Materials Literature
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We have studied the magnetic and magnetotransport properties of the perovskites La8Sr0.2Mn8Ni0.2O3 and La0.7Sr0.3Mn0.8Ni0.2O3. Ferromagnetic cluster behaviors have been observed. The most interesting feature is that the cluster-glass state exhibits both macroscopic insulator-like transport behavior and largely enhance…
The adsorption of organic contaminants on a hydrogen-terminated Si(111) surface was investigated using attenuated total reflection Fourier transform infrared spectroscopy. When the hydrogen-terminated Si(111) surface was exposed to dry air, the sharp Si–H monohydride peak became weaker and a broad component became vis…
We prepared SrBi2Ta2O9(SBT) ferroelectric thin films on SiO2/Si and on MgO buffered SiO2/Si substrates using laser ablation, in situ annealing and postannealing, and observed retention time longer than 7 days. On SiO2/Si substrates, only the samples annealed at 800 °C occasionally exhibited good memory properties. On…
Using ab initio molecular dynamics we study pressure-induced hydrogen sublattice amorphization in $\mathrm{Mg}(\mathrm{OH}{)}_{2}$ and $\mathrm{Ca}(\mathrm{OH}{)}_{2}$. Our calculations reproduce the experimental behavior of these two systems, with $\mathrm{Ca}(\mathrm{OH}{)}_{2}$ showing significantly more marked eff…
We have performed a systematic ground state geometry search for ${\mathrm{Ge}}_{n}$ neutrals and cations in the $n\ensuremath{\le}16$ size range using density functional theory--local density approximation and gradient-corrected methods. Like their silicon analogs, medium-sized Ge clusters are stacks of tricapped trig…
We present a phase-field model for the dynamics of the interface between two inmiscible fluids with arbitrary viscosity contrast in a rectangular Hele-Shaw cell. With asymptotic matching techniques we check the model to yield the right Hele-Shaw equations in the sharp-interface limit and compute the corrections to the…
We implement a phase-field simulation of the dynamics of two fluids with arbitrary viscosity contrast in a rectangular Hele-Shaw cell. We demonstrate the use of this technique in different situations including the linear regime, the stationary Saffman-Taylor fingers and the multifinger competition dynamics, for differ…
We report on how electrochromic coloration is affected by oxygen deficient stoichiometries in sputtered amorphous tungsten oxide (a-WO3−y) films. The electrochromic coloration efficiency increases with increasing oxygen deficiency in (a-WO3−y) films. No coloration is observed in nearly stoichiometric WO3 films. Raman…
Direct adiabatic temperature change as well as magnetic measurements were carried out on two different samples of ${\mathrm{Gd}}_{5}{\mathrm{Si}}_{2}{\mathrm{Ge}}_{2}$ composition for which calculations predicted a ``giant'' magnetocaloric effect (MCE). While magnetic measurements well reproduce published values, serv…
Poly(ether sulfone) and poly(ether sulfone ketone) copolymers (I–V) were synthesized by the nucleophilic substitution reaction of 4,4′-dihydroxy diphenyl sulfone (DHDPS, A) with various mole proportions 4,4′-difluoro benzophenone (DFBP, B) and 4,4′-difluoro diphenyl sulfone (DFDPS, C) using sulfolane as solvent in the…
We investigated the thermal decomposition behavior of three commercially available liquid crystalline polymers (LCPs), Vectra A950, Vectra B950, and Xydar SRT-900. The apparent activation energies (Ea) associated with the thermal degradation processes were determined by the Ozawa and Kissinger methods, using data from…
Polypyrrole–poly(vinyl alcohol) (PPy–PVA) composite films were prepared electrochemically by means of codeposition at a constant potential. Their sensing behaviors to various ethanol-vapor concentrations were investigated. Increasing the molar fraction of PVA up to PPy0.964PVA0.036 showed an increase of the sensitivit…
Kraft paper was coated with resins based on vegetable oils and then tested for mechanical properties, rate of biodegradation in soil, and ability to inhibit weed growth. Resins included oxidatively polymerized linseed oil (LO) and a polyester formed by the reaction of epoxidized soybean oil and citric acid (ESO–CA). T…
Organosoluble montmorillonite/polyimide hybrids were prepared using a monomer solution intercalation polymerization method. Montmorillonite was organo-treated with p-aminobenzoic acid and the organosoluble polyimide was based on pyromellitic dianhydride and 4,4′-diamino-3,3′-dimethyldiphenylmethane. The particle size…
Cobalt(II) has been utilized as an external paramagnetic (1)H NMR probe for the study of the structure of dendrimers that possess specifically located metal recognition sites. The isotropically shifted (1)H NMR signals of the Co(II) complexes of two 2,6-diamidopyridine-containing dendrimers have been fully assigned by…
We consider a melt of diblock copolymers consisting of a linear A block connected to a regularly branched B block. A simple “Alexander−de Gennes”-type calculation of the free energy for lamellar, cylindrical, and spherical microphases in strong segregation reveals large shifts in the phase boundaries as a function of…
The spreading of low molecular weight silicon oils (PDMS) on heterogeneous substrates has been studied by spectroscopic ellipsometry. Using different grafting times, we produced partially OTS-grafted substrates whose surface energy ranged from that of the bare silica surface (about 28 mN/m) to that of the completely O…
Samples in the MgO−TiO 2 system were prepared via the sol−gel technique with titanium and magnesium ethoxides as precursors and HNO 3 as hydrolysis catalyst. The analyzed magnesia to titania weight ratios were 0.1:0.9, 0.5:0.5, and 0.9:0.1 (0.05, 0.5, and 4.0 MgO:TiO 2 molar ratios). Samples were characterized with X-…
In this paper we study the phase behavior of blends of associating homopolymers A and B in the weak segregation regime. The homopolymers are “associating” in the sense that hydrogen bonds are possible between the A chains and the B chains. Hydrogen bonds between two A chains, or between two B chains, are not possible.…
Organized molecular systems (OMS) have been widely used in the formation of mineral solids to control their composition, morphology, and dimensions. In this paper, we synthesized tricalcium phosphate by mixing two microemulsions, one containing calcium in its aqueous phase, the other containing phosphate. The microemu…