Advanced Materials Research Vol. 1117

Abstract: In the present work, we demonstrate the theoretical feasibility of basic logic gates consisting of dipole-coupled Dronpa molecules, potentially permitting the realization of nanoscale, low energy consuming and dissipating, terahertz-frequency computers and digital signal processors. The operational principle is related to an experimentally demonstrated, electric field-induced switching behavior of proteins.

Abstract: Amorphous Nb-doped TiO₂ thin films were deposited on (100) Si and glass substrates at room temperature by RF magnetron sputtering and a mosaic-type Nb₂O₅-TiO₂ sputtering target. To adjust the amount of the niobium dopant in the film samples, appropriate numbers of Nb₂O₅ pellets were placed on the circular area of the magnetron target with intensive sputtering. By adjusting the discharge conditions and the number of niobium oxide pellets, films with dopant content varying between 0 and 16.2 at.% were prepared, as demonstrated by X-ray photoelectron spectroscopy data. The X-ray diffraction patterns of the as-deposited samples showed the lack of crystalline ordering in the samples. Surfaces roughness and energy band gap values increase with dopant concentration, as showed by atomic force microscopy and UV-Vis spectroscopy measurements.

Abstract: Most studies devoted to the development of nanostructured TiO₂ coatings focus mainly on the nanostructures obtained and bulk properties of material. Nanostructured TiO₂ sol-gel films were prepared on a mechanic-chemical and ultrasound cleaned glass substrates. Atomic force and field emission scanning electron microscopy results confirmed fast contamination of cleaned substrates. The analysis of obtained results indicated that soda-lime silicate glass substrate cleaning method could be used to tailor the formation of TiO₂ sol-gel coatings nanostructure.

Abstract: Distribution of active surface centers (DAC) spectroscopy is applied to study acid-base properties of solids. Surface characteristics of solid influences interface interaction in which this solid participates. Efficient approach to consider such interactions is to view them as acid-base ones, since acid-base interactions determine adsorption and bonding of organic molecules to solid surface. Paper describes application of method to study surface properties of components of luminescent materials, catalysts, gas sensors, proton membranes and polymer composites, and it was shown that their functional properties strongly depend on distribution of acid-base active surface centers.

Abstract: A variety of industrial minerals, such as kaolinite, feldspars, and etc., have been used as solid raw materials in the geopolymerization technology. The illite-containing raw material in this study was obtained by the use of sedimentation method. Clay and dust fractions was subjected to the treatment with NaOH alkaline solution and afterwards treated at different temperatures. Results obtained by X-ray diffraction, Scanning electron microscopy, nitrogen adsorption method confirmed the usability of Liepas deposit homogenized gray and red clays for possible realization of geopolymer method.

Abstract: To prepare coatings by electron-beam sputtering, targets have been designed and synthesized by a sol-gel method, based on SiO₂ and TiO₂ materials. The optimum basic compounds for the synthesis of stable silica sol and titanium are reported. Spectroscopic studies have been conducted for the coatings aiming at the characterization in terms of optical characteristics, such as refractive index, reflectance, transmission and absorption coefficients. The morphology of the layers was investigated by atomic force (AFM) and scanning electron (SEM) microscopies.

Abstract: The stability of silver halide colloids is reported to be important for the toxicological outcome. This study shows a well-suited and cheap condensation reaction to obtain negatively charged silver iodide (AgI) nanoparticles without additional stabilization agents. Charged AgI colloids were synthesized from silver nitrate and potassium iodide solutions. An excess of potassium iodide not only imparted a negative charge, but provided a narrow particle size distribution (50 ± 10 nm). The change of optical properties in the colloid was investigated by UV-VIS spectroscopy. A silver iodide exciton absorption band at peak ~421nm (2.93eV), red-shifted over time. The peak at half maximum intensity increased from 13.3nm to 14.8 nm, characterizing the dispersity of AgI colloidal particles. Colloidal particles stabilized after 33 hours. In-situ real-time UV-VIS measurements provide a tool to adjust the particle characteristics and may serve to further optimize the performance in biological applications.

Abstract: The possibility of functional nanostructured materials for electronic devices synthesis by sol-gel method have been discussed such as ferroelectrics (SrBi₂(Ta_xNb_1-x)₂O₉) , ferromagnetics (Fe_xCo_yO_z) and semiconductors (ZnO). The structural features of the surface (AFM), crystallization behavior (XRD) during the heating and properties of synthesized films are discussed. Achieved parameters suggest the possibility of using synthesized SBTN sol-gel films in non-volatile memory devices, semiconductors active ZnO layers in solar sells, ferromagnetics Fe_xCo_yO_z films in radioabsorbing covers.

Abstract: Nanostructured ZnO films are obtained by chemical bath deposition from zinc nitrate, hexamethylenetetramine and ammonia. The evolution of the structural and sub-structural properties of the films is characterized using high resolution scanning electron microscopy (SEM) and X-ray diffraction analysis. In particular, we detail here the influence of condensation time on the crystal phase, texture quality, lattice constants, grain size, coherent scattering domain size (CSD), microstrain, stress and concentration of dislocations. Obtained condensates have the wurtzite structure with lattice parameters in the range a = 0.3248-0.3254 nm and c = 0.5206-0.5214 nm, depending on the condensation time. The grain size and microstrain in the direction perpendicular to the crystallographic planes (002) are in the range L ~ 26-42 nm and ε ~ (0.59-3.09)·10^-3, respectively. Furthermore, the effects of deposition time on microstrain, stress and concentration of dislocations in the layers is established. By adjusting the condensation time, we are able to produce ZnO films with controlled structural properties: from nanorods to continuous nanostructured films.

Abstract: There were made and tested three types of polymer and nanographite composites: 1) Ethylene vinyl acetate copolymer (EVA) as matrix and extra-conductive highly structured carbon black (EHSCB) as conductive filler; 2) EVA matrix and carbon nanotubes (CNT) as filler; 3) EVA matrix and as filler are used optimal combination of two kind of conductive filler, EHSCB and CNT. Volatile organic compound vapour sensor-effect is tested for all composite types.