Materials Literature
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The defect centres formed in the thermoluminescent phosphor CaSO 4 :Dy on additionally doping with Na + (as a charge compensator) have been studied using the technique of electron paramagnetic resonance. The Na + ion at the Ca 2+ site is found to stabilize the observed SO 4 - radical. An important feature of the new S…
We compare the light scattering properties of polymer-dispersed liquid crystal films incorporating different nematic mixtures. We find that, when powered, the turbidity of these disparate films share a common quadratic dependence on the refractive index difference between the nematic and polymer. In contrast, when we…
Inelastic electron scattering using a two-beam channeling condition is used for the first time to create excitations having selectable even or odd symmetry relative to an atom column. The method is first established using plasmon and interband scattering in diamond. Next, for the carbon 1s absorption edge, scattering…
We present the fabrication of sub-50 nm Si pillars, ridges, and trenches with aspect ratios greater than 10 using ultrahigh resolution electron beam lithography and chlorine based reactive ion etching. These nanoscale Si features can be further reduced to 10 nm using an additional HF wet etch. No photoluminescence was…
Neutron diffraction measurements confirm the presence of long-range antiferromagnetic order in superlattices of cobalt oxide and nickel oxide. A single transition temperature between the values for bulk CoO and NiO is evident for two samples with 36 \AA{} periods as previously reported, but the separate Ni and Co orde…
Free-standing films of a smectic liquid crystal possessing the bulk phase sequence smectic A, ferroelectric smectic C, antiferroelectric smectic ${\mathit{C}}_{\mathit{A}}$ are studied. Using ellipsometric measurements, we show that the bulk phases still exist in films consisting of only four, three, and even two smec…
Photosynthesis of porous silicon is reported for the first time with visible-light irradiation in a hydrofluoric acid solution, which does not need any electrodes for anodization. The photosynthesized porous layer consisted of microparticles, and the photoluminescence spectra were very close to those of anodized porou…
Deuterium magnetic resonance of cylindrically confined liquid crystals reveal a structural transition driven by a homeotropic-to-planar anchoring transition in the nematic phase and an orientational wetting (quasicomplete-to-partial) transition in the isotropic phase as the molecular length of the surface coupling age…
We study the structure of nested multilayered systems composed of two infinite carbon tubules via density functional theory. The calculated intertubule distance is 3.39 \AA{}, comparable to the recent measurement of 3.4 \AA{}. In such a system, the energy gained by adding a new cylindrical layer around a central one i…
Diamond films are grown using microwave-plasma-enhanced chemical vapor deposition (CVD). Some samples are deposited using 0.1% oxygen in the reaction gas mixture. We have measured the cathodoluminescence spectra of these diamond films (at 77 K) and found that there is a significant difference between the samples grown…
Abstract To improve oil and water repellency, fluorine‐containing block copolymers, which were composed of methyl methacrylate (MMA), glycidyl methacrylate (GMA), and 1H, 1H, 2H, 2H‐heptadecafluorodecyl acrylate (PFA), were blended with an epoxy resin. It was expected that a glycidyl group would mesh with the epoxy re…
Abstract Irradiation of polystyrene by 15 Mrad gamma or exposure to a 254 nm ultraviolet (UV) light source leads to surface oxidation of the polymer to depths greater than 10 nm as opposed to ∼ 3 nm depth offered by either plasma or corona‐discharge treatment. Oxidation increases linearly with UV irradiation time. Mor…
The problem of bulk self-diffusion in quasi-crystals is studied. We propose one possible mechanism for this process. Our scenario for diffusion is based on properties specific of the structure of quasi-crystals. The order of magnitude of the diffusion coefficient for a simple model of structure is estimated. The possi…
A fivefold quasi-crystalline structure in a liquid has been obtained with five ultrasonic beams coming together in water according to a regular pentagonal array. A pressure scanning by means of a hydrophone probe has been made to show in a direct way the evidence of the quasi-crystalline pressure structure. Acousto-op…
A nonlinear optical spectroscopy based on degenerate four-wave mixing has made possible direct measurements of species temperature and concentration profiles through the boundary layer of a reactive plasma at atmospheric pressure. Spectra were obtained for CH and C(2) radicals over a range of conditions including thos…
The photostimulated luminescence of UV-irradiated BaFxCl2-x:Eu2+ phosphors is investigated. The PSL can be observed not only after X-ray irradiation but also after ultraviolet irradiation even when the wavelength of UV is larger than that of ionization. The saturation of PSL with duration of UV irradiation and the dif…
In order to investigate the site occupancy of the carbon atom in the ordered b.c.t. structure (Ll0, P4/mmm) of the τ-phase of carbon-doped Mn-Al permanent magnets a structure analysis by X-ray diffraction is attempted. The experiments are performed using a series of (Mn0.53Al0.47)1-xCx (x = 0 to 0.0315) pseudo-binary…
The effect of doping with either In or Cd on the electrical and thermoelectric properties of digenite (Cu1.8S) is studied as a function of temperature between 100 and 700 K. The results are discussed taking into account the relation between these properties and the crystal structure of non-stoichiometric copper sulphi…
In the present work the change of the easy magnetization direction from easy plane to easy axis of the primary compound Sm2Fe17 by absorbing nitrogen is directly observed by the domain pattern. The intrinsic magnetic parameters of nitrided Sm2Fe17Nx such as domain wall energy γ, average exchange constant A, domain wal…
Tin (II) oxide powder is coated at room temperature onto transparent glass substrates by direct thermal evaporation. The films have high transparency (more than 80%) in the visible and near-infrared regions of the electromagnetic spectrum. In the region between 300 and 1300 nm interference fringes are sharp and well d…