Materials Literature
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Undoped and rare-earth- (Pr, Nd, Eu, and Er) doped transparent Y3Al5O12 ceramics have been prepared, and their optical spectra have been measured. It is found that absorption coefficient of the undoped ceramic Y3Al5O12 is almost independent of wavelength with 0.258 cm−1, which gives transmittance of the undoped cerami…
Abstract New linear and three‐arm star thermoplastic elastomers (TPEs) comprising a rubbery polysobutylene (PIB) midblock flanked by glass polystyrene (PSt) blocks have been synthesized by living carbocationic polymerization in the presence of select additives by sequential monomer addition. First, isobutylene (IB) wa…
The vibrational spectra of a few oligomers of thiophene in the solid and solution are studied with the help of quantum mechanical calculations and of the theory of the effective conjugation coordinate recently developed. The aim of the work is to extract from the spectra structural probes to be used in the understandi…
Abstract Cold‐drawn Nylon‐11 films, which were prepared by stretching the melt‐quenched films to a draw ratio of 2.8: 1 at room temperature, were found to exhibit an electric displacement versus electric field hysteresis loop. The results confirmed that the Nylon‐11 film exhibited ferroelectric behavior at or below ro…
We present the O 1s and V 2p absorption edges of ${\mathrm{VO}}_{2}$ at room temperature and at T=120 \ifmmode^\circ\else\textdegree\fi{}C, i.e., below and above the metal-insulator transition temperature ${\mathit{T}}_{\mathit{c}}$\ensuremath{\approxeq}67 \ifmmode^\circ\else\textdegree\fi{}C. The O 1s spectra show a…
We present a microscopic mechanism of optical nonlinearity in conjugated polymers. It is shown that the bulk of the nonlinearity is determined by only two well-defined channels, even though an infinite number of channels are possible in principle. We are able to explain the complete frequency dependence of the third-h…
The frequency and line shape of the diamond Raman line are examined in detail for a series of microwave-plasma-assisted chemical-vapor-deposition films grown on Si. The Raman lines in the films appear at higher frequency (shifts of up to 3 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$) than that of natural diamond and th…
The temperature-dependent thermal conductivity \ensuremath{\kappa}(T) of amorphous silicon has been calculated from equilibrium molecular-dynamics simulations using the time correlations of the heat flux operator in which anharmonicity is explicitly incorporated. The Stillinger-Weber two- and three-body Si potential a…
Using an all-electron, self-consistent, full-potential, linear muffin-tin-orbitals method within the local-density approximation of density-functional theory, we have studied the structural properties and the elastic constants of Mo and ${\mathrm{MoSi}}_{2}$. The Mo and ${\mathrm{MoSi}}_{2}$ ground-state properties, l…
The electrical conductivity of polymer complexes of bis-2,6-diaminopyridinesulphoxide with CuCl 2 , CuBr 2 and CuI 2 was measured at different frequencies and temperatures. It was found that the conductivity increases as frequency and/or temperature increases. The dielectric constant, dielectric loss and relaxation ti…
Synthesis of 5,15‐Diaryl‐Substituted Porphyrins by Aminomethylation of Bis(4‐ethyl‐3‐methyl‐2‐pyrryl)phenylmethanes The synthesis of unsymmetrically diarylsubstituted porphyrins 11a‐g (yields 5–19%) is described. Aminomethylation of dipyrromethane 6a with Mannich reagent 9 in acetonitrile leads to the intermediate 10…
A truncated, 541-residue-long, Bacillus anthracis adenylate cyclase was expressed in Escherichia coli. The purified protein (CYA 62) exhibited catalytic and CaM-binding properties identical with those of the wild-type enzyme secreted by B. anthracis. The analysis of the secondary structure of the CYA 62 protein by Fou…
Abstract Stress corrosion cracking systems have been investigated using electrochemical noise monitoring. This involved analysis of the free corrosion potential noise together with associated current and current noise signals. By this means various characteristics associated with stress cracking processes can be disti…
Abstract Several test methods have been utilised to characterise the sulphide stress cracking (SSC) behaviour of tubular materials in sour service environments. The results have been analysed to predict the long term exposure behaviour of a range of downhole tubular steels. This has led to a better definition of suita…
This review summarizes the current state of materials development in nonlinear optics. The relevant properties and important materials constants of current commercial, and new, promising, inorganic and organic molecular and polymeric materials with potential in second and third order NLO applications are presented.
Reactive ion etching of monocrystalline and polycrystalline β-SiC and hydrogenated amorphous a-SiC:H in CF4/O2 mixtures was investigated. The a-SiC:H films, deposited by plasma-enhanced chemical vapor deposition, had the highest etch rate while monocrystalline β-SiC had the lowest etch rate at all compositions of the…
Organic and organometallic stilbazolium cations can be crystallized with various counterions; some of the resulting salts exhibit large SHG powder efficiencies. Approximately linear stilbazolium cations have a greater tendency to crystallize in noncentrosymmetric space groups than do cations with substantial geometric…
Abstract Recent evidence indicates that ferrous carbonate (FeCO3, siderite) plays a critical role in forming corrosion resistant scale. The temperature dependent precipitation kinetics of ferrous carbonate were studied using a powerful new "temperature ramped" approach. The activation energy calculated using a second…
This review gives a brief presentation of the basic concepts and calculation methods of the "anionic group theory" for the NLO effect in borate crystals. On this basis, boron-oxygen groups of various known borate structure types have been classified and systematic calculations were carried out for microscopic second-o…
In the recent past, conjugated polymers were found to have very fast, subpicosecond nonlinear optic response and χ (3) on the order of 10 -9 esu. We have been working on the synthesis of processible conjugated polymers in relation to their electrical conductivity properties. Once processibility was established, we wer…