Materials Literature
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The Holstein-Hubbard model is used to study high-temperature (T\ensuremath{\gtrsim}${\mathit{T}}_{\mathrm{phonon}}$/3) hopping transport when it is energetically favorable for carriers to pair as singlet small bipolarons. The semiclassical rates for one-electron transfers involving small polarons are found to be much…
A short group-theoretical discussion is given of phonon symmetries in different phases of the Pb(ZrxTi1−x)O3 (PZT) perovskite together with a description of the degeneracy splitting in consequence of the long-range Coulomb fields both in the paraelectric cubic phase and ferroelectric tetragonal and trigonal phases. Ph…
We have measured Raman spectra of free-standing porous silicon at 10 K. Porous silicon samples were prepared in aqueous and ethanoic electrolytes and the scattering was measured in the range of one- through four-phonon processes. A quantum size effect is clearly observed in the spectral change of the first- and second…
A magnetic field induced insulator to metal transition has been observed in both polycrystalline and single crystals samples of Pr0.7Ca0.3MnO3. Application of a magnetic field leads to a first-order phase transition from an insulating to a conducting state at low temperatures. The hysteresis associated with this trans…
A photodiode has been constructed from lightly boron doped, Si supported, thin film chemically vapor deposited (CVD) diamond which shows over five orders of magnitude discrimination between deep UV (≤220 nm) and visible light. A thin (10 nm) gold Schottky barrier with an associated Ti–Ag–Au ohmic contact was used to c…
For more then one century it has been observed that stress corrosion cracking (SCC) and corrosion fatigue (CF) corresponds to synergetic effects between corrosion and mechanics. Researchers and engineers have tried to translate such effects through empirical damage laws, in particular to predict crack velocities in me…
Hydrodynamic slip due to lack of molecular interfacial interactions is demonstrated rheologically as a function of molecular weight and temperature, by comparing poly(dimethyl siloxane) (PDMS) suspensions of bare and silane-treated glass spheres. The magnitude of interfacial slip between treated spheres and PDMS matri…
Analysis of x-ray diffraction from a single crystal of bis-benzene-1,2-dithiolato-Au(IV) [Au${(\mathrm{bdt})}_{2}$] at 125 K reveals a superstructure along the stacks of Au${(\mathrm{bdt})}_{2}$ molecules corresponding to a dimerization of the molecules along the stack. Within a dimer, intermolecular sulfur-sulfur con…
The demand for biodegradable chemicals is increasing as chemical producers and consumers anticipate more stringent standards for degradability in new and existing products. Poly(aspartic acid) (PAA) is an example of a chemical that shows promise as a biodegradable replacement for polyacrylic acid, a nonbiodegradable p…
Transcrystallization of polypropylene (PP) on the polytetrafluoroethylene (PTFE) fiber was investigated. Both nucleation rate and crystal growth rate were determined by a polarized optical microscope. Based on the theory of heterogeneous nucleation, it has been found that the induction time can correlate well with the…
Zirconia–alumina transformation-toughening nanolaminates were fabricated by reactive sputter deposition. The average crystallite size and volume fraction of each zirconia polymorph were determined by x-ray diffraction. The volume fraction of tetragonal zirconia, the phase necessary for transformation toughening, was f…
Poly(ethylene oxide) (PEO)-based protein-resistant surfaces function principally by a steric exclusion mechanism involving very high surface mobility and surface dynamics of the PEO chains. For such a surface to be effective, the dynamics and mobility of the chain must be maximized and, contradictorily, the underlying…
Supramolecular liquid–crystalline polymeric complexes based on a backbone that contains vinyl pyridine units and azobenzene or biphenyl derivatives that posses alkyl chains terminated by carboxylic acid have been obtained by the formation of intermolecular hydrogen bonds between the carboxylic acid and the pyridyl moi…
Six different classes of water-soluble polyphosphazenes have been synthesized and characterized. Several of the new polymers have been cross-linked to yield materials that absorb water to form hydrogels. This chapter examines the underlying concepts used in this work and describes the use of this chemistry to prepare…
First-principles calculations based on density-functional theory and the pseudopotential method have been used to investigate the influence of gradient corrections to the standard local-density-approximation technique on the equilibrium structure and energetics of rutile ${\mathrm{TiO}}_{2}$ and ${\mathrm{SnO}}_{2}$ p…
We have performed spatially resolved measurements of the charge-density-wave (CDW) response to bipolar current pulses. These measurements directly yield the distribution of the CDW phase slip, the temporal evolution of the CDW elastic-force and strain profiles, and the local relationship between the phase-slip rate an…
The Ag/MgO(100) interface has been studied by EXAFS. At room temperature, in agreement with previous investigations, silver at low coverage is shown to form a two-dimensional layer at the MgO(100) surface. EXAFS data demonstrate that the lattice parameter of the silver overlayer is expanded so as to fit the MgO parame…
Various approximate methods for the calculation of vibrational second hyperpolarizabilities are assessed on the basis of results for CH4, NH3, H2O, HF, and CO2. Three specific variations of the perturbation-theoretic approach are analyzed. These are defined by the types of terms retained in expansions which involve el…
Lanthanum modified lead zirconate titanate (PLZT) ceramics near a crossover between normal and relaxor ferroelectric states for Zr/Ti ratios of 40/60, 20/80, and 0/100 were investigated by dielectric spectroscopy, Sawyer–Tower polarization techniques and transmission electron microscopy. It was found possible to induc…
This book deals with the phenomenological theory of first-order structural phase transitions, with a special emphasis on reconstructive transformations in which a group-subgroup relationship between the symmetries of the phases is absent. It starts with a unified presentation of the current approach to first-order pha…