Materials Literature
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The polymer liquid crystal PLC is the PET/0.6PHB copolymer; PET=poly(ethylene terephthalate), PHB=ρ-hydroxybenzoic acid (LC): 0.6=the mole fraction of PHB. This is a multiphase system with PHB-rich islands in a PET-rich matrix. Tensile creep compliance was measured isothermally from 20 °C to 160 °C in 10 °C intervals.…
The zone-drawing (ZD) method was applied three times to the melt-spun poly(L-lactic acid) (PLLA) fibers of low molecular weight (Mv = 13,100) at different temperatures under various tensions. The mechanical properties and superstructure of the ZD fibers were investigated. The resulting ZD-3 fiber had a draw ratio of 1…
A novel bis(ether anhydride) monomer, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (4), was synthesized from the nitrodisplacement of 4-nitrophthalonitrile by the bisphenoxide ion of 9,9-bis(4-hydroxyphenyl)fluorene (1), followed by alkaline hydrolysis of the intermediate tetranitrile and dehydration of…
Tubular polypyrrole (PPy) could be synthesized by in situ doping polymerization in the presence of β-naphthalene sulfonic acid (NSA) as dopant. The resultant tubular PPy–NSA not only exhibits high room temperature conductivity (ςRT = 10 S/cm) but is also soluble in m-cresol. The molecular structure of PPy–NSA is ident…
We found that very high concentrations (up to 20% vol) of nitrogen in the ethanol/hydrogen gas mixture do not prejudice the diamond quality as determined by Raman spectroscopy. Nitrogen addition also increases the diamond growth rate, as was previously reported at low nitrogen concentrations. We observed that after a…
We investigate the evolution of electronic structure with dimensionality (d) of Ni-O-Ni connectivity in divalent nickelates, NiO $(3\ensuremath{-}d),$ ${\mathrm{La}}_{2}{\mathrm{NiO}}_{4},$ ${\mathrm{Pr}}_{2}{\mathrm{NiO}}_{4}$ $(2\ensuremath{-}d),$ ${\mathrm{Y}}_{2}{\mathrm{BaNiO}}_{5}$ $(1\ensuremath{-}d)$ and ${\ma…
Magnetism and transport properties are reported for hollandite-type manganese oxides ${\mathrm{K}}_{1.5}{(\mathrm{H}}_{3}{\mathrm{O})}_{x}{\mathrm{Mn}}_{8}{\mathrm{O}}_{16}$ $(0<x<0.5)$ having a tunnel structure. Three phase transitions are observed at ${T}_{1}$ (varies from 180 to 250 K, very sensitive to the s…
Tetrathiafulvalene analogues involving dihexyloxythiophene ( 1 ), ethylenedioxythiophene ( 2 ), and bis(3,4-dihexyloxy-2-thienyl)ethylene ( 3 ) as conjugating spacer and diversely substituted at the 1,3-dithiole ring (R) have been synthesized. Electronic absorption spectra show the expected decrease of HOMO−LUMO gap w…
The excess low-frequency $(1/f)$ electrical noise of three representative half-metallic oxides, ${\mathrm{CrO}}_{2},$ ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4},$ and ${\mathrm{La}}_{2/3}{\mathrm{Sr}}_{1/3}{\mathrm{MnO}}_{3},$ has been studied as a function of the temperature (5--300 K) and a magnetic field (up to 12 T). In $…
The volumetric heat capacity and thermal conductivity of silicon-dioxide films prepared using low-pressure chemical vapor deposition (LPCVD) are measured. The measurements employ the 3ω technique, which is extended to determine the thermal conductivity anisotropy and volumetric heat capacity of thin dielectric films.…
The reflectance of highly reduced ${\mathrm{SrTiO}}_{3\ensuremath{-}x}$ has been studied in samples where the carrier concentration---or oxygen-vacancy density --- varies from about ${10}^{18}$ to ${10}^{21} {\mathrm{cm}}^{\ensuremath{-}3}.$ Several phonon modes are strongly influenced by oxygen-vacancy density. Oxyge…
Electron-paramagnetic-resonance (EPR) studies in radiation damaged diamond enriched to 5% ${}^{13}\mathrm{C}$ have resulted in the identification of the nearest-neighbor divacancy center. It is the isotopic enrichment, and consequent observation of ${}^{13}\mathrm{C}$ hyperfine lines, that has permitted the structure…
Polycarbonates were synthesized by ring-opening copolymerizations of trimethylene carbonate (TMC) with 1,2- O -isopropylidene- d -xylofuranose-3,5-cyclic carbonate (IPXTC). Subsequent deprotection of the ketal protecting groups gave controlled quantities of vicinal diol pendant groups. Studies of TMC/IPXTC copolymeriz…
Nanocomposites have been made by mixing soft particles (polymer latex) with hard particles (silica) in aqueous dispersions and extracting water to produce a dense film. Segregation between the two kinds of particles can be controlled, and even suppressed. The elongational modulus is strongly increased by such fillers…
Angular measurements of magnetic resonance are used to investigate the surface anisotropy field as well as the exchange anisotropy field in spherical MnFe2O4 magnetic nanoparticles as a function of temperature and particle diameter (D). The resonance field is a combination of angular dependent and angular independent…
Translational energy distributions of neutral potassium atoms are reported as a function of potassium coverage after uv-laser-induced desorption from well-characterized adsorption sites on an epitaxial film of ${\mathrm{Cr}}_{2}{\mathrm{O}}_{3}(0001)/\mathrm{C}\mathrm{r}(110).$ Measurements using x-ray photoelectron s…
In the chromophore-quencher complex fac-[Re(Aqphen)(CO)(3)(py-PTZ)](+) (Aqphen is 12,17-dihydronaphtho[2,3-h]dipyrido[3,2-a:2',3'-c]-phenazine-12,17-dione; py-PTZ is 10-(4-picolyl)phenothiazine), Aqphen is a dppz derivative, containing a pendant quinone acceptor at the terminus of a rigid ligand framework. This introd…
In situ synchrotron radiation measurements of porous silicon (PS) strain have been performed during ultrahigh vacuum (UHV) thermal annealing. For a p+ sample, the initial lattice expansion shifts toward a contraction above 270 °C in relation with hydrogen desorption. For a p− sample, the strain variation is similar to…
The combined effect of shape and dielectric mismatch between dot and matrix on several electronic properties of semiconductor quantum dots have been studied. In particular, the electronic properties of spherical and cubic quantum dots that have been analyzed are the integrated density of states, the polarization self-…
In this paper we present the optical properties of various structural models for $a\ensuremath{-}\mathrm{Si}$ and $a\ensuremath{-}\mathrm{S}\mathrm{i}:\mathrm{H}.$ We discuss how topological disorder, hydrogen content, and different types of defects (dangling bonds and floating bonds) influence the shape of the optica…