Materials Literature
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Recently a new monoclinic phase in the PbZr(1-x)TixO3 ceramic system has been reported by Noheda et al. for the composition x= 0.48. In the present work, samples with Ti contents of x= 0.47 and 0.50, which are both tetragonal below their Curie points, have been investigated. In the sample with x= 0.50, the tetragonal…
The synthesis of bulk amounts of high quality single-walled carbon nanotubes (SWNTs) is accomplished by optimizing the chemical compositions and textural properties of the catalyst material used in the chemical vapor deposition (CVD) of methane. A series of catalysts are derived by systematically varying the catalytic…
Diffractive optical elements (DOEs) are characterized by a large negative dispersion. This property can be exploited to correct chromatic aberration in hybrid optical systems. The diffraction efficiency of phase DOEs decreases when the wavelength deviates from the design wavelength. Consequently, DOEs are usually appl…
We report x-ray absorption spectra of high temperature solid Pd at 1770 K, liquid Pd at 1850 K, and undercooled liquid Pd at 1770 and 1670 K (about 160 K below ${T}_{m}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1827\mathrm{K}$). Data of excellent quality were collected at the European Synchrotron Radiation Fac…
The magnetic properties of free ${\mathrm{Gd}}_{N}$ clusters ( $N\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}13$, 21, and 22) have been measured between 90 and 600 K in a Stern-Gerlach experiment. ${\mathrm{Gd}}_{13}$ and ${\mathrm{Gd}}_{21}$ are found to be superparamagnetic (SP) whereas ${\mathrm{Gd}}_{22}$ i…
The damage of Pb(Zr0.53Ti0.47)O3 thin film due to dry etching process was characterized in terms of the microstructure and electrical properties. The damaged layer seems to be amorphous and the thickness of the damaged layer is about 10 nm. The existence of such a layer in Pt/Pb(Zr0.53Ti0.47)O3/Pt ferroelectric capaci…
The dependence of polarization switching on thermal histories has been investigated for K1+-modified lead zirconate titanate (PZT) ceramics by Sawyer–Tower polarization methods. It was found that double-loop-like polarization characteristics in the aged condition could be reversed to normal single loop polarization ch…
A fundamental issue in ferroic systems (ferromagnetic and ferroelectric) is the scaling of the order parameter (magnetization or polarization) with size. Specifically, in ferroelectric thin films, deviations in the polarization can occur due to: (i) competition between thermal vibrations and the correlation energy (wh…
Perovskite Ba0.5Sr0.5TiO3 thin films have been synthesized on (001) LaAlO3 substrates by pulsed laser ablation. Extensive x-ray diffraction, rocking curve, and pole-figure studies suggest that the films are c-axis oriented and exhibit good in-plane relationship of 〈100〉BSTO//〈100〉LAO. Rutherford backscattering spectro…
The experimental evidence for orbital ordering in ${\mathrm{LaMnO}}_{3}$ and ${\mathrm{La}}_{0.5}{\mathrm{Sr}}_{1.5}{\mathrm{MnO}}_{4}$ is critically reexamined in the light of realistic calculations based on multiple scattering theory and finite difference method for the resonant x-ray scattered intensity at a forbid…
We studied ${\mathrm{Mn}}_{12}$-acetate by inelastic neutron scattering and diffraction. We separated the energy levels corresponding to the splitting of the lowest $S$ multiplet ( $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}10$ ground state). The irregular spacing of the transition energies unambiguously sho…
In layered manganites with orbital and charge orderings, the degeneracy of the Mn $4p$ orbitals as well as the $3d$ ones is lifted by the effects of the $4p$ bands and the local Coulomb interactions. We formulate the atomic scattering factor for the resonant x-ray scattering in the memory function method by taking int…
We report the synthesis and characterization of Nd0.5Sr0.5MnO3 thin films grown by the pulsed laser deposition technique on [100]-oriented LaAlO3 substrates. X-ray diffraction (XRD) studies show that the films are [101] oriented, with a strained and quasi-relaxed component, the latter increasing with film thickness. W…
A formulation of variational principles in terms of functional integrals is proposed for any type of local plastic potentials. The minimization problem is reduced to the computation of a path integral. This integral can be used as a starting point for different approximations. As a first application, it is shown how t…
Highly-ordered arrays of parallel carbon nanotubes were grown by pyrolysis of acetylene on cobalt within a hexagonal close-packed nanochannel alumina template at 650 °C. The nanotubes are characterized by a narrow size distribution, large scale periodicity, and high densities. Using this method ordered nanotubes with…
Allylurea (AU) was used as a reactive additive with poor aptitude to homopolymerization for obtaining grafted plasticized starch films with stabilized physical properties. Potato starch was mixed with AU (30–50 parts per hundred/pph) in a mixer operating at 125°C. Upon storage in well-defined hygrothermal conditions,…
A poly(methyl methacrylate) (PMMA)-clay hybrid resin was prepared via bulk polymerization methyl methacrylate monomer in the presence of montmorillonite intercalated with an ammonium salt of dctadecylamine. The products were characterized by infrared spectroscopy, X-ray diffraction, pyrolysis gas chromatography, and t…
Thermoplastic polyurethane elastomers were prepared from 4,4-diphenylmethane diisocyanate (MDI)/1,4-butanediol (BD)/poly(propylene glycol) (PPG) and MDI/BD/poly(oxytetramethylene glycol) (PTMG). The MDI/BD-based hard-segment content of polyurethane prepared in this study was of 39–65 wt %. These polyurethane elastomer…
Thermal degradation of polydimethylsiloxane (PDMS) polymers having hydroxyl (PS) and vinyl (PS-V) terminals was studied by pyrolysis-gas chromatography (PGC) in the temperature range from 550 to 950°C. The degradation products were primarily cyclic oligomers ranging from trimer (D3) to cyclomer D11 and minor amounts o…
A phosphorus-containing epoxy resin, 6-H-dibenz[c,e][1,2] oxaphosphorin-6-[2,5-bis(oxiranylmethoxy)phenyl]-6-oxide (DOPO epoxy resin), was synthesized and cured with phenolic novolac (Ph Nov), 4,4′-diaminodiphenylsulfone (DDS), or dicyandiamide (DICY). The reactivity of these three curing agents toward DOPO epoxy resi…