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Novel prospective materials for nonlinear optics
Votrubcová, Iveta ; Nižňanský, Daniel (referee) ; Němec, Ivan (advisor)
This bachelor thesis is focused on the preparation of novel materials for nonlinear optics and includes studies of twenty-eight crystallization systems, which provide twelve crystalline compounds - salts of 2-aminopyrimidine and 2,4,6-triaminopyrimidine with inorganic oxo-acids (nitric, perchloric, sulfuric, phosphoric, phosphorous). Studied materials have been identified and defined by a vibrational spectroscopy and X-ray structure analysis. From the prepared materials only aminopyrimidinium (1+) hydrogen phospite fulfils the symmetry conditions for the second harmonic generation. Efficiency of the second harmonic generation was afterwards defined for the powdered sample relatively to the KDP and urea standards.
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Příprava magnetických a optických nanočástic
Repko, Anton ; Němec, Ivan (referee) ; Nižňanský, Daniel (advisor)
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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Preparation of Fe2O3/SiO2 Nanocomposites from Molecular Precursor by Sol Gel Method and Doping of Iron(III) by Trivalent Metal Cations
Brázda, Petr ; Nižňanský, Daniel (advisor) ; Matějec, Vlastimil (referee) ; Grenéche, Jean-Marc (referee)
Přírodovědecká fakulta Univerzity Karlovy v Praze katedra anorganické chemie a Univerzita Štrasburk Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague and Université de Strasbourg Příprava nanokompozitů Fezos/Sioz z moleku!árního prekurzoru metodou so! gel a dopování Že|ezitých kationtů jinými trojmocnými kationty Preparation of Fezos/Sioz Nanocomposites from Molecutar Precursor by sol Gel Method and Doping of lron(lll) by Trivalent Metal Cations Souhrn disertačnípráce Summary of Thesis Petr Brázda Šrotitete(Supervisors): RNDr. Danie| NiŽňanský, PhD' Dr. Jean-Luc Rehspringer Praha 2009 Y Abstract Iron (III) oxide fonns two well-known polymorphs - the maghemite (y-Fe2O3), which is in fact a metastable phase, and is transformed into the hematite (cr-Fe2O3) at higher temperatures. At certain conditions, elusive e-Fe2O3 can be obtained as an intermediate between these two phases. e-Fe2O3 crystallizes in orlhorhombic space group Pna\ with lattice constants a: 509.5, b = 87g.9 and c:943.7 pm and is isomophous with r-A12O3, e-Ga2O3, AIFeO: and GaFeO3. Oxygen atoms form close pseudohexagonal packing with layers ABAC. kon cations occupy four different sites, three of them are octahedrally and one is tetrahedrally coordinated. There is eight formula units in unit cell. Structure of...
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