Materials Literature
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Reactions of aminosilanetriols RN(SiMe 3 )(Si(OH) 3 ) (R = 2,6-Me 2 C 6 H 3 ( 1a ), 2,6- i -Pr 2 C 6 H 3 ( 1b ), 2,4,6-Me 3 C 6 H 2 ( 1c )) with titanium orthoesters Ti(OR‘) 4 (R‘ = Et, i -Pr) in hexane at room temperature afford new cubic titanasiloxanes [RN(SiMe 3 )SiO 3 Ti(OR‘)] 4 ( 2a − f ) in nearly quantitative…
The absolute chirality of potassium dithionate, , , trigonal, space group P321, a = 9.782(1) Å, c = 6.298(2) Å, , Z = 3, R = 0.024, wR = 0.031 for 2586 unique observed reflections, has been determined at room temperature through a combination of single-crystal x-ray diffraction, including anomalous scattering, and opt…
Thin films made by annealing Cu(500 nm)/Al(7 nm)/SiO2/Si are investigated using Rutherford backscattering and resistivity measurements. Annealing these films in a low pressure of oxygen results in the formation of a thin surface layer of hole-free aluminum oxide which protects the underlying copper from oxidation. Eve…
During furnace N2O-based silicon oxynitride growth, the total concentration of NOx species varies strongly with the flow rate of N2O. At low flow rates the N2O decomposes at least partially in the cooler region of the furnace near the gas inlet. This results in lower than expected NOx (x=1,2) concentrations in the oxi…
Lanthanum modified lead zirconate titanate (PLZT) ceramics with a Zr/Ti ratio of 85/15 were investigated as a function of La content by dielectric spectroscopy, Sawyer–Tower polarization techniques, and electron microscopy. Tweedlike structures were found to evolve from normal μm-sized ferroelectric domains with incre…
Chiral conductivities of nanotubes are examined within the framework of the Boltzmann transport equation. Electron transport along a chiral trajectory is decomposed into current components along the tubule axis and its circumference. Within a constant relaxation time approximation, these components are derived from th…
The thermal stability in vacuum of amorphous tetrahedrally coordinated carbon (a-tC) films grown on Si has been assessed by in situ Raman spectroscopy. Films were grown in vacuum on room-temperature substrates using laser fluences of 12, 22, and 45 J/cm2 and in a background gas of either hydrogen or nitrogen using a l…
We report the realization of a bright and stable electroluminescent Schottky diode based on aluminum-porous silicon junction. White light, visible in normal daylight, is emitted when a reverse bias is applied to the device, promoting the junction breakdown. The device has a fast (100 ns) rise time of the light emissio…
Core-level photoabsorption has been used to determine the sp2 and sp3 bonding content of nanocrystalline diamond thin films grown using C60 or CH4 precursors. The C(1s) absorption spectra show clear bulk diamond excitonic and sp3 features with little evidence of sp2 bonding, while the Raman spectra measured from these…
For the first time, we present the calculation of the nonlinear optical coefficient of the (NAB) crystal from a systematic and quantitative standpoint. Based on the dielectric theory of complex crystals and the Levine bond charge model, the method of calculation of the second-order nonlinear optical tensor coefficient…
Broadband dielectric spectra are usually fitted to a superposition of contributions from one or several parametrized processes (Debye, Havriliak-Negami, etc.). This work proposes instead to extract continuous distributions of relaxation times from complex dielectric spectra by solving a Fredholm integral equation usin…
In this letter, we describe the formation and ultralow friction mechanisms of a surface film on boron carbide (B4C). This film results from sequential reactions between B4C and oxygen and between the resulting boron oxide (B2O3) and moisture; it can afford friction coefficients of 0.03 to 0.05 to sliding steel surface…
Elastic neutron scattering measurements characterizing the charge and magnetic order in L${\mathrm{a}}_{0.5}$S${\mathrm{r}}_{1.5}$Mn${\mathrm{O}}_{4}$ are presented. Superlattice reflections corresponding to an alternating ${\mathrm{Mn}}^{+3}/{\mathrm{Mn}}^{+4}$ pattern with wave vector ${\mathbf{q}}_{\mathrm{co}}\pha…
The modification of the potential-energy surface (PES) of H_2 dissociation over Pd(100) as induced by the presence of a (2x2) S adlayer is investigated by density-functional theory and the linear augmented plane wave method. It is shown that the poisoning effect of S originates from the formation of energy barriers hi…
Measurements in PMMA of both the energy flux into the tip of a moving crack and the total surface area created via the microbranching instability indicate that the instability is the main mechanism for energy dissipation by a moving crack in brittle, amorphous material. Beyond the instability onset, the rate of fractu…
A database of ab initio calculations of the chemisorption energy of CO over Ni(111), Cu(111), Ru(0001), Pd(111), Ag(111), Pt(111), Au(111), $\mathrm{Cu}{}_{3}$Pt(111), and some metallic overlayer structures is presented. The trends can be reproduced with a simple model describing the interaction between the metal $d$…
The following paper describes an in-situ approach to studies of hot filament chemical vapour deposition (HFCVD) thin film growth. It based on the use of a HFCVD experimental setup in the chamber of an environmental scanning electron microscope (ESEM). The initial stages of diamond thin film growth were examined at tim…
A new technique to measure the thermal conductivity k(T)of CVD diamond is presented. The thermal conductivity parallel to the surface of films with thicknesses ranging from 2 μm up to several hundred μm can be determined over a wide temperature range. The measurements are carried out with micromechanical devices, that…
Modern thin film sensor technology imposes stringent demands upon material quality, highly qualified downstream process technologies, device performance and integrity. Since the earliest stages of its development, crystalline thin film diamond has been promoted as a semiconductor material for high power, high frequenc…
Natural type IIb diamond surfaces of (100), (110), and (111) orientation, as well as chemical vapor deposited (CVD) diamond thin films with (100), (110), or mixed orientation are probed by photoelectron spectroscopy in the ultraviolet (UPS) and X-ray (XPS) energy regimes. Dramatic changes can be observed in the valenc…