In this work proposed cascade three-stage oat husk processing for isolation of low crystalline and lignin-free cellulose being perspective for chemical transformations. Such a product seems to be perspective for obtaining products which are important for chemical industry. The approach proposed includes stages of peroxide oxidative delignification, alkali treatment and mechanical activation in planetary mill. The optimal parameters of oxidative delignification were determined: the process temperature 100°C, the solid to liquid ratio 1 : 26, the hydrogen peroxide and acetic acid concentration 6 and 25 wt

Single-walled carbon nanotubes (SWCNTs) are promising materials for use in multifunctional polymer composites. A special feature of SWCNTs is their tendency to aggregate into bundles with 2D close packing. The coherence of such packing leads to the appearance of diffraction maxima at small-angle X-ray scattering. Using the Debye equation for X-ray scattering, this work presents the results of a theoretical analysis of the influence exerted by various parameters of SWCNT bundles (length and diameter of SWCNTs, transverse dimensions of SWCNT bundles, distribution of diameters and the number of SWCNTs in bundles) on the position, width, and shape of these diffraction peaks. To this end, atomic models of both the individual tubes and their bundles were constructed taking into account the diameter distribution of nanotubes, which has a significant effect. The results obtained can be used to correctly interpret the experimental diffraction data.

The work is dedicated to a research into the physicochemical aspects of carbon nanopowder production from the gas phase by the pyrolysis of the initial precursors in a cyclic adiabatic process in a flow-through chemical compression reactor (CCR). The method allows the production of carbon nanomaterials, such as the carbon nanoparticles and globular soot particles, as well, as the core-shell structures representing the 4-7 nm composite particles with a SiC crystal core covered with graphene layers. Products have controlled and reproducible properties, and output capacity of the method is sufficient for technological purposes. The nanopowders are characterized by high-resolution transmission electron (TEM) and scanning electron (SEM) microscopy, X-ray diffraction analysis and Raman spectroscopy. The nanomaterials were used to manufacture their aqueous suspensions - nanofluids, which have shown their effectiveness in enhancing oil recovery in oil displacement technologies.

Total X-ray scattering and atomic pair distribution analysis (PDF) were used to study structure of anisotropic two-dimensional (2D) MoS2 nanoparticles in MoS2/Al2O3 catalysts. We demonstrated that PDF analysis can be used not only to determine the atomic ordering but also to assess the geometry and size of 2D MoS2 nanoparticles in the catalysts. In refinement of PDFs, discrete atomistic modeling was used to account for finite size and shape effects. The values of MoS2 slab length elucidated from the PDF data were smaller than values obtained from high-resolution transmission electron microscopy (HRTEM) data due to defectiveness and multi-domain structure of the MoS2 nanoparticles. It was suggested that increase in the temperature of heat treatment of oxide precursors leads to decrease in deformation of the MoS2 nanoparticles in sulfided catalysts.

Despite the fact that metastable aluminum oxides are actively used in industry, there is a discrepancy in the literature regarding their crystal structure. All this leads to difficulties in data interpretation and, as a consequence, classification problems. This work is aimed at solving these tasks. The main features of powder X-ray diffraction of typical samples of three Al2O3 polymorphs (γ-, χ-, η-) are analyzed. Specifics and fundamental differences in X-ray scattering and their relationship with the structural organization at the nanostructure level are clearly shown. The work demonstrates the possibilities of analyzing experimental powder X-ray diffraction data using a modern approach based on the Debye Scattering Equation for studying the organization of such complex systems.

The data presented in this article relate to the scientific article "Pyrolysis of a mixture of monosilane and alkanes in a compression reactor to produce nanodispersed silicon carbide" [1]. In the above article, a method is proposed for producing nanosized silicon carbide powder by compression in a cyclic process of a chemical reactor. Pyrolysis is initiated in mixtures of monosilane and hydrocarbon with argon. The article also presents the analysis data of the obtained product by X-ray diffraction and electron microscopy.

In the presence of acidic catalysts based on the Sibunit-4 material the effects of mechanical activation and a lignin impurities on both the reactivity of cellulose and yields of products (monosaccharides and furfurals) being achieved during the hydrolysis of the polysaccharide isolated by hydrotropic cooking of miscanthus, wheat straw, and fruit shells of oats were studied. Activation was shown to significantly increase the reactivity of all substrates and the yields of the target products. Impurities of lignin led to decreasing product yields

It is known that the physical and chemical properties of ultradispersed systems and nanomaterials are defined by features of the atomic structure. For structural investigations X-ray diffraction analysis is one of the main methods. Diffraction patterns contain information on the structure and morphology of nanoparticles: the shape and size of crystallites, the presence of defects and microstresses of atomic order, the mutual orientation of the blocks and the inter-grain boundaries of structured systems.

DIANNA is a free software developed to simulate atomic models of structures for an ensemble of nanoparticles and to calculate their whole X-ray powder diffraction patterns and the radial distribution function. The main objects of investigation are the particles whose coherent scattering domains do not exceed several nm. DIANNA is based on the ab initio method using the Debye scattering equation. This method makes it possible to obtain information on the atomic structure, shape and size of nanoparticles. It can be applied also to non-periodic materials or coherently ordered nanostructures. Basic program features, methods and some examples are demonstrated.

