Estimation of particle size using the Debye equation and the Scherrer formula for polyphasic TiO2 powder

There are two methods to estimate the particle size from X-ray diffraction data: the Debye equation and the Scherrer formula. The main goal of this study is to describe the methodology of particle size estimation on the base of two these methods and to apply it to TiO2 powder to determine the diameters and the mass content of anatase and brookite components. The studied nano-dispersed TiO2 powder was synthesized by the sol-gel method. The proposed method of particle size estimation consists of several steps: 1. Approximation of diffraction peaks by Gaussians and calculation of initial values of particle size with the use of the Scherrer formula; 2. Iterations with the use of the Debye equation to obtain more accurate particle size values; 3. Calculation of the mass content of different components corresponding to the minimum R-factor. © Published under licence by IOP Publishing Ltd.Russian Science Foundation, RSF: 17-79-20165The research was supported by the Russian Science Foundation (Project 17-79-20165) and carried out in ISSC UB RAS

Chemical Bath Deposition of Cu2S Thin Films From Thiosulphate Solutions

Present work was executed with the financial support of the program 211 of the Government of the Russian Federation № 02.A03.21.0006

TiO2 paste for DSSC photoanode: preparation and optimization of application method

Received: 27.03.2020. Accepted: 20.10.2020. Published:30.12.2020.We propose a simple method of TiO2 paste preparation from titania powder (Degussa) and organic binders (terpineol, ethyl cellulose) for making a continuous photoactive layer of a dye-sensitized solar cell (DSSC). The prepared paste was characterized by using thermogravimetric and X-ray diffraction methods for comparison with commercial paste (Solaronix). The TiO2 layer parameters for applying and annealing were optimized by varying the layer thickness and using different masks. The surface morphology of annealed layers was controlled by optical microscopy. Before TiO2 paste applying and after annealing, the conductive glass (fluorine-tin oxide — FTO) was treated by TiCl4 hydrochloric acid solution. The structure of DSSCs were composed FTOglass / TiO2 layer sensitized Ruthenium complex (N719 dye)/ iodide-based electrolyte / Pt counter electrode/ FTO glass. The DSSC photovoltaic characteristics were measured under AM 1.5G irradiation and demonstrated to be close to those of photoanodes based on the prepared and commercial pastes.The team of authors is grateful to the Russian Science Foundation for financial support, grant No. 17‑79‑20165. A. S Steparuk would like to acknowledge the financial support for the analytical studies of synthesized compounds from the Ministry of Education and Science of the Russian Federation within the framework of the State Assignment for Research (project no. AAAA-A19‑119012490006‑1)

Hybrid nanoparticles based on sulfides, oxides, and carbides

The methods for synthesis of hybrid nanoparticles based on sulfides, oxides, and carbides of heavy and transition metals were considered. The problem of the influence of the method of synthesis of the hybrid nanoparticles on their atomic structure, morphology of the nanomaterials, and functional properties was analyzed. The areas of practical use of the hybrid nanoparticles were proposed. © 2013 Springer Science+Business Media New York

Effect of the size and structure factors on the magnetic susceptibility of nanoparticles of cadmium sulfide

The dependence of the Van Vleck component of the magnetic susceptibility of nanostructured cadmium sulfide CdS on the geometry and structure of CdS nanoparticles has been established by analyzing the data obtained from diffraction and magnetic measurements. It has been found that a decrease in the size of wurtzite CdS nanoparticles leads to an increase in the degree of distortion of the sp 3 orbitals (i. e., the degree of covalence), which reaches a limiting value for elongated particles with an average size of 9 nm. In particles with smaller sizes, the character of the orbital distortion sharply changes, and the Van Vleck contribution returns to the value typical of coarse-grained CdS. Nanoparticles less than 9 nm in size have a specific disordered close-packed structure and a centrosymmetric shape. The data obtained have made it possible to understand the reason of the dimensional phase transition from the crystalline state to a specific nanostate of cadmium sulfide. © 2012 Pleiades Publishing, Ltd

Atomic structure of a 1T-TiSe2 surface layer from photoelectron and Auger electron holography data

A three-dimensional (3D) reconstruction of the atomic structure of the (100) surface of a 1T-TiSe 2 layered dichalcogenide crystal has been performed from X-ray photoelectron and Auger electron diffraction data. The diffraction patterns of the emission of Auger electrons of Se(LMM) selenium and photoelectrons of Ti2p titanium have been considered as holographic diagrams. Being processed with the scattering pattern extraction algorithm using the maximum entropy method (SPEA-MEM), they provide individual 3D images of the nearest environment of selenium and titanium atoms in the TiSe 2 lattice. Using reconstructed 3D images, the positions of 128 atoms in the 2 × 2 × 1. 5-nm region of the surface layer of TiSe 2 have been determined. The structure of the surface has a 1T polytype. Interatomic distances in the layer and van der Waals gap are larger than the respective parameters in the bulk of the crystal. It is assumed that titanium layers in two Se-Ti-Se upper surface structural units are displaced along the [001] axis. The structure of the surface layer can be described by a unit cell of the P3 space group with the parameters a = 3. 85 Å and c = 14. 4 Å. © 2012 Pleiades Publishing, Ltd