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Příprava magnetických a optických nanočástic
Repko, Anton ; Nižňanský, Daniel (advisor) ; Němec, Ivan (referee)
Title: Preparation of magnetic and optical nanoparticles Author: Anton Repko Department: Department of Inorganic Chemistry, Faculty of Science, Charles University of Prague Supervisor: RNDr. Daniel Nižňanský, Ph.D. Supervisor's e-mail address: niznansk@natur.cuni.cz Abstract: In the present work we study methods of preparation of magnetic and optical nanoparticles by hydrothermal method. Specifically, we prepared particles of cobalt ferrite (CoFe2O4) and sodium yttrium fluoride (NaYF4) doped by Yb3+ a Er3+ from corresponding nitrates in the system of water - ethanol - oleic acid, and in modified systems. By this method, it is possible to prepare particles of narrow size distribution (monodisperse particles). Pre- pared particles of ferrite show superparamagnetism and particles of NaYF4 up-conversion, i.e. conversion of infrared (980 nm) to visible light. Keywords: nanocrystals, superparamagnetism, up-conversion, CoFe2O4, NaYF4, hydrothermal synthesis
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Quantitative analysis of actinolite in the Pilsen Basin area by X-ray powder diffraction
Chlupáčová, Monika ; Havlíček, David (advisor) ; Nižňanský, Daniel (referee)
Increased concentration of suspended particles of the PM10 fraction, transportation and construction industry have serious impact on health. In Pilsen, the Air Improvement Programme in Pilsen Municipality takes place in accordance with the Pilsen Municipal Development Programme, the Regional Emissions Reduction Programme of the Pilsen Region and the National Emissions Reduction Programme of the Czech Republic. This thesis aims on determining the content of actinolite, azbestos mineral from amphibole group, in the samples from the Pilsen Basin. Altogether 23 samples from Pilsen municipal area were measured using the quantitative analysis method and X-ray powder diffraction. The actinolite content was determined in the samples.
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Preparation and Characterization of Iron (III) Oxide Nanocomposites Substituted with Scandium
Kaščáková, Dorota ; Nižňanský, Daniel (advisor) ; Tyrpekl, Václav (referee)
In this work a preparation and characterization of nanoparticles of iron(III) oxide substituted with scandium in SiO2 matrix is described. The nanoparticles were prepared by the sol-gel method yielding mostly β-Fe2O3 substituted with various amount of scandium(III) ions. Mossbauer spectroscopy was carried out to determine purity of the samples and the content of other iron oxides phases. System was characterized by magnetic measurements. Powder X - ray diffraction was used to verify the composition and to determine the lattice parameter and particle size. β-Fe2O3 is formed at the temperatures of 1000 and 1100 ◦ C at composition Fe2−xScxO3 for x ≥ 0.2 and at temperature 1100 ◦ C for x = 0.1. Lattice parameter is linearly dependent on the scandium content and depends also on the annealing temperature. At temperatures higher than 1250 ◦ C, β-Fe2O3 is transformed into hematite. Key words: iron(III) oxide, scandium, sol-gel, Mossbauer spectroscopy, X-ray diffraction, magnetic measurements 1
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Synthesis of nanostructured ZnFe2O4 as a sorbent for H2S removal from syngas
Košťálová, Zuzana ; Nižňanský, Daniel (advisor) ; Vojtíšek, Pavel (referee)
The use of sorption properties of materials as sorbents for removing unwanted substances from gasified solid or liquid fuels (coal, oil, natural gas and biomass) in the heating plant industry seems to be more suitable than existing technology. In this diploma work, ZnFe2O4 is studied as a possible sorbent for the removal of H2S from gasified fuel. ZnFe2O4 has been prepared by various methods in the form of nanoparticles and nanocomposites. The prepared samples were characterized by powder X- ray diffraction, electron microscopy, BET measurement and thermal analysis. Further, the sorption activity of the samples was studied with regard to H2S. The results were evaluated with respect to the possible application of the prepared materials in heating plant industry. Keywords: ZnFe2O4, H2S absorption, sol-gel method, sol-gel auto-combustion method, SBA-15.
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Titania-based nanomaterials
Zabloudil, Adam ; Kubíček, Vojtěch (advisor) ; Nižňanský, Daniel (referee)
Titanium dioxide colloid with a size of particles between 20 - 40 nm was prepared. Subsequently, three substances were syntetized - methylen bis(phosphonic) acid H4L1 , 4-phosphono-butyric acid H3L2 and 4-hydroxy-4,4-diphosphono-butyric acid H5L3 . Surface of the colloidal nanoparticles was modified using these substances (H4L1 , H3L2 and H5L3 ). Then stability of these systems was studied using acid-base titration and addition of calcium ions. Keywords: TiO2, nanoparticles, surface modification
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Preparation of magnetic nanoparticles by hydrothermal method
Repko, Anton ; Nižňanský, Daniel (advisor) ; Buršík, Josef (referee) ; del Puerto Morales, Maria (referee)
Hydrothermal method of nanoparticle preparation, involving oleic acid, has received certain attention in the last years. However, the published works lack systematic approach to the subject, and the mechanism was not thoroughly investigated, so as to achieve a predictable outcome of the synthesis. The present work investigated the influence of composition of organic and water phase on the synthesis of cobalt ferrite (cobalt(II)-iron(III) oxide) and magnetite nanoparticles, and the mechanism of nanoparticle formation was proposed. Organic phase was based on pentanol, octanol or toluene, containing the precursor - metal oleate. Besides hydrophobic particles, it was even possible to directly prepare hydrophilic oleate-coated particles by using water phase with sodium oleate. Synthetic procedure was then simplified by a separate preparation of cobalt-iron oleate, which led also to a product of narrower size distribution and better phase purity. Size control in the range of 6-11 nm and a batch yield of ca. 500 mg was achieved. Attention was given also to the surface modification of the particles, thus imparting them hydrophilicity. Small di- or tricarboxylic acids were utilized, as well as carboxylmethyl dextran and titanium dioxide. Titanium dioxide required additional protection with...
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