It is known, that the physicochemical properties of materials are defined directly by features of the structure and morphology.Studying of atomic structure and nanostructure of such small objects is an actual problem.X-ray diffraction method can be used for this purpose.Anisotropic broadening of the diffraction peaks, redistribution of the intensities or appearance of diffuse scattering can appear for nanomaterials.Standard X-ray diffraction techniques are often not applicable in this case.These tasks can be solved by the Debye Function Analysis (DFA) method, based on Debye scattering equation (DSE).It is full-profile method which is applicable for any an arbitrary atoms collection, and therefore can be used for crystalline objects, non-crystalline materials or nanostructures.Possibilities of modelling diffraction patterns by the DFA by our software [1] will be shown for specific examples of various nanocrystalline materials.It is public-domain software available on the website: www.sourceforge.net/projects/dianna.

Abstract For the first time, the detailed structure of χ-Al2O3 and η-Al2O3 surface has been established by implementing the NMR crystallography approach. The surface of η-Al2O3 has been demonstrated to be formed primarily by the (111) facets, while the χ-Al2O3 surface is a combination of (111) and (110) facets. This observation supports the block model of aluminum oxides previously proposed by Tsybulya and Kryukova [S. V. Tsybulya, G. N. Kryukova, Phys. Rev. B 77 (2008) 024112.]. The additional terminal OH groups, observed experimentally and not contributing to (111) and (110) theoretical calculations, are considered to be bonded to the tetrahedral aluminum sites. Their origin is related to the junctions of crystallographic faces of spinel building blocks, being a part of discussed model. Higher content of these terminal OH groups in χ-Al2O3 is a result of more junctions in the case of its more mosaic structure compared to η-Al2O3.

Abstract The metastable nanocrystalline γ-Ga2O3 with the particles’ dimensions about 2 nm was prepared by coprecipitation method and its structure was studied using X-ray powder diffraction. The corresponding diffraction pattern is characterized by a strong broadening of diffraction peaks. The Debye function analysis method (DFA) was applied to calculate the full profile of the XRD pattern for the first time. Earlier reported structural models of the γ-Ga2O3 were examined with respect to experimental diffraction data. The influence of crystallite sizes on the diffraction pattern was considered. The obtained structure of the disordered γ-Ga2O3 has vacancies in 8a and 16d spinel positions and additional atoms in 8b, 16c and 48f non-spinel positions. The proposed structure differs from those reported by the ratio between occupancies of the tetrahedral and octahedral gallium positions.

Bath composition for cathodic electrodeposition of non-stoichiometric hydrated tungstic acid with high electrochromic efficiency is optimized with account for selective electroreduction of certain isopolytungstates. XRD data for thin electrodeposited films and chemically synthesized bulk tungstic acid dihydrate are compared in the context of reversible oxidation and reduction in hydrogen atmosphere, in presence of Pt catalyst. XPS and TEM techniques are attracted to understand the nature of reversible and less reversible transformations of films in the course of their storage and operation. (C) 2016 Elsevier B.V. All rights reserved.

The study is aimed to determine the most perspective and effective fine-grinding mills for lignocellulosic biomass mechanical activation. Physicochemical characteristics were studied for milled crystalline cellulose and milled dry birch sawdust after their treatment in various devices - ball, planetary, ring, vortex gas driven and vortex mechanically driven mills. XRD analysis method was used for phases identification, crystallinity index (CI) and mean size of coherent-scattering region (CSR) measuring. These values are suggested to be used for an assessment of the efficiency of mechanical activation process. Mean particle size (l) of milled materials was measured with help of optic microscopy as well. As the most perspective device for future detailed investigation to be done the vortex mechanically driven mill is selected. This type of mill provides both the least electrical power consumption and activation time at adequate particles destruction level and marked mechanical activation demonstrated for dry birch saw dust (it was detected the reduction of l and CI from l similar to 3700 mu m/CI = 74 % to l similar to 22 mu m/CI = 56 %).

Systems with an ordered (quasiordered) packing of nanosized particles or a regular arrangement of pores are specific objects of research for diffraction methods. Such organized systems (nanostructures) are often characterized by diffraction effects in the form of additional diffraction peaks depending on the type of packing. At research of the structured samples it is important to determine the nanostructure parameters and characteristics associated with the shape and sizes of the particles or pores. Approaches will be considered below, allow to determine the parameters of nanostructures from the diffraction data

Solid acidic catalysts for the processing of cellulose in the value-added chemical (glucose and 5-hydroxymethylfurfural) in aqueous media ware prepared on the basis of graphite-like carbon "Sibunit - 4" using sulfonation by sulfuric acid at different temperatures, followed by treatment in water at 180 degrees C. Prepared catalysts were characterized by low-temperature nitrogen adsorption and acid-base titration. Testing of catalytic activity in the hydrolysis of the mechanically activated microcrystalline cellulose was carried out at 180 degrees C and 1 MPa of argon. The main products of the process are glucose and 5-hydroxymethylfurfural with yields up to 46 and 22 mol. %. Comparison of the results of the activity and stability of catalysts showed that the most promising is the catalyst sulfated at 200 degrees C.