STRUCTURE AND MAGNETIC PROPERTIES OF Mn–Zn-FERRITES

Synthesis conditions, structure and magnetic properties of Mn-Zn-ferrites prepared by spray pyrolysis of solutions of manganese, zinc and iron nitrates have been considered. The applied technique provides low-temperature (650 °C) obtaining highly dispersed (7-8 nm) powder of Mn0.5Zn0.5Fe2O4 ferrite with a narrow size distribution. Synthesis of Mn0.5Zn0.5Fe2O4 at low temperature avoids MnII → MnIII oxidation reaction that influences the ferrite properties. IR data collected from the ferrite samples obtained both in air and in N2 ambient indicate their high structural and concentration homogeneity. Magnetic measurements confirm single-phase structure of the Mn0.5Zn0.5Fe2O4 powders and give no evidence of the presence of individual iron oxide phases. Curie temperature (375-380 K) is consistent with the theoretically calculated value for Mn1-xZnxFe2O4 (x = 0.5) (Tc = 365÷385 K). Parameters of Moessbauer spectra of the ferrites are typical of FeIII state in oxide solid solutions with a considerable ionicity contribution in Fe-O bonds (δ = 0.33÷0.34 mm/s). FeII state was not revealed by Moessbauer spectroscopy that indicates the absence of FeIII → FeII reduction accompanying the MnII → MnIII oxidation process

Effect of fluoride-mediated transformations on electrocatalytic performance of thermally treated TiO2 nanotubular layers

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Synthesis of ZnO mesoporous powders and their application in dye photodegradation

ZnO materials have attracted considerable interest due to their large - scale potential applications for photodiodes, photocatalysis, sensing and others. For photocatalytical application, ZnO is usually prepared with a mesoporous structure, providing a large surface area for enhancing the system performance. Nowadays, various methods have been explored to prepare ZnO porous powders and films. Among them , the most important and more common techniques to synthetize mesoporous ZnO particles are wet chemical methods , including precipitation from inorganic or organic solution s and sol - gel, owing to their simplicity and low cost. Herein, we studied ZnO mesoporous powder synthesis based on preparation and further thermal decomposition of zinc hydroxide chloride hydrate precursor. The attention was given to the role of reaction medium in the formation of final products and to the photocatalytic activity of the synthesized ZnO.This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skło dowska - Curie grant agreement No 645662.publishe

Electrocatalytic activity of Au nanoparticles onto TiO2 nanotubular layers in oxygen electroreduction reaction: size and support effects

Electrocatalytic activity of both bare high-ordered TiO2 nanotubes (TNTs) and gold nanoparticles (Au NPs) loaded TNTs toward oxygen reduction reaction (ORR) has been examined by cyclic voltammetry (CV). Cyclic voltammograms for Au NPs-TNT electrodes are characterized by an additional wave observed at less negative potentials which is responsible for oxygen electroreduction on the surface of gold NPs. The overpotential for O-2 reduction on the Au surface grows with increasing the temperature of TNT annealing and the Au NPs size. The nature of the effects observed was explained by peculiarities of the electron transport through Schottky barrier formed at the Au NPs - TiO2 interface. The width of the Schottky barrier, determined by semiconductor doping level and Au NPs size, plays a key role in the mechanism of electron transport through the space charge region. (C) 2016 Elsevier Ltd. All rights reserved

A study on the carbohydrate and nitrogen metabolism in Prunus Persica

Thesis (Ph. D. (Agric.)) -- University of Stellenbosch, 1980.Full text to be digitised and attached to bibliographic record

EFFECT OF -Fe2O3/In2O3 NANO-HETEROSTRUCTURE ON ITS SENSITIVITY TO METHANE

Structural features of thin-film γ-Fe2O3/In2O3 hetero-junctions and their gas-sensing features has been studied. Two mechanisms of adsorbed CH4 molecule effect on electric conductivity of the layers depending on operating temperature were propose

HETERO-STRUCTURIZED -Fe2O3-In2O3 NANOCOMPOSITE OBTAINED BY SOL-GEL APPROACH

Sol-gel technology was used to prepare heterogeneous Fe2O3-In2O3 nanocomposite consisting of -Fe2-xInxO3 solid solution and two modifications of -Fe2O3 – cubic (C--Fe2O3) and tetragonal (Q--Fe2O3), which are active in adsorption and catalytic processes

Advanced Metaloxide Nanomaterials for Gas Sensors with Controlled Properties

Sol-gel approach based on inorganic metal precursors was used to obtain Fe2O3−In2O3 nanocomposites with different microstructure and grain size. The synthesis conditions, which result in the formation of metastable γ-Fe2O3 phase, were revealed. This phase stabilized in the Fe2O3−In2O3 composites was found to be more active in adsorption and catalysis as compared to thermodynamically stable α-Fe2O3. The Fe2O3−In2O3 compositions suitable for the selective detection of O3, NO2 and C2H5OH were proposed

HETERO-STRUCTURIZED -Fe2O3-In2O3 NANOCOMPOSITE OBTAINED BY SOL-GEL APPROACH

Sol-gel technology was used to prepare heterogeneous Fe2O3-In2O3 nanocomposite consisting of -Fe2-xInxO3 solid solution and two modifications of -Fe2O3 – cubic (C--Fe2O3) and tetragonal (Q--Fe2O3), which are active in adsorption and catalytic processes

EFFECT OF -Fe2O3/In2O3 NANO-HETEROSTRUCTURE ON ITS SENSITIVITY TO METHANE

Structural features of thin-film γ-Fe2O3/In2O3 hetero-junctions and their gas-sensing features has been studied. Two mechanisms of adsorbed CH4 molecule effect on electric conductivity of the layers depending on operating temperature were propose