Materials Literature
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Abstract Tensile properties of isotactic polypropylene filled with particulate kaolin fillers were evaluated in the composition range 0–60 wt % kaolin. Tensile modulus increased with filler concentration while breaking elongation and tensile strength decreased. The modulus increase was attributed to the restriction on…
Multilayered thin-film circuits in microelectronic devices are confined in dielectrics for insulation between layers. The confinement produces mechanical stress in the circuit. During operation, the stress can enhance or retard electromigration. This interaction has been analyzed using thermodynamics of irreversible p…
The electronic structure of ${\mathrm{Li}}_{\mathit{x}}$${\mathrm{Ni}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$O has been investigated using x-ray photoemission spectroscopy (XPS), bremsstrahlung isochromat spectroscopy (BIS), and model-Hamiltonian cluster calculations. The measurements support the conclusion that the Li…
The electronic structure of ${\mathrm{SrFeO}}_{3}$ has been investigated by x-ray photoemission and ultraviolet photoemission spectroscopy. We find that the ground state consists of heavily mixed ${\mathit{d}}^{4}$ and ${\mathit{d}}^{5}$L states, reflecting the large covalency. The Fe 3s core-level splitting, together…
We use time-, wavelength-, temperature-, polarization-resolved luminescence to elucidate the nature of the absorbing and ‘‘band edge’’ luminescing states in 32 Å diameter wurtzite CdSe quantum crystallites. Time-resolved emission following picosecond size-selective resonant excitation of the lowest excited state shows…
Abrasive wear is likely to occur whenever a hard asperity or a trapped hard particle is dragged across a softer surface, and it has been estimated that this form of wear contributes to as many as half of the wear problems that are met in industry. Such damaging hard particles may be external contaminants, products of…
Mechanical equipment used in BP operations is subjected to extremely adverse conditions, often in remote locations. Downtime due to wear and component failure can be very costly and the need to choose materials based upon an understanding of wear resistance is required. Selection is often based on the economics of com…
In this paper some recent studies on the friction of diamond are reported. These include a study of friction tracks by reflection electron microscopy (REM); analysis of wear debris using electron and x-ray diffraction, and infrared spectroscopy; friction experiments with various lubricants. These researches showed tha…
20 µm diameter spray-dried agglomerates made up of 210 nm zirconia particles have been individually tested by crushing between rigid plates using a modified nanoindenter. The results show that the agglomerates support considerable stress before deforming. Both the elastic and plastic deformations of the agglomerates h…
We study the adsorption of long, linear polymer chains from a melt or a semi-dilute solution onto a solid wall, the adsorption of a monomer on a surface site being irreversible. Using scaling arguments, we derive the concentration profile and the extension of the polymer layer, which has been washed out with pure solv…
UV absorption spectra of KCl:Sb 3+ crystals have been studied in detail. Six absorption bands are observed at 271.0, 210.8, 201.7, 199.4, 195.5 and 191.4 nm, the first five bands of which are attributable to the A, B, C 1 , C 2 and C 3 bands due to an s 2 to sp transition in the Sb 3+ ion, while the last is due to the…
Ni-Ti shape memory actuators respond to temperature changes with a shape change. Therefore, they are sensors and actuators. They combine large motion, rather high forces and small size, thus providing high work output. They usually consist of only a single piece of metal, e.g., a helical spring, and do not require sop…
The electron paramagnetic resonance (EPR) of an Mn 2+ (S=5/2) impurity in the ferroelastic and para-elastic phase of BiVO 4 crystals with a single domain, grown by the Czochralski method, has been investigated using an X-band spectrometer. The rotation patterns of the resonance fields measured on the crystallographic…
We report the room-temperature near-infrared emission (1.0–1.4 μm), the fluorescence lifetimes, and the gain measurements of the tetraoxo manganese specie MnO3−4(Mn5+,3d2) in single crystals of Sr5(PO4)3Cl and Ca2PO4Cl. The relatively long fluorescence lifetimes, 100 and 425 μs for MnO3−4 doped Ca2PO4Cl and MnO3−4 dop…
The diffusion of protons in the superionic phase of CsHSO 4 was investigated by quasielastic neutron scattering (QNS) on the IRIS spectrometer at the pulsed spallation neutron source ISIS, Rutherford Appleton Laboratory, UK. Two processes with different characteristic times could be distinguished: long-range translati…
Neutron diffraction experiments have been carried out in order to investigate the ordered structures of the high temperature phase of two different Cu-Zn-Al alloys. It has been confirmed that the alloys exhibit an L2 1 superstructure below a critical temperature T c2 ; a B2 superstructure between T c2 and T c1 , and a…
The temperature evolution of the frequencies and absorption cross section of the infrared-active phonons near 795 cm -1 and 695 cm -1 and the Raman-active mode near 355 cm -1 follow that of the symmetry-breaking order parameter of the alpha - beta phase transition in quartz. The IR signal at 695 cm -1 and the Raman si…
In the present paper, dielectric, polarization, and Raman results have been combined to identify the existence of a ferroelectric phase transition in the substitutionally disordered dipolar system, ${\mathrm{KTa}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Nb}}_{\mathit{x}}$${\mathrm{O}}_{3}$, for low Nb concentra…
The elasticity and hardness of a-C and a-C:H are related to their mean network coordinations. It is shown that ${\mathit{sp}}^{2}$ sites contribute no rigidity if they form graphitic clusters, as suggested by experiment and electronic structure calculations, despite their having coordinations above the critical value…
Superconductors are considered in which there occur fluctuations of one crystallographic structure inside another. The role of these heterostructural fluctuations on superconducting properties are analysed. The occurrence of these fluctuations explains anomalous saggings of Mössbauer factor at phase transition in high…