Příprava a Charakterizace Perovskitových Nanostruktur

Hricov, Štefan

The present Bachelor's thesis is focused on the improvement of the hydrothermal condi- tions for BaTiO3 nanoparticles synthesis to obtain better morphology, narrow size distri- bution, and high purity of the prepared product. Particular emphasis is on the influence of different parameters in reaction, such as co-solvent, co-surfactant, the ratio between oleic acid to oleylamine, and ex-situ sodium oleate, on the resulting structure and morphology of BaTiO3 nanoparticles. The structural purity was examined with powder X-ray diffraction with Rietveld refinement to obtain and follow changes in lattice parameters and coherent domain sizes. Moreover, from the refinement of PXRD patterns, the rough estimate of a synthesis by-product (BaCO3) abundance was extracted. Furthermore, implementing the spherical harmonics function within the Rietveld refinement allowed us to access the average nanocrystallite shapes with direction-dependent crystallite sizes. The crystallite shapes and sizes were compared with the physical nanoparticle size obtained from trans- mission electron microscopy experiments. The thesis is completed with attenuated total reflectance Fourier-transform infrared spectroscopy spectra, which gave us insight into the attachment of the oleic acid at the nanoparticle surface. Keywords: BaTiO3,...

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