obtaining the real-space images of the layered-antiferromagnetic state concurrent with 1-nm-stepped atomic terraces in layered-structure manganite La1.4Sr1.6Mn2O7. The three-dimensional analysis of spin alignment could…
A detailed crystal-field splitting analysis is given for the 26 lowest-energy multiplet manifolds, LJ2S+1, of Nd3+(4f3) in polycrystalline ceramic garnet Y3Al5O12 (YAG). The absorption spectra obtained between 8K and room temperature, and between 1750 and 350nm, and the fluorescence spectrum obtained at 8K and observe…
We report on the effects of composition and external magnetic field on the microwave permeability tensor of $\mathrm{Ni}∕\ensuremath{\gamma}{\text{\ensuremath{-}}\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ nanocomposites. When compared to the zero-field case, the field measurements of the permeability tensor $\overline{\ensurem…
Tight-binding molecular dynamics simulations reveal interesting physical trends in amorphous carbon networks. The variation of $s{p}^{3}$ fraction, or mean coordination, is found to be linear over the whole possible range of densities. The density at the floppy transition is $\ensuremath{\sim}0.5\phantom{\rule{0.3em}{…
CO oxidation on PtO2(110) has been studied using density functional theory calculations. Four possible reaction mechanisms were investigated and the most feasible one is the following: (i) the O at the bridge site of PtO2(110) reacts with CO on the coordinatively unsaturated site (CUS) with a negligible barrier; (ii)…
The dependence of resistivity on temperature in thin metal films is investigated by extending the model of Mayadas and Shatzkes to include temperature dependence. It is shown that previous interpretations of a dominant grain boundary mechanism are not necessarily correct, and that the combined influence of grain bound…
This paper summarizes the analysis of the influence of anisotropy on the stress-optic coefficients and the determination of the stress-optic tensor components π11−π12 and π44 using an infrared polariscope and calibration with four-point bending of thin silicon samples. Values obtained are π11−π12=9.88×10−13Pa−1 and π4…
Schmidt and Eberl demonstrated the construction of tubes with submicron diameters by the method of folding thin solid films [Nature (London)NATUAS 410, 168 (2001)]. In their method, a thin film is folded 180° and brought into adhesive contact with itself. The resulting sealed loop forms a nanotube with the thickness o…
Electronic structures and magnetic properties of various possible ternary transition-metal compounds based on zincblende ZnTe and CdTe semiconductors are systematically explored by using an accurate density-functional method. Half-metallic (HM) ferromagnetism is found in the ZnTe and CdTe heavily doped with Cr, V, and…